INTRODUCING
INTERSTELLAR BLEND™
GLUCOSE BLOCKER
MASTER GLUCOSE TRANSPORT INHIBITOR
200:1 Concentration
Stop sugar dead in its tracks! The lower you keep your blood sugar the slower you age.
mTOR Overactivation (induced by unchecked high blood glucose) is a Key Factor in Aging
Directions: Take 1/8-1/4 tsp every 4-6 hours in coffee, water or fresh squeezed grapefruit juice. Check blood sugar upon waking, afternoon, before dinner and 2 hours after. Follow 22/2 one meal a day protocol.
*Fasting blood sugar should be between 70-90. Post meal blood sugar between 90-120 and quickly drop back under 100. Adjust dosage accordingly.
Pairs well with:
Jing Force, Thermo, Peel, Spice.
BEST ONE TOUCH GLUCOSE MONITOR TO BUY; zero mess or fuss takes 10 seconds. Check anywhere.
Featuring: Acanthopanax Senticosus (Rupr. Maxim.) Harms • Acer Nikoense Maxim. • Achyranthesbidentata Blume • Alchemilla Vulgaris Leaves And Flowers • Alisma Orientalis(Sam.)Juzep • Allium Cepa L. • Alstonia Macrophylla Wall. Ex G. Don. • Andrographis Paniculata (Burm. F.) Nees) • Anemarrhena Asphodeloides Bunge • Angelica Dahurica (Fisch.Ex Hoffm.) Benth. Et Hook.F. • Angelica Sinensis (Oliv.) Diels • Anthocyanin-Rich Berry- – Blueberry • Apigenin – Celery Seed • Apium Graveolens L. • Arbutus Unedo L. Roots Bark Aqueous • Arctium Lappa L • Asparagus Racemosus Willd • Astragalus Mongholicus Bunge • Astragaus Membrana- Ceus (Milkvetch Root) • Atractylodes Lancea( Thunb.)Dc. • Atractylodes Macrocephala Koidz. • Bauhinia Megalandra Leaves • Blackcurrant Polyphenols – Ribes Nigrum L • Cardamonin • Catalpol From Rehmannia Glutinosa (Chinese Foxglove Root • Chlorogenic Acid – Green Coffee Bean • Chrysin – Pinus Mon-Ticola Dougl. • Cinnamomum Cassia (Cassia Bark) • Cistanche Tubulosa • Citrus Maxima (Burm) Merr. • Citrus Medica Leaves • Coix Lachryma Jobi L. • Coptis Chinensis Franch. • Cordyceps Sinensis( Berk.)Sacc. • Cornus Officinalis (Asiatic Cornelian Cherry Fruit) • Crataegus Pin.Nati Fida Bge • Curcumin – Curcuma Longa L. • Cynodon Dactylon • Cytochalasin B – Drechslera Dematioidea • Daidzein – Soybean • Dendrobium Nobile Lindl • Egcg • Epicatechin • Epigallocatechin • Eriobotrya Japonica (Loquat Leaf) • Euonymus Alatus (Thunb.) Sieb. • Euphorbia Humifusa • Fenugreek (Trigonella Foenum-Graecum L. Seed) • Ficus Carica Linn • Fisetin – Cotinus Coggygria Scop. • Formononetin – Astragalus Mongholicus Bunge • Fructus Ligustri Lucidi • Fucoxanthin – Thallus Japonica • Ganoderma Lucidum(Leyss. Ex Fr.)Karst. • Gaultheria Phillyreifolia And G. Poeppigii Berries • Genistein – Glycine Max (Linn.) Merr • Glycyrrhiza Inflata • Gneyulins A And B From The Bark Of Gnetum Gnemonoides – Gnetum Gnemonoides • Gossypol – Cottonseed • Graviola (Annona Muricata) – Annona Muricata • Guava (Psidium Guajava) – Psidium Guajava • Gymnema Sylvestre (Retz.) Schult • Gynostemma Pentaphyllum • Helichrysum (Helichrysum Italicum) • Herba Fumariae • Honeybush (Cyclopia Genistoides) • Hordeurn Vulgare L. • Isoquercitrin • Kaempferol Galanga L • Kaempferol 3-O-Α-Rhamnoside Purified From Bauhinia Megalandra Leaves • Kurarinone From Sophora Flavescens Root • Lagerstroemia Speciosa • Laminaria Japonica • Lavandula Stoechas • Levisticum Officinale (Apiaceae) Leaf And Stem • Litchi Chinensis Sonn.Seed – Litchi Chinensis Sonn.Seed • Lonicera Japonica Thunb. (Honeysuckle Flower) • Lycium Barbarum L. Polysaccharide • Lycium Chinense Mill. • Maqui Berries (Aristotelia Chilensis) • Momordica Charantia L. • Morus Alba L Root And Peel • Mulberry Leaf • Myricetin – Myrica Rubra (Lour.) S. Et Zucc • Naringenin – Amacardi-Um Occidentale L. • Naringin – Citrus Grandis • Nelumbo Nucifera Gaertn • Nigella Sativa L. (Ranunculaceae) Seeds • Ophiopogon Japonicaus (Dwarf Lilyturf Tuber) • Oridonin – Rabdosia Rubescens • Oroxylum Indicum Seed • Paeonia Lactiflora Pall • Panax Ginseng C. A. Meye • Panax Notoginseng(Burk.)F.H.Chen • Pelargonidin-3-O-Glucoside Fragaria Virginiana • Persimmon Tannin • Phloretin – Bark Of Apple Trees • Phlorizin – Bark Of Apple Trees • Platycodon Grandifloru Seed And Root • Polygonatum Odoratum (Mill.) Druce • Polygonatum Sibiricum Delar. Ex Redoute • Polygonum Multiflorum (Fleeceflower Root) • Poria Cocos(Schw.)Wolf • Portulaca Oleracea L. • Prunella Vulgaris L. • Psidium Guajava Linn. Leaf • Pterocarpus Marsupium Roxb • Quercetin – • Quercetin-3-O-Glucoside – • Quercetin-4′-O-Glucoside (Q4′Glc) – Sophora Flavescens Ai • Quinidine (9S)-6′-Methoxycinchonan-9-Ol; • Radix Bupleuri • Ranawara (Cassia Auriculata) Dried Flowers • Resveratrol – Polygonum Cuspidatum Sieb.Et Zucc. • Rhodiola Rosea L • Rosa Laevigata Michx. • Salvia Miltiorrhiza Bge • Schisandrae Chinensis Fructus • Silybin – Silybum Marianum (L.) Gaertn. • Sophora Flavescens • Sophoraflavanone – Sophora Moorcroftiana, • Syzygium Aromaticum-Derived Triterpenes Oleanolic Acid (Oa) And Maslinic Acid (Ma) • Tangeretin – Citrus Reticulata Blanco Peel • Taraxacum Mongolicum Hand.-Mazz. • Thymus Praecox Subsp. Skorpilii Var. Skorpilii (Syn. Thymus Praecox Subsp. Jankae (Celak.) Jalas) • Tiliroside – Tribulus Terrestris L. • Trichosanthes Kirilowii Maxim. • TURKESTERONE • Xanthohumol – Humulus Lupulus Linn. • Zea Mays L. • (+)-Cryptocaryone – Cryptocarya Concinna Hance • (+)-Pteryxin – Peucedanum Harry-Smithii Var. Subglabrum
SCIENCE:
sodium–glucose cotransporter 2 (SGLT2 ) inhibitors from natural products : discovery of next-generation antihyperglycemic agents
“Plant‐derived glucose transport inhibitors with potential antitumor activity
Glucose , a key nutrient utilized by human cells to provide cellular energy and a carbon source for biomass synthesis, is internalized in cells via glucose transporters that regulate glucose homeostasis throughout the human body . glucose transporters have been used as important targets for the discovery of new drugs to treat cancer, diabetes , and heart disease, owing to their abnormal expression during these disease conditions. Thus far, several glucose transport inhibitors have been used in clinical trials, and increasing numbers of natural products have been characterized as potential anticancer agents targeting glucose transport.
The present review focuses on natural product glucose transport inhibitors of plant origin, including alkaloids, flavonoids and other phenolic compounds, and isoprenoids, with their potential antitumor properties also discussed.
SGLT2 inhibitors as calorie Restriction mimetics: Insights on longevity pathways and Age-related diseases
flavonoids CAPABLE OF inhibitING glucose uptake in cells
organ protection by SGLT2 inhibitors: role of metabolic energy and water conservation
improve ment of skeletal muscle insulin sensitivity by 1 week of SGLT2 inhibitor use
Background and Aims: It is currently unclear whether sodium–glucose co-transporter 2 (SGLT2 ) inhibitor administration can improve the insulin sensitivity as well as rapidly reduce plasma glucose concentrations in humans during the early phase of treatment initiation. This study aimed to investigate the effect of SGLT2 inhibitor on insulin sensitivity in the early phase of treatment initiation.
Methods and Results: This single-center, open label, and single-arm prospective study recruited 20 patients (14 men) with type 2 diabetes mellitus (T2DM). We examined the patients’ metabolic parameters before and 1 week after SGLT2 inhibitor (10 mg/day of empagliflozin) administration. The glucose infusion rate (GIR) was evaluated using the euglycemic hyperinsulin emic glucose clamp technique. Changes in laboratory and anthropometric parameters before and after SGLT2 inhibitor administration were analyzed according to the change in the GIR. The BMI, body fat amount, skeletal muscle amount, systolic blood pressure, and triglyceride level significantly decreased along with the treatment , while urinary glucose level and log GIR value significantly increased. Notably, changes in the GIR after SGLT2 inhibitor administration, which indicated improvement in peripheral insulin sensitivity , were negatively correlated with T2DM duration and positively with reduction in fluctuation of daily plasma glucose profiles before and after treatment .
Conclusion: SGLT2 inhibitor improved insulin sensitivity in the skeletal muscle independent of anthropometric changes. Patients with short duration of T2DM and insulin resistance can be good candidates for short-term SGLT2 inhibitor administration to improve insulin sensitivity in the skeletal muscle.
natural products as lead compounds for sodium glucose cotransporter (SGLT) inhibitors
inhibition of the intestinal glucose transporter GLUT2 by flavonoids
The discovery of novel compound classes endowed with biological activity is at the heart of chemical biology and medicinal chemistry research. This enables novel biological insights and inspires new approaches to the treatment of diseases. Cancer cells frequently exhibit altered glycolysis and glucose metabolism and an increased glucose demand. Thus, targeting glucose uptake and metabolism may open up novel opportunities for the discovery of compounds that differentiate between normal and malignant cells.
This review discusses the different chemical approaches to the development of novel inhibitors of glucose uptake through facilitative glucose transporters (GLUTs), and focusses on the most advanced and potent inhibitor classes known to date. GLUT inhibitors may find application not only in the treatment of cancer, but also of other proliferative diseases that exhibit glucose addiction
glucose control by the kidney: an emerging target in diabetes
INGREDIENTS:
Acanthopanax senticosus (Rupr. Maxim.) Harms extract
Fundamental studies on the inhibitory action of Acanthopanax senticosus Harms on glucose absorption
Aim of the study: Acanthopanax senticosus Harms extract (ASE) is used as an ingredient of over-the-counter drugs and function al foods, such as health supplements, in Japan. ASE exhibits a hypoglycemic effect; however, the mechanism of the hypoglycemic effect is not clear. In the present study, we investigated whether ASE has a glucose absorption inhibitory action.
Materials and methods: We examined the effects of ASE on α-amylase and α-glucosidase activities, and on glucose uptake in Caco-2 cells. We also examined the effects of ASE oral administration on glucose tolerance in type 2 diabetes mellitus model db/db mice.
Results: The addition of ASE inhibited α-glucosidase activity but not α-amylase activity . The α-glucosidase inhibitory activity of ASE was approximately 1/13 of that of acarbose. The addition of ASE inhibited 2′-deoxy-d-glucose (DG) uptake in human intestinal Caco-2 cells, and the inhibitory activity of ASE was approximately 1/40 of that of phloretin. Kinetic analysis of glucose uptake indicated that ASE has no effects on DG uptake through passive diffusion, but that ASE inhibits intracellular DG uptake chiefly by inhibiting transport via a glucose transporter . In the glucose tolerance study, db/db mice orally administered ASE for 3 days showed significantly lower plasma glucose level than the control group 30 min after sucrose loading, without affecting plasma insulin levels . In addition, ASE oral administration significantly inhibited α-glucosidase activity in the small intestine mucosa extirpated from the mice.
Conclusion: These findings indicate that ASE may be useful as an ingredient of functional foods to improve postprandial hyperglycemia and prevent type II diabetes mellitus. Acanthopanax senticosus Harms extract (ASE) suppressed glucide absorption by the inhibition of intestinal α-glucosidase activity and glucose uptake . ASE is expected to inhibit the rapid rise in blood glucose level immediately after a meal and to improve impaired glucose tolerance in type II diabetes mellitus .
Acer nikoense
Cyclic diarylheptanoids as Na+-glucose cotransporter (SGLT) inhibitors from Acer nikoense
Two cyclic diarylheptanoids, acerogenins A (1) and B (2) have been isolated from the bark of Acer nikoense as inhibitors of Na+–glucose cotransporter (SGLT). Acerogenins A (1) and B (2) inhibited both isoforms, SGLT1 and SGLT2 . Structure–activity relationship of acerogenin derivatives on inhibitory activity of SGLT as well as conformational analysis of 1 and 2 on the basis of J-resolved HMBC spectra and X-ray analysis were discussed.
Achyranthes bidentata Bl.root extract
Unexplored Potential of traditional Chinese medicine in diabetes mellitus
Diabetes is one of the most prevalent disease worldwide and is associ–ated with one of the highest morbidities and mortality rates associated. Like the western and conventional medicines, traditional Chinese medicine (TCM ) has promising results in the ailment of diabetes and its associated complications. But still the use of TCM is refrained for further explorations due to inadequate knowledge of active pharmaceutical ingredient and its isolation. Thus, this review will highlight some of the key concepts and rational behind the therapeutic regimen of TCM aiming towards diabetes treatment. A detailed study of all the articles including research as well as reviews, which were available on the world wide web was performed. The review includes MEDLINE and EMBASE databases using keywords alone or in combinations, such as diabetes, diabetic complications, Chi–nese therapy, traditional chinese medicine, diabetic neuropathy, diabetic nephropathy, diabetic retinopathy, diabetic complications , α-amylase and several others. TCM collectively is an effective and comparatively safe in the treatment of diabetes mellitus and its associated complications. Sig–nificant results are seen in monotherapy and in combination therapy with current conventional drugs. The effects include controlling glycemic levels along with the mitigation of diabetes associated complications. Focus on clinical trials and further investigations might help in concluding TCM as one of the most effective and safe treatment therapies. TCM holds enor–mous potential by virtue of its mechanism of action by maintaining the homeostasis in the body and thereby exhibiting pharmacological action.
Alchemilla vulgaris
Phytochemical screening of Alchemilla Vulgaris (leaves and flowers), Sophora Japonica, and Crataegus Azarolus (leaves and fruits), have been determined, and the results showed that the different plant parts of the studied plants contained the following compounds: phenols, carbohydrates, flavonoids, saponins, tannins, and glycosides.
While it has shown the absence of alkaloids and cardinols, except the leaves of Crataegus Azarolus that contained alkolois. The effect of Alchemilla Vulgaris (leaves and flowers), Sophora Japonica, and Crata egus Azarolus (leaves and fruits) on lipase activity and α–amylase activity were screened by used different extracts[MeOH; MeOH 70% EtOH; EtOH70%; Hexane; Chloroform]. to test their anti-obesity activity using porcine pancreatic lipase inhibitory assay, and porcine pancreatic α–amylase.
The results showed that the extract obtained with polar solvents have a good inhibitory activity, and the highest effect on lipase activity was in the MeOH extracts but the highest effect onα –amylase activity was in the MeOH 70% extracts, on the contrary the non-polar solvents (Hexane; Chloroform) have a very weak effect on lipase and α–amylase activity, also we showed that the polar extracts of Alchimalla Vulgaris (leaves and flowers) have the highest effect on lipase activity and α–amylase activity comparative with the extracts of Sophora Japonica, and Crata egus Azarolus (leaves and fruits).
These results suggest that the chemical content of polar extracts of these plants might be of therapeutic interest with respect to the treatment of obesity. International Journal of Ac ademic Scientific Research.
Alisma orientalis (Sam.) Juzep extract
Chemical constituents from Alisma orientalis extracts with hypoglycemic effect
Objective: To study the chemical constituents in Alisma orientalis extracts with hypoglycemic effect.
Methods: To study the in vivo hypoglycemic effects of A. orientalis extracts, high fat diet (HFD)-induced insulin resistance male C57BL/6J mice were treated with water and ethanol extracts of A. orientalis in diet, and glucose tolerance test was carried out following the intervention. Silica gel, ODS, and preparative HPLC were used to isolate the compounds. Their chemical structures were elucidated on the basis of NMR and MS spectral data.
Results: Sixteen compounds were identified as sitosterol (1), palmitic acid (2), heptadecanoic acid (3), eicosanoic acid (4), 11-deoxy-alisol B (5), 23-acetate alisol B (6), 23-acetate alisol C (7), alisol B (8), 24-acetate alisol A (9), alisol G (10), 24-acetate alisol F (11), alisol L (12), alisol C (13), alisol F (14), alisol A (15), and 16-oxo-24-acetate alisol A (16), and nine of the triterpenes could improve glucose uptake in HepG2 cells.
Conclusion: Compounds 3 and 4 are isolated from A. orientalis for the first time. The water and ethanol extracts of A. orientalis could improve glucose tolerance test. Triterpenes may be one of the therapeutic material basis in hypoglycemic activities in A. orientalis.
Allium cepa L.extract
Extracts and flavonoids from onion are described as having anti-diabetic activities. We here demonstrate that an onion extract and individual flavonoids thereof diminish glucose uptake mediated by the intestinal glucose transporter SGLT1 when expressed in oocytes and studied in mouse intestinal segments in vitro. Strongest inhibition of SGLT1 was observed for quercetin-4′-O-glucoside (Q4′glc) in oocytes but with only moderate inhibition in jejunal segments of mice. An oral glucose tolerance test (OGTT) performed in obese/hyperglycaemic mice revealed that the onion extract to reduce blood glucose increases significantly. However, an OGTT performed in healthy volunteers after administration of the onion extract failed to reveal an effect on glucose and insulin levels .
Despite its capability to inhibit intestinal glucose uptake via SGLT1 in vitro and in mice in vivo, the onion extract did not alter blood glucose levels during an OGTT in human volunteers and this may predominantly be due to a dosing effect.
Alstonia macrophylla
Three new picraline-type alkaloids, alstiphyllanines E–G (1–3) and a new ajmaline-type alkaloid, alstiphyllanine H (4) were isolated from the leaves of Alstonia macrophylla together with 16 related alkaloids (5–20). Structures and stereochemistry of 1–4 were fully elucidated and characterized by 2D NMR analysis. Alstiphyllanines E and F (1 and 2) showed moderate Na+–glucose cotransporter (SGLT1 and SGLT2 ) inhibitory activity.
A series of a hydroxy substituted derivatives 21–28 at C-17 of the picraline-type alkaloids have been derived as having potent SGLT inhibitory activity . 10-Methoxy-N(1)-methylburnamine-17-O-veratrate (6) exhibited potent inhibitory activity, suggesting that the presence of an ester side chain at C-17 may be important to show SGLT inhibitory activity. Structure activity relationship of alstiphyllanines on inhibitory activity of SGLT was discussed.
Andrographis paniculata Nees
Mechanistic understanding of PtyroneTM: A plant based natural anti diabetic product
Objective: To investigate the combinatorial effect of hydroalcoholic extracts of Andrographis paniculata Nees. and Pterocarpus marsupium Roxb. plants prospective to diabetes management.
Methods: Taking a lead from the scientific literature, in silico studies have also been designed for the screening of anti-diabetic targets against andrographolide and pterostilbene compounds followed by in vivo studies from Andrographis paniculata Nees. and Pterocarpus marsupium Roxb. Furthermore, the diabetes was induced by STZ model and the impact of Andrographis paniculata Nees. and Pterocarpus marsupium Roxb. have been conformed by relative expression studies by qPCR.
Results: Our results have shown that andrographolide and pterostilbene are SGLT2 inhibitors and selective PPARγ agonists in in silico studies. Later, during in vivo mRNA expression studies confirming the same pattern. The findings of the study has shown to overcome the common knowledge of the only C–glycoside based molecules inhibiting the SGLT2 .
Conclusions: The possible mechanism for PtyroneTM in the management of diabetes could be a selective PPARγ agonist, GLUT4 translocation and SGLT2 inhibition molecule.
Anemarrhena asphodeloides Bunge extract
antidiabetic activity of a xanthone compound, mangiferin
Mangiferin (MF) isolated from Anemarrhena asphodeloides Bunge rhizome, was tested for antidiabetic activity in KK-Ay mice, an animal model of type-2 diabetes. MF lowered the blood glucose level of KK-Ay mice 3 weeks after oral administration (p < 0.01). However, no effect on the blood glucose level in normal mice was seen, indicating that MF could be useful in treating type-2 diabetes.
In addition, MF improve d hyperinsulin emia and, on insulin tolerance test, reduced blood glucose levels of KK-Ay mice. From these findings, it seems likely that MF exerts its antidiabetic activity by decreasing insulin resistance.
Angelica dahurica (Fisch.ex Hoffm.) Benth. et Hook.f. extract
Phellopterin isolated from Angelica dahurica reduces blood glucose level in diabetic mice
Insulin resistance is the critical condition for the development of metabolic syndrome s including type II diabetes and heart disease. To investigate the active components of Angelica dahurica root which is known to increase insulin sensitivity, its methanol extract was subfractionated. The ethyl acetate (EtOAc) fraction of the Angelica dahurica root extract significantly promote d adipocyte differentiation in 3T3-L1 preadipocyte cells. Among the three compounds isolated from the EtOAc extract (bergapten (1), imperatorin (2) and phellopterin (3)), phellopterin (3) induced the highest adipocyte differentiation at 25 and 50 μg/mL. In addition, treatment with imperatorin (2) and phellopterin (3) increased the mRNA expression of peroxisome proliferator-activated receptors γ (PPARγ).
In diabetic animal model induced by high-fat diets (HFD) and streptozotocin (STZ), administration of phellopterin (3), 1 mg/kg and 2 mg/kg) significantly reduced the levels of blood glucose, triglycerides and total cholesterol. Taken together, these results indicate that phellopterin (3) enhances adipocytes differentiation in 3T3-L1 preadipocytes, phellopterin (3) significantly prevents HFD/STZ-induced type Ⅱ diabetes.
The present study also provides phellopterin (3) may be a valuable therapeutic alternative for enhancing insulin sensitivity through promotion of adipocyte differentiation and by increasing mRNA expression levels of PPARγ, which is a major mediator of insulin sensitivity.
Angelica sinensis extract
This study aimed to investigate the therapeutic effects of Angelica sinensis polysaccharide (ASP), an active component derived from a water extract of Angelica sinensis, in high-fat diet (HFD)-fed BALB/c mice. The potential mechanisms underlying the activity of this compound were also considered. Specifically, serum and hepatic biochemical parameters were evaluated and key proteins involved in the lipid/glucose metabolism were analyzed. Long-term feeding with a HFD induced severe fatty liver and hyperglycemia .
Histological examination clearly showed that ASP reduced lipid accumulation in the liver and attenuate d hepatic steatosis in HFD-fed mice. In addition, ASP markedly alleviated serum and liver lipid disorders and fatty liver via the upregulation of PPARγ expression and the activation of adiponectin-SIRT1-AMPK signaling. Furthermore, ASP also significantly relieved severe oxidative stress , demonstrating that ASP might attenuate nonalcoholic fatty liver disease via a “two-hit” mechanism. In addition, ASP reduced blood glucose levels and ameliorated insulin resistance via the regulation of related metabolic enzymes and by activating the PI3K/Akt pathway in HFD-fed mice.
Our findings revealed that ASP might be used as an alternative dietary supplement or health care product to ameliorate metabolic syndrome in populations that consistently consume HFDs.
anthocyanin-rich berry-extract
Polyphenols contained within plant tissues are consumed in significant amounts in the human diet and are known to influence a number of biological processes. This study investigated the effects of an anthocyanin-rich berry-extract on glucose uptake by human intestinal Caco-2 cells. Acute exposure (15 min) to berry extract (0.125%, w/v) significantly decreased both sodium-dependent (Total uptake ) and sodium-independent (facilitated uptake ) 3H-D-glucose uptake .
In longer-term studies, SGLT1 mRNA and GLUT2 mRNA expression were reduced significantly. Polyphenols are known to interact directly with glucose transporters to regulate the rate of glucose absorption . Our in vitro data support this mechanism and also suggest that berry flavonoids may modulate post-prandial glycaemia by decreasing glucose transporter expression.
Further studies are warranted to investigate the longer term effects of berry flavonoids on the management of glycaemia in human volunteers.
apigenin
Objectives: The antiproliferative mechanisms of flavonoid drugs inpancreatic cancer cells remain unclear. In this study, we evaluated the effects of the flavonoid apigenin on glucose uptake , on the expression of the glucose transporter 1 (GLUT-1), and on the phosphoinositide 3-kinase (PI3K)/Akt pathway in human pancreatic cancer cells.
Methods: Human pancreatic cancer cells were treated with apigenin and then underwent glucose uptake assays. Real-time reverse transcription-polymerase chain reaction and Western blot analysis were conducted to evaluate GLUT-1 and pAkt expression in CD18 and S2-013 human pancreatic cancer cells after treatment with apigenin or PI3K inhibitors (LY294002 and wortmannin).
Results: Apigenin (0-100 μM) significantly inhibited, in a dose-dependent fashion, glucose uptake in CD18 and S2-013 human pancreatic cancer cell lines. Apigenin inhibited both GLUT-1 mRNA and protein expression in a concentration- and time-dependent fashion. The PI3K inhibitors , like apigenin, downregulated both GLUT-1 mRNA and protein expression.
Conclusions: Our results demonstrate that the flavonoid apigenin decreases glucose uptake and downregulates the GLUT-1 glucose transporter in human pancreatic cancer cells . In addition, the inhibitory effects of apigenin and the PI3K inhibitors on GLUT-1 are similar, indicating that the PI3K/Akt pathway is involved in mediating apigenin’s effects on downstream targets such as GLUT-1.
Unraveling the inhibition of intestinal glucose Transport by Dietary Phenolics: A Review
Background: Glucose transport across the intestinal brush border membrane plays a key role in metabolic regulation. Depending on the luminal glucose concentration, glucose is mainly transported by the sodium-dependent glucose transporter (SGLT1 ) and the facilitated-transporter glucose transporter (GLUT2 ). SGLT1 is apical membrane-constitutive and it is active at a low luminal glucose concentration, while at concentrations higher than 50 mM, glucose is mainly transported by GLUT2 (recruited from the basolateral membrane). Dietary phenolic compounds can modulate glucose homeostasis by decreasing the postprandial glucose response through the inhibition of SGLT1 and GLUT2.
Methods: Phenolic inhibition of intestinal glucose transport has been examined using brush border membrane vesicles from rats, pigs or rabbits, Xenopus oocytes and more recently Caco-2 cells, which are the most promising for harmonizing in vitro experiments.
Results: Phenolic concentrations above 100 μM has been proved to successfully inhibit the glucose transport. Generally, the aglycones quercetin, myricetin, fisetin or apigenin have been reported to strongly inhibit GLUT2, while quercetin-3-O-glycoside has been demonstrated to be more effective in SGLT1. Additionally, epigallocatechin as well as epicatechin and epigallocatechin gallates were observed to be inhibited on both SGLT1 and GLUT2.
Conclusion: Although, valuable information regarding the phenolic glucose transport inhibition is known, however, there are some disagreements about which flavonoid glycosides and aglycones exert significant inhibition , and also the inhibition of phenolic acids remains unclear. This review aims to collect, compare and discuss the available information and controversies about the phenolic inhibition of glucose transporters. A detailed discussion on the physicochemical mechanisms involved in phenolics-glucose transporters interaction s is also included.
Apium graveolens L. extract
Objectives: To analyze the effect of celery leaf extract on blood glucose and plasma insulin levels in elderly pre-diabetics.
Methods: This study was conducted between March and November 2014 at the Faculty of medicine , Syiah Kuala University, Banda Aceh, Indonesia. A quasi-experimental pretest-posttest with a control group was conducted with elderly pre-diabetic volunteers. The subjects included 16 elderly pre-diabetics older than 60 (6 males and 10 females). The subjects were randomly divided into 2 groups: a control group (placebo-treated) and a treatment group (celery-treated). The treatment consisted of celery leaf extract capsules at the dose of 250 mg, 3 times per day (morning, afternoon and evening), 30 minutes before a meal, for 12 days. Data analysis was performed using the t-test (p<0.05).
Results: There was a significant decrease in pre-prandial plasma glucose levels (p=0.01) and post-prandial plasma glucose levels (p=0.00), but no significant increase in plasma insulin levels (p=0.15) after celery leaf treatment in elderly pre-diabetics.
Conclusion: Celery was effective at reducing blood glucose levels , but there was a lack of association between blood glucose levels and plasma insulin levels in elderly pre-diabetics.
Arbutus unedo L. roots bark
Ethnopharmacological relevance: Arbutus unedo L., (Ericaceae) is one of the most traditional plants commonly used to treat diabetes in people living in Eastern Morocco region particularly in Taza and Beni Mellal.
Aim of the study: The aim of the study was to find if there is a scientific support to the ethnopharmacological relevance use of Arbutus unedo L., roots bark (AU) to treat diabetes .
Materials and methods: We studied the effects of crude aqueous extract of AU on intestinal glucose absorption using short-circuit current technique in vitro and oral glucose tolerance test in vivo.
Results: The aqueous extract of AU (10 µg/mL to 1 mg/mL) induced concentration-dependent inhibition of sodium -dependent glucose transport across isolated mouse jejunum. The maximal inhibition was obtained with 1 mg/mL, which exhibited more than 80% of the Phloridzin inhibition with an IC50 close to 216 µg/mL. A 6-week AU ingestion (2 g/(kg day)), improved oral glucose tolerance as efficiently as metformin (300 mg/(kg day)). Arbutus unedo L. and metformin also reduced body weight.
Conclusions: Arbutus unedo L. roots bark aqueous extract directly inhibited the electrogenic intestinal absorption of glucose in vitro. In addition it improved oral glucose tolerance and lowered body weight in rats after chronic oral administration in vivo. These results add a scientific support to the ethnopharmacological relevance use of Arbutus unedo L. roots bark to treat diabetes .
Arctium lappa L extract
diabetes is a metabolic disease highly widespread worldwide, and the most common form is the type 2 diabetes mellitus (T2DM). A large number of synthetic drugs are currently available for the treatment of diabetes ; however, they present various side effects and, for this reason, people are increasingly inclined to search natural alternative treatments . Among these, Arctium lappa (A. lappa) has interesting anti-diabetic activities, exerted by improving glucose homeostasis and reducing insulin -resistance. In addition, A. lappa exerts a marked antioxidant activity , an effect known to play a pivotal role in the treatment of T2DM.
The purpose of this review is to analyse scientific evidence in order to evaluate the role of A. lappa and its bioactive compounds in management of T2DM. The literature search performed provided only in vitro and animal-based studies. No clinical studies have been conducted in order to investigate the effect of A. lappa on T2DM patients. However, available literature provides evidence for further clinical trials in order to confirm these claimed activities on humans .
Asparagus Racemosus
Asparagus racemosus roots have been shown to enhance insulin secretion in perfused pancreas and isolated islets. The present study investigated the effects of ethanol extracts of A. racemosus roots on glucose homeostasis in diabetic rats, together with the effects on insulin action in 3T3 adipocytes. When administered orally together with glucose, A. racemosus extract improved glucose tolerance in normal as well as in two types of diabetic rats. To investigate the possible effects on carbohydrate absorption, the sucrose content of the gastrointestinal tract was examined in 12 h fasted rats after an oral sucrose load (2·5 g/kg body weight). The extract significantly suppressed postprandial hyperglycaemia after sucrose ingestion and reversibly increased unabsorbed sucrose content throughout the gut. The extract also significantly inhibited the absorption of glucose during in situ gut perfusion with glucose.
Furthermore, the extract enhanced glucose transport and insulin action in 3T3-L1 adipocytes. Daily administration of A. racemosus to type 2 diabetic rats for 28 d decreased serum glucose , increased pancreatic insulin, plasma insulin , liver glycogen and total oxidant status. These findings indicate that antihyperglycaemic activity of A. racemosus is partly mediated by inhibition of carbohydrate digestion and absorption, together with enhancement of insulin secretion and action in the peripheral tissue. Asparagus racemosus may be useful as a source of novel antidiabetic compounds or a dietary adjunct for the management of diabetes.
Astragaus membrana
Meta-analysis of the clinical value of Astragalus membranaceus in diabetic nephropathy
Aim of study: Nowadays diabetic nephropathy (DN) has become a serious problem. Astragalus membranaceus is a traditional herb used for thousands of years in China and East Asia for kidney disease. In modern medicine , Astragalus shows significant renal protective effect in DN. We aimed to systematically review the randomized and semi-randomized control trials to ascertain its role in the treatment of DN.
Materials and methods: PUBMED, MEDLINE, Chinese journal full-test database (CJFD), Chinese biological and medical database were searched by computer and manual searching. Two assessors independently reviewed each trial. 25 studies comprising 21 RCTs and 4 CCTs were involved including 1804 patients (945 in treatment group and 859 in control group).
Results and conclusions: Astragalus injection had more therapeutic effect in DN patients including renal protective effect (BUN, SCr, CCr and urine protein) and systemic state improve ment (serum albumin level ) compared with the control group.
Ethnopharmacological relevance: This study investigates the effect of Astragalus in DN patients. It suggests that although of unknown bioactive ingredients and mechanism of renal protection , the role of Astragalus in the treatment of DN can be disclosed and of profound significance.
Astragalus mongholicus Bunge extract
Aim of the study: To establish the mechanism underlying the improve ment of glucose toxicity by Astragalus polysaccharide (APS), which occurred via an AMP activated protein kinase (AMPK )-dependent pathway.
Methods: In vivo and in vitro effects of APS on glucose homeostasis were examined in a type 2 diabetes mellitus (T2DM) rat model. The T2DM rat model was duplicated by a high-fat diet (58% fat, 25.6% carbohydrate, and 16.4% protein) and a small dose of streptozotocin (STZ, 25 mg/kg, ip). After APS therapy (700 mg·kg−1·d−1, ig) for 8 weeks, blood glucose , glycosylated hemoglobin, and serum insulin were measured. insulin sensitivity was evaluated by the comprehensive analysis of oral glucose tolerance tests (OGTT) and HOMA IR index. Hepatic glycogen was observed by the PAS staining method. The expression and activity of skeletal muscle AMPK α and acetyl-CoA carboxylase (ACC), and the phosphorylation of hepatic glycogen synthase (GS), the glycogen synthase (GS),were measured by Western blotting. Glucose uptake was measured with the 2-deoxy-[3H]-D-glucose method in C2C12 cells.
Results: The hyperglycemia status, insulin sensitivity , glucose uptake , and activation level of AMPK in diabetic rats were improve d in response to APS administration. APS could also alleviate glucose toxicity in cultured mouse cells by the activation of AMPK.
Conclusion: APS can alleviate glucose toxicity by increasing liver glycogen synthesis and skeletal muscle glucose translocation in the T2DM rat model, via activation of AMPK.
Atractylodes lancea (Thunb.) DC. extract
The purpose of this study was to examine the effects of Atractylodes lancea (A.l.) in a dose-dependent manner on lipid levels and plasma glucose in diabetic rats induced with streptozotocin (STZ). The Sprague-Dawley rats were randomly classified into five groups: normal, STZ-control and three experimental groups [A.l.-1, diabetic treated with ethanolic extract of A.l. (1 g/kg b.w.), A.l.-2, diabetic administered with ethanolic extract of A.l. (2 g/kg b.w.), and A.l.-3, diabetic administered with ethanolic extract of A.l. (3 g/kg b.w.)]. The normal and STZ-control group were fed an AIN-93 diet and the three experimental groups were administered with A.l. extract at doses of 1, 2, and 3 g/kg b.w./day, respectively, for 14 days. The plasma glucose levels in all the experimental groups were significantly lower than the STZ-control group after 14 days of treatment .
The total cholesterol of the A.l.-3 and triglyceride levels , atherogenic index (AI) of all three experimental groups were significantly lower than the STZ-control group. The ALT and AST activities at A.l.-2, A.l.-3 were significantly lower than the STZ-control group.
This result that demonstrate the administration of Atractylodes lancea can reduce hyperglycemia and hyperlipidemia risk in diabetic rats.
Atractylodes macrocephala Koidz extract
Aim of the study: To isolate a complex polysaccharide (AMP-B) from Atractylodes macrocephala Koidz and study its phtsico-chemical properties and hypoglycemic activity .
Methods: The root of Atractylodes macrocephala K. was extracted with water and precipitated with ethanol, dialyzed against water and freeze-dried to get the crude polysaccharides (AMP). A complex polysaccharide (AMP-B) was isolated and purified on DEAE-cellulose column. The model of diabetes rats was established with alloxan injection through the tail vein. Male rats were divided into 5 groups: the normal group, the control group, and three AMP-B-fed groups. Measuring the blood glucose, water and food consumption, thymus and pancreas index, and studying cut sections of pancreas tissues.
Results: AMP-B is a complex-polysaccharide, elemental analysis of AMP-B shown C 32.84%, H 5.68%, and N 1.79%. The neutral polysaccharide content of AMP-B was 50.3%, uronic acid was 40.4%, and protein was 11.5%. Monosaccharide composition of AMP-B was determined by GC, AMP-B composed of Glc, Gal, Man, Ara and Rha in a molar ratio of 3.0:2.5:1.3:3.5:1.0. AMP-B was found to reduce blood glucose level in alloxan-diabetic rats markedly at doses of 50, 100 and 200 mg.kg-1 by ig, but no effect in normal rat. AMP-B was found to decrease the consumption of water and food, recover pancreas damage of diabetic rats obviously, inhibited the atrophy of thymus and pancreas of the diabetic rats induced by alloxan.
Conclusion: AMP-B showed significant hypo-glycemic effect on the experimental hyperglycemia s rats induced by alloxan.
Bauhinia megalandra leaves
Aqueous extract of Bauhinia megalandra leaves was able to inhibit the intestinal glucose absorption in a concentration-dependent way and additive to phlorizine. Moreover, B. megalandra leaf extract drastically reduced the 14C-glucose uptake by enterocyte brush border membrane vesicles. The B. megalandra leaf extract administrated orally, simultaneously with glucose improve d the glucose tolerance with a significant reduction of the 30-min peak. The extract did not have an effect on the glucose tolerance when glucose was administrated subcutaneously.
blackcurrant polyphenols
Postprandial glycemic responses to meals are inhibited by polyphenol-rich plant foods. Combinations of polyphenols may be particularly effective through complementary mechanisms. A randomized, controlled, double-blinded cross-over trial was conducted in healthy volunteers to test the hypothesis that apple and blackcurrant polyphenol-rich drinks would reduce postprandial blood glucose concentrations .
Secondary outcomes included insulin and glucose -dependent insulin otropic polypeptide (GIP) secretion. Twenty men (mean age 26 y, SD 8) and 5 postmenopausal women (mean age 57 y, SD 3) consumed a placebo drink (CON) and 2 polyphenol-rich drinks containing fruit extracts: either 1200 mg apple polyphenols (AE), or 600 mg apple polyphenols+600 mg blackcurrant anthocyanins (AE+BE), in random order with a starch and sucrose meal. Incremental areas under the curve (iAUC) for plasma glucose concentrations were lower following AE+BE over 0–30 and 0–120 min compared with CON; mean differences (95% CI) −32 mmol/L·min (−41, −22, P<.0005) and −52 mmol/L min (−94, −9, P<.05), respectively. AE significantly reduced iAUC 0–30 min (mean difference −26 mmol/L min, −35, −18, P<.0005) compared with CON, but the difference over 120 min was not significant.
Postprandial insulin , C-peptide and GIP concentrations were significantly reduced relative to CON. A dose response inhibition of glucose transport was demonstrated in Caco-2 cells, including total and GLUT-mediated transport, and SGLT1 -mediated glucose transport was strongly inhibited at all doses in Xenopus oocytes, following 10 min incubation with 0.125–4 mg apple polyphenols/ml.
In conclusion, ingestion of apple and blackcurrant polyphenols decreased postprandial glycemia, which may be partly related to inhibition of intestinal glucose transport.
cardamonin
Rapid postprandial blood glucose elevation can cause lifestyle-related diseases, such as type II diabetes. The absorption of food-derived glucose is primarily mediated by sodium /glucose cotransporter 1 (SGLT1 ). Moderate SGLT1 inhibition can help attenuate postprandial blood glucose elevation and prevent lifestyle-related diseases. In this study, we established a CHO cell line stably expressing human SGLT1 and examined the effects of phytochemicals on SGLT1 activity. Among the 50 phytochemicals assessed, tangeretin and cardamonin inhibited SGLT1 activity.
Tangeretin and cardamonin did not affect the uptake of L-leucine, L-glutamate, and glycyl-sarcosine. Tangeretin, but not cardamonin, inhibited fructose uptake, suggesting that the inhibitory effect of tangeretin was specific to the monosaccharide transporter, whereas that of cardamonin was specific to SGLT1. Kinetic analysis suggested that the suppression of SGLT1 activity by tangeretin was associated with a reduction in Vmax and an increase in Km, whereas suppression by cardamonin was associated with a reduction in Vmax and no change in Km. Oral glucose tolerance tests in mice showed that tangeretin and cardamonin significantly suppressed the rapid increase in blood glucose levels.
In conclusion, tangeretin and cardamonin were shown to inhibit SGLT1 activity in vitro and lower blood glucose level in vivo.
Catalpol from Rehmannia glutinosa
Catalpol is one of the active principles from roots of Rehmannia glutinosa Steud (Scrophulariaceae) that is widely used to treat diabetic disorders in Chinese traditional medicine using the name of Di-Huang, which is used to investigate the mechanisms for lowering of plasma glucose in streptozotocin-induced diabetic rats (STZ-diabetic rats). Catalpol decreased plasma glucose in a dose-related manner, and this action was reduced by pretreatment with naloxone or naloxonazine. An increase of plasma β-endorphin by catalpol was also observed in parallel.
The plasma glucose lowering action of catalpol was deleted in bilateral adrenalectomized rats. Moreover, catalpol enhanced β-endorphin release from the isolated adrenal medulla of STZ-diabetic rats. Otherwise, plasma glucose lowering action of catalpol failed to produce in opioid μ-receptor knockout mice. Also, repeated administration of catalpol for 3 days in STZ-diabetic rats resulted in a marked reduction of phosphoenolpyruvate carboxykinase (PEPCK) expression in liver and an increased expression of glucose transporter subtype 4 (GLUT 4) in skeletal muscle. These effects were also reversed by blockade of opioid μ-receptors.
Our results suggested that catalpol increased glucose utilization through increase of β-endorphin secretion from adrenal gland in STZ-diabetic rats.
The hypoglycemic and anti-diabetic effect of Rehmannia glutinosa oligosaccharide (ROS) in glucose -induced hyperglycemic and alloxan-induced diabetic rats and its mechanism was investigated in this paper.
It was found that pretreatment of ROS in normal rats with 100 mg/kg for 3 days, i.p., induced a partial prevention of hyperglycemia caused by glucose (2 g/kg, i.p.), while when hyperglycemia was induced in adrenalectomized (ADX) rats, the preventive effect of ROS on hyperglycemia was lost. In alloxan-induced diabetic rats, ROS (100 mg/kg for 15 days, i.p.) showed a significant decrease in blood glucose level and hepatic glucose -6-phosphatase activity with an increase in hepatic glycogen content.
Furthermore, ROS raised plasma insulin level and lowered plasma corticosterone level in alloxan-induced diabetic rats. The results indicated that oligosaccharide of Rehmannia glutinosa Libosch. exerted a significant hypoglycemic effect in normal and alloxan-induced diabetic rats.
The regulatory mechanism of ROS on glucose metabolism was adrenal dependent and had a close relation with the neuroendocrine system.
The hypoglycemic effects of water extract and stachyose extract (Part III) from Rehmannia glutinosa Libosch. were investigated in this paper by oral administration to normal, glucose – and adrenaline-induced hyperglycemic and alloxan-induced diabetic rats.
The results showed that Part III had the effect of lowering fasted plasma glucose level and partially preventing hyperglycemia induced by glucose (2.5 g · kg−1, i.p.) and adrenaline (300 μg · kg−1, i.p.), respectively, but no obvious dose-dependent effect was found when it was administered at the doses of 100, 200 and 400 mg · kg−1 for 6 days, i.g. In alloxan-induced diabetic rats, Part III (200 mg · kg−1 for 15 days, i.g.) gave a significant decrease in blood glucose level .
The results suggested that Part III, which is mainly composed of stachyose from Rehmannia glutinosa Libosch., had a significant hypoglycemic effect in glucose – and adrenaline-induced hyperglycemic and alloxan-induced diabetic rats.
The ethanol precipitate fraction (RG-WP) obtained from the hot water extract from rhizome of Rehmannia glutinosa Libosch. f. hueichingensis Hsiao is mainly composed of pectin-like polysaccharide, and exhibited hypoglycemic activity in normal and streptozotocin-induced mice by intraperitoneal administration of the fraction.
The results obtained after chemical modification and proteinase treatments of RG-WP suggest that the activity exists in the polysaccharide moiety. Furthermore, the effect of RG-WP on the activities of enzymes responsible for the glucose metabolism in the liver of normal mouse was studied to elucidate the mechanism of the hypoglycemic activity.
Administration of RG-WP to normal mice significantly increased the activities of hepatic glucokinase and glucose -6-phosphatase dehydrogenase, but decreased those of hepatic glucose-6-phosphatase and phosphofructokinase. RG-WP stimulated the secretion of insulin and reduced the glycogen content in the liver of normal mouse.
chlorogenic acid
The effects of chlorogenic acid (CA) on hepatic glucose output, blood glucose levels and on glucose tolerance were analysed. Hepatic uptake of CA and its effects on hepatic catabolism of L-alanine and glucose -6-phosphatase (G-6-Pase) activity were also evaluated. CA (1 mM) inhibited about 40% of G-6-Pase activity (p < 0.05) in the microsomal fraction of hepatocytes, but no effect was observed on production of glucose from gluconeogenesis or on L-alanine catabolism, at various concentrations of CA (0.33, 0.5 and 1 mM), in liver perfusion experiments.
Since there were indications of a lack of uptake of CA by the liver, it is possible that this compound did not reach sufficiently high intracellular levels to inhibit the target enzyme. Accordingly, intravenous administration of CA also failed to provoke a reduction in blood glucose levels. However, CA did promote a significant reduction (p < 0.05) in the plasma glucose peak at 10 and 15 min during the oral glucose tolerance test, probably by attenuating intestinal glucose absorption, suggesting a possible role for it as a glycaemic index lowering agent and highlighting it as a compound of interest for reducing the risk of developing type 2 diabetes.
Methods: Forty male Sprague-Dawley rats were randomly and equally divided into four groups: normal chow (NC), high-fat diet (HFD), HFD with low-dose CGA (20 mg/kg, HFD-LC), and HFD with high-dose CGA (90 mg/kg, HFD-HC). The oral glucose tolerance test was performed, and fast serum insulin (FSI) was detected using an enzyme-linked immunosorbent assay. The mRNA expression levels of glucose transporters (Sglt-1 and Glut-2) and proglucagon (Plg) in different intestinal segments (the duodenum, jejunum, ileum, and colon) were analyzed using quantitative real-time polymerase chain reaction . SGLT-1 protein and the morphology of epithelial cells in the duodenum and jejunum was localized by using immunofluorescence.
Conclusion: An HFD can cause a glucose metabolism disorder in the rat intestine and affect body glucose homeostasis . CGA can modify intestinal glucose metabolism by regulating the expression of intestinal glucose transporters and Plg, thereby controlling the levels of blood glucose and insulin to maintain glucose homeostasis .
Chrysin
Effect of dietary polyphenols on fructose uptake by human intestinal epithelial (Caco-2) cells
Intake of high-fructose products is associated with metabolic syndrome development. We investigated if dietary polyphenols can interfere with fructose absorption by the human intestinal epithelial Caco-2 cell line.
Acutely, several polyphenols induced a significant decrease (15–20%) in 14C-fructose uptake. Chronically, 14C-fructose uptake was also affected by polyphenols; quercetin, chrysin and apigenin (100 µM) were the most effective (±25% decrease). These compounds (100 µM) appear to interfere with both GLUT2 and GLUT5 activity; accordingly, they caused a very marked decrease in the mRNA expression levels of GLUT2 (≅90%) and GLUT5 (≅75%). The effect of these compounds on 14C-fructose uptake does not involve interference with PKC, PKA, PI3K and p38 MAPK intracellular signaling pathways.
Quercetin, apigenin and chrysin might decrease the intestinal absorption of fructose. Further studies are needed to test for their beneficial effects on metabolic syndrome.
Cinnamomum cassia
Cinnamon extract lowers glucose , insulin and cholesterol in people with elevated serum glucose
Cinnamon (肉桂 ròu guì) has in vitro insulin potentiating activity , and proanthocyanidins from cinnamon prevent in vitro formation of advanced glycation end products. Some human studies were equivocal, but several have shown beneficial effects of cinnamon supplementation on circulating glucose, lipids, and/or insulin.
This placebo-controlled double-blind trial tested the effects of a dried water extract of cinnamon (Cinnamomum cassia) on circulating glucose, lipids, insulin, and insulin resistance. Men and women from Beijing and Dalian, China, were invited to participate if they had fasting serum glucose >6.1 mmol/L or 2-h glucose >7.8 mmol/L. Participants, (173 were enrolled and 137 completed the study) were randomly assigned to receive either a spray-dried, water extract of cinnamon (Cinsulin ®), 250 mg/capsule, or a placebo, twice a day for two months. Mean ± SEM age of participants was 61.3 ± 0.8 years, BMI was 25.3 ± 0.3 and M/F ratio was 65/72.
After 2 mo, fasting glucose decreased (p < 0.001) in the cinnamon extract-supplemented group (8.85 ± 0.36 to 8.19 ± 0.29 mmol/L) compared with the placebo group (8.57 ± 0.32 to 8.44 ± 0.34 mmol/L, p = 0.45). glucose 2 h after a 75 g carbohydrate load, fasting insulin , and HOMA-IR also decreased with cinnamon extract compared with placebo. Total and LDL-cholesterol decreased with cinnamon extract and HDL-cholesterol decreased in both the cinnamon-extract and placebo groups.
In conclusion, supplementation with 500 mg of water-extract of cinnamon for two months reduced fasting insulin , glucose , total cholesterol, and LDL cholesterol and enhanced insulin sensitivity of subjects with elevated blood glucose.
Cistanche tubulosa
Anti-hyperglycemic and hypolipidemic effects of Cistanche tubulosa in type 2 diabetic db/db mice
Ethnopharmacological relevance: The dried succulent stem of Cistanche tubulosa (Schenk) R. Wight is one component of traditional Chinese medicine prescriptions for diabetes. However, there have been no modern scientific reports to confirm this traditional claim for the Cistanche species until now. Thus, we investigated the effects of Cistanche tubulosa on glucose homeostasis and serum lipids in male BKS.Cg-Dock7m +/+ Leprdb/J (db/db) mice, a model of type 2 diabetes.
Materials and methods: The verbascoside and echinacoside contents of Cistanche tubulosa powder were evaluated using HPLC. The total phenolic content, polysaccharide content and antioxidant activity of Cistanche tubulosa powder were also evaluated. Then, different doses of Cistanche tubulosa (equivalent to 120.9, 72.6 or 24.2 mg verbascoside/kg) were administered orally once daily for 45 days to male db/db mice. Age matched db/+ mice were used as normal controls. body weight, fasting blood glucose, postprandial blood glucose and insulin tolerance test were measured during the experiment. At the time of sacrifice, blood was collected for measurement of insulin level, the homeostatic model assessment of insulin resistance (HOMA-IR), and total cholesterol, triglyceride, HDL-c, LDL-c and VLDL-c levels ; liver and muscle were harvested for measurement of glycogen levels.
Results: Cistanche tubulosa significantly suppressed the elevated fasting blood glucose and postprandial blood glucose levels, improve d insulin resistance and dyslipidemia, and suppressed body weight loss in db/db mice. However, Cistanche tubulosa did not significantly affect serum insulin levels or hepatic and muscle glycogen levels.
Conclusion: This study provides scientific evidence for the traditional use of Cistanche tubulosa to treat diabetes, suggesting that Cistanche tubulosa has the potential for development into a functional food ingredient or drug to prevent hyperglycemia and treat hyperlipidemia.
Echinacoside (ECH) and acteoside (ACT), the major constituents of Cistanche tubulosa, suppress the increase in postprandial blood glucose level. Although ECH and ACT have been reported to weakly inhibit α-glucosidases, the underlying mechanism remains unclear. Therefore, we focused on the regulatory mechanism of dietary glucose absorption.
In this study, we aimed to clarify the inhibitory effects of ECH and ACT on sodium-dependent glucose cotransporter (SGLT) 1-mediated gastro intestinal glucose absorption. Uptake experiments were performed using human intestinal Caco-2 cells and the fluorescence glucose analogue, 2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-d–glucose (2-NBDG). Sodium-dependent 2-NBDG uptake was successfully estimated and this uptake was completely inhibited by an SGLT inhibitor phlorizin. ECH and ACT inhibited sodium-dependent 2-NBDG uptake in a concentration-dependent manner. However, this inhibition was not observed under sodium-free condition.
This study suggested that the inhibitory effects of ECH and ACT on SGLT1-mediated glucose uptake contribute to suppression of increased postprandial blood glucose level.
Citrus maxima (Burm) Merr. extract
The aim of the present study was to evaluate antihyperglycemic activity of methanol extract of Citrus maxima leaf (MECM) in streptozotocin (STZ; 65 mg/kg b.w.) induced diabetic rats. Three days after STZ induction, diabetic rats received MECM orally at a dose of 200 and 400 mg kg-1 body weight daily for 15 days. Glibenclamide (0.5 mg kg -1 p.o.) was used as a reference drug. blood glucose levels were measured on days 0, 4, 8 and 15.
Serum biochemical parameters viz. SGOT, SGPT and ALP were estimated. The TBARS and GSH levels of the pancreas, kidney and liver were determined. MECM significantly (P<0.001) and in a dose dependent manner normalized blood glucose levels, serum biochemical parameters, decreased lipid peroxidation, and recovered GSH as compared to those of STZ control.
The present study inferred that in STZ-induced diabetic Wistar rats, C. maxima leaf demonstrated a potential antihyperglycemic effect that might be attributed to its antioxidant property.
Citrus medica L. var.sarcodactylis Swingle extract
Phytochemical and antihyperglycemic Studies on Citrus medica l.Leaves (Etrog) Growing in Egypt
From 70% aqueous methanol extract of the defatted powdered leaves of Citrus medica L. var. Etrog, six compounds,namely, β–sitosterol–glucoside (1), sakuranetin (2), 7–O–methylaromadendrin (3), dihydrokaempferide (4), hesperitin (5)and rutin (6) were isolated and identified by physicochemical and spectral data (UV, MS and NMR). Compounds 2–4 arenewly reported from the genusand 5 is newly reported from the species. The extract was safe up to 2g/kg.bwt. Thehistopathological changes on liver, kidney and pancreas were assessed.
The antioxidant activity was calculated to102.9μ g/ml. The antihyperglycemic activity exerted a significant reduction in blood glucose level to (105.2±8.35) indiabetic rats after one month of treatment with a dose of 200 mg/kg and to (87.4±6.30) with 400mg, when compared toGliclazide standard (110.8±7.24) (P< 0.05).
As a conclusion, the methanol extractof the defatted powdered leaves of Etrogexhibits a significant antihyperglycemic activity which might be attributed to the presence of flavonoid compounds.
Coix seed extract
Objective: To discuss the effect of coix seed polysaccharide on model rats with glucose and lipid metabolism disorder induced by clozapine.
Methods: Divided 50 SD rats of SPF grade into five groups randomly according to the body mass,namely the normal control group,the model group,the metformin group and the coix seed polysaccharide group of high-dose and low-dose,10 rats in each group. Model rats with glucose and lipid metabolism disorder were induced by clozapine. The normal control group and the model group were given saline solution by gavage;the metformin group was given 0.2 g/kg of metformin twice a day by gavage;the coix seed polysaccharide group of high-dose and low-dose were respectively given 0.2 g/kg and 0.1 g/kg of coix seed polysaccharide twice a day by gavage. Detected the body mass, the levels of fasting plasma glucose and postprandial 2 h plasma glucose, and the content of leptin and adiponcetin in serum of rats.
Results: Compared with those in the normal control group,the body mass and the levels of fasting plasma glucose ,postprandial 2 h plasma glucose and leptin in serum of rats in the model group from the 14 th day to the56 thday were obviously increased,while the level of adiponcetin in serum was obviously decreased,differences being significant(P 0.05,P 0.01). Compared with those in the model group,the body mass and the levels of fasting plasma glucose ,postprandial 2 h plasma glucose and leptin in serum of rats in the coix seed polysaccharide group of high-dose and low-dose and the metformin group from the 42 thday to the 56 thday were obviously decreased, while the levels of adiponcetin in serum were obviously decreased,differences being significant(P 0.05,P 0.01).
Conclusion: Coix seed polysaccharide has good prevention and treatment for model rats with glucose and lipid metabolism disorder induced by clozapine. Its mechanism probably is related to the regulation of the levels of glucose, leptin and adiponcetin.
Coptis chinensis Franch.extract
Hypoglycemic and Hypocholesterolemic Effects of Coptis chinensis Franch Inflorescence
Hypocholesterolemic and hypoglycemic activities of Coptis chinensis franch inflorescence (Coptis inflorescence) were studied using animal models. Serum total and LDL cholesterol of rats fed a diet containing 1% cholesterol and 0.5% cholic acid increased, as compared with those of rats fed a normal diet. The level of total and LDL cholesterol were reduced markedly in a dose dependent manner, in rats given Coptis inflorescence extract orally at doses of 0.25, 0.5 g/kg.day for 4 weeks. In diabetic rats induced by alloxan, Coptis inflorescence extract showed a significant (p < 0.05) blood sugar lowering activity at all experimented doses (0.125, 0.25 and 0.5 g/kg.day). The highest reduction of blood sugar was about 58% when the rats were given Coptis inflorescence extract orally at a dose of 0.5 g/kg.day for 3 weeks. The 100 g dried water extract of Coptis inflorescence contained 8.11 g total alkaloid, 3.34 g berberin, 1.08 g palmatine and 0.66 g jatrorrhizine, which had long been identified as active compounds in Coptis chinensis franch root (Coptis root). Thus, the results suggest that Coptis inflorescence would be effective in the prevention and management of coronary artery disease by lowering serum cholesterol and blood sugar .
Cordyceps
Cordyceps, an entomopathogenic fungus, contains many health-promoting ingredients. Recent reports indicate that the consumption of cordyceps helps reduce blood–sugar content in diabetics. However, the mechanism underlying this reduction in circulatory sugar content is not fully understood. Methanolic extracts were prepared from the fruiting bodies of Paecilomyces tenuipes, and 4-beta acetoxyscirpendiol (4-ASD) was eventually isolated and purified. /glucose transporter-1 (SGLT-1) was expressed in Xenopus oocytes, and the effect of 4-ASD on SGLT-1 was analyzed utilizing a voltage clamp and by performing 2-deoxy-D-glucose (2-DOG) uptake studies. 4-ASD was shown to significantly inhibit SGLT-1 activity compared to the non-treated control in a dose-dependent manner.
In the presence of the derivatives of 4-ASD (diacetoxyscirpenol or 15-acetoxyscirpendiol), SGLT-1 activity was greatly inhibited in an 4-ASD-like manner. Of these derivatives, 15-acetoxyscirepenol inhibited SGLT-1 as well as 4-ASD, whereas diacetoxyscirpenol was slightly less effective.
Taken together, these results strongly indicate that 4-ASD in P. tenuipes may lower blood sugar levels in the circulatory system. We conclude that 4-ASD and its derivatives are effective SGLT-1 inhibitors.
Cornus officinalis Sieb. et Zucc extract
Background: Anthocyanins are phytochemicals with a multitude of pharmacological actions including anti-diabetic and anti-hyperlipidemic effects. This study was undertaken to evaluate the anti-hyperglycemic and anti-hyperlipidemic effects of cornelian cherry (Cornus mas L., CM) fruits – that are rich in anthocyanins and known to have medicinal properties– in alloxan-induced diabetic rats.
Methods: Twenty-eight adult male rats were randomly assigned to four groups of seven animals each: non-diabetic control, diabetic control, glibenclamide-treated (0.6 mg/kg/day; 4 weeks) and CM fruit-treated (2 g/day; 4 weeks) group. diabetes was induced by a single injection of alloxan (120 mg/kg). Fasting serum levels of glucose , total cholesterol (TC), low- (LDL-C) and high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), aspartate (AST) and alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were measured at the end of study period.
Results: diabetic rats had significantly elevated levels of serum glucose , LDL-C, TG, AST, ALP and ALT and decreased levels of HDL-C compared to the non-diabetic group (p<0.05). treatment with either glibenclamide or CM counterbalanced the above-mentioned abnormalities. The effects of CM were comparable to those of glibenclamide at the doses tested in this study. Serum glucose , TG, ALP and HDL concentrations in the normal group were significantly changed compared to the diabetic control group (p<0.05). There were no significant changes in evaluated biochemical parameters between the glibenclamide and CM groups with normal group. Histopathological examinations revealed a less severe hepatic portal inflammation in the CM-treated vs. other study groups.
Results: Dietary supplementation with CM fruits effectively prevents the development of diabetes mellitus , dyslipidemia and hepatic inflammation in alloxan-induced diabetes .
Crataegus pin.nati fida Bge extract
Regulation Effects of Crataegus pinnatifida Leaf on glucose and Lipids metabolism
The leaf of Crataegus pinnatifida (Rosaceae) is commonly consumed either raw or cooked to improve digestion and promote blood circulation in China. To investigate the regulation effects of it on glucose and lipid metabolism , the flavonoids fraction was prepared and analyzed by HPLC and LC−MS. In vivo, at doses of 250 and 500 mg/kg, the flavonoids fraction showed inhibitory effects on TG and glucose absorption , accelerating effects on gastrointestinal transit but no effect on gastric emptying. In vitro, treatment of 3T3-L1 preadipocytes with 30 μg/mL flavonoids fraction significantly suppressed the accumulation of TG and free fatty acid . It also suppressed the gene expressions of C/EBPα, PPARγ, SREBP 1c, aP2 and adiponectin but did not affect that of leptin. C. pinnatifida leaf may be useful for type 2 diabetics and hyperlipidemics as a foodstuff.
Cynodon dactylon
Isolation and in silico evaluation of antidiabetic molecules of Cynodon dactylon (L.)
Cynodon dactylon is a potential source of metabolites such as flavanoids, alkaloids, glycosides and β-sitosterol and has been traditionally employed to treat urinary tract and other microbial infections and dysentery. The present work attempts to evaluate the activity of C. dactylon extracts for glycemic control.
Aqueous extracts of C. dactylon analyzed by HPLC–ESI MS have identified the presence of apigenin, luteolin, 6-C-pentosyl-8-C-hexosyl apigenin and 6-C-hexosyl-8-C-pentosyl luteolin. Evaluation of hypoglycemic activity through an extensive in silico docking approach with PPARγ (Peroxisome Proliferator-Activated Receptor), GLUT-4 (glucose transporter -4) and SGLT2 (sodium glucose co-transporter -2) revealed that luteolin, apigenin, 6-C-pentosyl-8-C-hexosyl apigenin, 6-C-hexosyl-8-C-pentosyl luteolin interact with SGLT2 . Interaction s of these molecules with Gln 295 and Asp 294 residues of SGLT2 have been shown to compare well with that of the phase III drug, dapagliflozin.
These residues have been proven to be responsible for sugar sensing and transport. This work establishes C. dactylon extract as a potential SGLT2 inhibitor for diabetic neuropathy thus enabling a possibility of this plant extract as a new alternative to existing diabetic approaches.
Cytochalasin B
Cytochalasin B: inhibition of glucose and Glucosamine Transport
Cytochalasin B has been shown to potently inhibit the transport of glucose , deoxyglucose , and glucosamine by Novikoff hepatoma cells in suspension culture without affecting their intracellular phosphorylation and metabolism . Deoxyglucose transport is inhibited by cytochalasin B in a simple competitive manner. Although this inhibition is not sufficient to explain the biological action of the drug on cytokinesis, it does explain earlier observations on inhibition by cytochalasin B of the incorporation of glucose and glucosamine, and probably of other extracellular precursors, into macromolecules by various types of cells.
Curcumin
We investigated the effect of curcumin on insulin resistance and glucose homeostasis in male C57BL/KsJ-db/db mice and their age-matched lean non-diabetic db/+ mice. Both db/+ and db/db mice were fed with or without curcumin (0.02%, wt/wt) for 6 wks. Curcumin significantly lowered blood glucose and HbA1c levels , and it suppressed body weight loss in db/db mice. Curcumin improved homeostasis model assessment of insulin resistance and glucose tolerance, and elevated the plasma insulin level in db/db mice.
Hepatic glucokinase activity was significantly higher in the curcumin-supplemented db/db group than in the db/db group, whereas glucose -6-phosphatase and phosphoenolpyruvate carboxykinase activities were significantly lower. In db/db mice, curcumin significantly lowered the hepatic activities of fatty acid synthase, β-oxidation , 3-hydroxy-3-methylglutaryl coenzyme reductase, and acyl-CoA: cholesterol acyltransferase. Curcumin significantly lowered plasma free fatty acid , cholesterol, and triglyceride concentrations and increased the hepatic glycogen and skeletal muscle lipoprotein lipase in db/db mice.
Curcumin normalized erythrocyte and hepatic antioxidant enzyme activities (superoxide dismutase, catalase, gluthathione peroxidase) in db/db mice that resulted in a significant reduction in lipid peroxidation. However, curcumin showed no effect on the blood glucose , plasma insulin , and glucose regulating enzyme activities in db/+ mice.
These results suggest that curcumin seemed to be a potential glucose-lowering agent and antioxidant in type 2 diabetic db/db mice, but had no affect in non-diabetic db/+ mice.
daidzein
Over the last decades, the incidence of type 2 diabetes (T2D) is increasing substantially. Emerging evidences from epidemiological studies have shown the association between higher intake of soy isoflavones and reduced risk of T2D and its associated health risks. Daidzein, a soy isoflavone, has been found to have a promising therapeutic potential in managing T2D pathophysiology. Fermented soybean is the major source of daidzein; however, it can also be formed via the consumption of its glycosylated moiety, daidzin with subsequent hydrolysis by intestinal bacterial enzyme.
Many studies reported the prophylactic effect of daidzein on the improve ment of hyperglycemia , insulin resistance, dislipidemia, obesity , inflammation , and other complications associated with T2D. The molecular mechanisms underlying the action of daidzein include diverged pathways where daidzein has been shown to interact with several signaling molecules and receptors to achieve desirable effect. Although the specific molecular mechanism is still elusive, further studies are thus needed to understand it in detail.
In this review, we discuss the antidiabetic potential of daidzein with respect to the evidences from various clinical, preclinical, and cell culture studies and the underlying molecular mechanism in a precise way to have a comprehensive account on this isoflavone with promising therapeutic potential.
Dendrobium nobile Lindl extract
Effects of the extracts from Dendrobium nobile lindl on blood sugar in normal and hyperglycemic mice
Objective: To observe hypoglycemic effects of polysaccharide and alkaloids from Dendrobium nobile lindl in hyperglycemic mice induced by adrenalin.
Methods: The hyperglycemic model was induced by adrenalin. After intragastric administration of polysaccharide and alkaloids, the blood glucose level of each groups mice were determined.
Results: The polysaccharide and alkaloids could significantly lower the blood glucose level in the model mice, but no significantly effect was observed in the normal mice.
Conclusions: The polysaccharide and alkaloids from Dendrobium nobile lindl have hypoglycemic action on adrenal model mice.
epigallocatechin gallate
Intestinal glucose uptake is mainly performed by the sodium-dependent glucose transporter, SGLT1. The transport activity of SGLT1 was markedly inhibited by green tea polyphenols, this inhibitory activity being most pronounced in polyphenols having galloyl residues such as epicatechin gallate (ECg) and epigallocatechin gallate (EGCg). Experiments using brush-border membrane vesicles obtained from the rabbit small intestine demonstrated that ECg inhibited SGLT1 in a competitive manner, although ECg itself was not transported via SGLT1.
The present results suggest that tea polyphenols such as ECg interact with SGLT1 as antagonist-like molecules, possibly playing a role in controlling the dietary glucose uptake in the intestinal tract.
Regulation of intestinal glucose transport by tea catechins
Intestinal glucose uptake is mainly performed by its specific transporters, such as SGLT 1, GLUT 2 and 5 expressed in the intestinal epithelial cells. By using human intestinal epithelial Caco-2 cells we observed that intestinal glucose uptake was markedly inhibited by tea extracts. While several substances in green tea seem to be involved in this inhibition, catechins play the major role and epicatechin gallate (ECg) showed the highest inhibitory activity.
Since our Caco-2 cells did not express enough amount of SGLT 1, the most abundant intestinal glucose transporter, the effect of ECg on SGLT 1 was evaluated by using brush border membrane vesicles obtained from the rabbit small intestine. ECg inhibited SGLT 1 in a competitive manner, although ECg itself was not transported via the glucose transporters.
These results suggest that tea catechins could play a role in controlling the dietary glucose uptake at the intestinal tract and possibly contribute to blood glucose homeostasis.
Dietary polyphenols decrease glucose uptake by human intestinal Caco-2 cells
The effect of different classes of dietary polyphenols on intestinal glucose uptake was investigated using polarised Caco-2 intestinal cells. glucose uptake into cells under sodium -dependent conditions was inhibited by flavonoid glycosides and non-glycosylated polyphenols whereas aglycones and phenolic acids swere without effect. Under sodium -free conditions, aglycones and non-glycosylated polyphenols inhibited glucose uptake whereas glycosides and phenolic acids were ineffective.
These data suggest that aglycones inhibit facilitated glucose uptake whereas glycosides inhibit the active transport of glucose. The non-glycosylated dietary polyphenols appear to exert their effects via steric hindrance, and (−)-epigallochatechingallate, (−)-epichatechingallate and (−)-epigallochatechin are effective against both transporters.
Numerous studies propose that epigallocatechin-3-gallate (EGCG), an abundant polyphenol in green tea, has anti-cancer properties. However, its mechanism of action in breast cancer remains unclear. This study investigated the capacity of EGCG to suppress breast cancer cell growth in vitro and in vivo, characterizing the underlying mechanisms, focusing on the effect of EGCG on glucose metabolism. EGCG reduced breast cancer 4T1 cell growth in a concentration- (10–320 μM) and time- (12–48 h) dependent manner. EGCG induced breast cancer apoptotic cell death at 24 h, as evidenced by annexin V/PI, caspase 3, caspase 8 and caspase 9 activation. Furthermore, EGCG affected the expression of 16 apoptosis-related genes, and promoted mitochondrial depolarization. EGCG induced autophagy concentration-dependently in 4T1 cells by modulating the levels of the autophagy –related proteins Beclin1, ATG5 and LC3B.
Moreover, EGCG affected glucose, lactate and ATP levels. Mechanistically, EGCG significantly inhibited the activities and mRNA levels of the glycolytic enzymes hexokinase (HK), phosphofructokinase (PFK), and lactic dehydrogenase (LDH), and to a lesser extent the activity of pyruvate kinase (PK). In addition, EGCG decreased the expression of hypoxia-inducible factor 1α (HIF1α) and glucose transporter 1 (GLUT1), critical players in regulating glycolysis.
In vivo, EGCG reduced breast tumor weight in a dose-dependent manner, reduced glucose and lactic acid levels and reduced the expression of the vascular endothelial growth factor (VEGF). In conclusion, EGCG exerts an anti-tumor effect through the inhibition of key enzymes that participate in the glycolytic pathway and the suppression of glucose metabolism.
To study the effects of polyphenols on the Na+/glucose cotransporter (SGLT1 ) response, SGLT1 was expressed in Xenopus oocytes by injecting cRNA synthesized from the cloned cDNA of the small intestine cotransporter of rats, and the electrical response elicited by glucose or galactose was measured by a voltage clamping method. Most phenol derivatives had no effect on the response. However, the polyphenols (+)-catechin, (−)-epicatechin gallate (ECg), and (−)-epigallocatechin gallate (EGCg), which are components of green tea, caused an inhibition of the response, which was almost independent of glucose concentration.
The inhibition constants were estimated to be 2.3 mM for (+)-catechin and 0.45 mM for both ECg and EGCg, assuming the noncompetitive inhibition mechanism. Saponin prepared from tea seeds also inhibited the response significantly. Tannic acid and aqueous extracts of teas induced nonspecific electrical responses in both cRNA-injected and noninjected oocytes at lower concentrations than those that caused an inhibition of the SGLT1 response when their dose-dependent effects were examined.
These results are possibly helpful in the development of a dietary supplement for diabetic patients.
Background: Water soluble polysaccharide derived from green tea (WSP) is produced as byproducts when catechins were extracted from green tea. Although inhibitory effect of green tea catechins on the glucose transport in small intestine has been studied, the hypoglycemic efficacy of the WSP or its combinational effect has not been studied. In order to investigate hypoglycemic efficacy of the WSP or its combinational effect with green tea extract (GTE), co-consumption of GTE and WSP with wheat starch was investigated using in vitro digestion coupled with Caco-2 cells. The mechanism of the intestinal glucose transport was elucidated throughout the gene expression of the intestinal glucose transporters, which included sodium dependent glucose transporter (SGLT1 ) and glucose transporter 2 (GLUT2 ), using quantitative real-time polymerase chain reaction (qRT-PCR).
Results: The co-digestion of wheat starch with GTE during the small intestinal phase was the most rapidly digested into reducing sugar (73.96 g L−1) compared to itself (48.44 g L−1), WSP (60.35 g L−1), and GTE + WSP (61.81 g L−1). intestinal glucose transport was 11.82, 7.59, 4.49, and 2.40% for wheat starch, wheat starch with GTE, WSP, and GTE + WSP, respectively. The highest decreased expression pattern in SGLT1 was observed when cells treated with wheat starch + GTE + WSP (0.66-fold) compared to GTE or WSP treatment.
Conclusion: The results suggested that co-consumption of green tea derived products with wheat starch could delay the intestinal absorption of glucose. Results from the current study suggested that GTE and WSP could be the useful supplements of dietary therapy for hyperglycemia to delay glucose absorption.
epicatechin
Unraveling the inhibition of intestinal glucose Transport by Dietary Phenolics: A Review
Background: glucose transport across the intestinal brush border membrane plays a key role in metabolic regulation. Depending on the luminal glucose concentration, glucose is mainly transported by the sodium – dependent glucose transporter (SGLT1 ) and the facilitated-transporter glucose transporter (GLUT2 ). SGLT1 is apical membrane-constitutive and it is active at a low luminal glucose concentration, while at concentrations higher than 50 mM, glucose is mainly transported by GLUT2 (recruited from the basolateral membrane). Dietary phenolic compounds can modulate glucose homeostasis by decreasing the postprandial glucose response through the inhibition of SGLT1 and GLUT2.
Methods: Phenolic inhibition of intestinal glucose transport has been examined using brush border membrane vesicles from rats, pigs or rabbits, Xenopus oocytes and more recently Caco-2 cells, which are the most promising for harmonizing in vitro experiments.
Results: Phenolic concentrations above 100 μM has been proved to successfully inhibit the glucose transport. Generally, the aglycones quercetin, myricetin, fisetin or apigenin have been reported to strongly inhibit GLUT2 , while quercetin-3-O-glycoside has been demonstrated to be more effective in SGLT1. Additionally, epigallocatechin as well as epicatechin and epigallocatechin gallates were observed to be inhibited on both SGLT1 and GLUT2 .
Conclusion: Although, valuable information regarding the phenolic glucose transport inhibition is known, however, there are some disagreements about which flavonoid glycosides and a glycones exert significant, inhibition, and also the inhibition of phenolic acids remains unclear. This review aims to collect, compare and discuss the available information and controversies about the phenolic inhibition of glucose transporters. A detailed discussion on the physicochemical mechanisms involved in phenolics-glucose transporters interactions is also included.
epigallocatechin
Unraveling the inhibition of intestinal glucose Transport by Dietary Phenolics: A Review
Background: glucose transport across the intestinal brush border membrane plays a key role in metabolic regulation. Depending on the luminal glucose concentration, glucose is mainly transported by the sodium – dependent glucose transporter (SGLT1 ) and the facilitated-transporter glucose transporter (GLUT2 ). SGLT1 is apical membrane-constitutive and it is active at a low luminal glucose concentration, while at concentrations higher than 50 mM, glucose is mainly transported by GLUT2 (recruited from the basolateral membrane). Dietary phenolic compounds can modulate glucose homeostasis by decreasing the postprandial glucose response through the inhibition of SGLT1 and GLUT2 .
Methods: Phenolic inhibition of intestinal glucose transport has been examined using brush border membrane vesicles from rats, pigs or rabbits, Xenopus oocytes and more recently Caco-2 cells, which are the most promising for harmonizing in vitro experiments.
Results: Phenolic concentrations above 100 μM has been proved to successfully inhibit the glucose transport. Generally, the aglycones quercetin, myricetin, fisetin or apigenin have been reported to strongly inhibit GLUT2 , while quercetin-3-O-glycoside has been demonstrated to be more effective in SGLT1 . Additionally, epigallocatechin as well as epicatechin and epigallocatechin gallates were observed to be inhibited on both SGLT1 and GLUT2 .
Conclusion: Although, valuable information regarding the phenolic glucose transport inhibition is known, however, there are some disagreements about which flavonoid glycosides and aglycones exert significant inhibition , and also the inhibition of phenolic acids sremains unclear. This review aims to collect, compare and discuss the available information and controversies about the phenolic inhibition of glucose transporters . A detailed discussion on the physicochemical mechanisms involved in phenolics-glucose transporters interaction s is also included.
Eriobotrya japonica
Sesquiterpene glycoside, nerolidol-3-O-α-l-rhamnopyranosyl(1→4)-α-l-rhamnopyranosyl(1→2)-[α-l-rhamnopyranosyl(1→6)]-β-d-glucopyranoside was isolated from dried leaves of loquat [Eriobotrya japonica (Thunb.) Lindl., Rosaceae].
Hypoglycemic effects of this natural product were assessed in normal and alloxan-diabetic mice model. Animals received orally administration of the sesquiterpene glycoside in dose of 25 and 75 mg/kg. The anti-hyperglycemic effect was compared with gliclazide’s. The dose of 25 and 75 mg/kg both exerted a significant () hypoglycemic effect in alloxan-diabetic mice throughout the test and a slight effect in normal mice.
Euonymus alatus (Thunb.) Sieb.extract
inhibitory activity of Euonymus alatus against alpha-glucosidase in vitro and in vivo
The major goal in the treatment of diabetes mellitus is to achieve near-normal glycemic control. To optimize both fasting blood glucose and postprandial glucose levels is important in keeping blood glucose levels as close to normal as possible. α-glucosidase is the enzyme that digests dietary carbohydrate, and inhibition of this enzyme could suppress postprandial hyperglycemia .
The purpose of this study was to test the inhibitory activity of methanol extract of Euonymus alatus on α-glucosidase in vitro and in vivo to evaluate its possible use as an anti-diabetic agent. Yeast α-glucosidase inhibitory activities of methanol extract of E. alatus were measured at concentrations of 0.50, 0.25, 0.10, and 0.05 mg/ml. The ability of E. alatus to lower postprandial glucose was studied in streptozotocin-induced diabetic rats. A starch solution (1 g/kg) with and without E. alatus extract (500 mg/kg) was administered to diabetic rats by gastric intubation after an overnight fast.
Plasma glucose levels were measured at 30, 60, 90, 120, 180, and 240 min. plasma glucose levels were expressed in increments from baseline, and incremental areas under the response curve were calculated. Extract of E. alatus,which had an IC50 value of 0.272 mg/ml, inhibited yeast α-glucosidase activity in a concentration-dependent manner. A single oral dose of E. alatus extract significantly inhibited increases in blood glucose levels at 60 and 90 min (p<0.05) and significantly decreased incremental response areas under the glycemic response curve (p<0.05).
These results suggest that E. alatus has an antihyperglycemic effect by inhibiting α-glucosidase activity in this animal model of diabetes mellitus.
Euphorbia humifusa extract
Three new hydrolyzable tannins, euphormisins M1, M2 and M3, were isolated from Euphorbia hymifusa WILLD., and respectively characterized as 1, 3, 6-tri-O-galloyl-4-O-bravifolincarboxyl-β-D-glucose (19), an oxidative metabolite (23) of geraniin, and 1, 3, 6-tri-O-galloyl-α-D-glucose (18), by spectroscopic and chemical methods. A new ellagic acid glucoside (16) and fifteen known tannins, including geraniin (8) and four dimers [euphorbins A (13), B (14), excoecarianin (15) and eumaculin A (12)], were also isolated.
Fenugreek
Fenugreek (Trigonella foenum-graecum L. seed) is a food with traditional medicinal use in diabetes. Beneficial effects have been demonstrated in diabetic animals and both insulin -dependent and non-insulin-dependent diabetic subjects. Effects of a lipid extract A, crude ethanolic extract B, further sub-fractions of B (saponin-free C, saponin D and sapogenin E) and a gum fibre fraction F on intestinal sodium-dependent glucose uptake were investigated in vitro using rabbit intestinal brush border membrane vesicles. All fraction s except A inhibited glucose–uptake at 0.33 and/or 3.3mg/mL (p < 0.001).
Greatest inhibition was observed with fractions D and E. Diosgenin and trigonelline (compounds reported in fenugreek)also inhibited glucose –uptake (IC50 values approximately 3mg/ml, equivalent to 8mM and 19mM respectively) but did not account for the activity of the crude extracts. Fenugreek extracts had no effect on basal levels of glycogen phosphorylase a (HGPa) activity in rat hepatocyte suspensions. However fractions C and E caused a marginal but statistically significant inhibition (18.9 and 15.1% respectively, p < 0.05) of glucagon induction of this enzyme suggesting a glucagon-antagonist effect. Diosgenin (1.65mg/ml; 4mM) inhibited glucagon-induced HGPa activity by 20% (p < 0.05), and was more effective than trigonelline (non significant inhibition of 9.4% at 1.65mg/ml, 10mM).
Ficus carica Linn extract
Context: The decoctions of Ficus carica Linn. (Moraceae) leaves are used in the folklore treatment of diabetes .
Objective: To evaluate the effect of F. carica on glucose and lipids levels , carbohydrate metabolism enzymes and β-cells protective effects in type 2 diabetes .
Material and methods: diabetes was induced in 15 days high-fat diet (HFD)-fed Wistar rats by intraperitoneal injection of streptozotocin (STZ) (40 mg/kg). The ethyl acetate extract (250 and 500 mg/kg) of F. carica leaves was administered for 28 days. Oral glucose tolerance (OGTT) and intraperitoneal insulin tolerance tests (ITT) were evaluated on 15th and 25th days, respectively.
Results: The ethyl acetate extract (250 and 500 mg/kg) of n F. carica leaves showed significant effect (p < 0.005) in the levels of blood glucose , total cholesterol (TC), triglycerides (TG), body weight and hepatic glycogen. In OGTT, F. carica (250 and 500 mg/kg) significantly (p < 0.005) detained the increase in blood glucose levels at 60 and 120 min and in ITT, F. carica enhanced the glucose utilization significantly (p < 0.005) over 30 and 60 min compared to diabetic control. Further, the altered activities of key carbohydrate metabolizing enzymes such as glucose -6-phosphatase, fructose-1,6-bisphosphatase and hexokinase in the liver tissue of diabetic rats were significantly (p < 0.005) reverted to near normal levels upon treatment with F. carica. Immumohistochemical studies of islets substantiated the cytoprotective effect on pancreatic β-cells.
Discussion and conclusions: F. carica leaves exerted significant effect on carbohydrate metabolism enzymes with promising hypoglycemic and hypolipidemic activities in type 2 diabetic rats.
fisetin
The actions of fisetin on glucose metabolism in the rat liver
Fisetin is a flavonoid dietary ingredient found in the smoke tree (Cotinus coggyria) and in several fruits and vegetables. The effects of fisetin on glucose metabolism in the isolated perfused rat liver and some glucose -regulating enzymatic activities were investigated. Fisetin inhibited glucose , lactate, and pyruvate release from endogenous glycogen. Maximal inhibitions of glycogenolysis (49%) and glycolysis (59%) were obtained with the concentration of 200 µM.
The glycogenolytic effects of glucagon and dinitrophenol were suppressed by fisetin 300 µM. No significant changes in the cellular contents of AMP, ADP, and ATP were found. Fisetin increased the cellular content of glucose 6-phosphate and inhibited the glucose 6-phosphatase activity . Gluconeogenesis from lactate and pyruvate or fructose was inhibited by fisetin 300 µM. Pyruvate carboxylation in isolated intact mitochondria was inhibited (IC50 = 163.10 ± 12.28 µM); no such effect was observed in freeze-thawing disrupted mitochondria.
It was concluded that fisetin inhibits glucose release from the livers in both fed and fasted conditions. The inhibition of pyruvate transport into the mitochondria and the reduction of the cytosolic NADH-NAD+ potential redox could be the causes of the gluconeogenesis inhibition . Fisetin could also prevent hyperglycemia by decreasing glycogen breakdown or blocking the glycogenolytic action of hormones.
Fructus Ligustri Lucidi extract
Hypoglycemic Effect of Fructus Ligustri Lucidi
The decoction of Fructus Ligustri Lucidi (FLL) 15.30 g/kg ig for 10 days significantly decreased the blood glucose level in normal mice. FLL 30 g/kg before or after the treatment of alloxan also decreased the blood glucose level in alloxan diabetic mice. The elevation of blood glucose level induced by adrenaline or glucose was antagonized by FLL.
Fucoxanthin
Transcriptomic analysis reveals effects of fucoxanthin on intestinal glucose transport
Fucoxanthin, one of carotenoid pigments from plants and algae, is known to regulate blood glucose and insulin levels. The mechanism of its hypoglycemic activity has drawn a lot of scientific interest in recent years. In this study, we investigated the effects of fucoxanthin on intestinal glucose transport using a murine model.
Our data demonstrated that fucoxanthin was able to decrease blood glucose level and alleviate insulin resistance significantly. The results from RNA-seq based transcriptomic analysis, suggested that fucoxanthin acted as a key regulator in insulin /PI3K/AKT/mTOR signaling and PKA/AMPK /mTOR signaling pathways. Moreover, fucoxanthin ingestion resulted in a significant reduction in the protein expression of intestinal glucose transporters, such as SGLT-1, and led to decreased translocation of GLUT-2, which contributed to the regulation of blood glucose level.
Together, our findings provided a mechanistic insight into the regulatory effect of fucoxanthin on blood glucose.
Ganoderma lucidum(Leyss. ex Fr.)Karst.extract
Hypoglycemic effect of Ganoderma lucidum polysaccharides
Aim of study: To investigate the hypoglycemic effect of Ganoderma lucidum polysaccharides (Gl-PS) in the normal fastedmice and its possible mechanism.
Methods: Normal fasted mice were given a single dose of Gl-PS 25, 50, and100 mg/kg by ip and the serum glucose was measured at 0, 3, and 6 h after administration. Gl-PS 100 mg/kg werealso given by ip and the serum glucose and insulin levels were measured at 0 min, 30 min, 1 h, 3 h, 6 h, and 12 h.Pancreatic islets were isolated and incubated with glucose 5.6 mmol/L and different concentration of Gl-PS, theinsulin content of islets and insulin release were examined. The islets fluorescent intensity of [Ca2+]i was alsostudied with a confocal microscope. Verapamil and egtazic acid were used to testify whether the insulin -releasingeffect of Gl-PS was mediated by its ability to raise the Ca2+ influx.
Results: Gl-PS dose-dependently lowered the serum glucose levels at 3 h and 6 h after administration. Gl-PS 100 mg/kg raised the circulating insulin levels at1 h after administration. In vitro, Gl-PS had no effect on islets insulin content, but it stimulated the insulin releaseafter incubation with glucose 5.6 mmol/L. Confocal microscope showed that Gl-PS 100 mg/L had the capacity toraise the [Ca2+] i. The insulin-releasing effect of Gl-PS was inhibited by verapamil/egtazic acid .
Conclusion: Gl-PS possesses the hypoglycemic effect on normal mice; one mechanism is through its insulin-releasing activity due to a facilitation of Ca2+ inflow to the pancreatic β cells.
Effects of the Extracts of Ganoderma lucidum on blood glucose level in Rats
Gaultheria phillyreifolia
Berries are rich food sources of potentially health-beneficial (poly)phenols. However, they may undergo chemical modifications during gastrointestinal digestion. The effect of simulated gastrointestinal digestion on the content and composition of secondary metabolites from Gaultheria phillyreifolia and G. poeppigii berries was studied. The influence of the digested extracts on the in vitro metabolism and absorption of carbohydrates was evaluated. After simulated digestion, 31 compounds were detected by UHPLC-DAD-MS.
The total content of anthocyanins decreased by 98–100%, flavonols by 44–56%, phenylpropanoids by 49–75% and iridoids by 33–45%, the latter showing the highest stability during digestion. Digested extracts inhibited α-glucosidase (IC50 2.8–24.9 μg/mL) and decreased the glucose uptake in Caco-2 cells by 17–28%. Moreover, a decrease in the mRNA expression of glucose transporters SGLT1 (38–92%), GLUT2 (45–96%), GLUT5 (28–89%) and the enzyme sucrase-isomaltase (82–97%) was observed.
These results show the effect of simulated gastrointestinal digestion on the content and composition of Gaultheria berries.
genistein
Genistein is a dietary-derived plant product that inhibits the activity of protein-tyrosine kinases. We show here that it is a potent inhibitor of the mammalian facilitative hexose transporter GLUT1. In human HL-60 cells, which express GLUT1, genistein inhibited the transport of dehydroascorbic acid , deoxyglucose , and methylglucose in a dose-dependent manner. Transport was not affected by daidzein, an inactive genistein analog that does not inhibit protein-tyrosine kinase activity , or by the general protein kinase inhibitor staurosporine. Genistein inhibited the uptake of deoxyglucose and dehydroascorbic acid in Chinese hamster ovary (CHO) cells overexpressing GLUT1 in a similar dose-dependent manner. Genistein also inhibited the uptake of deoxyglucose in human erythrocytes indicating that its effect on glucose transporter function is cell-independent. The inhibitory action of genistein on transport was instantaneous, with no additional effect observed in cells preincubated with it for various periods of time. Genistein did not alter the uptake of leucine by HL-60 cells, indicating that its inhibitory effect was specific for the glucose transporters .
The inhibitory effect of genistein was of the competitive type, with a K of approximately 12 μM for inhibition of the transport of both methyl-glucose and deoxy-glucose. Binding studies showed that genistein inhibited glucose-displaceable binding of cytochalasin B to GLUT1 in erythrocyte ghosts in a competitive manner, with a K of 7 μM. These data indicate that genistein inhibits the transport of dehydroascorbic acid and hexoses by directly interacting with the hexose transporter GLUT1 and interfering with its transport activity, rather than as a consequence of its known ability to inhibit protein-tyrosine kinases.
These observations indicate that some of the many effects of genistein on cellular physiology may be related to its ability to disrupt the normal cellular flux of substrates through GLUT1, a hexose transporter universally expressed in cells, and is responsible for the basal uptake of glucose.
Genistein directly inhibits GLUT4-mediated glucose uptake in 3T3-L1 adipocytes
The isoflavone-derivative genistein is commonly applied as an inhibitor of tyrosine kinases. In this report we analyze the effect of genistein on insulin -stimulated glucose uptake in 3T3-L1 adipocytes. In these cells insulin -induced glucose uptake is primarily mediated by the GLUT4 glucose transporter.
We observed that pre-treatment with genistein did not affect insulin -induced tyrosine kinase activity of the insulin receptor or activation of protein kinase B. On the other hand, genistein acted as a direct inhibitor of insulin-induced glucose uptake in 3T3-L1 adipocytes with an IC50 of 20 μM. We conclude that apart from acting as a general tyrosine kinase inhibitor, genistein also affects the function of other proteins such as the GLUT4 transporter.
These data suggest that caution must be applied when interpreting data on the involvement of tyrosine kinase activity in glucose uptake in 3T3-L1 adipocytes.
glycyrrhiza inflata
A new neutral polysaccharide, named AGP, was extracted from glycyrrhiza residue by 5% NaOH alkaline solution and purified by DEAE-cellulose and Sephadex G-150. A single and symmetrical peak was shown by HPLC, indicating that AGP is a homogeneous polysaccharide with a molecular weight of 2.89 × 103 KDa. The specific rotation of AGP was detected by a polarimeter and it was +45°. Monosaccharide composition analysis indicated that AGP was consisted of l-rhamnose: l-arabinose: d-xylose: d-mannose: d-glucose and d-galactose with a molar ratio of 1:2.33:2.85:0.69:3.05:1.54. The structure of AGP was analyzed by GC–MS, periodate oxidation, Smith degradation, FT-IR, methylation and NMR, which indicated that the AGP was composed of → 6)-β-d-Glcp-( → backbone and the →4)-α-d-Xylp-(1→, →5)-α-l-Araf-(1→, →3)-α-l-Rhap-(1→, →6)-α-d-Galp-(1→, →3,6)-α-Manp-(1→ and →1)-β-d-Glcp as branches.
The results of Congo red experiment and circular dichroism (CD) showed that there was triple helix conformation in AGP. The micro-structure of AGP were detected by scanning electron microscopy (SEM), which concluded that the shape of AGP was a “thin slice” and its structure is not regular. The crystal configuration was identified by X-ray diffraction (XRD), showing that there is no crystal structure. Furthermore, the AGP exhibited certain inhibition activity on α-glucosidase.
Gnetum gnemonoides
Gneyulins A (1) and B (2), two new stilbene trimers consisting of oxyresveratrol constituent units, and noidesols A (3) and B (4), two new dihydroflavonol-C-glucosides, were isolated from the bark of Gnetum gnemonoides. The structures and configurations of 1−4 were elucidated on the basis of 2D NMR correlations and X-ray analysis. Gneyulins A (1) and B (2) showed inhibition of Na+–glucose transporters (SGLT-1 and SGLT-2).
Gossypol
Endofacial competitive inhibition of the glucose transporter 1 activity by gossypol
Gossypol inhibits the transport of hexoses in HL-60 and CHO cells.
We determined the dose dependence from the effect of gossypol on the transport of methylglucose and deoxyglucose in HL-60 cells. We have previously shown that HL-60 cells express the glucose transporter GLUT1 and efficiently transport hexoses (53). We used a 30-s uptake assay to determine the kinetic constants of transport. When gossypol was added at the beginning of the uptake assay, it inhibited the uptake of deoxyglucose and methylglucose by HL-60 cells in a dose-dependent manner (Fig. 1, A and B). Fifty percent inhibition was observed at ∼30 μM.
Graviola (Annona muricata)
Background: Annona muricata has been used in folklore in the management of diabetes . A major strategy in decreasing postprandial hyperglycemia in diabetes involves the inhibition of carbohydrate-hydrolyzing enzymes – α-amylase and α-glucosidase . Thus, this study evaluated the in vivo and in vitro inhibitory potentials of the different parts (fruit-pulp, leaf, stem-bark and root-bark) of Annona muricata.
Methods: A total of 120 Wistar rats were treated with methanol extracts for 28 days after which blood and tissue samples were collected for α-amylase assay. In vitro inhibitory properties of methanol, ethyl acetate and dichloromethane extracts of the various parts of the plant on α-amylase and α-glucosidase activities were performed using standard procedures. The mode and mechanism of interaction s between the enzymes and extracts (and isolated acetogenin) were determined using various kinetic interpolations and in silico experiments.
Result: The fruit-pulp and root-bark methanolic extracts better -inhibited plasma and tissue amylase in vivo. The in vitro studies revealed that the stem-bark methanolic, fruit-pulp ethyl acetate, and leaf dichloromethane extracts, better inhibited α-amylase activity compared with the standard acarbose. Also, the leaf methanol, fruit-pulp ethyl acetate, and root-bark dichloromethane extract better inhibited α-glucosidase activity . These observations were corroborated with their higher Bmax and Vmax and lower Kd values. All the extracts exhibited an “uncompetitive” type of inhibition pattern. Also, the isolated acetogenin (15-acetyl guanacone) from the fruit-pulp showed a better binding affinity compared to the standard drug, Metformin.
Conclusion: Better natural remedy for diabetic s can be obtained from Annona muricata with minimal or no adverse side effects.
Effect of Annona Muricata L. on metabolic Parameters in diabetes mellitus: A Systematic Review
In recent decades, numerous scientific investigations have been conducted to study the antidiabetic effects of Annona muricata L. However, no comprehensive evidence-based systematic review regarding this topic is available. Hence, this study was conducted to systematically evaluate the studies of the efficacy of A. muricata in diabetes management. Six online databases used to search for the related articles.
The search terms used were A. muricata/ soursop in combination with diabetes, glucose, and insulin. Seventeen studies were identified that fit the inclusion criteria (1 clinical, 10 in vivo, 4 in vitro, 1 in vivo/ in vitro and 1 in silico). A clinical study showed the positive adjuvant effect of A. muricata to glibenclamide in type 2 diabetes patients. In vivo studies reported beneficial effects of A. muricata in murine models to include decreasing fasting blood glucose level, attenuating diabetes -associated weight loss, increasing serum insulin , improving the lipid profile, normalizing the activity of antioxidant enzymes, and exerting pancreas-protective and hepatoprotective effects. In vitro studies of A. muricata demonstrated its potential for reducing post-prandial glucose level by inhibiting pancreatic α-amylase, lipase, and α-glucosidase and lowering oxidative stress by inhibiting glycation and lipid peroxidation. Additionally, the in-silico study suggested a positive effect of A. muricata in enhancing insulin sensitivity. A. muricata showed a promising effect on the metabolic parameters in diabetes mellitus.
Considering that A. muricata is widely consumed worldwide, further exploration of its therapeutic potential is worthwhile.
guava (Psidium guajava)
In Vitro and In Vivo inhibition of intestinal glucose Transport by Guava (Psidium Guajava) Extracts
Methods and results: This study investigated the effects of different guava leaf and fruit extracts on intestinal glucose transport in vitro and on postprandial glucose levels in vivo. Substantial dose- and time-dependent glucose transport inhibition (up to 80%) was observed for both guava fruit and leaf extracts, at conceivable physiological concentrations in Caco-2 cells. Using sodium -containing (both glucose transporters , sodium -dependent glucose transporter 1 [SGLT1 ] and glucose transporter 2 [GLUT2 ], are active) and sodium -free (only GLUT2 is active) conditions, we show that inhibition of GLUT2 was greater than that of SGLT1 . inhibitory properties of guava extracts also remained stable after digestive juice treatment , indicating a good chemical stability of the active substances. Furthermore, we could unequivocally show that guava extracts significantly reduced blood glucose levels (≈fourfold reduction) in a time-dependent manner in vivo (C57BL/6N mice). Extracts were characterized with respect to their main putative bioactive compounds (polyphenols) using HPLC and LC-MS.
Gymnema sylvestre
Gymnemic acids sInhibit sodium-Dependent glucose transporter
To evaluate the activity of botanicals used in Chinese traditional medicine as hypoglycemic agents for diabetes type II prevention and/or treatment , extracts prepared from 26 medicinal herbs were screened for their inhibitory activity on sodium -dependent glucose transporter 1 (SGLT1 ) by using two-electrode voltage-clamp recording of glucose uptake in Xenopus laevis oocytes microinjected with cRNA for SGLT1 . Showing by far the strongest SGLT1 inhibitory effect, the phytochemicals extracted from Gymnema sylvestre (Retz.) Schult were located by means of activity -guided fraction ation and identified as 3-O-β-d-glucuronopyranosyl-21-O-2-tigloyl-22-O-2-tigloyl gymnemagenin (1) and 3-O-β-d-glucuronopyranosyl-21-O-2-methylbutyryl-22-O-2-tigloyl gymnemagenin (2) by means of LC-MS/MS, UPLC-TOF/MS, and 1D/2D-NMR experiments.
Both saponins exhibited low IC50 values of 5.97 (1) and 0.17 μM (2), the latter of which was in the same range as found for the high-affinity inhibitor phlorizin (0.21 μM). As SGLT1 is found in high levels in brush-border membranes of intestinal epithelial cells, these findings demonstrate for the first time the potential of these saponins for inhibiting electrogenic glucose uptake in the gastrointestinal tract.
Gynostemma Pentaphyllum
Anti-diabetic activity evaluation of a polysaccharide extracted from Gynostemma pentaphyllum
In current study, a polysaccharide (GPP) was successfully extracted from Gynostemma pentaphyllum herb. Monosaccharide composition of GPP was rhamnose, arabinose, galactose, glucose , xylose, mannose, galacturonic acid and glucuronic acid in a molar ratio of 4.11: 7.34: 13.31: 20.99: 1.07: 0.91: 4.75: 0.36. Molecular weight and polydispersity (Mw/Mn) of GPP were 4.070 × 104 Da and 1.037, respectively. Primary structure features of GPP were determined to be a polysaccharide by FT-IR and NMR.
Fasting blood sugar of diabetic mice decreased from 17.56 mmol/L to 7.42 mmol/L by orally administration of 0.5 mL GPP (1 mg/mL) for 30 days. GPP exhibited a dose-dependent inhibition effect on α-glucosidase activity. Moreover, GPP could inhibit the glucose absorption and affect the protein expression of GLUT2, but not the protein expression of SGLT1 . These results indicated GPP could be used as an effective ingredient to prevent and cure diabetes.
helichrysum (Helichrysum italicum)
Several plant extracts rich in flavonoids have been reported to improve hyperglycemia by inhibiting digestive enzyme activities and SGLT1 -mediated glucose uptake. In this study, helichrysum (Helichrysum italicum) and grapefruit (Citrus × paradisi) extracts inhibited in vitro enzyme activities. The helichrysum extract showed higher inhibitory activity of α-glucosidase (IC50 = 0.19 mg/mL) than α-amylase (IC50 = 0.83 mg/mL), whereas the grapefruit extract presented similar α-amylase and α-glucosidase inhibitory activities (IC50 = 0.42 mg/mL and IC50 = 0.41 mg/mL, respectively).
Both extracts reduced maltose digestion in noneverted intestinal sacs (57% with helichrysum and 46% with grapefruit). Likewise, both extracts inhibited SGLT1 -mediated methylglucoside uptake in Caco-2 cells in the presence of Na+ (56% of inhibition with helichrysum and 54% with grapefruit). In vivo studies demonstrated that helichrysum decreased blood glucose level s after an oral maltose tolerance test (OMTT), and both extracts reduced postprandial glucose levels after the oral starch tolerance test (OSTT). Finally, both extracts improved hyper-insulin emia (31% with helichrysum and 50% with grapefruit) and HOMA index (47% with helichrysum and 54% with grapefruit) in a dietary model of insulin resistance in rats. In summary, helichrysum and grapefruit extracts improve postprandial glycemic control in rats, possibly by inhibiting α-glucosidase and α-amylase enzyme activities and decreasing SGLT1-mediated glucose uptake.
Herba fumariae
Fumaria officinalis belongs to family papaveraceae and is traditionally used to treat hypertension, hepatitis and diabetes. The current study was conducted to evaluate in vitro and in vivo antidiabetic activity of Fumaria officinalis. Aerial parts of the plant were sequentially extracted with n-hexane, chloro form, methanol and water. Phytochemical analysis was carried out on all extracts. Antioxidant activity was determined by 2,2-diphenyl-1-picryl hydrazyl (DPPH) inhibition method. In vitro alpha-amylase inhibitory activity was performed on all extracts by using dinitrosalicylic acid . Effect of aqueous and methanolic extracts of F. officinalis on blood glucose was evaluated in normo-glycaemic rats and alloxan induced diabetic rats. Glimepiride 0.2 mg/kg was used as standard therapy in diabetic rats.
Results showed that methanolic extract exhibited the maximum percentage inhibition of DPPH (86.30%) and alpha-amylase inhibition (94.01%) at 500 µg/ml and 16 mg/ml concentration respectively. Administration in normo-glycaemic rats did not show any significant decrease in blood glucose level at 500 and 750 mg/kg dosage. Aqueous and methanolic extracts exhibited a significant hypoglycaemic effect (p˂0.05) at all doses. A significant increase in the body weight and an improvement in liver and kidney function tests of diabetic rats were observed. These extracts also reduced the damage to the cells of glomeruli, interstitial inflammation, necrosis of tubular cells and thrombosis in the kidney, the enlargement of sinusoids and steatosis in the liver of diabetic rats.
This study concludes that F. officinalis may have antidiabetic potential possibly due to its antioxidant and alpha-amylase inhibitory activities.
Hordeurn vulgare L. extract
The phenolic profiles, hypoglycemic activity , and molecular mechanism of the effect on type 2 diabetes mellitus (T2DM) of four highland barley varieties were investigated in the present study. The fundamental phenolics in highland barley were ferulic acid , naringin, and catechin, which mainly existed in bound form. These varieties showed favorable hypoglycemic activity via inhibition of α-glucosidase and α-amylase activities, enhancement of glucose consumption, glycogen accumulation and glycogen synthase 2 (GYS2) activity , and down-regulation of glucose -6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (PEPCK) activities. Specifically, ZQ320 variety exhibited the strongest hypoglycemic activity compared to the other varieties. Highland barley phenolics could inhibit gluconeogenesis and motivate glycogen synthesis via down-regulating the gene expression of G6Pase, PEPCK, and glycogen synthase kinase 3β (GSK3β), while activating the expression of insulin receptor substrate-1 (IRS-1), phosphatidylinositol 3 kinase (PI3K), serine/threonine kinase (Akt), GYS2, and glucose transporter type 4 (GLUT4 ).
Therefore, phenolics from highland barley could be served as suitable candidates for therapeutic agent in T2DM to improve human health.
honeybush (Cyclopia genistoides)
Extracts of Cyclopia species are used as food ingredients. In vitro α-glucosidase (AG) inhibition by ultrafiltered C. genistoides extract, fraction s enriched in xanthones (XEF) and benzophenones (BEF), as well as mangiferin, isomangiferin, 3-β-D-glucopyranosyliriflophenone (I3G) and 3-β-D-glucopyranosyl-4-O-β-D-glucopyranosyliriflophenone (IDG) was determined with acarbose as positive control. XEF was more potent than the extract and BEF (IC50 = 43.3, 95.5 and 205.7 μg mL−1, respectively). Compounds demonstrated potency in the descending order: acarbose (IC50 = 44.3 μM) > mangiferin (102.2 μM) > isomangiferin (119.8 μM) > I3G (237.5 μM) > IDG (299.4 μM). The combination index (CI) was used to determine synergism (CI < 0.7) as demonstrated for combinations of acarbose with XEF, BEF or the respective compounds at 50% and 75% effect levels.
The greatest potential acarbose dose reductions (>six-fold) across all effect levels were calculated for combinations of acarbose with mangiferin or isomangiferin, explaining the greater acarbose dose reduction potential of XEF vs. BEF. The effect of batch-to-batch variation (n = 10) of raw plant material on AG inhibition was quantified at a fixed concentration (160 μg mL−1). XEFs (xanthone content = 223–481 g kg−1) achieved AG inhibition of 63–72%, whereas BEFs (benzophenone content = 114–251 g kg−1) achieved AG inhibition of 26–34%, with weak linear correlation (R2 < 0.43) between target compound content of the fractions and their achieved AG inhibition.
Thus, extract fraction s of C. genistoides, enriched in xanthones and benzophenones, show potential in reducing the effective dose of acarbose required to prevent postprandial hyperglycaemia.
isoquercitrin
Glucagon-like peptide (GLP)-1 is a potent glucose -dependent insulin otropic gut hormone released from intestinal L cells. The aim of this study was to investigate isoquercitrin as an inhibitor of dipeptidyl peptidase IV (DPP-IV) and determine whether it affects GLP-1 release in normal mice and NCI-H716 cells. In vitro, we used chromogenic substrate method detection methods to measure DPP-IV. We found that isoquercitrin was a competitive inhibitor , with IC50 and Ki values of 96.8 and 236 μM, respectively.
Isoquercitrin and sitagliptin also stimulated GLP-1 release in NCI-H716 cells. In vivo, a type 2 diabetic mouse model was established, and oral treatment with different concentration of isoquercitrin and sitagliptin for 8 weeks significantly decreased the fasting blood glucose level . The weight and the levels of serum GLP-1 and insulin of the mice in the isoquercitrin group were higher than those in the model group (P < 0.001). An oral glucose tolerance test showed that the isoquercitrin significantly inhibited postprandial blood glucose changes in a dose-dependent manner.
These findings demonstrated the hypoglycemic effects of isoquercitrin and indicated that isoquercitrin improved insulin sensitivity by targeting DPP-IV.
High glucose (HG)‑induced endothelial apoptosis serves an important role in the vascular dysfunction associated with diabetes mellitus (DM). It has been reported that isoquercitrin (IQC), a flavonoid glucoside, possesses an anti‑DM effect, but the mechanism requires further investigation. The present study investigated the effect of IQC against HG‑induced apoptosis in human umbilical vein endothelial cells (HUVECs) and explored its molecular mechanism. HUVECs were treated with 5 or 30 mM glucose for 48 h. Endothelial cell viability was monitored using the Cell Counting Kit‑8 assay. mitochondrial membrane potential was detected by JC‑1 staining.
Apoptosis was observed by TUNEL staining and flow cytometry. Western blotting was used for the analysis of apoptosis‑associated proteins Bax, Bcl‑2, cleaved (C)‑caspase3, total‑caspase3, p53 and phosphorylated p53. Reverse transcription‑quantitative PCR was used to analyze the mRNA expression levels of Bax, Bcl‑2 and p53. Immunofluorescence staining was utilized to detect the expression levels and distribution of p53 and ubiquitin specific peptidase 10 (USP10) in HUVECs.
The results revealed that IQC significantly attenuate d HG‑induced endothelial apoptosis, as shown by decreased apoptotic cells observed by TUNEL, JC‑1 staining and flow cytometry. Moreover, under HG stress , IQC treatment markedly inhibited the increased expression levels of the pro‑apoptotic proteins p53, Bax and C‑caspase3, and increased the expression levels of the anti‑apoptotic protein Bcl‑2 in HUVECs. However, the anti‑apoptotic effect of IQC against HG was partially blunted by increasing p53 protein levels in vitro. IQC influenced the mRNA expression levels of Bax and Bcl‑2 in response to HG, but it did not affect the transcription of p53. Notably, IQC inhibited the HG‑induced phosphorylation of p53 at Ser15 and the nuclear transport of USP10, destabilizing p53 and increasing the proteasomal degradation of the p53 protein.
The current findings revealed that IQC exerted a protective effect against the HG‑induced apoptosis of endothelial cells by regulating the proteasomal degradation of the p53 protein, suggesting that IQC may be used as a novel therapeutic compound to ameliorate DM‑induced vascular complications .
Quercetin and Isoquercitrin Inhibiting Hepatic Gluconeogenesis Through LKB1-AMPK α Pathway
Objective: To observe the impact of quercetin and isoquercitrin on gluconeogenesis in hepatocytes.
Methods: Mouse primary hepatocytes were cultured with lactic acid and pyruvic acid . After treatment with quercetin and isoquercitrin for 24 hours, the glucose concentration in the culture supernatant was determined. RT-PCR was used to detect the mRNAs of PEPCK, G6Pase, LKB1, and AMPK α. Protein levels of LKB1, AMPK α, and Thr172 phosphorylation were evaluated by Western blot.
Results: The glucose concentration in the gluconeogenesis group (GN) was significantly higher than in the control group (C), but the glucose concentrations in the high level quercetin(group 80Q) and high level isoquercitrin (group 80I) were significantly lower than in the group GN, P<0.01. In the group 80Q, and group 80I, the mRNA levels of PEPCK and LKB1were significantly lower than in the group GN (P<0.01), and the G6Pase mRNA were significantly lower than in the group GN (P<0.05). The protein levels of LKB1 and the phosphorylation of AMPK α Thr172 in the group 80Q, group 40I, and group 80I were higher than in the group GN. The effects of quercetin and isoquercitrin on LKB1 and AMPK α were similar to those of metformin.
Kaempferol
Our aim was to investigate the effect of several dietary polyphenols on glucose uptake by breast cancer cells. Uptake of 3H-deoxy-D-glucose (3H-DG) by MCF-7 cells was time-dependent, saturable, and inhibited by cytochalasin B plus phloridzin. In the short-term (26 min), myricetin, chrysin, genistein, resveratrol, kaempferol, and xanthohumol (10–100 µM) inhibited 3H-DG uptake. Kaempferol was found to be the most potent inhibitor of 3H-DG uptake [IC50 of 4 µM (1.6–9.8)], behaving as a mixed-type inhibitor.
In the long-term (24 h), kaempferol (30 µM) was also able to inhibit 3H-DG uptake , associated with a 40% decrease in GLUT1 mRNA levels. Interestingly enough, kaempferol (100 µM) revealed antiproliferative (sulforhodamine B and 3H-thymidine incorporation assays) and cytotoxic (extracellular lactate dehydrogenase activity determination) properties, which were mimicked by low extracellular (1 mM) glucose conditions and reversed by high extracellular (20 mM) glucose conditions. Finally, exposure of cells to kaempferol (30 µM) induced an increase in extracellular lactate levels over time (to 731 ± 32% of control after a 24 h exposure), due to inhibition of MCT1-mediated lactate cellular uptake.
In conclusion, kaempferol potently inhibits glucose uptake by MCF-7 cells, apparently by decreasing GLUT1-mediated glucose uptake. The antiproliferative and cytotoxic effect of kaempferol in these cells appears to be dependent on this effect.
In diabetes mellitus, the excessive rate of glucose production from the liver is considered a primary contributor for the development of hyperglycemia , in particular, fasting hyperglycemia . In this study, we investigated whether kaempferol, a flavonol present in several medicinal herbs and foods, can be used to ameliorate diabetes in an animal model of insulin deficiency and further explored the mechanism underlying the anti-diabetic effect of this flavonol. We demonstrate that oral administration of kaempferol (50 mg/kg/day) to streptozotocin-induced diabetic mice significantly improve d hyperglycemia and reduced the incidence of overt diabetes from 100% to 77.8%.
This outcome was accompanied by a reduction in hepatic glucose production and an increase in glucose oxidation in the muscle of the diabetic mice, whereas body weight, calorie intake, body composition, and plasma insulin and glucagon levels were not altered. Consistently, treatment with kaempferol restored hexokinase activity in the liver and skeletal muscle of diabetic mice while suppressed hepatic pyruvate carboxylase activity and gluconeogenesis.
These results suggest that kaempferol may exert antidiabetic action via promoting glucose metabolism in skeletal muscle and inhibiting gluconeogenesis in the liver.
Obesity-associated insulin resistance (IR) is a major risk factor for developing type 2 diabetes and an array of other metabolic disorders. In particular, hepatic IR contributes to the increase in hepatic glucose production and consequently the development of fasting hyperglycemia. In this study, we explored whether kaempferol, a flavonoid isolated from Gink go biloba, is able to regulate hepatic gluconeogenesis and blood glucose homeostasis in high-fat diet-fed obese mice and further explored the underlying mechanism by which it elicits such effects.
Oral administration of kaempferol (50 mg/kg/day), which is the human equivalent dose of 240 mg/day for an average 60 kg human, significantly improved blood glucose control in obese mice, which was associated with reduced hepatic glucose production and improved whole-body insulin sensitivity without altering body weight gain, food consumption or adiposity. In addition, kaempferol treatment increased Akt and hexokinase activity, but decreased pyruvate carboxylase (PC) and glucose-6 phosphatase activity in the liver without altering their protein expression.
Consistently, kaempferol decreased PC activity and suppressed gluconeogenesis in HepG2 cells as well as primary hepatocytes isolated from the livers of obese mice. Furthermore, we found that kaempferol is a direct inhibitor of PC. These findings suggest that kaempferol may be a naturally occurring antidiabetic compound that acts by suppressing glucose production and improving insulin sensitivity. Kaempferol suppression of hepatic gluconeogenesis is due to its direct inhibitory action on the enzymatic activity of PC.
kurarinone
Na+-glucose cotransporter (SGLT) inhibitory flavonoid s from the roots of Sophora flavescens
The methanol extract of Sophora flavescens, which is used in traditional Chinese medicine (sophorae radix), showed potent Na+–glucose cotransporter (SGLT) inhibitory activity . Our search for active components identified many well-known flavonoid antioxidants: kurarinone, sophoraflavanone G, kushenol K, and kushenol N.
Diabetes mellitus currently affects as many as 400 million people worldwide, creating a heavy economic burden and stretching health care resources. A dysfunction of glucose homeostasis underlies the disease. Despite advances in the treatment of diabetes , many patients still suffer from complications and side effects; hence, development of more effective treatments for diabetes is still desirable. SGLT2 is the principle cotransporter involved in glucose reabsorption in the kidney . SGLT2 inhibition reduce s glucose reabsorption by the kidney and ameliorates plasma glucose concentration. The interest in natural products that can be used for the inhibition of SGLT2 is growing. The flavonoid phlorizin, which can be isolated from the bark of apple trees, has been used as lead structure due to its inhibitory activity of SGLT1 and SGLT2.
Some phlorizin -derived synthetic compounds, including canagliflozin, dapagliflozin, empagliflozin, ipragliflozin, and ertugliflozin, are approved by the food and drug administration to treat type 2 diabetes mellitus (T2DM), whereas others are under clinical trials investigation. In addition, other natural product-derived compounds have been investigated for their ability to improve blood glucose control.
The present review summarizes the natural products with SGLT2 inhibitory activity, and the synthetic compounds obtained from them, and discusses their application for the treatment of diabetes.
Lagerstroemia speciosa
Seven ellagitannins, lagerstroemin (1), flosin B (2), stachyurin (3), casuarinin (4), casuariin (5), epipunicacortein A (6), and 2, 3-(S)-hexahydroxydiphenoyl-α/β-d–glucose (7), together with one ellagic acid sulfate, 3-O-methyl-ellagic acid 4′-sulfate (8), ellagic acid (9), and four methyl ellagic acid derivatives, 3-O-methylellagic acid (10), 3,3′-di-O-methylellagic acid (11), 3,4,3′-tri-O-methylellagic acid (12), and 3,4,8,9,10-pentahydroxydibenzo[b,d]pyran-6-one (13), were identified by the bioassay-directed isolation from the leaves of Lagerstroemia speciosa (L.) Pers. The chemical structures of these components were established on the basis of one- and two-dimensional NMR and high-resolution mass spectroscopic analyses.
Other known compounds, including corosolic acid , gallic acid , 4-hydroxybenzoic acid , 3-O-methylprotocatechuic acid , caffeic acid , p-coumaric acid , kaempferol, quercetin, and isoquercitrin, were also isolated from the same plant. The obtained ellagitannins exhibited strong activities in both stimulating insulin -like glucose uptake (1−5 and 7) and inhibiting adipocyte differentiation (1 and 4) in 3T3-L1 cells. Meanwhile, ellagic acid derivatives (10−13) showed an inhibitory effect on glucose transport assay. This study is the first to report an inhibitory effect for methyl ellagic acid derivatives.
Banaba (Lagerstroemia speciosa L.) has been recognized as a folk medicine for diabetes in the Philippines. A hot water extract (HWE) of banaba leaves dose-dependently suppressed the elevation of blood glucose after oral administration of starch, but had no such effect after ingestion of glucose . The HWE was fraction ated using HP-20 column chromatography, and its methanol fraction (HPME) was found to suppress the elevation of blood glucose after oral administration of starch.
The inhibitory action of the HWE on activities of alpha-amylase and alpha-glucosidases was then examined in vitro. The HWE inhibited the activities of alpha-amylase, maltase, glucoamylase, sucrase and isomaltase, with estimated IC50 values of 0.53, 0.89, 1.24, 2.85 and 4.95mg/mL, respectively. The HPME also inhibited alpha-amylase and glucoamylase with IC50 values of 0.44 and 0.83 mg/mL, respectively.
These results suggest that the inhibitory effect of banaba on postprandial hyperglycemia is due to inhibition of alpha-amylase and alpha-glucosidases. Banaba may be a useful natural material for the prevention and therapy of diabetes.
Antidiabetes and Anti-obesity activity of Lagerstroemia speciosa
The leaves of Lagerstroemia speciosa (Lythraceae), a Southeast Asian tree more commonly known as banaba, have been traditional ly consumed in various forms by Philippinos for treatment of diabetes and kidney related diseases . In the 1990s, the popularity of this herbal medicine began to attract the attention of scientists worldwide. Since then, researchers have conducted numerous in vitro and in vivo studies that consistently confirmed the antidiabetic activity of banaba. Scientists have identified different components of banaba to be responsible for its activity . Using tumor cells as a cell model, corosolic acid was isolated from the methanol extract of banaba and shown to be an active compound. More recently, a different cell model and the focus on the water soluble fraction of the extract led to the discovery of other compounds. The ellagitannin Lagerstroemin was identified as an effective component of the banaba extract responsible for the activity.
In a different approach, using 3T3-L1 adipocytes as a cell model and a glucose uptake assay as the functional screening method, Chen et al. showed that the banaba water extract exhibited an insulin-like glucose transport inducing activity. Coupling HPLC fraction ation with a glucose uptake assay, gallotannins were identified in the banaba extract as components responsible for the activity , not corosolic acid . Penta-O-galloyl-glucopyranose (PGG) was identified as the most potent gallotannin. A comparison of published data with results obtained for PGG indicates that PGG has a significantly higher glucose transport stimulatory activity than Lagerstroemin. Chen et al. have also shown that PGG exhibits anti-adipogenic properties in addition to stimulating the glucose uptake in adipocytes.
The combination of glucose uptake and anti-adipogenesis activity is not found in the current insulin mimetic drugs and may indicate a great therapeutic potential of PGG.
Laminaria japonica extract
he rhizoid of Laminaria japonica is widely used in Chinese medicine as a treatment for diabetes. Therefore, a bioactivity-tailored isolation and detailed chemical characterization was used to identify the antidiabetes compounds found in the L. japonica rhizoid. Liquid chromatography/mass spectrometry (LC/MS), proton NMR and carbon NMR spectra analyses demonstrated that the active compound was butyl-isobutyl-phthalate (BIP). BIP demonstrated a significant concentration-dependent, non-competitive inhibitory activity against α-glucosidase in vitro, with an IC50 of 38 μm.
In vivo, the ethyl acetate fraction (EAF) and purified BIP displayed a significant hypo-glycemic effect in streptozocin-induced diabetic mice. The present study indicates BIP could be considered as an α-glucosidase inhibitor and developed as an important anti-diabetes agent for type II diabetes therapy.
Laminaria japonica (LJ) and Hizikia fusiforme (HF) are brown seaweeds known to have various health-promoting effects. In this study, we investigated the anti-diabetic effects and possible mechanism(s) of LJ and HF by using both in vitro and in vivo models. C2C12 myotubes, mouse-derived skeletal muscle cells, treated with LF or HF extracts were used for the in vitro model, and muscle tissues from C57BL/6N mice fed a high-fat diet supplemented with 5% LF or HF for 16 weeks were used for the in vivo model. Although both the LF and HF extracts significantly inhibited α-glucosidase activity in a dose-dependent manner, the HF extract had a superior α-glucosidase inhibition than the LF extract. In addition, glucose uptake was significantly increased by LJ– and HF-treated groups when compared to the control group.
Phosphorylation of protein kinase B and AMP-activated protein kinase was induced by LJ and HF in both the vivo and in vitro skeletal muscle models. Furthermore, LJ and HF significantly decreased tumor necrosis factor-α whereas both extracts increased interleukin (IL)-6 and IL-10 production in lipopolysaccharide-stimulated C2C12 myotubes. Taken together, these findings imply that the brown seaweeds LJ and HF could be useful therapeutic agents to attenuate muscle insulin resistance due to diet-induced obesity and its associated inflammation .
Lavandula stoechas
Ameliorative potential of Lavandula stoechas in metabolic syndrome via multitarget interaction s
Ethnopharmacological importance: Decoction and infusion prepared from aerial parts of Lavandula stoechas L. (L. stoechas) have been traditionallyused as remedy against several components of metabolic syndrome (MetS) and associated disorders including type II diabetes and cardiovascular diseases by Anatolian people.
Aim of the study: The aim is to elucidate the potential ameliorative effects of L. stoechas aqueous extracts on insulin resistance and inflammation models through multitarget in vitro approaches and also to elucidate mechanism of action by analyzing transcriptional and metabolic responses.
Materials and methods: An aqueous extract was prepared and fraction ated to give rise to ethyl acetate (EE) and butanol (BE) extracts. The anti-insulin resistance effects of BE and EE were evaluated on palmitate induced insulin resistance model of H4IIE, C2C12 and 3T3L1 cells by using several metabolic parameters. Specifically, whole genome transcriptome analysis was performed by using microarray over 55.000 genes in control, insulin resistant and EE (25 µg/mL) treated insulin resistant H4IIE cells. Anti-inflammatory effects of both extracts were analyzed in LPS-stimulated RAW264.7 macrophages.
Results: Both EE and BE at low doses (25–50 µg/mL) significantly decreased hepatic gluconeogenesis in H4IIE cell line by suppressing the expression of PEPCK and G6Pase. In C2C12 myotubes, both extracts increased the insulin stimulated glucose uptake more effective ly than metformin. Both extracts decreased the isoproterenol induced lipolysis in 3T3L1 cell line. Moreover, they also effective ly increased the expression of lipoprotein lipase protein level in insulin resistant myotubes at low doses. EE increased the protein level of PPARγ and stimulated the activation AKT in insulin resistant H4IIE and C2C12 cell lines. The results obtained from biochemical assays, mRNA/protein studies and whole genome transcriptome analyses were found to be complementary and provided support for the hypothesis that EE might be biologically active against insulin resistance and act through the inhibition of liver gluconeogenesis and AKT activation. Besides, LPS induced inflammation in RAW264.7 macrophages was mainly inhibited by EE through suppression of iNOS/NO signaling, IL1β and COX-2 genes. HPLC-TOF/MS analysis of EE of L. stoechas mainly resulted in caffeic acid, apigenin, luteolin, rosmarinic acid and its methyl ester, 4-hydroxybenzoic acid, vanillic acid, ferrulic acid and salicylic acid.
Conclusion: Data suggest that EE of L. stoechas contains phytochemicals that can be effective in the treatment /prevention of insulin resistance and inflammation. These results validate the traditional use of L. stoechas in Anatolia against several metabolic disorders including metabolic syndrome.
Background: The present study described the phytochemical profile of Lavandula stoechas essential oils, collected in the area of Ain-Draham (North-West of Tunisia), as well as their protective effects against alloxan-induced diabetes and oxidative stress in rat.
Methods: Essential oils samples were obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC–MS. Rats were divided into four groups: Healthy Control (HC); diabetic Control (DC); Healthy + Essential Oils (H + EO) and diabetic + Essential Oils (D + EO).
antidiabetic and antioxidant activities were evaluated after subacute intraperitoneally injection of Lavandula stoechas essential oils (50 mg/kg b.w., i.p.) to rats during 15 days.
Results: The principal compounds detected are: D-Fenchone (29.28%), α-pinene (23.18%), Camphor (15.97%), Camphene (7.83%), Eucapur (3.29%), Limonene, (2.71%) Linalool, (2.01%) Endobornyl Acetate (1.03%). The essential oils also contained smaller percentages of Tricyclene, Cymene, Delta-Cadinene, Selina-3,7(11)-diene. Furthermore, we found that Lavandula stoechas essential oils significantly protected against the increase of blood glucose as well as the decrease of antioxidant enzyme activities induced by aloxan treatment. Subacute essential oils treatment induced a decrease of lipoperoxidation as well as an increase of antioxidant enzyme activities.
Conclusions: These findings suggested that lavandula stoechas essential oils protected against diabetes and oxidative stress induced by alloxan treatment. These effects are in partly due to its potent antioxidant properties.
Medicinal properties of Mediterranean plants against glucose and lipid disorders
There are several components isolated from plants grown in Mediterranean environment exhibiting significant beneficial properties against a variety of disorders related to lipid or glucose metabolism. In this context, plant species (e.g. Salvia officinalis, Rosmarinus officinalis, Lavandula stoechas, Melissa officinalis, Mentha piperita, Thymus vulgaris,Origanum majorana, Sideritis raeseri, Ocimum basilicum, Pistacia lentiscus, Crocus sativus, Daucus carota) may act against lipid or carbohydrate metabolic disorders through their antioxidant, anti-inflammatory or other properties, or due to the beneficial action s of their compounds.
New horizons are very promising, since these plant species have been used both in traditional medicine and in current clinical practice.
Levisticum officinale
Levisticum officinale (Apiaceae) is a favorite food spice. Iranian folk medicine claims that it has a prominent antidyslipidemic property but this is not documented scientifically so far. This study evaluated antidyslipidemic and the other antidiabetic aspects of the stem and leaf hydroalcoholic extract of it (LOE). Regarding oral glucose tolerance test results, LOE (500 mg/kg) administration 30 min before glucose loading significantly decreased the blood glucose level (13%) at 90 min in male rats.
Additionally, LOE treatment (500 mg/kg, orally, once a day) for 14 days significantly reduced the serum glucose level (24.97%) and markedly improve d the lipid profile and the insulin , creatinine, alanine aminotransferase and aspartate aminotransferase serum levels in diabetic rats. Moreover, LOE effective ly amended the impaired antioxidant status and ameliorated lipid peroxidation in the plasma and pancreas and liver tissues of diabetics. Also, 14 days LOE treatment, significantly decreased the renal sodium –glucose cotransporter 2 and facilitated glucose transporter 2 (GLUT2) mRNA levels and GLUT2 gene expression in the enterocytes of jejunum tissue in comparison with diabetic untreated rats.
HPLC method revealed the presence of chlorogenic acid, rosmarinic acid, caffeic acid, quercetin and luteolin and GC-MS analysis detected bioactive compounds like phthalides, thymol, phytol, hexanoic acid , carene and menthofuran. LOE showed α-amylase (αΑ) inhibitory activity and in silico studies predicted that among extract ingredients luteolin, quercetin, rosmarinic, caffeic, and hexanoic acids shave the greatest αΑ inhibition potecy. Thus, current results justify antidyslipidemic value of L. officinale and shed light on more antidiabetic health benefits of it.
Litchi chinensis Sonn.seed extract
Phenolic composition of litchi (Litchi chinensis Sonn.) pulp from three cultivars was tentatively characterized and quantified by HPLC–MS. Pulp from hemaoli, a wild litchi cultivar, showed the highest content of total phenolics, flavonoids and procyanidins, the latter accounting for the majority of phenolic compounds identified. In hemaoli, (−)-epicatechin was the predominant compound, whereas flavone glycosides accounted for the majority of the phenolic compounds identified in Feizixiao and Lanzhu cultivars, with quercetin rhammosyl-rutinoside being predominant.
Hemaoli pulp caused the highest enhancement of glucose consumption rate in HepG2 cells, followed by Feizixiao pulp. This bioactivity was significantly correlated with antioxidant capacity, and total content of phenolics, flavonoids, and procyanidins of different cultivars. (−)-Epicatechin, but not quercetin rhammosyl-rutinoside, also resulted in a significant rise in glucose consumption activity.
These results showed that litchi cultivars with high (−)-epicatechin content or high procyanidin content may have great potential as hypoglycaemic foods.
In this study, a novel homogeneous polysaccharide (LSP-W-4, MW = 6.70 kDa) was isolated and purified from the seeds of Litchi chinensis Sonn. Monosaccharide composition analysis indicated that LSP-W-4 is a heteropolysaccharide consisting of arabinose, mannose, glucose and galactose in a molar ratio of 6.33:3.88:10.35:1.00. A detailed structural analysis revealed that LSP-W-4 has a backbone consisting of 1,4-α-Glcp and 1,4-β-Manp, as well as four branched chains including of T-α-Galp, T-α-Araf, α-Araf-(1 → 5)-α-Araf-(1 → and α-Araf-(1 → 5)-α-Araf-(1 → 5)-α-Araf-(1 → attached to O6 of 1,4-β-Manp and 1,4-α-Glcp. LSP-W-4 exhibited significant inhibitory activity both against yeast (Saccharomyces cerevisiae) and mammalian (rat-intestinal acetone powder) α-glucosidase , with IC50 values of 75.24 μM and 66.97 μM, respectively, with both such inhibitory activities being more powerful than those of acarbose.
A kinetic analysis revealed that LSP-W-4 inhibited the activities of both yeast and mammalian α-glucosidase in a typical non-competitive manner, with KM values of 0.43 mmol/L and 0.53 mmol/L, respectively.
Lonicera japonica Thunb. extract
hyperglycemia and dyslipidemia are classic features for diabetes mellitus (DM). In this study, one fraction of the crude polysaccharides extracted from Lonicera japonica flower buds (LJP) were investigated for its hypolipidaemic and hypoglycaemic activities by means of streptozotocin (STZ)-induced diabetic rats. Interestingly, after orally administrated with 800 mg/kg body weight (B.W.) LJP for 42 days, the food and water intake and the levels of sugar and insulin in blood for the diabetic rats were drastically decreased, while the contents of liver and skeletal muscle glycogen and the concentrations of hepatic pyruvate kinase and hexokinase were obviously increased (p < 0.01 or p < 0.05). The levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterin (LDL-C) and very-low-density lipoprotein-cholesterin (VLDL-C) were significantly descended, while high-density lipoprotein-cholesterin (HDL-C) was significantly ascended (p < 0.01 or p < 0.05). In addition, the oxidant stress in liver was restored as well.
The results suggested that LJP could be considered as an ingredient of functional foods for diabetes, and this is the first report about the hypo-glycemic and hypolipidemic effects of the polysaccharides extracted from Lonicera japonica.
Lycium chinense Mill. extract
Study on Anti-obesity and Hypoglycemic Effects of Lycium chinense Mill Extracts
This study was designed to evaluate the anti-obesity and hypoglycemic effects of Gugija (Lycium chinense Mill) extracts in 3T3-L1 adipocytes. We investigated the -amylase and -glucosidase inhibitory activities of extracts from Gugija. Gugija was extracted by 70% EtOH and 80% MeOH and aqueous, respectively. A single oral dose of Gugija extract inhibited the increase of blood glucose levels significantly at 0, 30, 60, 90 and 120 min and decreased incremental response areas under the glycemic response curve. These results suggest that Gugija 70% EtOH extracts may delay carbohydrate digestion and reduce postprandial hyperglycemia.
In addition, triglyceride content in 3T3-L1 adipocytes decreased at higher concentrations of Gugija 70% EtOH extract. Free fatty acid content in 3T3-L1 adipocytes was increased at higher concentrations of Gugija 70% EtOH extract. Also, glucose transporter 4 (GLUT4 ), the key insulin signaling pathway transcription factor, was remarkably increased by the Gugija 70% EtOH extract when compared to those of control cells in protein expression levels. Therefore, Gugija can be developed as an effective anti-obesity and hypo-glycemic agent.
maqui berries (Aristotelia chilensis)
Aim. The impetus of our study was to investigate the effects of a nutritional supplement Delphinol®, an extract of maqui berries (Aristotelia chilensis) standardised to ≥25% delphi-nidins and ≥35% total anthocyanins, on postprandial blood glucose and insulin levels and identify the physiologic mecha-nism involved.Methods. Postprandial blood glucose and insulin were investi-gated in double-blind, placebo-controlled, cross-over fashion in ten volunteers with moderate glucose intolerance. Longer term effects on blood sugar levels were investigated in strep-tozotocin-diabetic rats over a four months period. Effects of maqui berry delphinidins on sodium –glucose symport were examined in rodent jejenum of the small intestine.Results. Delphinol® intake prior to rice consumption statisti-cal signi”cantly lowered post prandial blood glucose and in-sulin as compared to placebo.
We identified an inhibition of Na+-dependant glucose transport by delphinidin, the princi-pal polyphenol to which Delphinol® is standardised. In a dia-betic rat model the daily oral application of Delphinol® over a period of four months signi”cantly lowered fasting blood glu-cose levels and reached values indistinguishable from healthy non-diabetic rats.Conclusion.
Our results suggest a potential use of Delphinol®for natural ly controlling post-prandial blood glucose owed to inhibition of sodium glucose co-transporter in small intestine.
Momordica charantia L. extract
The hypoglycaemie effect of orally administered extracts of Momordica charantia L. fruits was examined in normoglycaemic or cyproheptadine-induced hyperglycaemic mice. The aqueous extract reduced the fasting glucose levels of hyperglycaemic or normoglycaemic mice. However, the ethanol extract did not affect the fasting or nonfasting glucose levels significantly in both groups of mice. There was no significant difference between the glucose-loaded and glucose-loaded plus aqueous extract given group. On the other hand, oral glucose-loading of the cyproheptadine-induced hyperglycaemic animals reduced the fasting glucose levels significantly.
These results showed that aqueous extract of M. charantia fruits has a hypoglyeaemic activity without improving the tolerance to glucose in cyproheptadine-induced diabetic mice.
Effect of Momordica charantia, a bitter vegetable popularly known as Karolla, on fasting and post prandial (2 hours after 75 gm oral glucose intake) serum glucose levels were studied in 100 cases of moderate non-insulin dependent diabetic subjects. Drinking of the aqueous homogenized suspension of the vegetable pulp led to significant reduction (p < 0.001) of both fasting and post-prandial serum glucose levels. This hypoglycaemic action was observed in 86 (86%) cases. Five cases (5%) showed lowering of fasting serum glucose only.
Anti-diabetic properties and phytochemistry of Momordica charantia L. (Cucurbitaceae)
Unripe fruit, seeds and aerial parts of Momordica charantia Linn. (Cucurbitaceae) have been used in various parts of the world to treat diabetes. Oral administration of the fruit juice or seed powder causes a reduction in fasting blood glucose and improves glucose tolerance in normal and diabetic animals and in humans. Animal and in vitro data support both insulin secretagogue and insulin omimetic activity of the fruit. However, enhanced insulin levels in vivo in response to its administration have not been observed. Although a wide range of compounds have been isolated from Momordica charantia, notably steroidal compounds and proteins, the orally active antidiabetic principle has not been adequately identified. A polypeptide, p-insulin, produces hypoglycaemic effects in humans and animals on subcutaneous injection, but oral activity is questionable.
Other reported hypoglycaemic principles from Momordica charantia include the sterol glucoside mixture charantin (fruit) and the pyrimidine nucleoside vicine (seeds). However these are only effective at doses too high to account for all the activity of the plant extract. Principal toxicity of Momordica charantia in animals is to the liver and reproductive system. These effects have not been reported in humans despite widespread use of the fruit medicinally and as a vegetable.
antihyperglycemic effects of three extracts from Momordica charantia
Momordica charantia (L.) (Cucurbitaceae) commonly known as bitter gourd or karela is a medicinal plant, used in Ayurveda for treating various diseases, one of which is diabetes mellitus. In this study, various extract powders of the fresh and dried whole fruits were prepared and their blood glucose lowering effect compared by administrating them orally to diabetic rats. The aqueous extract powder of fresh unripe whole fruits at a dose of 20 mg/kg body weight was found to reduce fasting blood glucose by 48%, an effect comparable to that of glibenclamide, a known synthetic drug.
This extract was tested for nephrotoxicity, hepatotoxicity and biochemical parameters such as SGOT, SGPT and lipid profile. The extract did not show any signs of nephrotoxicity and hepatotoxicity as judged by histological and biochemical parameters. Thus the aqueous extract powder of Momordica charantia, an edible vegetable, appears to be a safe alternative to reducing blood glucose.
The antidiabetic activity of Momordica charantia L. (Cucurbitaceae) with exercise was investigated in KK-Ay mice, an animal model with type 2 diabetes with hyperinsulin emia. The water extract of the fruit of Momordica charantia L. (MC) with exercise reduced the blood glucose of KK-Ay mice 5 weeks after oral administration (p<0.001), and also significantly lowered the plasma insulin of KK-Ay mice under similar conditions (p<0.01). The blood glucose of MC with exercise is lower than that of MC only or exercise only 5 weeks after the administration. MC with exercise decreased blood glucose in a glucose tolerance test. These results suggest that MC with exercise is useful for type 2 diabetic cure.
Background: Studies on several preclinical models of type 2 diabetes mellitus have been conducted to establish the hypoglycemic activity of Momordica charantia L. Concerned with appropriateness of these models, we designed a systematic review to establish the efficacy and safe ty of M. charantia L. in preclinical models of type 2 diabetes mellitus .
Methods: Review authors will search without language restriction in MEDLINE/PubMed, Web of Science, Embase, Scopus, and CINAHL databases through April 2019. Search filters will be applied to enhance search efficiency. The authors will search for gray literature in Google and Google Scholar, OpenGrey, and ProQuest Dissertations & Theses. Two authors will evaluate full texts, extract data, and asses risk of bias independently. The review will include randomized or non-randomized studies that assessed the efficacy or safe ty of M. charantia L. with vehicle control group. The primary endpoint will be fasting blood glucose level. We will use Egger’s test to assess publication biases. Chi-square test and I2 will be used to assess heterogeneity in effect size of the primary outcome. Using RevMan software version 5.3, the authors will perform a meta-analysis of quantitative data.
Discussion: The strength of evidence will be rated as high, moderate, low, or very low using GRADE framework for animal studies. This systematic review will potentially improve research practice by identifying risks of bias and design features that compromise translatability and contribute to evidence-based clinical trial design.
Extracts of Momordica charantia Suppress Postprandial hyperglycemia in Rats
Momordica charantia (bitter melon) is commonly known as vegetable insulin, but the mechanisms underlying its hypo-glycemic effect remain unclear. To address this issue, the effects of bitter melon extracts on postprandial glycemic responses have been investigated in rats. An aqueous extract (AE), methanol fraction (MF) and methanol insoluble fraction (MIF) were prepared from bitter melon. An oral sucrose tolerance test revealed that administration of AE, MF or MIF each significantly suppressed plasma glucose level s at 30 min as compared with the control. In addition, the plasma insulin level at 30 min was also significantly lower after MF administration than in the control in the oral sucrose tolerance test.
By contrast, these effects of bitter melon extracts were not observed in the oral glucose tolerance test. In terms of mechanism, bitter melon extracts dose-dependently inhibited the sucrase activity of intestinal mucosa with IC50 values of 8.3, 3.7 and 12.0 mg/mL for AE, MF and MIF, respectively. The fraction with a molecular weight of less than 1,300 (LT 1,300) obtained from MF inhibited the sucrase activity most strongly in an uncompetitive manner with an IC50 value of 2.6 mg/mL.
Taken together, these results demonstrated that bitter melon suppressed postprandial hyperglycemia by inhibition of α-glucosidase activity and that the most beneficial component is present in the LT 1,300 fraction obtained from MF.
Morus alba L root and peel extract
Polyphenols-Rich natural products for treatment of diabetes
Currently, experimental and clinical evidences showed that polyphenols-rich natural products, like nutraceuticals and food supplements, may offer unique treatment modalities in type 2 diabetes mellitus (DM), due to their biological properties. natural products modulate the carbohydrate metabolism by various mechanisms, such as restoring beta-cells integrity and physiology, enhancing insulin releasing activity, and the glucose using. Sea buckthorn berries, red grapes, bilberries, chokeberries and popular drinks like cocoa, coffee and green tea are all rich in polyphenols and may decrease the insulin response, offering a natural alternative of treatment in diabetes.
Therefore, researches are now focused on potential efficacies of different types of polyphenols, including flavonoids, phenolic acids, lignans, anthocyans and stilbenes. Animal and human studies showed that polyphenols modulate carbohydrate and lipid metabolism, decrease glycemia and insulin resistance, increase lipid metabolism and optimize oxidative stress and inflammatory processes. It is important to understand the proper dose and duration of supplementation with polyphenols-rich extracts in order to guide effective therapeutic interventions in diabetic patients.
Mulberry Leaf extract
Effect of Buan Mulberry on metabolic improve ment in Streptozotocin-Induced diabetic Rats
This study was designed to evaluate the anti-diabetic effects of Buan mulberries by using an insulin -dependent diabetes mellitus animal model. Several studies have shown that mulberries have metabolism -improving, antioxidant, and lipid-lowering properties in rats with streptozotocin (STZ)-induced diabetes.
In this study, Sprague-Dawley male rats were randomly assigned to 1 normal control group and 5 STZ-induced diabetes groups: rats that had STZ-induced diabetes and did not receive any agents (diabetic group; negative control), rats that had STZ-induced diabetes and received insulin (insulin group; positive control), rats that had STZ-induced diabetes and received 0.5% mulberry extract (0.5% mulberry group), rats that had STZ-induced diabetes and received 1.0% mulberry extract (1.0% mulberry group), and rats that had STZ-induced diabetes and received 2.0% mulberry extract (2.0% mulberry group).
Mulberry extracts were administered to the diabetic animals for 4 weeks. The rats that received mulberry extracts showed lower body weights and insulin levels, as well as higher kidney weights, blood glucose levels, urine quantities, and water intake in comparison with the normal controls. Further, the insulin concentrations in the mulberry-fed animals were higher than those in the diabetic group, and the kidney weights, blood glucose levels , urine quantities, and water intake in the mulberry-fed animals were lower than the corresponding values in the diabetic controls.
These results suggest that mulberry may be an effective function al food to prevent diabetes–related complications.
myricetin
Unraveling the inhibition of intestinal glucose Transport by Dietary Phenolics: A Review
Background: Glucose transport across the intestinal brush border membrane plays a key role in metabolic regulation. Depending on the luminal glucose concentration, glucose is mainly transported by the sodium– dependent glucose transporter (SGLT1 ) and the facilitated-transporter glucose transporter (GLUT2). SGLT1 is apical membrane-constitutive and it is active at a low luminal glucose concentration, while at concentrations higher than 50 mM, glucose is mainly transported by GLUT2 (recruited from the basolateral membrane). Dietary phenolic compounds can modulate glucose homeostasis by decreasing the postprandial glucose response through the inhibition of SGLT1 and GLUT2.
Methods: Phenolic inhibition of intestinal glucose transport has been examined using brush border membrane vesicles from rats, pigs or rabbits, Xenopus oocytes and more recently Caco-2 cells, which are the most promising for harmonizing in vitro experiments.
Results: Phenolic concentrations above 100 μM has been proved to successfully inhibit the glucose transport. Generally, the aglycones quercetin, myricetin, fisetin or apigenin have been reported to strongly inhibit GLUT2, while quercetin-3-O-glycoside has been demonstrated to be more effective in SGLT1. Additionally, epigallocatechin as well as epicatechin and epigallocatechin gallates were observed to be inhibited on both SGLT1 and GLUT2.
Conclusion: Although, valuable information regarding the phenolic glucose transport inhibition is known, however, there are some disagreements about which flavonoid glycosides and aglycones exert significant inhibition, and also the inhibition of phenolic acids remains unclear. This review aims to collect, compare and discuss the available information and controversies about the phenolic inhibition of glucose transporters. A detailed discussion on the physicochemical mechanisms involved in phenolics-glucose transporters interaction s is also included.
Myricetin, quercetin and catechin-gallate inhibit glucose uptake in isolated rat adipocytes
The facilitative glucose transporter, GLUT4, mediates insulin-stimulated glucose uptake in adipocytes and muscles, and the participation of GLUT4 in the pathogenesis of various clinical conditions associated with obesity, visceral fat accumulation and insulin resistance has been proposed. Glucose uptake by some members of the GLUT family, mainly GLUT1, is inhibited by flavonoids, the natural polyphenols present in fruits, vegetables and wine. Therefore it is of interest to establish if these polyphenolic compounds present in the diet, known to be effective antioxidants but also endowed with several other biological activities such as protein-tyrosine kinase inhibition, interfere with GLUT4 function.
In the present study, we show that three flavonoids , quercetin, myricetin and catechin-gallate, inhibit the uptake of methylglucose by adipocytes over the concentration range of 10–100 μM. These three flavonoids show a competitive pattern of inhibition, with Ki=16, 33.5 and 90 μM respectively. In contrast, neither catechin nor gallic acid inhibit methyl glucose uptake. To obtain a better understanding of the interaction among GLUT4 and flavonoids, we have derived a GLUT4 three-dimensional molecular comparative model, using structural co-ordinates from a GLUT3 comparative model and a mechanosensitive ion channel [PDB (Protein Data Bank) code 1MSL] solved by X-ray diffraction.
On the whole, the experimental evidence and computer simulation data favour a transport inhibition mechanism in which flavonoids and GLUT4 interact directly, rather than by a mechanism related to protein-tyrosine kinase and insulin signalling inhibition. Furthermore, the results suggest that GLUT transporters are involved in flavonoid incorporation into cells.
Naringenin
The citrus fruit flavonoid naringenin suppresses hepatic glucose production from Fao hepatoma cells
Hepatic gluconeogenesis is the major source of fasting hyperglycemia. Here, we investigated the role of the citrus fruit flavonoid naringenin, in the attenuation of hepatic glucose production from hepatoma (Fao) cells. We show that naringenin, but not its glucoside naringin, suppresses hepatic glucose production. Furthermore, unlike insulin-mediated suppression of hepatic glucose production, incubation of hepatocytes with the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor Ly294002 had no effect on the ability of naringenin to suppress hepatic glucose production. Further, naringenin did not increase phosphorylation of Akt at Ser473 or, Thr308, indicating this down-stream target of PI3-kinase is also not a player in naringenin-mediated suppression of hepatic glucose production.
Importantly, like the dimethylbiguanide, metformin, naringenin significantly decreased cellular ATP levels without increasing cell cytotoxicity. Together, these results suggest that the aglycone, naringenin, has a role in the attenuation of hyperglycemia and may exert this effect in a manner similar to the drug, metformin.
Certain flavonoids inhibit glucose uptake in cultured cells. In this report, we show that the grapefruit flavanone naringenin inhibited insulin-stimulated glucose uptake in proliferating and growth-arrested MCF-7 breast cancer cells. Our findings indicate that naringenin inhibits the activity of phosphoinositide 3-kinase (PI3K), a key regulator of insulin-induced GLUT4 translocation, as shown by impaired phosphorylation of the downstream signaling molecule Akt. Naringenin also inhibited the phosphorylation of p44/p42 mitogen-activated protein kinase (MAPK). inhibition of the MAPK pathway with PD98059, a MAPK kinase inhibitor, reduced insulin-stimulated glucose uptake by approximately 60%. The MAPK pathway therefore appears to contribute significantly to insulin-stimulated glucose uptake in breast cancer cells.
Importantly, decreasing the availability of glucose by lowering the glucose concentration of the culture medium inhibited proliferation, as did treatment with naringenin. Collectively, our findings suggest that naringenin inhibits the proliferation of MCF-7 cells via impaired glucose uptake. Because a physiologically attainable dose of 10 µM naringenin reduced insulin-stimulated glucose uptake by nearly 25% and also reduced cell proliferation, naringenin may possess therapeutic potential as an anti-proliferative agent.
inhibition of intestinal and renal Na+-glucose cotransporter by naringenin
Reduction in glucose uptake constitutes a possible means of controlling diabetic hyperglycemia . Using purified intestinal brush border membrane vesicles and everted intestinal sleeves, we have demonstrated that naringenin, a flavonoid present in citrus fruits and juices, significantly inhibited glucose uptake in the intestine. In addition, naringenin also elicited inhibitory action s towards glucose uptake in renal brush border membrane vesicles. Naringin, a glycoside of naringenin, was totally inactive in these aspects. Naringenin exhibited moderate inhibitory action on glucose uptake in rabbit intestinal brush border membrane vesicles, and showed strong inhibitory action in rat everted intestinal sleeves. The IC50 values were 205.9 and 2.4 μmol/l, respectively. Lineweaver–Burk analysis demonstrated that naringenin inhibited glucose uptake in rat everted intestinal sleeves in a competitive manner with a Ki value of 1.1 μmol/l. Glucose uptake activities in both the intestinal and renal brush border membrane vesicles of diabetic rats were significantly higher than in normal rats.
Naringenin (500 μM) reduced glucose uptake by more than 60% in both the intestinal and renal brush border membrane vesicles of diabetic rats to a level similar to that of the normal rats. The IC50 values of naringenin in the renal brush border membrane vesicles of normal and diabetic rats were 323.9 and 166.1 μmol/l, respectively. These results suggest that inhibition of intestinal glucose uptake and renal glucose reabsorption explains, in part at least, the in vivo antihyperglycemic action of naringenin and its derivatives. The possible application of these natural compounds in controlling hyperglycemia warrants further investigations.
Metformin is a widely used drug for the treatment of type 2 diabetes (T2D). Its blood glucose-lowering effects are initially due to inhibition of hepatic glucose production and increased peripheral glucose utilization. Metformin has also been shown to have several beneficial effects on cardio vascular risk factors and it is the only oral antihyperglycaemic agent thus far associated with decreased macrovascular complications in patients with diabetes.
Adenosine Monophosphate Activated-Protein Kinase (AMPK ) is a major cellular regulator of lipid and glucose metabolism. Recent evidence shows that pharmacological activation of AMPK improves blood glucose homeostasis, lipid profiles, blood pressure and insulin-resistance making it a novel therapeutic target in the treatment of T2D. Naringenin a flavonoid found in high concentrations as its glycone naringin in citrus fruits, has been reported to have antioxidant, antiatherogenic, anti- dyslipidemic and anti-diabetic effects. It has been shown that naringenin exerts its anti-diabetic effects by inhibition of gluconeogenesis through upregulations of AMPK hence metformin-like effects. Naringin has further been shown to have non-glycemic affects like metformin that mitigate inflammation and cell proliferation. This review evaluates the potential of naringenin as anti-diabetic , anti-dyslipidemic anti-inflammatory and antineoplastic agent similar to metformin and proposes its further development for therapeutic use in clinical practice.
Obesity and the onset of diabetes are two closely linked medical complications prevalent globally. Postprandial hyperglycemia is one of the earliest abnormalities of glucose homeostasis associated with type 2 diabetes (T2D). Postprandial glucose levels can be regulated through α-glucosidase inhibition. The present study aims to demonstrate the potent inhibitory role of naringenin against α-glucosidase activit.
The mode of inhibition of naringenin was examined by measuring enzyme activity in vitro with different concentrations of substrate using Lineweaver–Burk plot analysis. It shows competitive inhibition towards mammalian α-glucosidase thereby competing with α-limit dextrins and oligosaccharide residues for binding in the active site. Similar results have been obtained from the molecular docking analyses, where naringenin shows preferential binding for the active sites in each of the evaluated human intestinal α-glucosidase enzymes. Post-docking intramolecular hydrogen bonding analysis shows water molecule mediated hydrogen bonding for N-terminal maltase glucoamylase and N-terminal sucrase isomaltase. Naringenin’s docked pose in the C-terminal maltase glucoamylase active site does not show any particular water mediated interaction similar to the co-crystallized acarbose. Further, our results suggest that naringenin (25 mg/kg) exerts significant inhibition of intestinal α-glucosidase activity in vivo thereby delaying the absorption of carbohydrates in T2D rats, thus resulting in significant lowering of postprandial blood glucose levels.
Both in vitro and in vivo results were compared to the commercially available α-glucosidase inhibitor acarbose. Our findings clearly indicate that naringenin dampens postprandial glycemic response and offers a potential complementary approach in the management of T2D.
flavonoids are important natural compounds with diverse biologic activities. Citrus flavonoids constitute an important series of flavonoids . Naringin and its aglycone naringenin belong to this series of flavonoids and were found to display strong anti-inflammatory and antioxidant activities. Several lines of investigation suggest that naringin supplementation is beneficial for the treatment of obesity , diabetes , hypertension, and metabolic syndrome . A number of molecular mechanisms underlying its beneficial activities have been elucidated. However, their effect on obesity and metabolic disorder remains to be fully established. Moreover, the therapeutic uses of these flavonoids are significantly limited by the lack of adequate clinical evidence.
This review aims to explore the biologic activities of these compounds, particularly on lipid metabolism in obesity, oxidative stress, and inflammation in context of metabolic syndrome.
In the present study, the putative antihyper-glycemic and antioxidant effects of a flavanone, narin-genin, were evaluated in comparison with those of glyclazide, a standard drug for therapy of diabetes mel-litus. diabetes was induced experimentally in 12-h-fasted rats by intraperitoneal injections of first strepto-zotocin(50mg/kgb.w.) and then of nicotinamide (110 mg/kg b.w.) after a 15-min interval. Untreated diabetic rats revealed the following in comparison with normal rats: significantly higher mean levels of blood glucose and glycosylated hemoglobin, significantlylower mean levels of serum insulin , significantly lower mean activities of pancreatic antioxidant enzymes(superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase), significantly lower mean levels of plasma non-enzymatic antioxidants (reduced glutathione, vitamin C , vitamin E), significantly elevated mean levels of pancreatic malondialdehyde (MDA) and significantly elevated mean activities of serum alanine amino transferase (ALT), aspartate amino transferase (AST), alkaline phosphatase(ALP) and lactate dehydro-genase (LDH).
Following oral administration of naringe-nin (50 mg/kg b.w./day) to diabetic rats for 21 days, the following observations were made in comparison withuntreated diabetic rats: significantly lower mean levels offasting blood glucose and glycosylated hemoglobin, sig-nificantly elevated serum insulin levels, significantly higher mean activities of pancreatic enzymatic antioxi-dants, significantly higher mean levels of plasma non-enzymatic antioxidants, lower mean pancreatic tissuelevels of MDA and lower mean activities of ALT, AST,ALP and LDH in serum. The values obtained in thenaringenin-treated animals approximated those observedin glyclazide-treated animals. Histopathological studiesappeared to suggest a protective effect of naringenin onthe pancreatic tissue in diabetic rats.
These results suggestthat naringenin exhibits antihyperglycemic and antioxi-dant effects in experimental diabetic rats.
Huyou (Citrus changshanensis) is rich in naringin and neohesperidin, which are natural flavanone glycosides with a range of biological activities. Among the different fruit parts, i.e. flavedo, albedo, segment membrane (SM), and juice sacs (JS), albedo showed the highest contents of both compounds, with 27.00 and 19.09 mg/g DW for naringin and neohesperidin, respectively. Efficient simultaneous purification of naringin and neohesperidin from Huyou albedo was established by the combination of macroporous D101 resin chromatography and high-speed counter-current chromatography (HSCCC). Purified naringin and neohesperidin were identified by both HPLC and LC–MS, and their effects on glucose consumption were investigated in HepG2 cells. Cells treated with naringin and neohesperidin showed increased consumption of glucose, and this was associated with increased phosphorylation of AMP-activated protein kinase (AMPK ).
Therefore, naringin and neohesperidin from Huyou may act as potential hypoglycaemic agents through regulation of glucose metabolism.
antidiabetic effects of hesperidin and naringin in type 2 diabetic rats
This study was designed to investigate the effect of hesperidin and naringin on serum glucose , blood glycosylated hemoglobin and serum insulin levels in high fat fed (HFD)/streptozotocin (STZ)-induced type 2 diabetic rats. In addition, the effect on serum lipid profile, adiponectin and resistin levels, cardiac function parameters and liver and muscle glycogen contents was assessed.
Hesperidin and naringin were orally and daily administered at a dose level of 50 mg/kg b.w. for 30 days to HFD/STZ type 2 diabetic rats. Both hesperidin and naringin supplementation potentially ameliorated the elevated levels of glucose , glycosylated hemoglobin, AST, LDH and CK-MB and the lowered serum insulin level and hepatic and muscle glycogen content of insulin resistant diabetic rats. Both compounds were also found to alleviate lipid profile and serum adiponectin and resistin levels.
These results showed that hesperidin and naringin have potential antihyperglycemic and antidyslipidemic efficacies as well as cardiac function improving action in HFD/STZ-induced type 2 diabetic rats.
Nelumbo nucifera Gaertn extract
Effect of Nelumbo nucifera rhizome extract on blood sugar level in rats
Oral administration of the ethanolic extract of rhizomes of Nelumbo nucifera markedly reduced the blood sugar level of normal, glucose -fed hyperglycemic and streptozotocin-induced diabetic rats, when compared with control animals. The extract improve d glucose tolerance and potentiated the action of exogenously injected insulin in normal rats. When compared with tolbutamide, the extract exhibited activity of 73 and 67% of that of tolbutamide in normal and diabetic rats, respectively.
The seeds of Nelumbo nucifera (Lotus) have been used in the traditional system of medicine for various ailments including diabetes. The present study was aimed at analyzing the levels of biologically important trace elements in the lotus seeds by atomic absorption spectroscopy and evaluating the hypoglycemic properties of seed ash on streptozotocin-induced diabetes in rats. diabetic rats treated with lotus seed ash at a concentration of 200 mg/kg body weight orally for 30 days exhibited significant hypoglycemic activity.
The presence of trace elements in appreciable amounts in the seeds may play a direct or indirect role on insulin secretion or its action in a synergetic manner. The hypo-glycemic activity of the ash was comparable with glyclazide. The role of trace elements in disorders related to diabetes is also discussed briefly.
This study was aimed to investigate an acute toxicity and effects of Nelumbo nuciferaflower extract (NNFE) on hyperglycemic and hypolipidemic effects in streptozytocin-induced diabetic rats. In vivo acute toxicity study of NNFE was carried out by once oral admin-istration various doses (0, 500, 1000, 1500 and 2000 mg/kg) of the extract to healthy male adult W istar rats. Sign or symptom of toxicity and mortality were examined within 24 h and further period of 14 days. The studies of effects of the extract on hypoglycemic and hypolipidemic activities were performed by given the extract at a dose of 250 mg/g b.w. to STZ-induced diabetic rats orally and daily for 8 weeks.
The results revealed that the extract did not produce any signs or symptoms of toxicity and the mortal rats were not found during the period of ob-servation. Furthermore, the extract at a dose of 250 mg/kg significantly (p<0.05) decreased the levels of fasting blood glucose (FBG), total cholesterol (TC), triglycerides (TG), low density lipoprotein (LDL), and blood urea nitrogen (BUN) but increased high density lipoprotein (HDL) in the NNFE– treated diabetic rats compared to diabetic controls. However, the extract did not alter creatinine in diabetic treated rats compared to diabetic controls.
These findings indicate that NNFE had non acute toxicity but possesses hypoglycemic and hypolipidemic ac-tivities. NNFE is one of alternative beneficial products in a treatment of diabetes.
Hypoglycemic and hypolipidemic effects of Nelumbo nucifera flower in Long-Evans rats
The study was conducted to assess the hypolipidemic and hypoglycemic effects of Nelumbo nucifera flowers powder in Long-Evans rats.
Methods: Experimental rats were made hyperlipidemic and diabetic (type 2 ) by feeding high fat diet (Lab diet, Dalda and Coconut oil = 4: 3: 1) and injecting alloxan respectively. N. nucifera flowers powder in different percentages was mixed with the regular Lab Diet for 21 days feeding. Serum total cholesterol, triglyceride, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and blood glucose levels were evaluated in various groups.
Results: Feeding with N. nucifera flowers powder at different percentages to hyperlipidemic groups showed diverse but a significant (P<0.05) decrease in serum total cholesterol, triglyceride and LDL-cholesterol levels when compared to control group while HDL-cholesterol level was increased significantly (P<0.05). Routine feeding with N. nucifera flowers powder for 21 days resulted in significant decrease in the blood glucose levels of alloxan-induced diabetic rats. Both 20% and 10% of N. nucifera flower powders with Lab Diet significantly (P<0.05) decreased blood glucose level up to 48% and 34%, respectively in comparison to the drug control group treated with glibenclamide which was found with the decreasing capability up to 66% where the higher percentage of N. nucifera flower powder was found to exert more prominent effect in lowering blood glucose level.
During comparison to the control group, the above mentioned percentages of N. nucifera flowers powder was found to reduce the blood glucose level around 32.05% and 47.92% respectively. Although not prominent, but the data revealed that the sample was endowed with the body weight declining capability.
Conclusion: Results of the experiments affirm that the flower of N. nucifera has potent hypoglycemic and hypolipidemic properties and might be useful in these patients.
Ophiopogon japonicus(L.f.)KerGawl extract
Effects of polysaccharide in Ophiopogon japonicus on blood glucose in gestational diabetic rats
Aim: To investigate the effects of polysaccharide in Ophiopogon japonicus on blood glucose in gestational diabetic rats.Methods: The models of gestational diabetic rats were established with alloxan by intraperitoneal injection administration.Polysaccharide in Ophiopogon japonicus was given by intragastric administration on 14 days.The blood glucose levels of rats at the day 0,7,14 were detected respectively, their body weight and serum insulin levels detected by the method of radioimmunoassay at the day 0,14 were analyzed.
Results: The blood glucose levels were significantly decreased in gestational diabetic rats treated by polysaccharide in Ophiopogon japonicus at the day 7,14 compared with model group(P0.01),and it showed no effects on the levels of blood insulin and the body weight of rats.
Conclusion: Polysaccharide in Ophiopogon japonicus could decrease the levels of blood glucose in gestational diabetic rats. It maybe relate to increase the hepatic cell intakeing the amylaceum, and increase the composition of the hepatic glycogen.
Oridonin
Plant‐derived glucose transport inhibitors with potential antitumor activity
Glucose, a key nutrient utilized by human cells to provide cellular energy and a carbon source for biomass synthesis, is internalized in cells via glucose transporters that regulate glucose homeostasis throughout the human body. Glucose transporters have been used as important targets for the discovery of new drugs to treat cancer, diabetes , and heart disease, owing to their abnormal expression during these disease conditions. Thus far, several glucose transport inhibitors have been used in clinical trials, and increasing numbers of natural products have been characterized as potential anticancer agents targeting glucose transport.
The present review focuses on natural product glucose transport inhibitors of plant origin, including alkaloids, flavonoids and other phenolic compounds, and isoprenoids, with their potential antitumor properties also discussed.
The Warburg effect is an important characteristic of tumor cells, making it an attractive therapeutic target. Current anticancer drug development strategies predominantly focus on inhibitors of the specific molecular effectors involved in tumor cell proliferation. These drugs or natural compounds, many of which target the Warburg effect and the underlying mechanisms, still need to be characterized. To elucidate the anticancer effects of a natural diterpenoid, oridonin, we first demonstrated the anticancer activity of oridonin both in vitro and in vivo in colorectal cancer (CRC) cells. Then miRNA profiling of SW480 cells revealed those intracellular signaling related to energy supply was affected by oridonin, suggesting that glucose metabolism is a potential target for CRC therapy. Moreover, our results indicated that oridonin induced metabolic imbalances by significantly inhibiting glucose uptake and reducing lactate export through significantly downregulating the protein levels of GLUT1 and MCT1 in vitro and vivo.
However, the ATP level in oridonin-treated CRC cells was not decreased when oridonin block ed the glucose supply, indicating that oridonin induced autophagy process, an important ATP source in cancer cells . The observation was then supported by the results of LC3-II detection and transmission electron microscopy analysis, which confirmed the presence of autophagy. Furthermore, p-AMPK was rapidly deactivated following oridonin treatment , resulting in downregulation of GLUT1 and induction of autophagy in the cancer cells.
Thus our finding helped to clarify the anticancer mechanisms of oridonin and suggested it could be applied as a glucose metabolism –targeting agent for cancer treatment.
Oroxylum indicum seed
The combined effect of Oroxylum indicum seed extracts (OISE) or major flavonoids from OISE and acarbose on reducing postprandial blood glucose (PBG) levels was investigated in vitro and in vivo. In vitro, the IC50 values of OISE and baicalein against α-glucosidase were 43.4 ± 0.731 μg mL−1 and 25.9 ± 0.412 μg mL−1 respectively. A combination of acarbose with OISE or baicalein synergistically inhibited rat intestinal α-glucosidase . The combination index (CI) values for acarbose with OISE ranged from 0.33 to 0.75, suggesting a synergistic but not additive effect. OISE was determined to be a non-competitive inhibitor of maltose-hydrolyzing activity. In vivo, OISE were administered to normoglycemic and diabetic mice, either alone or in combination with acarbose.
At doses between 50 and 200 mg kg−1, OISE enhanced the efficacy of acarbose by up to 5-fold. These results demonstrated that OISE enhances the efficacy of acarbose in vivo, and that the combination of OISE and acarbose displayed a synergistic effect in vitro. Therefore, OISE can be used to design dietary supplements to treat diabetes.
Paeonia lactiflora Pall extract
Paeoniflorin and 8-debenzoylpaeoniflorin were isolated from the dried root of Paeonia lactiflora Pall. (Ranunculaceae). They produced a significant blood sugar lowering effect in streptozotocin-treated rats and had a maximum effect at 25 min after treatment.
This hypoglycemic action was also observed in normo-glycemic rats only at 1 mg/kg. The antihyperglycemic activity of 8-debenzoylpaeoniflorin seems lower than that of paeoniflorin. plasma insulin was not changed in paeoniflorin-treated normoglycemic rats indicating an insulin-independent action. Also, this glucoside reduced the elevation of blood sugar in glucose challenged rats. Increase of glucose utilization by paeoniflorin can thus be considered. There are no previous data showing the hypo-glycemic activity of paeoniflorin and/or 8-debenzoylpaeoniflorin in rats.
Pelargonidin-3-O-glucoside
Plant‐derived glucose transport inhibitors with potential antitumor activity
Glucose, a key nutrient utilized by human cells to provide cellular energy and a carbon source for biomass synthesis, is internalized in cells via glucose transporters that regulate glucose homeostasis throughout the human body. Glucose transporters have been used as important targets for the discovery of new drugs to treat cancer, diabetes , and heart disease, owing to their abnormal expression during these disease conditions.
Thus far, several glucose transport inhibitors have been used in clinical trials, and increasing numbers of natural products have been characterized as potential anticancer agents targeting glucose transport.
The present review focuses on natural product glucose transport inhibitors of plant origin, including alkaloids, flavonoids and other phenolic compounds, and isoprenoids, with their potential antitumor properties also discussed.
Panax ginseng C. A. Meye extract
AbstractRecent pharmacokinetic studies have revealedthat ginsenosides, the major ingredients of ginseng (theroots ofPanax ginseng), are present in the plasma collectedfrom subjects receiving ginseng, and speculated that gin-senosides might be actively transported via glucose trans-porters. We evaluated whether ginsenosides Rb1and Rg1,and their metabolites from enteric bacteria act as substratesof sodium–glucose cotransporter (SGLT) 1, the major glucose transporter expressed on the apical side ofintestinal epithelial cells. First, we evaluated the competingeffects of ginseng extract and ginsenosides on the uptake of[14C]methyl-glucose, a substrate of SGLT1 , by SGLT1–overexpressing HEK293 cells. A boiling water extract ofginseng inhibited SGLT1 in a concentration-dependentmanner with an IC50value of 0.85 mg/ml. By activity–guided fraction ation, we determined that the fraction con-taining ginsenosides displayed an inhibitory effect onSGLT1.
Of the ginsenosides evaluated, protopanaxatriol-type ginsenosides were not found to inhibit SGLT1 ,whereas protopanaxadiol-type ginsenosides, includingginsenosides Rd, Rg3,Rh2,F2and compound K, exhibitedsignificant inhibitory effects on SGLT1, with ginsenosideF2having the highest activity with an IC50value of23.0lM. Next, we measured the uptake of ginsenoside F2and compound K into Caco-2 cells, a cell line frequentlyused to evaluate the intestinal absorption of drugs. The uptake of ginsenoside F2and compound K into Caco-2cells was not competitively inhibited by glucose.
Furthermore, the uptake of ginsenoside F2and compound K into SGLT1-overexpressing HEK293 cells was not significantlyhigher than into mock cells. Ginsenoside F2and compoundK did not appear to be substrates of SGLT1, although thesecompounds could inhibit SGLT1. Ginsenosides might beabsorbed by passive diffusion through the intestinal membrane or actively transported via unknown transporters other than SGLT1.
Anti-diabetic effects of Panax notoginseng saponins and its major anti-hyperglycemic components
Ethnopharmacological relevance: Panax notoginseng (Burk) F.H. Chen (Araliaceae) is a well-known and commonly used traditional Chinese herb for treatment of various diseases , such as hemostasis, edema and odynolysis.
Aim of study: Our aim was to investigate the mechanisms of anti-hyper glycemic and anti-obese effects of Panax notoginseng saponins (PNS) in KK-Ay mice, and explore the components in PNS for such effects.
Materials and methods: KK-Ay mice received daily intraperitoneal injections of PNS 200 mg/kg or vehicle for 30 days while ginsenoside Re 14 mg/kg, Rd 15 mg/kg, Rg1 40 mg/kg, Rb1 60 mg/kg and notoginsenoside R1 6 mg/kg for 12 days. Fasting blood glucose levels (FBGL), glucose tolerance (GT), serum insulin , leptin levels , body weight changes, food intake, adipose tissues and blood fat levels were measured at different time points.
Results: The PNS group had significantly lower FBGL, improve d GT and smaller body weight incremental percentage after the 30-day treatment . Additionally, Rb1 exhibited significant reduction of FBGL on day 12, and Re also exhibited a decreasing trend after the 12-day treatment .
Conclusions: PNS possess anti-hyperglycemic and anti-obese activities by improving insulin-and leptin sensitivity, and Rb1 is responsible for the anti-hyperglycemic effect among the five saponins in KK-Ay mice.
Skeletal muscle is an important organ for controlling the development of type 2 diabetes. We discovered Panax notoginseng roots as a candidate to improve hyperglycemia through in vitro muscle cells screening test. Saponins are considered as the active ingredients of ginseng. However, in the body, saponins are converted to dammarane-type triterpenes, which may account for the anti-hyperglycemic activity. We developed a method for producing a dammarane-type triterpene extract (DTE) from Panax notoginseng roots and investigated the extract’s potential anti-hyperglycemic activity. We found that DTE had stronger suppressive activity on blood glucose levels than the saponin extract (SE) did in KK-Ay mice.
Additionally, DTE improved oral glucose tolerance, insulin sensitivity, glucose uptake, and Akt phosphorylation in skeletal muscle. These results suggest that DTE is a promising agent for controlling hyperglycemia by enhancing glucose uptake in skeletal muscle.
Anti-diabetic Potential of Panax Notoginseng Saponins (PNS): A Review
herbal medicines have traditionally played a major role in the management of diabetes in Asian countries for centuries. Panax notoginseng (Burk) F. H. Chen (Araliaceae) known as Tiánqī or san qi is a well-known medicinal herb in Asia for its long history of use in Chinese medicine. Qualified as ‘the miracle root for the preservation of life’, it has been used in China for 600 years, for treatment of various diseases. Panax notoginseng saponins (PNS) are the key active components. PNS have been widely used in China for treatment of cardio-vascular diseases. However, scientific studies have shown a wide range of other pharmacological applications including anti-cancer, neuroprotective and anti-inflammatory agents, immunologic adjuvant and prevention of diabetes complications.
Recently, hypoglycemic and anti-obesity properties of PNS have also been demonstrated. The present review highlights the effects of PNS on glucose production and absorption, and on inflammatory processes that seem to play an important role in the development of diabetes.
Panax notoginseng, a well-known and commonly used traditional Chinese herb, has been used in China for six hundred years. Panax notoginseng Saponins (PNS) were extracted from the root of the plant. This is the first study on anti-hyperglycemic and anti-obese effects of PNS in genetic model mice. Additionally, the preventive effect on diabetic nephropathy was investigated. Animals received intraperitoneal injections of PNS 50 or 200 mg/kg daily. On day 12, 22 and 30, PNS-treated groups had significantly lower fasting blood glucose levels and smaller body weight incremental percentage. After a 12-day treatment, glucose tolerance of PNS groups were significantly improved; these indices in PNS-treated mice exhibited a dose-dependent improvement.
Furthermore, on day 30, the serum insulin resistance index and triglyceride levels of PNS-treated groups decreased significantly, and the development of the mice glomerular lesions was prevented significantly. The results in this present paper indicate that PNS possesses anti-diabetes and anti-obese activities and may prove to be of clinical importance in improving the management of type 2 diabetes.
Panaxnotoginseng(Burk.)F.H.Chen extract
The Effects and Mechanism of Saponins of Panax notoginseng on glucose metabolism in 3T3-L1 Cells
This study was carried out to determine the effect of saponins of Panax notoginseng (SPN), a naturally occurring cardiovascular agent, on: (1) glucose uptake , (2) GLUT4 translocation and (3) glycogen synthesis in 3T3-L1 adipocytes. Electrospray ionization-Mass spectrometry (ESI-MS) was used to determine the structural characterization of the major active components of SPN. 3T3-L1 adipocytes were cultured and treated with 100 nM insulin alone or with 10, 50 and 100 μg/ml of SPN. [3H]2-deoxyglucose glucose uptake, GLUT4 immunofluorescence imaging and glycogen synthesis assay were carried out to determine the effects of SPN on glucose metabolism.
Under insulin stimulation, SPN significantly increased glucose uptake in a dose-dependent manner; 50 μg/ml of SPN increased glucose uptake by 64% (p < 0.001). Immunofluorescence imaging and analysis have revealed that 50 and 100 μg/ml of SPN increased GLUT4 in the plasma membrane by 3-fold and 6-fold respectively (p < 0.001). Furthermore, the incorporation of D-[U-14C] glucose into glycogen was enhanced by 53% in 3T3-L1 cells treated with 100 μg/ml of SPN (p < 0.01 vs. insulin stimulation alone). SPN, a naturally occurring agent used to treat ischemic cardio-cerebral vascular disease in China, enhanced insulin -stimulated glucose uptake and glycogen synthesis in adipocytes.
The results of this study indicate that SPN may have a therapeutic potential for hyperglycaemia in type 2 diabetes.
persimmon tannin
Regulation of postprandial blood glucose levels is an effective therapeutic proposal for type 2 diabetes treatment . In this study, the effect of persimmon tannin on starch digestion with different amylose levels was investigated both in vitro and in vivo. Oral administration of persimmon tannin–starch complexes significantly suppressed the increase of blood glucose levels and the area under the curve (AUC) in a dose-dependent manner compared with starch treatment alone in an in vivo rat model. Further study proved that persimmon tannin could not only interact with starch directly but also inhibit α-amylase and α-glucosidase strongly, with IC50 values of 0.35 and 0.24 mg/mL, separately. In addition, 20 μg/mL of persimmon tannin significantly decreased glucose uptake and transport in Caco-2 cells model.
Overall, our data suggested that persimmon tannin may alleviate postprandial hyperglycemia through limiting the digestion of starch as well as inhibiting the uptake and transport of glucose .
Phloretin
Phloretin inhibits Zika virus infection by interfering with cellular glucose utilisation
Zika virus (ZIKV) is a re-emerging Flavivirus that has been linked to microcephaly and other neurological pathologies. In this study, phloretin, a glucose transporter inhibitor natural ly derived from plants, was used to investigate the glucose dependence of ZIKV replication in host cells. The results showed that phloretin significantly decreased infectious titres of two ZIKV strains, namely MR766 (African genotype) and PRVABC59 (Puerto Rico genotype). The 50% effective concentration (EC50) of phloretin against MR766 and PRVABC59 was 22.85 µM and 9.31 µM, respectively. Further analyses demonstrated that decreased viral production was due to host-targeted inhibition , including decreased apoptotic caspase-3 and -7 activities and reduced phosphorylation of Akt/mTOR pathways . In addition, upon disruption of cellular glucose availability within host cells using 2-deoxy-d-glucose , ZIKV propagation was inhibited.
Collectively, we demonstrate phloretin inhibition of ZIKV propagation and provide evidence of glucose utilization pathways as being important for ZIKV propagation. The activity of phloretin and its role in inhibiting glucose uptake could provide a useful foundation for the development of ZIKV antivirals.
Phloretin, a naturally occurring dihydrochalcone, is known to inhibit tumor cell growth in vitro and in vivo. To clarify the anti-tumor effects of phloretin, its apoptosis-inducing effects in B16 melanoma 4A5 cells were examined. Phloretin induced the internucleosomal DNA fragmentation typical of apoptosis in B16 melanoma cells. The addition of extracellular glucose remarkably inhibited the phloretin-induced apoptosis in the cells. When apoptosis was strongly induced in the B16 cells by phloretin, protein kinase C activity was inhibited in the cells.
Our results suggest that phloretin induced apoptosis in B16 melanoma 4A5 cells mainly through the inhibition of glucose transmembrane transport. inhibition of protein kinase C activity by phloretin probably promote s the ratio of apoptotic cells in the cells.
Phloretin (Ph), a natural product found in apples and pears with glucose transporter (GLUT) inhibitory activity, exerts antitumor effects. However, little is known about its effects on human liver cancer. The purpose of this study is to test the cytotoxic effects of Ph on HepG2 cells and to identify the underlying molecular pathways. Human hepatocellular carcinoma specimens and HepG2 show a high level of GLUT2 transporter activity in the cell membrane. Real-time PCR and MTT assays demonstrate that Ph-induced cytotoxicity correlates with the expression of GLUT2. Flow cytometry and DNA fragmentation studies show that 200 μM Ph induces apoptosis in HepG2, which was reversed by glucose pretreatment. GLUT2 siRNA knockdown induced HepG2 apoptosis, which was not reversed by glucose. Western blot analysis demonstrates that both intrinsic and extrinsic apoptotic pathways in addition to Akt and Bcl-2 family signaling pathways are involved in Ph-induced cell death in HepG2 cells. Furthermore, using flow cytometry analysis, a mitochondrial membrane potential assay and Western blot analysis, we show that cytochalasin B, a glucose transport inhibitor, enhances the Ph-induced apoptotic effect on HepG2 cells, which was reversed by pretreatment with glucose.
Furthermore, we found significant antitumor effects in vivo by administering Ph at 10 mg/kg intraperitoneally to severe combined immune deficiency mice carrying a HepG2 xenograft. A microPET study in the HepG2 tumor-bearing mice showed a 10-fold decrease in 18F-FDG uptake in Ph-treated tumors compared to controls. Taken together, these results suggest that Ph-induced apoptosis in HepG2 cells involves inhibition of GLUT2 glucose transport mechanisms.
inhibition of glucose transport into brain by phlorizin, phloretin and glucose analogues
An indicator dilution technique with 22Na+ as the intravascular marker was used to measure unidirectional transport of d-[6-3H]glucose from blood into the isolated, perfused dog brain. 18 compounds which are structurally related to glucose were tested for their ability to inhibit glucose transport. The data suggest that no single hydroxyl group is absolutely required for glucose transport, but rather that glucose binding to the carrier probably occurs through hydrogen bonding at several sites (hydroxyls on carbons 1, 3, 4 and 6). In addition, α-d–glucose has higher affinity for the carrier than does β-d–glucose .
A separate series of experiments demonstrated that phlorizin and phloretin are competitive inhibitors of glucose transport into brain; however, phloretin is partially competitive and inhibits at lower concentrations than does phlorizin . inhibition by phlorizin and phloretin is mutually competitive, indicating that these compounds compete for binding to the glucose carrier.
Comparison with the results reported in the literature for similar studies using the human erythrocyte demonstrates a fundamental similarity between glucose transport systems in the blood -brain barrier and erythrocyte.
Human triple-negative breast cancer (TNBC) is the most aggressive and poorly understood subclass of breast cancer. glucose transporters (GLUTs) are required for glucose uptake in malignant cancer cells and are ideal targets for cancer therapy. To determine whether the inhibition of GLUTs could be used in TNBC cell therapy, the apple polyphenol phloretin (Ph) was used as a specific antagonist of GLUT2 protein function in human TNBC cells.
Interestingly, we found that Ph (10–150 μM, for 24 h) inhibited cell growth and arrested the cell cycle in MDA-MB-231 cells in a p53 mutant-dependent manner, which was confirmed by pre-treatment of the cells with a p53-specific dominant-negative expression vector. We also found that Ph treatment (10–150 μM, for 24 h) significantly decreased the migratory activity of the MDA-MB-231 cells through the inhibition of paxillin/FAK, Src, and alpha smooth muscle actin (α-sMA) and through the activation of E-cadherin. Furthermore, the anti-tumorigenic effect of Ph (10, 50 mg/kg or DMSO twice a week for six weeks) was demonstrated in vivo using BALB/c nude mice bearing MDA-MB-231 tumor xenografts. A decrease in N-cadherin, vimentin and an increase in p53, p21 and E-cadherin were detected in the tumor tissues.
In conclusion, inhibition of GLUT2 by the apple polyphenol Ph could potentially suppress TNBC tumor cell growth and metastasis.
Asymmetrical binding of phloretin to the glucose transport system of human erythrocytes
The sidedness of phloretin binding to the glucose carrier has been determined by comparing the type of inhibition produced in zerotrans entry and zerotrans exit experiments. Initial rates of zerotrans entry were measured by the method of R.D. Taverna and R.G. Langdon (Biochim. Biophys. Acta 298:412–421, 1973), which involves pink ghosts loaded with glucose oxidase; this obviates the problem of rapid substrate accumulation inside the cells. With phloretin equilibrated across the membrane, the inhibition of entry was competitive, and the inhibition of exit noncompetitive.
The experimental procedures were validated by showing that the inhibition by cytochalasin B, known to bind inside but not outside, was noncompetitive in entry and competitive in exit, as predicted. It was also demonstrated that even after pre-incubation of the cells with a relatively high concentration of phloretin, the phloretin adsorbed in the membrane did not significantly alter the rate of carrier reorientation.
The results show that the outward-facing form of the glucose carrier, but not the inward-facing form, bears a phloretin binding site; thus phloretin, as well as cytochalasin B, is bound asymmetrically, phloretin outside and cytochalasin B inside.
glucose transporters (GLUTs) are required for glucose uptake in malignant cells, and they can be used as molecular targets for cancer therapy. An RT-PCR analysis was performed to investigate the mRNA levels of 14 subtypes of GLUTs in human colorectal cancer (COLO 205 and HT-29) and normal (FHC) cells. RT-PCR (n = 27) was used to assess the differences in paired tissue samples (tumor vs normal) isolated from colorectal cancer patients. GLUT2 was detected in all tested cells.
The average GLUT2 mRNA level in 12 of 27 (44.4%) cases was 2.4-fold higher in tumor compared to normal tissues (*, p = 0.027). Higher GLUT2 mRNA expression was preferentially detected in advanced-stage tumors (stage 0 vs 3 = 16.38-fold, 95% CI = 9.22–26.54-fold; *, p = 0.029). The apple polyphenol phloretin (Ph) and siRNA methods were used to inhibit GLUT2 protein expression. Ph (0–100 μM, for 24 h) induced COLO 205 cell growth cycle arrest in a p53-dependent manner, which was confirmed by pretreatment of the cells with a p53-specific dominant negative expression vector. Hepatocyte nuclear factor 6 (HNF6), which was previously reported to be a transcription factor that activates GLUT2 and p53, was also induced by Ph (0–100 μM, for 24 h).
The antitumor effect of Ph (25 mg/kg or DMSO twice a week for 6 weeks) was demonstrated in vivo using BALB/c nude mice bearing COLO 205 tumor xenografts. In conclusion, targeting GLUT2 could potentially suppress colorectal tumor cell invasiveness.
phlorizin
Purpose: NAFLD is a hepatic component of type 2 diabetes mellitus (T2D), in which impaired hepatic glucose production plays an important role. inhibitors of sodium glucose transporter 2 (SGLT2 ) reduce glycemia and exert beneficial effects on diabetic complications . Recently, dual SGLT1 /2 inhibition has been proposed to be more effective in reducing glycemia. We hypothesized that improving hepatic glucose metabolism induced by SGLT1 /2 inhibition could be accompanied by beneficial effects on NAFLD progression.
Methods: Glycemic homeostasis , hepatic glucose production and NAFLD features were investigated in obese T2D mice, treated with SGLT1 /2 inhibitor phlorizin for 1 week.
Results: T2D increased glycemia; insulin emia; hepatic expression of phosphoenolpyruvate carboxykinase (PEPCK), glucose -6-phosphatase (G6Pase) and glucose transporter 2 (Slc2a2 gene); hepatocyte nuclear factors 1A/4A/3B-binding activity in Slc2a2; endogenous glucose production; liver weight, plasma transaminase concentration as well as hepatic inflammation markers, and induced histological signals of non-alcoholic steatohepatitis (NASH, according to NASH-CRN Pathology Committee System). phlorizin treatment restored all these parameters (mean NASH score reduced from 5.25 to 2.75 P<0.001); however, plasma transaminase concentration was partially reverted and some hepatic inflammation markers remained unaltered .
Conclusion: NAFLD accompanies altered hepatic glucose metabolism in T2D mice and that greatly ameliorated through short-term treatment with the dual SGLT1 /2 inhibitor . This suggests that altered hepatic glucose metabolism participates in T2D-related NAFLD and highlights the pharmacological inhibition of SGLTs as a useful approach not only for controlling glycemia but also for mitigating development and/or progression of NAFLD.
A pharmacokinetic and pharmacodynamic (PK-PD) model for the inhibitory effect of sodium –glucose cotransporter (SGLT) inhibitors on renal glucose reabsorption was developed to predict in vivo efficacy . First, using the relationship between renal glucose clearance and plasma glucose level in rats and both the glucose affinity and transport capacity obtained from in vitro vesicle experiments, a pharmacodynamic model analysis was performed based on a nonlinear parallel tube model to express the renal glucose transport mediated by SGLT1 and SGLT2 . This model suitably expressed the relationship between plasma glucose level and renal glucose excretion. A PK-PD model was developed next to analyze the inhibitory effect of phlorizin on renal glucose reabsorption . The PK-PD model analysis was performed using averaged concentrations of both the drug and glucose in plasma and the corresponding renal glucose clearance.
The model suitably expressed the concentration-dependent inhibitory effect of phlorizin on renal glucose reabsorption . The in vivo inhibition constants of phlorizin for SGLT in rats were estimated to be 67 nM for SGLT1 and 252 nM for SGLT2 , which are similar to the in vitro data reported previously. This suggests that the in vivo efficacy of SGLT inhibitors could be predicted from an in vitro study based on the present PK-PD model.
The present model is based on physiological and biochemical parameters and, therefore, would be helpful in understanding individual differences in the efficacy of an SGLT inhibitor .
Effect of phlorizin on SGLT2 expression in the kidney of diabetic rats.
Background: The purpose of our study was to determine whether increased SGLT2 expression in the kidney of diabetic rats was associated with the development of hypertension and to investigate the effect of phlorizin (P) on blood pressure and SGLT2 expression in diabetic rats.
Methods: The animals were divided into two groups: Control (C) and streptozotocin-induced diabetic (D) rats were used to evaluate SGLT2 activity in brush border membrane vesicles (BBMV) using a rapid filtration technique. Others animals were divided into two groups: Normal (NSD) or high salt diet (4%)(HSD), and subdivided in four groups: C, C+P, D, D+P. Systolic blood pressure (SBP) was recorded for 30 days by the use of a telemetric system and at day 30 urine samples (24 h) were collected to evaluate renal function and SGLT2 expression in the renal cortex.
Results: At day 30, diabetic animals with NSD or HSD exhibited hyperglycemia , lower body weight, glycosuria , diuresis, decrease natriuresis, increased SBP values and SGLT2 expression. In diabetic rats, phlorizin treatment decreased hyperglycemia and prevented development of hypertension, decreased SGLT2 activity in BBMV but did not modify SGLT2 expression.
Conclusions: In conclusion, SGLT2 inhibition prevented the development of hypertension in diabetic rats as well as hyperglycemia , suggesting a hypertensive mechanism associated with SGLT2 activity and the likelihood that increased SGLT2 expression may be associated with progression of diabetic renal complications .
The sodium glucose cotransporter SGLT1 expressed mainly in the intestine and kidney has been explored extensively for understanding the mechanism of sugar cotransport and its inhibition by a classical competitive inhibitor , phlorizin (Pz). It has been shown that inhibition of SGLT1 by Pz involves its interaction followed by major conformational changes in the Pz binding domain (PBD) in C-terminal loop 13. However, the mechanism of Pz inhibition and its interaction with other members of SGLT is not known.
In this hypothesis, we performed molecular modeling of SGLT1 -loop 13 with Pz and carried out primary sequence analyses and secondary structure predictions to determine qualitatively similar PBDs in C-termini of human SGLT2 -4, except for vSGLT, which contains an unstructured short C-terminus. The ranking of predictions of Pz interaction strongly agrees with the following ranking of previously reported Pz inhibition : SGLT2 >SGLT1 >SGLT4>SGLT3>>vSGLT. In addition, the sugar binding residues were found to be quite conserved among all SGLT members investigated here.
Based on these preliminary analyses, we propose that other Pz-sensitive SGLTs are also inhibited via mechanism similar to SGLT1 where an aglucone of Pz, phloretin, interacts with PBD and glucoside moiety with sugar binding residues. Our hypothesis sets the stage for future analyses on investigation of Pz interaction with SGLT family and further suggests that Pz modeling may be explored to design novel inhibitors targeting several SGLT members.
Phloridzin is the specific and competitive inhibition of sodium / glucose cotransporter s in the intestine (SGLT1 ) and kidney (SGLT2 ). This property which could be useful in the management of postprandial hyperglycemia in diabetes and related disorders. Phloridzin is one of the dihydrochalcones typically contained in apples and in apple-derived products . The effect of phloridzin orally doses 5, 10, 20 and 40 mg/kg body weight on diabetes was tested in a streptozotocin-induced rat model of diabetes type 1. From beneficial effect of this compound is significant reduction of blood glucose levels and improve dyslipidemia in diabetic rats. As a well-known consequence of becoming diabetic , urine volume and water intake were significantly increased. Administration of phloridzin reduced urine volume and water intake in a dose-dependent manner. Phloretin decreases of food consumption, as well as a marked lowering in the weight. In conclusion, this compound could be proposed as an antihyperglycemic and antihyperlipidemic agent in diabetes and potential therapeutic in obesity.
Apple Trees to sodium glucose Co-transporter inhibitors: A Review of SGLT2 inhibition
The kidney plays a key role in glucose homeostasis . The delineation of the role of SGLTs throughout the body has been a major advancement in our understanding of the kinetics of glucose in the body . Our better understanding of the physiology of renal glucose homeostasis and recent pharmacological advances have brought us to a point where pharmacological modulation of this system is possible. Although diabetes management is an obvious candidate to benefit from these advances, other medical conditions such as obesity may also eventually be targeted via methods to modulate either SGLT1 or SGLT2 .
Currently, a host of studies are underway evaluating the effects of the SGLT2 inhibitor dapagliflozin. Although the published studies offer a great deal of promise, there is still some concern regarding potential side effects, namely urinary tract and genital infections. As data from phase 3 trials develop, many of these unanswered questions will be resolved.
In addition to dapagliflozin, several other SGLT2 inhibitors , an SGLT anti-sense molecule, and SGLT1 inhibitors are being developed. Eventually, pharmacological or biological modulation of these transporters will almost certainly offer us a useful method of disease intervention.
Phloridzin is a dihydrochalcone typically contained in apples. In this study, it is shown that a diet containing 0.5% phloridzin significantly reduced the blood glucose levels in streptozotocin (STZ)-induced diabetic mice after 14 days. We detected phloridzin in the plasma of STZ-induced diabetic mice fed the phloridzin diet for 14 days, although its concentration was much lower than that of the phloridzin metabolites. A quantitative RT-PCR analysis showed a reversal of STZ induction of the sodium /glucose cotransporter gene SGLT1 and the drug-metabolizing enzyme genes Cyp2b10 and Ephx1 in the small intestine of mice fed a 0.5% phloridzin diet. These mice also showed a reversal of the STZ-mediated renal induction of the glucose -regulated facilitated glucose transporter gene GLUT2.
Dietary phloridzin improved the abnormal elevations in blood glucose levels and the overexpression of SGLT1, Cyp2b10, and Ephx1 in the small intestine of STZ-induced diabetic mice.
Methods: Glycemic homeostasis , hepatic glucose production and NAFLD features were investigated in obese T2D mice, treated with SGLT1 /2 inhibitor phlorizin for 1 week.
Results: T2D increased glycemia; insulin emia; hepatic expression of phosphoenolpyruvate carboxykinase (PEPCK), glucose -6-phosphatase (G6Pase) and glucose transporter 2 (Slc2a2 gene); hepatocyte nuclear factors 1A/4A/3B-binding activity in Slc2a2; endogenous glucose production; liver weight, plasma transaminase concentration as well as hepatic inflammation markers, and induced histological signals of non-alcoholic steatohepatitis (NASH, according to NASH-CRN Pathology Committee System). phlorizin treatment restored all these parameters (mean NASH score reduced from 5.25 to 2.75 P<0.001); however, plasma transaminase concentration was partially reverted and some hepatic inflammation markers remained unaltered .
Conclusion: NAFLD accompanies altered hepatic glucose metabolism in T2D mice and that greatly ameliorated through short-term treatment with the dual SGLT1 /2 inhibitor . This suggests that altered hepatic glucose metabolism participates in T2D-related NAFLD and highlights the pharmacological inhibition of SGLTs as a useful approach not only for controlling glycemia but also for mitigating development and/or progression of NAFLD.
Individuals with non-insulin dependent or insulin-dependent diabetes mellitus present insulin resistance in peripheral tissues. This is reflected in a subnormal whole body insulin-dependent glucose utilization, largely dependent on skeletal muscle. Glucose transport across the cell membrane of this tissue is rate limiting in the utilization of the hexose. Therefore, it is possible that a defect exists in insulin-dependent glucose transport in skeletal muscle in diabetic states. This review focuses on two questions: is there a defect at the level of glucose transporters in skeletal muscle of diabetic animal models, and is this a consequence of abnormal insulin or glucose levels? The latter question arises from the fact that these parameters usually vary inversely to each other. glucose transport into skeletal muscle occurs by two membrane proteins, the GLUT1 and GLUT4 gene products. By subcellular fraction and Western blotting with isoform-specific antibodies, it was determined that isolated plasma membranes (PM) contain GLUT4 and GLUT1 proteins at a molar ratio of 3.5:1 and that an intracellular fraction (internal membranes; IM) different from sarcoplasmic reticulum contains only GLUT4 transporters.
The IM furnishes transporters to the PM in response to insulin. Both transporter isoforms bind cytochalasin B in a D-glucose -protectable fashion. In streptozocin-induced diabetes of the rat with normal fasting insulin levels and marked hyperglycemia , the number of cytochalasin B-binding sites and of GLUT4 proteins diminishes in the PM whereas the GLUT1 proteins increase to a new ratio of about 1.5:1 GLUT4 :GLUT1. In the IM, the levels of GLUT4 protein drop, as does the cellular GLUT4 mRNA. To investiga