Enzyme changes and glucose utilisation in diabetic rabbits: the effect of Gymnema sylvestre, R.Br

In silico evaluation of naturally isolated triterpene glycosides (TG) from Gymnema sylvestre towards diabetic treatment

Diabetes is a metabolic disorder which is characterised by high levels of blood glucose. Most of the oral drugs available today for the treatment of diabetes are associated with various side-effects. Herbal medicines are considered relatively safer alternatives and Gymnema sylvestre (GS) is one such known traditional medicinal plant widely used for the treatment of diabetes. In our previous work, we isolated active triterpene glycosides (TG) from Gymnema sylvestre (GS) and screened for yeast α-glucosidase inhibitory activity in vitro. The present study aims to use in silico techniques to understand and predict the inhibitory role of the isolated triterpene glycosides (TG); Gymnemic acid I, IV, VII and gymnemagenin against disaccharidase enzymes. enzyme kinetic analysis using Lineweaver-Burk plot indicated that TG competitively inhibited yeast α-glucosidase at IC50 concentration with Ki 0.0028 μM. TG also exhibited significant inhibitory activity against mammalian sucrase and maltase respectively, compared to control.

PRACTICAL APPLICATIONS

The molecular docking simulation reveals that TG is capable of docking well with crystallographic structures of the selected enzyme targets. Inhibition of α-glucosidases could delay the absorption of glucose in the blood during post-meal digestion. Thus the current study highlights the dietary intervention of TG towards the selected enzyme targets, thus making TG a potential nutraceutical candidate towards management of blood glucose.

Radio-protective efficacy of Gymnema sylvestre on Pangasius sutchi against gamma (60Co) irradiation

PURPOSE

Freshwater fish Pangasius sutchi was used in this study as a vertebrate model. We evaluated the induction of certain antioxidant enzymes in various vital organs. The radioprotective efficacy of Gymnema sylvestre leaves extract (GS) [25 mg/kg Body Weight (B.W)] and its bioactive compound Gymnemagenin (GG) [0.3 mg/kg B.W] was compared with Amifostine (Ami), the only radioprotector clinically approved by the US-FDA [Ami- 83.3 mg/kg B.W] against different doses of gamma radiation - ⁶⁰Co (Lethal Dose: LD₃₀-9.2 Gy, LD₅₀-10.2 Gy and LD₇₀-11.4 Gy).

MATERIALS AND METHODS

This study was done via stress marker enzymes, cell cycle analysis (CCA) and DNA damage assay prediction with molecular docking, which are reported here for the first time. The results indicate an elevated LPO level and decreased level of CAT, SOD and GSH due to oxidative stress initiation by ⁶⁰Co Ionizing Radiation (IR) on 4th day and slightly reduced on 32nd day while the reverse observed when the fishes were pretreated with Ami, GS and GG. Similarly, CCA and dead/live cells counts were conducted with pretreatment of Ami, GS and GG against ⁶⁰Co IR dose (LD₅₀-10.2 Gy).

RESULTS

In CCA, G0/G1 phase was observed to be the highest in Ami and lowest in GG, against ⁶⁰Co IR doses 10.2 Gy which was 51.76 ± 7.55. The dead cells range observed in pretreated group of Ami, GS and GG was lowest in Ami and highest in GG and live cells (highest in Ami and lowest in GG) as compared to ⁶⁰Co IR group (86.43 ± 3.42 and 8.77 ± 5.95). Thus, antioxidant profile improvement by oxidative stress reduction and gradual progression of different phases of cell cycle except the apoptotic phase along with the live cells counts indicates that the radio-protective efficacy of GS is similar to Ami.

CONCLUSION

Predictive assessment was carried out by docking of Ami, various components of GS with p53, NF-κβ cells and Rad51 proteins structures responsible for CCA, apoptosis and repair mechanism. These structural proteins were docked with other structural proteins like USP7, TNF-α and partner and localizer of BRCA2 associated (PALB2/BRCA2) complex which made us perform these systemic efforts to find the functional activity of these known radio-protectants.

The effect of Gymnema sylvestre supplementation on glycemic control in type 2 diabetes patients: A systematic review and meta-analysis

This systematic review and meta-analysis aims to find the effect of Gymnema sylvestre (GS) supplementation on glycemic control in type-2 diabetes mellitus (T2DM). PubMed, Cochrane library, Google Scholar, and Science Direct were searched from inception to June 2020 to identify the studies that reported GS supplementation on glycemic parameters. Standardized mean difference (SMD) was calculated by comparing the post-intervention data with baseline data. SMDs with 95% confidence intervals (CIs) were pooled using a random-effects model. Our meta-analysis consisting of 10 studies with a total of 419 participants showed that GS supplementation significantly reduces fasting blood glucose (FBG) (SMD 1.57 mg/dl, 95% CI 2.22 to -0.93, p < .0001, I² 90%), postprandial blood glucose (PPBG) (SMD 1.04 mg/dl, 95% CI 1.53 to -0.54, p < .0001, I² 80%), and glycated haemoglobin (HbA1c) (SMD 3.91, 95% CI 7.35 to -0.16%, p < .0001, I² 99%) compared to baseline. Further, our study also found that GS significantly reduces triglycerides (SMD 1.81 mg/dl, 95% CI 2.95 to -0.66, p < .0001, I² : 96%), and total cholesterol (SMD 4.10 mg/dl, 95% CI 7.21 to -0.99, p < .0001, I² : 98%) compared to baseline. Our study shows that GS supplementation is effective in improving glycemic control and reducing lipid levels in T2DM patients and suggests that such supplementation might be used as an effective therapy for the management of T2DM and its associated complications to an extent.

Phytopharmacological Possibilities of Bird Cherry Prunus padus L. and Prunus serotina L. Species and Their Bioactive Phytochemicals

Wild cherry is a plant observed in the form of trees or shrubs. This species comprises about twenty kinds of plants and the most popular are two, Prunus padus L. and Prunus serotina L., whose properties and content of phytochemical compounds are subject to studies. Wild cherry contains many active compounds, including tocopherols, vitamins, polyphenols and terpenes, which can have beneficial effects on health. On the other hand, wild cherry contains cyanogenic glycosides. Nevertheless, current research results indicate pro-health properties associated with both P. serotina and P. padus. The aim of this study was to collect and present the current state of knowledge about wild cherry and to review available in vitro and in vivo studies concerning its antioxidant, anti-inflammatory, antibacterial and antidiabetic activity. Moreover, the current work presents and characterizes phytochemical content in the leaves, bark and fruits of P. padus and P. serotina and compiles data that indicate their health-promoting and functional properties and possibilities of using them to improve health. We find that the anatomical parts of P. padus and P. serotina can be a valuable raw material used in the food, pharmaceutical and cosmetic industries as a source of bioactive compounds with multi-directional action.

De novo transcriptome of Gymnema sylvestre identified putative lncRNA and genes regulating terpenoid biosynthesis pathway

Gymnema sylvestre is a highly valuable medicinal plant in traditional Indian system of medicine and used in many polyherbal formulations especially in treating diabetes. However, the lack of genomic resources has impeded its research at molecular level. The present study investigated functional gene profile of G. sylvestre via RNA sequencing technology. The de novo assembly of 88.9 million high quality reads yielded 23,126 unigenes, of which 18116 were annotated against databases such as NCBI nr database, gene ontology (GO), KEGG, Pfam, CDD, PlantTFcat, UniProt & GreeNC. Total 808 unigenes mapped to 78 different Transcription Factor families, whereas 39 unigenes assigned to CYP450 and 111 unigenes coding for enzymes involved in the biosynthesis of terpenoids including transcripts for synthesis of important compounds like Vitamin E, beta-amyrin and squalene. Among them, presence of six important enzyme coding transcripts were validated using qRT-PCR, which showed high expression of enzymes involved in methyl-erythritol phosphate (MEP) pathway. This study also revealed 1428 simple sequence repeats (SSRs), which may aid in molecular breeding studies. Besides this, 8 putative long non-coding RNAs (lncRNAs) were predicted from un-annotated sequences, which may hold key role in regulation of essential biological processes in G. sylvestre. The study provides an opportunity for future functional genomic studies and to uncover functions of the lncRNAs in G. sylvestre.

A novel Gymnema sylvestre extract protects pancreatic beta-cells from cytokine-induced apoptosis

Inflammatory cytokines such as interleukin-1β, TNF-α, and interferon-γ are known to be involved in mediating β-cells death in diabetes mellitus (DM). Thus, protecting from β-cells death in patients with DM may be a useful target in alleviating symptoms of hyperglycemia. Traditional plant-based remedies have been used to treat DM for many centuries and may play a role in protecting β-cell from death. An example of these remedies is Gymnema sylvestre (GS) extract. In this study, we investigated the effect of this plant extract on β-cells apoptosis. Om Santal Adivasi (OSA®) maintained cell membrane integrity in MIN6 cells and mouse islets. Om Santal Adivasi significantly protected MIN6 cells and mouse islets from cytokine-induced apoptosis. In the presence of cytokines, OSA® significantly reduced the expression and activity of caspase-3. The antiapoptotic effect of OSA® as shown by microarray analysis is largely mediated by activating pathways involved in cell survival (mainly casein kinase II pathway) and the free radical scavenger system (specifically superoxide dismutase and catalase). This study indicates that the GS isolate OSA® protects against cytokine-induced apoptosis of β-cells by increasing the expression of cell survival pathways and free radical scavenger system.

Antidiabetic plant-derived nutraceuticals: a critical review

Diabetes mellitus (DM) is one of the major health problems in the world, especially amongst the urban population. Chemically synthesized drugs used to decrease the ill effects of DM and its secondary complications cause adverse side effects, viz., weight gain, gastrointestinal disturbances, and heart failure. Currently, various other approaches, viz., diet control, physical exercise and use of antidiabetic plant-derived molecules/foods are advocated to manage DM, as they are economical with fewer or no side effects. This review mainly focuses on antidiabetic plants, chemically characterized plant molecules and plant-based foods in the treatment of DM. Very little science-based evidence is available on the mechanism of action of plant-derived food molecules on the DM targets. Critical DM targets include α-amylase, α-glucosidase, DPP-IV, aldose reductase, PPAR-γ, AMP kinase and GLUT4. In-depth studies carried out on a few of those targets with specific mechanisms of action are addressed in this review. This review may help future researchers in identifying a right plant molecule to treat DM or to develop food formulations for DM management.

Comparative evaluation of anti-obesity effect of Aloe vera and Gymnema sylvestre supplementation in high-fat diet fed C57BL/6J mice

Background:

The aim of the present study was to investigate, anti-obesity effect of Aloe vera (AV), and Gymnema sylvestre (GS) whole extract powders administration to high-fat diet (HFD) fed C57BL/6J mice for 12 weeks.

Materials and Methods:

At the end of experiment, different parameters such as body weight, feed intake, organ weights, fasting blood glucose, oral glucose tolerance test, plasma lipid levels, and expression analysis of adipocytokines were evaluated.

Results:

At the end of experimental period, oral administration of both herbs showed a significant (P < 0.05 and P < 0.001) decrease in the plasma glucose and lipid levels in HFD fed mice. In addition, increased in the epididymal fat (E. fat) weight in the HFD group was significantly (P < 0.05) reduced on GS administration alone. Finally, quantitative mRNA expression analysis of adiponectin gene was significantly up-regulated in AV supplementation. Further, no effect was observed with the both herbs on pro-inflammatory cytokines (interleukin 6 and tumor necrosis factor-a) in the E. fat tissue of HFD fed group.

Conclusions:

The anti-obesity and other metabolic studies depend on the type of diet, different parts of herbal extractions, and animal models used. Further studies are required in this area to strengthen the anti-obesity effects of herbs with active component, and it can be used a pro-drug instead of whole extract.

Anti-obesity effect of milk fermented by Lactobacillus plantarum NCDC 625 alone and in combination with herbs on high fat diet fed C57BL/6J mice

The effect of dietary supplementation of milk fermented with indigenous probiotic Lactobacillus plantarum (LP625) alone and in combination with herbs (Aloe vera and Gymnema sylvestre) was investigated on high fat diet (HFD, 60 kcal% fat) fed mice for 12 weeks. Administration of LP625 alone or in combination with both herbs lowered the final body weight, however, a significant difference was observed with LP625 supplemented Gymnema sylvestre only as compared to the HFD fed group (25.06±0.18 vs 27.29±0.72 g, P<0.05). Similarly, the epididymal fat mass, fasting blood glucose and serum insulin levels were significantly (P<0.05) decreased by all treatment groups. In addition, a protective effect against the rise in serum and liver triglycerides, and in liver total cholesterol levels was found with the consumption of LP625 alone or in combination with herbs. Furthermore, the HFD fed mice showed a remarkable increase in the epididymal fat cell size, whereas administration of LP625 alone or in combination with herbs exhibited a significant decrease in the size. Finally, a significant increase in the relative mRNA expression of thermogenic proteins, i.e. uncoupling protein-2 (UCP-2, 1.16±0.25 fold change, P<0.05) and a decrease in pro-inflammatory markers, such as tumour necrosis factor-α and interleukin-6 (1.55±0.18 and 3.10±0.58 fold change, respectively, P<0.05) were due to LP625 supplementation in the HFD fed group. This shows that LP625 alone or supplemented with herbs seems to protect against diet induced obesity by decreasing the body and epididymal fat weight through upregulation of UCP-2 expression and reduced expression of pro-inflammatory cytokines.

Antidiabetic and Antilipidemic Effect of Musa balbisiana Root Extract: A Potent Agent for Glucose Homeostasis in Streptozotocin-Induced Diabetic Rat

Folklore studies have revealed that Musa balbisiana Colla (MB; Family: Musaceae) has high medicinal properties. The purpose of the present study is to evaluate antihyperglycemic, and antioxidant activity of MB extracts in streptozotocin (STZ) induced diabetic rats. In vitro antioxidant and antidiabetic activity of MB extracts, i.e., root extract (RE), shoot extract and inflorescence extract were determined by using various methods viz 1,-1-diphenyl-2-picrylhydrazyl (DPPH) and a method to assess their possible effect on glucose diffusion across gastrointestinal tract and identify bioactive compound of potent extract. In vivo antilipidemic and antidiabetic activity was evaluated by administrating oral dose of RE for 15 days on STZ- induced diabetic rat. RE showed highest antioxidant activity by scavenging DPPH radical (IC50 32.96 μg/ml) and inhibit 30% glucose movement in vitro. The methanol extract of root showed the presence of calyx [4] arene category of the compound. Furthermore, RE treated rat revealed a reduction in fasting blood glucose (62.5%), serum total cholesterol (36.2%), triglyceride (54.5%), and low-density lipoprotein (50.94%) after 15 days as compared to STZ treated animal. There was an initiation of regenerative structures of the affected organs after 15 days of RE treatment. Histopathological observations clearly differentiate the structural changes in pancreas, liver, and kidney of STZ and RE treated group. The presence of calyx [4] arene class of compound may be responsible for its antioxidant and antidiabetic properties by absorbing glucose in vivo.

Novel nutraceutic therapies for the treatment of metabolic syndrome

Nutraceutic therapies such as berberine, bitter melon, Gymnema sylvestre, Irvingia gabonensis, resveratrol and ursolic acid have been shown to help control metabolic syndrome (MetS). The effect of berberine on glucose and lipid metabolism, hypertension, obesity and MetS has been evaluated in animal models and humans. Most clinical trials involving bitter melon have been conducted to evaluate its effect on glucose metabolism; nevertheless, some studies have reported favorable effects on lipids and blood pressure although there is little information about its effect on body weight. Gymnema sylvestre helps to decrease body weight and blood sugar levels; however, there is limited information on dyslipidemia and hypertension. Clinical trials of Irvingia gabonensis have shown important effects decreasing glucose and cholesterol concentrations as well decreasing body weight. Resveratrol acts through different mechanisms to decrease blood pressure, lipids, glucose and weight, showing its effects on the population with MetS. Finally, there is evidence of positive effects with ursolic acid in in vitro and in vivo studies on glucose and lipid metabolism and on body weight and visceral fat. Therefore, a review of the beneficial effects and limitations of the above-mentioned nutraceutic therapies is presented.

Methanolic leaf extract of Gymnema sylvestre augments glucose uptake and ameliorates insulin resistance by upregulating glucose transporter-4, peroxisome proliferator-activated receptor-gamma, adiponectin, and leptin levels in vitro

Aims:

The present study was undertaken to evaluate the effect of methanolic leaf extract of Gymnema sylvestre (MLGS) on glucose transport (GLUT) and insulin resistance in vitro.

Materials and Methods:

Peroxisome proliferator-activated receptor-gamma (PPAR-γ) and GLUT-4 expression were assessed in L6 myotubes for concluding the GLUT activity, and adiponectin and leptin expression was studied in 3T3 L1 murine adipocyte cell line to determine the effect of MLGS (250-750 μg/ml) on insulin resistance.

Results:

The findings of the experiments have demonstrated a significant and dose-dependent increase in glucose uptake in all the tested concentrations of MLGS, further the glucose uptake activity of MLGS (750 μg/ml) was at par with rosiglitazone (50 μg/ml). Concomitantly, MLGS has shown enhanced GLUT-4 and PPAR-γ gene expressions in L6 myotubes. Furthermore, cycloheximide (CHX) had completely abolished the glucose uptake activity of MLGS when co-incubated, which further confirmed that glucose uptake activity of MLGS was linked to enhanced expression of GLUT-4 and PPAR-γ. In addition, in another experimental set, MLGS showed enhanced expression of adiponectin and leptin, thus confirms the ameliorative effect of MLGS on insulin resistance.

Conclusion:

These findings suggest that MLGS has an enhanced glucose uptake activity in L6 myotubes, and ameliorate the insulin resistance in 3T3 L1 murine adipocyte cell line in vitro.

Antidiabetic activities of aqueous ethanol and n-butanol fraction of Moringa stenopetala leaves in streptozotocin-induced diabetic rats

Background

Moringa stenopetala has been used in traditional health systems to treat diabetes mellitus. The aim of this study was to investigate the antidiabetic activity of aqueous ethanol and n-butanol fraction of Moringa stenopetala leaves in streptozotocin (STZ) induced diabetic rats.

Methods

The aqueous ethanol extract and n-butanol fraction of Moringa stenopetala leaves hydroalcoholic (500 mg/kg body weight) and metformin (150 mg/kg body weight) were administered to diabetic rats. Blood glucose, lipid profiles, liver and kidney function were examined after 14 days of experiment. Histopathological profile of the pancreas was also observed in diabetic rats at the end of study. An oral sucrose challenge test was also carried out to assess the post prandial effect of the extract.

Results

Oral administration of the aqueous ethanol and n-butanol extracts of Moringa stenopetala leaves (500 mg/kg body weight) and metformin (150 mg/kg) significantly reduced blood glucose level (P < 0.05), improved serum lipid profiles, liver enzymes and kidney functions in diabetic rats after 14 days. The extracts also improved damage of islet of Langerhan’s in diabetic rats. The plant material reduced the post-prandial glucose level (P < 0.001) at the dose of 750 mg/kg.

Conclusion

These findings revealed that both the aqueous ethanol and n-butanol extracts of Moringa stenopetala leaves possess antihyperglycemic and antihyperlipidemic properties, and alleviate STZ-induced pancreatic damage in diabetic rats. The beneficial effects of plant material in inhibition of diabetes-induced complications are being investigated.

Ultrasound-assisted extraction of gymnemic acids from Gymnema sylvestre leaves and its effect on insulin-producing RINm-5 F β cell lines

INTRODUCTION

Gymnema sylvestre is an important anti-diabetic medicinal plant, hence it is necessary to study the effective extraction of its active medicinal components.

OBJECTIVE

To develop an efficient ultrasound-assisted extraction method for anti-diabetic gymnemic acids from Gymnema sylvestre leaves and measure their effect on insulin-producing RINm-5 F β cells.

METHODS

Box-Behnken's design and response surface methodology was applied to the ultrasound-assisted extraction of gymnemic acids from Gymnema sylvestre leaves. Analysis of gymnemic acids was carried out by high-performance thin-layer chromatography by converting total gymnemic acids into gymnemagenin by alkali hydrolysis. Effects of extracts on insulin production were tested on cultured, insulin-producing RINm-5 F β cell lines.

RESULTS

The point prediction tool of the design expert software predicted 397.9 mg gymnemic acids per gram of the defatted G. sylvestre leaves using ultrasound-assisted extraction, with ethanol at 60 °C for 30 min. The predicted condition shows 93.34% validity under experimental conditions. The ultrasound-assisted extract caused up to about four times more insulin production from RINm-5 F β cells than extracts obtained from Soxhlet extraction.

CONCLUSIONS

Response surface methodology was successfully used to improve the extraction of gymnemic acids from G. sylvestre leaves. The ultrasound-assisted extraction process may be a better alternative to prepare such herbal extracts because it saves time and may prevent excess degradation of the target analytes.

Effect of biologically synthesized gold nanoparticles on alloxan-induced diabetic rats-an in vivo approach

Development of novel antidiabetic agents using various organic compounds and biomolecules has been in practice for a long time. Recently, nanomaterials are also being used in antidiabetic studies for their unique properties such as small size, biocompatibility and ability to penetrate cell membrane for carrying drugs. Herein, in vivo antidiabetic activity of gold nanoparticles (AuNPs) synthesized using the antidiabetic potent plant Gymnema sylvestre R. Br on wistar albino rats has been evaluated. The formation of AuNPs and their morphology were confirmed using spectroscopic and microscopic analyses, respectively. The treatment of AuNPs has shown significant reduction in blood glucose level on diabetic rats. AuNPs were also tested for its anti-inflammatory effect by estimating the serum levels of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and high-sensitive C-reactive protein (CRP).

Gymnemic acids inhibit sodium-dependent glucose transporter 1

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 fractionation 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.

A systematic review of Gymnema sylvestre in obesity and diabetes management

The prevalence of obesity is associated with many health-related problems. Currently, more than 300 million people are considered to be obese. According to the World Health Organization (WHO), by 2030, 87 and 439 million people will be affected in India and the world, respectively. Today, herbal medicines are gaining interest in the treatment of obesity and diabetes, because of their minimal side effects. Gymnemic acid - an active component isolated from Gymnema sylvestre - has anti-obesity and antidiabetic properties, decreases body weight and also inhibits glucose absorption. Several components extracted from Gymnema prevent the accumulation of triglycerides in muscle and liver, and also decrease fatty acid accumulation in the circulation. In this paper, an attempt has been made to review the effects of various extracts from Gymnema sylvestre in the regulation of carbohydrate and lipid metabolism in both animal and clinical studies.

Quantitative estimation of gymnemagenin in Gymnema sylvestre extract and its marketed formulations using the HPLC-ESI-MS/MS method

INTRODUCTION

Gymnema sylvestre, with gymnemic acids as active pharmacological constituents, is a popular ayurvedic herb and has been used to treat diabetes, as a remedy for cough and as a diuretic. However, very few analytical methods are available for quality control of this herb and its marketed formulations.

OBJECTIVES

To develop and validate a new, rapid, sensitive and selective HPLC-ESI (electrospray ionisation)-MS/MS method for quantitative estimation of gymnemagenin in G. sylvestre and its marketed formulations.

METHOD

HPLC-ESI-MS/MS method using a multiple reactions monitoring mode was used for quantitation of gymnemagenin. Separation was carried out on a Luna C-18 column using gradient elution of water and methanol (with 0.1% formic acid and 0.3% ammonia).

RESULTS

The developed method was validated as per International Conference on Harmonisation Guideline ICH-Q2B and found to be accurate, precise and linear over a relatively wide range of concentrations (5.280-305.920 ng/mL). Gymnemagenin contents were found from 0.056 ± 0.002 to 4.77 ± 0.59% w/w in G. sylvestre and its marketed formulations.

CONCLUSION

The method established is simple, rapid, with high sample throughput, and can be used as a tool for quality control of G. sylvestre and its formulations.

Investigation of intracellular signalling cascades mediating stimulatory effect of a Gymnema sylvestre extract on insulin secretion from isolated mouse and human islets of Langerhans

AIM

Traditional plant-based remedies such as Gymnema sylvestre (GS) extracts have been used to treat diabetes mellitus for many centuries. We have shown previously that a novel GS extract, OSA®, has a direct effect on insulin secretion but its mode of action has not been studied in detail Thus this study investigated the possible underlying mechanism(s) by which OSA® exerts its action.

METHODS

The effects of OSA® on [Ca(2+)]i and K(+) conductances were assessed by Ca(2+) microfluorimetry and electrophysiology in dispersed mouse islets and MIN6 β-cells, respectively. Isolated mouse (from 20 to 25 mice) and human (from 3 donors) islets, and MIN6 β-cells, were used to investigate whether the stimulatory effect of OSA® on insulin secretion was dependent on the presence of extracellular calcium and protein kinase activation.

RESULTS

OSA ®-induced insulin secretion from mouse islets and MIN6 β-cells was inhibited by nifedipine, a voltage-gated Ca(2+) channel blocker, and by the removal of extracellular Ca(2+), respectively. OSA® did not affect the activities of KATP channels or voltage-dependent K(+) channels in MIN6 β-cells but it caused an increase in intracellular Ca(2+) ([Ca(2+)]i) concentrations in Fura-2-loaded mouse islet cells. The insulin secretagogue effect of OSA® was dependent, in part, on protein kinase activation since incubating mouse or human islets with staurosporine, a general protein kinase inhibitor, resulted in partial inhibition of OSA®-induced insulin secretion. Experiments using permeabilized, Ca(2+)-clamped MIN6 β-cells revealed a Ca(2+)-independent component action of OSA® at a late stage in the stimulus-response coupling pathway. OSA®-induced insulin secretion was unexpectedly associated with a decrease in intracellular cAMP levels.

CONCLUSIONS

These data indicate that the GS isolate OSA® stimulates insulin secretion from mouse and human islets in vitro, at least in part as a consequence of Ca(2+) influx and protein kinase activation.

An evidence-based systematic review of gymnema (Gymnema sylvestre R. Br.) by the Natural Standard Research Collaboration

An evidence-based systematic review of gymnema (Gymnema sylvestre R. Br.), including written and statistical analysis of scientific literature, expert opinion, folkloric precedent, history, pharmacology, kinetics/dynamics, interactions, adverse effects, toxicology, and dosing.

Functional food and diabetes: a natural way in diabetes prevention?

Diabetes shows a wide range of variation in prevalence around the world and it is expected to affect 300 million by the year 2025. In a prevention framework where banning policies and educational strategies lead the interventions, functional foods (FFs) with their specific health effects could, in the future, indicate a new mode of thinking about the relationships between food and health in everyday life. Functional ingredients, such as stevioside, cinnamon, bitter melon, garlic and onion, ginseng, Gymnema sylvestre and fenugreek, have been addressed for their specific actions towards different reactions involved in diabetes development. New strategies involving the use of FF should be validated through large-scale population trials, considering validated surrogate end points to evaluate the effect of FF in prevention of chronic diseases such as type 2 diabetes mellitus.

Double-blind, placebo-controlled clinical evaluation of an Ayurvedic formulation (GlucoCare capsules) in non-insulin dependent diabetes mellitus

Diabetes mellitus describes a metabolic disorder of multiple etiologies characterized by insulin resistance, relative insulin deficiency and hyperglycemia with disturbances of carbohydrate, fat and protein metabolism. The goal for treatment of diabetes is to prevent its acute manifestations and long-term microvascular and macrovascular complications. The present study was conducted to evaluate the efficacy and safety of an Ayurvedic formulation (GlucoCare Capsules) in non-insulin dependent diabetes mellitus. Fifty NIDDM patients of pitta-kapha prakriti attending the outpatient department of the Government Ayurvedic Medical College, Guwahati, Assam, India were included in the study, and randomly divided into 2 groups, GlucoCare and placebo. All received either GlucoCare or placebo in a dose of 2 capsules twice daily, before meals for 3 months. All 50 patients completed the study - no drop outs, withdrawals or patients lost to follow up. The GlucoCare group showed significant improvement in symptoms from the 2(nd) month till the end of the study. GlucoCare was well tolerated by all patients throughout the treatment period with no evidence of adverse effects. The study indicates clinical efficacy of GlucoCare Capsules in the management of NIDDM in those belonging to pitta-kapha prakriti. The formulation is well tolerated and appears safe in the dosage used.

Antidiabetic activity of alcoholic stem extract of Gymnema montanum in streptozotocin-induced diabetic rats

In the present study, the effect of alcoholic stem extract of Gymnema montanum (GMSt) on blood glucose, plasma insulin, and carbohydrate metabolic enzymes were studied in experimental diabetes. Diabetes mellitus was induced by a single intraperitoneal injection of STZ (60 mg/kg bw). Five days after STZ induction, diabetic rats received GMSt orally at the doses of 25, 50, 100 and 200mg/kg daily for 3 weeks. Graded doses of stem extract showed a significant reduction in blood glucose levels and improvement in plasma insulin levels. The effect was more pronounced in 100 and 200mg/kg than 50mg/kg. GMSt showed significant increase in hexokinase, Glucose-6-phosphate dehydrogenase and glycogen content in liver of diabetic rats while there was significant reduction in the levels of glucose-6-phosphatase and fructose-1,6-bisphosphatase. The present study clearly indicated significant antidiabetic effect with the stem extract of G. montanum and lends support for its traditional usage.

Antidiabetic, hypolipidemic and histopathological analysis of Dillenia indica (L.) leaves extract on alloxan induced diabetic rats

OBJECTIVE

To investigate antidiabetic, hypolipidemic histopathological analysis of Dillenia indica (D. indica) methanolic leaves (DIME) extract in alloxan induced diabetic rat by administering oral doses (250 and 500 mg/kg body weight).

METHODS

Blood glucose levels were measured using blood glucose test strips with elegance glucometer on weekly intervals till the end of study (i.e. 3 weeks). Other parameters e.g. liver profile, renal profile and total lipid levels were determined in normal and alloxan induced diabetic rats after oral administration of the extract for 21 days. Histopathological changes in diabetic rat organs (pancreas, liver and kidney) were also observed after extract treatment.

RESULTS

Daily oral administration DIME (250 and 500 mg/kg body weight) and glibenclamide (10 mg/kg) showed beneficial effects on blood glucose level (P < 0.001) as well as improving kidney, liver functions and hyperlipidaemia due to diabetes. The extract treatment also showed to enhanced serum insulin level and body weight of diabetic rats as compared to diabetic control group. Furthermore, the extract has a favorable effect on the histopathological changes of the pancreas, liver and kidney in alloxan induced diabetes.

CONCLUSIONS

D. indica possess antidiabetic property as well improve body weight, liver profile, renal profile and total lipid levels. DIME has also favorable effect to inhibit the histopathological changes of the pancreas and kidney in alloxan induced diabetes.

A novel Gymnema sylvestre extract stimulates insulin secretion from human islets in vivo and in vitro

Many plant-based products have been suggested as potential antidiabetic agents, but few have been shown to be effective in treating the symptoms of Type 2 diabetes mellitus (T2DM) in human studies, and little is known of their mechanisms of action. Extracts of Gymnema sylvestre (GS) have been used for the treatment of T2DM in India for centuries. The effects of a novel high molecular weight GS extract, Om Santal Adivasi, (OSA(R)) on plasma insulin, C-peptide and glucose in a small cohort of patients with T2DM are reported here. Oral administration of OSA(R) (1 g/day, 60 days) induced significant increases in circulating insulin and C-peptide, which were associated with significant reductions in fasting and post-prandial blood glucose. In vitro measurements using isolated human islets of Langerhans demonstrated direct stimulatory effects of OSA(R) on insulin secretion from human ß-cells, consistent with an in vivo mode of action through enhancing insulin secretion. These in vivo and in vitro observations suggest that OSA(R) may provide a potential alternative therapy for the hyperglycemia associated with T2DM.

In vitro callus and in vivo leaf extract of Gymnema sylvestre stimulate β-cells regeneration and anti-diabetic activity in Wistar rats

A methanol extract of Gymnema sylvestre leaf and callus showed anti-diabetic activities through regenerating β-cells. Optimum callus was developed under stress conditions of blue light with 2,4-D (1.5 mg/l) and KN (0.5 mg/l), which induced maximum biomass of green compact callus at 45 days, as determined by growth curve analysis. Leaf and optimum callus extracts contains gymnemic acid, which was analyzed using TLC, HPTLC and HPLC methods. The research reported here deals with leaf and callus extracts of G. sylvestre, which significantly increase the weight of the whole body, liver, pancreas and liver glycogen content in alloxan-induced diabetic rats (Wistar rats). The gymnemic acid of leaf and callus extracts significantly increases the regeneration of β-cells in treated rats, when compared with the standard diabetic rats. It could have potential as a pharmaceutical drug for insulin-dependent diabetes mellitus (IDDM).

Herbals used for diabetes, obesity, and metabolic syndrome

Diabetes mellitus and particularly noninsulin-dependent diabetes (type 2 diabetes) is an increasingly prevalent condition worldwide with serious consequences of multiorgan involvement and in particular cardiovascular and renal disease. Obesity is a significant risk factor for type 2 diabetes, and its incidence has doubled in the past 2 decades among younger adults, adolescents, and children globally. Inflammation and insulin resistance are the underlying mechanisms for metabolic syndrome (MetS) and its increased risk of cardiovascular, renal, and pulmonary morbidity and mortality. MetS is affecting younger populations with adverse consequences seen in later years. Dietary supplements and herbals are often marketed for these conditions. This article review common herbals and supplements marketed or used by patients with diabetes, obesity, and MetS.

Antihyperglycemic and hypolipidemic effects of Helicteres isora roots in alloxan-induced diabetic rats: a possible mechanism of action

The antihyperglycemic and hypolipidemic activities of Helicteres isora Linn. (Sterculiaceae) root extracts were investigated in alloxan-induced diabetic rats and a possible mechanism of the blood glucose lowering action was studied. Alloxan-induced diabetic rats experienced 69.13 and 51.14%, 22.60 and 21.89%, 30.12 and 19.96%, and 50.05 and 34.29% reduction in blood glucose, total cholesterol, triglycerides, and urea levels following oral administration of butanol and aqueous ethanol extracts of H. isora root, respectively, at 250 mg/kg for 10 days. The beneficial effects of these extracts were supported by evidence from histological examinations of the liver, pancreas, and kidney. Following the treatment with both extracts, the degenerative changes caused by alloxan in pancreatic cells were restored, particularly with the butanol extract. Histological examination convincingly showed the restoration of pancreatic islets, kidney glomeruli, and liver to its normal size. These results suggest that H. isora roots possess antidiabetic principles and can be useful for treatment of diabetes.

A novel dihydroxy gymnemic triacetate isolated from Gymnema sylvestre possessing normoglycemic and hypolipidemic activity on STZ-induced diabetic rats

AIM OF THE STUDY

Gymnema sylvestre (Asclepiadaceae) is emerging as a potential treatment for the management of diabetes. The leaves are used in herbal medicine preparations. The present study was carried out to isolate and identify the putative antidiabetic compound based on bioassay-guided fractionation.

MATERIALS AND METHODS

An active compound dihydroxy gymnemic triacetate has been isolated from Gymnema sylvestre acetone extract and its optimum dose has been determined and patented. An optimum dose of dihydroxy gymnemic triacetate (20mg/kg body weight) was orally administered for 45 days to streptozotocin diabetic rats for the assessment of plasma glucose, insulin, glycated hemoglobin (HbA1c), tissue glycogen, lipid parameters such as triglycerides, total cholesterol, LDL-cholesterol, HDL-cholesterol and activities of hepatic marker enzymes, such as aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and acid phosphatase (ACP) in normal and streptozotocin diabetic rats.

RESULTS

Dihydroxy gymnemic triacetate at 20mg dose produced significant effects on all biochemical parameters studied compared to diabetic control group.

CONCLUSIONS

These results indicate that dihydroxy gymnemic triacetate, the compound from Gymnema sylvestre, possessed hypoglycemic and hypolipidemic activity in long-term treatment and hence it could be used as a drug for treating diabetes.

Partial regeneration of beta-cells in the islets of Langerhans by Nymphayol a sterol isolated from Nymphaea stellata (Willd.) flowers

Reduction of the beta-cell mass is critical in the pathogenesis of diabetes mellitus. The discovery of agents which induce regeneration of pancreatic beta-cells would be useful to develop new therapeutic approaches to treat diabetes. The present study was aimed at identifying a new agent for the control of diabetes through regeneration of pancreatic beta cells and insulin secretory potential. Nymphaea stellata flower chloroform extract (NSFCExt) showed significant plasma glucose lowering effect. Further NSFCExt was utilized to isolate and identify the lead compound based on bioassay guided fractionation; we found Nymphayol (25,26-dinorcholest-5-en-3beta-ol) a new crystal [space group P2(1) (No. 4), a=9.618(5), b=7.518(5), c=37.491(5)]. It was purified by repeat column. The structure was determined on the basis of X-ray crystallography and spectral data. Oral administration of Nymphayol for 45 days significantly (p<0.05) lowered the blood glucose level and more importantly it effectively increased the insulin content in diabetic rats. In addition, Nymphayol increased the number of beta cell mass enormously. Islet-like cell clusters in the islets of Langerhans were clearly observed based on histochemical and immunohistochemical study.

Gymnemic acid interacts with mammalian glycerol-3-phosphate dehydrogenase

In a previous study, we found interaction of gymnemic acid (GA) with glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a key enzyme in glycolysis. We now examined interaction of GA with glycolytic and related enzymes. We found that (1) GA induced a band smearing of glycerol-3-phosphate dehydrogenase (G3PDH) as well as that of GAPDH in SDS-PAGE, (2) GA diminished the G3PDH band detected by an antibody to phosphoserine, and (3) GA inhibited the G3PDH activity. The GA-induced smearing of the G3PDH band was diminished by prior incubation of GA with gamma-cyclodextrin. GA gave no effects on the electrophoretic and phosphoserine bands of other glycolytic enzymes. NAD and NADH diminished the GA-induced smearing of the G3PDH and GAPDH bands in different concentration-dependent manner. Pretreatment of G3PDH with heated SDS-containing buffer or pretreatment with hydroxylamine diminished the GA-induced smearing of G3PDH. Deacylation of GA by alkaline hydrolysis diminished the smearing of G3PDH band, thereby indicating that the acyl moieties of GA were necessary for the GA-induced smearing of G3PDH. These results indicated the interaction of GA with G3PDH, an enzyme involved in glycerol metabolism. These studies suggest that GA may have some pharmacological activities including antidiabetic activity and lipid lowering effects via interaction with GAPDH and G3PDH.