Phytochemical and pharmacological properties of Gymnema sylvestre: an important medicinal plant. Biomed Res Int. 2014;2014:1-18. [PMID: 24511547 PMCID: PMC3912882 DOI: 10.1155/2014/830285]

De novo in vitro shoot morphogenesis from shoot tip-induced callus cultures of Gymnema sylvestre (Retz.) R.Br. ex Sm

Background

Gymnema sylvestre is a medicinal woody perennial vine known for its sweetening properties and anti-diabetic therapeutic uses in the modern and traditional medicines. Its over-exploitation for the therapeutic uses and to meet the demand of pharmaceutical industry in raw materials supply for the production of anti-diabetic drugs has led to considerable decline in its natural population.

Results

An efficient system of shoot bud sprouting from nodal segment explants and indirect plant regeneration from apical meristem-induced callus cultures of G. sylvestre have been developed on Murashige and Skoog (MS) medium amended with concentrations of cytokinins. Of the three growth regulators tested, N⁶-benzylaminopurine (BAP) was the most efficient and 2.0 mg L⁻¹ gave the best shoot formation efficiency. This was followed by thidiazuron (TDZ) and kinetin (Kin) but, most of the TDZ-induced micro shoots showed stunted growth. Multiple shoot formation was observed on medium amended with BAP or TDZ at higher concentrations. The produced micro shoots were rooted on half strength MS medium amended with auxins and rooted plantlets acclimatized with 87% survival of the regenerates.

Conclusions

The developed regeneration system can be exploited for genetic transformation studies, particularly when aimed at producing its high yielding cell lines for the anti-diabetic phytochemicals. It also offers opportunities for exploring the expression of totipotency in the anti-diabetic perennial vine.

Chromatography Based Metabolomics and In Silico Screening of Gymnema sylvestre Leaf Extract for Its Antidiabetic Potential

Gymnema sylvestre, popularly known as gurmar, is extensively used in traditional systems of medicine for diabetes, stomach ailments, liver diseases, and cardiac disorders. Dried leaf powder of G. sylvestre was extracted through soxhlation using 70% (v/v) alcohol. The hydroalcoholic extract was concentrated to 1/4th of its volume and basified to isolate gymnemic acid enriched extract using chloroform. The isolated extract was checked for its antioxidant potential against 1, 1-diphenyl-2-picryl-hydrazyl (DPPH), which showed scavenging activity of 82.31% at 80 μg/mL of extract. Quality control analysis of the extract was carried out by TLC. Chloroform and methanol (9.5:0.5, v/v) were used as a solvent system and separated compounds were detected at 254 and 366 nm. A total of 13 metabolites were separated. However, major peaks were at R_f 0.12, 0.69, 0.79, and 0.85. Further, UPLC-MS fingerprinting of the extract was done using acetonitrile and 0.5% formic acid in water as mobile phase in gradient elution mode. A total of 21 metabolites were separated and tentatively identified from the database. Deacyl gymnemic acid and quercetin are the two major metabolites found in the extract. Gymnemic acid, deacyl gymnemic acid, and quercetin were docked with ten different proteins associated with glucose metabolism, transport, and glucose utilization. It has been observed that gymnemic acid was more potent than deacyl gymnemic acid in terms of binding affinity towards proteins and showed a favorable interaction with amino acid residues at the active site. Thus, the present study gives an insight of identified metabolites with protein interaction and a reason for the hypoglycemic potential of deacyl gymnemic acid enriched extract, which can be further explored for in vitro and in vivo studies to establish its phytopharmacological and therapeutic effect.

Role of medicinal plants in the management of diabetes mellitus: a review

Medicinal plants have a vast potential in the treatment of various ailments due to the presence of therapeutically important phytochemicals. Diabetes is a serious metabolic disorder and several marketed medications are available to alleviate the symptoms of diabetes. However, these over the counter drugs are expensive and associated with several complications. Herbal medicines are gaining importance as they are cost-effective and also display improved therapeutic effects with lesser side effects. The present review includes the reports available on medicinal plants used for treating diabetes complications. The aim of the review is to categorize and summarize the available information on medicinal plants with anti-diabetic properties and suggesting outlooks for future research. A systematic search was performed on medicinal plants with anti-diabetic properties using several search engines such as Google Scholar, PubMed, Science Direct and other online journals and books. All the plants listed in this review are native to Asian countries and are routinely used by the traditional practitioners for the treatment of various ailments. Based on the literature data available, a total of 81 medicinal plants with anti-diabetic, anti-hyperglycemic, hypoglycemic, anti-lipidemic and insulin mimetic properties have been compiled in this review. This review provides useful information about the different medicinal plants for treating diabetes-associated complications. Further research can be carried out to study the active constituents and mechanism of these plants.

Risk assessment of substances used in food supplements: the example of the botanical Gymnema sylvestre

Botanicals and preparations derived from these are among the substances frequently added to foods and food supplements, yet the safety of many botanicals has not been systematically assessed. In the context of the EU‐FORA fellowship programme, the fellow performed an assessment on the safety of the botanical Gymnema sylvestre, in accordance with EFSA's guidance on the assessment of safety of botanicals. Although preparations of G. sylvestre are marketed as food supplements, they may appeal to people who are suffering from metabolic syndrome and/or diabetes mellitus. A scientific literature search was carried out using PubMed/MEDLINE and EMBASE electronic databases. Experience was gained by the fellow in systematic data extraction from scientific publications, structuring of the data and evaluating toxicological key parameters, outcomes of clinical significance, pharmacokinetic and pharmacodynamic interactions, uncertainties and methodological shortcomings of studies. Limited evidence from toxicological in vivo studies and human clinical studies suggested lack of relevant adverse effects of this botanical. However, human studies provided some indications that certain Gymnema extracts may enhance the glucose‐lowering effects of certain antidiabetic drugs. Considering the uncertainties for the composition of different Gymnema preparations, potential herb–drug interactions and the indications of glucose lowering or hypoglycaemic effects, the use of Gymnema‐based food supplements in combination with authorised antidiabetic drugs may be associated with risks. The procedures learned for the safety evaluation of Gymnema may be similarly applied by the fellow for the risk assessment of other substances with nutritional or physiological effect added to foods and food supplements. Furthermore, apart from learning by conducting exercises in risk assessment, the fellow was able to develop other skills (e.g. communication skills), diversify his competencies and expand his network of scientific connections for future collaborations in the field of nutritional risk assessment.

Effects of myo-inositol, gymnemic acid, and L-methylfolate in polycystic ovary syndrome patients

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine and metabolic disorder, characterized by chronic anovulation/oligomenorrhea, hyperandrogenism, and insulin-resistance. Moreover, some studies propose a possible association between insulin resistance and hyperhomocysteinemia, which is a significant long-term risk for factor for atherogenesis and chronic vascular damage, especially in situations where insulin levels are increased. Insulin-sensitizing agents are used in the treatment of PCOS: in fact, inositols were shown to have insulin-mimetic properties. Synergic action to myo-inositol is that of gymnemic acids that have antidiabetic, anti-sweetener, and anti-inflammatory activities. Gymnemic acid formulations have also been found useful against obesity due to their ability to delay the glucose absorption in the blood. L-methyl-folate increases peripheral sensitivity to insulin, maintaining folatemia stable, and thus restoring normal homocysteine levels. Unlike folic acid, L-methyl folate has a higher bioavailability, no drug/food interferences, high absorption, and it is stable to UV-A exposure. The aim of our study is to compare the clinical, endocrine, and metabolic parameters in 100 PCOS women treated with myo-inositol, gymnemic acid, and l-methylfolate (Group A) or myo inositol and folic acid only (Group B), continuously for 6 months. From a clinical point of view, it was noticed a more significant improvement of the menstrual cycle regularity and a more significant reduction of BMI in Group A. Moreover, a more significant decrease of total testosterone and increase of SHBG serum levels were noticed in Group A. The metabolic assessment found a more significant decrease of total cholesterol and homocysteine levels; OGTT glycemia and insulinemia values were significantly more improved after treatment with myo-inositol + gymnemic acid. In conclusion, we can state that a good option for the treatment of PCOS is the combined administration of myo-inositol + gymnemic acid + l-methyl-folate, especially for overweight/obese patients with marked insulin resistance and with associated hyperhomocysteinemia.

Discrimination of different geographic varieties of Gymnema sylvestre, an anti-sweet plant used for the treatment of type 2 diabetes

Gymnema sylvestre (Retz.) R.Br. ex Sm. (Asclepiadaceae) is a well-known Ayurvedic anti-sweet plant for the treatment of type 2 diabetes mellitus. Although it was previously proposed that G. sylvestre exhibits chemical variation based on geography, most research on G. sylvestre has used material originating from India. Morphological and anatomical descriptions, ITS1-5.8S-ITS2 DNA sequencing, and acid hydrolysis analyses showed that G. sylvestre samples from Vietnam are distinguishable from those of Indian origin and thus suggest a dissimilarity among G. sylvestre samples with different geographic distributions. An LC-MS-guided strategy targeting 3β-glucuronide oleane-triterpenes in the Vietnamese G. sylvestre variety led to the isolation of four known compounds and nine previously undescribed compounds, named gymnemosides ND1-ND9. None of the isolated compounds were reported in the Indian sample, further supporting the geo-diversity of G. sylvestre. Three compounds, gymnemosides ND7-9, exerted significant stimulatory effects on the uptake of 2-NBDG in 3T3-L1 adipocyte cells and thus have potential as lead molecules for anti-diabetes agents.

Phytotherapy in the Management of Diabetes: A Review

Phytotherapy has long been a source of medicinal products and over the years there have been many attempts to use herbal medicines for the treatment of diabetes. Several medicinal plants and their preparations have been demonstrated to act at key points of glucidic metabolism. The most common mechanisms of action found include the inhibition of α-glucosidase and of AGE formation, the increase of GLUT-4 and PPARs expression and antioxidant activity. Despite the large amount of literature available, the actual clinical effectiveness of medicinal plants in controlling diabetes-related symptoms remains controversial and there is a crucial need for stronger evidence-based data. In this review, an overview of the medicinal plants, which use in the management of diabetes is supported by authoritative monographs, is provided. References to some species which are currently under increasing clinical investigation are also reported.

Controversy of oral hypoglycemic agents in type 2 diabetes mellitus: Novel move towards combination therapies

AIM

As diabetes mellitus is multi-factorial disease, use of several oral hypoglycemic agents (OHAs) is the main stay of pharmacological treatment. The treatment has become more challenging and controversial as OHAs are heterogeneous in their mode of action that causes unwanted side effects. Complementary approaches such as use of medicinal plants and dietary polyunsaturated fatty acids (PUFA) with hypoglycemic and hypolipidemic activities are therefore imperative. A vast literature has independently documented the effects of OHAs, medicinal plants and PUFA for management of diabetes. In the present article, we have reviewed the current literature to describe the effects of commonly used OHAs, their mechanisms of action and reported controversies. The antidiabetic potential of herbs and/or formulations and omega-3 PUFA with its potential benefits and mode of action is also discussed.

METHODS

PUBMED, MEDLINE, Cochrane Library etc., were searched for relevant articles using appropriate terms (until February 2015). Human and animal studies were selected for the review. Data extraction was carried out by one author and checked by second author.

RESULTS

There is still controversy over the safety profile of OHAs. Medicinal herbs with hypoglycemic activities are increasingly sought because of its natural origin, active constituents and minimal side effects. The current literature suggests that supplementation with PUFA improves macro- and microvascular complications.

CONCLUSION

There is a need for best possible individualized treatment based on variations in biochemical parameters with combinational therapy of nutritional/herbal supplementations. Such a combination may be helpful for better management of diabetes and its complications.

In vivo pharmacokinetic interaction by ethanolic extract of Gymnema sylvestre with CYP2C9 (Tolbutamide), CYP3A4 (Amlodipine) and CYP1A2 (Phenacetin) in rats

Gymnema sylvestre (GS) is a medicinal herb used for diabetes mellitus (DM). Herbs are gaining popularity as medicines in DM for its safety purpose. The aim of the present study was to evaluate in vivo pharmacokinetic (PK) interaction between allopathic drugs tolbutamide (TOLBU), amlodipine (AMLO), and phenacetin (PHENA) at low (L) and high (H) doses with ethanolic extract (EL) from GS. EL was extracted and subjected to TLC, total triterpenoid content (19.76 ± 0.02 W/W) and sterol content (0.1837 ± 0.0046 W/W) estimation followed by identification of phytoconstituents using HRLC-MS and GC-MS. PK interaction study with CYP2C9, CYP3A4 and CYP1A2 enzymes were assessed using TOLBU, AMLO and PHENA respectively to index cytochrome (CYP) mediated interaction in rats after concomitant administration of EL extract (400 mg/kg) from GS for 7 days. The rats were divided into four groups for each PK study where, group I and II were positive control for low and high dose of test drugs (CYP substrates) while group II and IV were orally administered EL. The PK study result of PHENA indicated that area under the plasma concentration-time curve (AUC_0-24) was significantly (P < 0.0001) increased by 1.4 (L) and 1.3-fold (H), plasma concentration (C_max) was significantly (P < 0.001) increased by 1.6 (L) and 1.4-fold (H). Whereas for TOLBU; clearance rate (CL) was significantly (P < 0.0001) decreased by 2.4 (L) and 2.3-fold (H), C_max, was significantly (P < 0.001) decreased by 26.5% (L) and 50.4% (H) and AUC_0-24 was significantly (P < 0.0001) decreased by 59.8% (L) and 57.5% (H). Thus, EL is seen to be interacting with CYP1A2 by inhibiting its metabolic activity. HRLC-MS and GC-MS helped identify the presence of gymnemic acid (GA), triterpenoids and steroids in EL which could be the reason for PK interaction of CYP1A2 and CYP2C9. Also, in silico structure based site of metabolism study showed Fe accessibility and intrinsic activity for GA-IV, GA-VI, GA-VII and GA-X with CYP2C9. PK parameters of AMLO were not significantly affected by pre-treatment of EL. Thereby our findings indicate that co-administration of GS with drugs that are metabolized by CYP2C9 and CYP1A2 could lead to potential HDI.

Natural Health Products and Diabetes: A Practical Review

The prevalence of natural health product (NHP) use in Canada is extensive. Patients with chronic diseases, including diabetes, use NHPs at a higher rate than the general population. Many NHPs exert hypoglycemic effects, among other effects relevant to diabetes management. To provide a practical, clinical review of NHPs with such effects targeted to pharmacists, a literature search was performed to collect data on the efficacy and safety profiles of 10 commonly used NHPs that exert antidiabetic properties. The following NHPs are included in this clinical review: alpha-lipoic acid, chromium, magnesium, bitter melon, cinnamon, fenugreek, gymnema, milk thistle, Reishi mushroom and white mulberry. Given the potential of NHPs to additively cause hypoglycemia when used concurrently with conventional medications, pharmacists should be up to date with current evidence around NHPs that may affect diabetes care to prevent adverse reactions and interactions. In addition, effective and respectful communication with patients around NHP use and collaboration with various health-care providers are essential in the patient care process.

An Overview of Herbal Products and Secondary Metabolites Used for Management of Type Two Diabetes

Diabetes mellitus is a common effect of uncontrolled high blood sugar and it is associated with long-term damage, dysfunction, and failure of various organs. In the adult population, the global prevalence of diabetes has nearly doubled since 1980. Without effective prevention and management programs, the continuing significant rise in diabetes will have grave consequences on the health and lifespan of the world population, and also on the world economy. Supplements can be used to correct nutritional deficiencies or to maintain an adequate intake of certain nutrients. These are often used as treatments for diabetes, sometimes because they have lower costs, or are more accessible or "natural" compared to prescribed medications. Several vitamins, minerals, botanicals, and secondary metabolites have been reported to elicit beneficial effects in hypoglycemic actions in vivo and in vitro; however, the data remain conflicting. Many pharmaceuticals commonly used today are structurally derived from natural compounds from traditional medicinal plants. Botanicals that are most frequently used to help manage blood glucose include: bitter melon (Momordica charantia), fenugreek (Trigonella foenum graecum), gurmar (Gymnema sylvestre), ivy gourd (Coccinia indica), nopal (Opuntia spp.), ginseng, Russian tarragon (Artemisia dracunculus), cinnamon (Cinnamomum cassia), psyllium (Plantago ovata), and garlic (Allium sativum). In majority of the herbal products and secondary metabolites used in treating diabetes, the mechanisms of action involve regulation of insulin signaling pathways, translocation of GLUT-4 receptor and/or activation the PPARγ. Several flavonoids inhibit glucose absorption by inhibiting intestinal α-amylase and α-glucosidase. In-depth studies to validate the efficacies and safeties of extracts of these traditional medicinal plants are needed, and large, well designed, clinical studies need to be carried out before the use of such preparations can be recommended for treatment and/or prevention of diabetes. The main focus of this review is to describe what we know to date of the active compounds in these, along with their glucose-lowering mechanisms, which are either through insulin-mimicking activity or enhanced glucose uptake.

Determination of Gymnemic Acid I as a Protein Biosynthesis Inhibitor Using Chemical Proteomics

The plant Gymnema sylvestre has been used widely in traditional medicine as a remedy for several diseases, and its leaf extract is known to contain a group of bioactive triterpene saponins belonging to the gymnemic acid class. Gymnemic acid I (1) is one of the main components among this group of secondary metabolites and is endowed with an interesting bioactivity profile. Since there is a lack of information about its specific biological targets, the full interactome of 1 was investigated through a quantitative chemical proteomic approach, based on stable-isotope dimethyl labeling. The ribosome complex was found to be the main partner of compound 1, and a full validation of the proteomics results was achieved by orthogonal approaches. Further biochemical and biological investigations revealed an inhibitory effect of 1 on the ribosome machinery.

Pharmacological basis for the medicinal use of polyherbal formulation and its ingredients in cardiovascular disorders using rodents

BACKGROUND

A compound herbal formulation (POL4) has been used in the indigenous system of medicine to treat cardiometabolic disorders like diabetes and associated hypertension. POL4 and most of its constituents have not been studied widely for its therapeutic use in hypertension. This study is aimed to determine the efficacy and possible insight into mechanism(s) for the medicinal use of POL4 and its ingredients in hypertension.

METHODS

The aqueous methanolic extracts of POL4 (POL4.Cr) and its components [Cichorium intybus (Ci.Cr), Gymnema sylvestre (Gs.Cr), Nigella sativa (Ns.Cr) and Trigonella foenum graecum (Tfg.Cr)] were tested for blood pressure lowering activity in anaesthetized Sprague-Dawley rats. To assess the vasomodulatory effect, isolated tissue experiments were performed on rat aortic strips using isometric force transducer coupled with PowerLab data acquisition system.

RESULTS

Administration of POL4 to rats caused a dose-dependent (1-100 mg/kg) fall in mean arterial pressure (MAP) with maximum effect of 85.33 ± 1.76% at 100 mg/kg, similar to the effect of verapamil. All ingredients of POL4 also decreased blood pressure with varying efficacy in following order Ns.Cr ≅ Ci.Cr > Tfg.Cr > Gs.Cr. In rat aortic preparations, POL4 and its ingredients inhibited K+ (80 mM)-induced contractions, Ci.Cr was the most potent followed by Ns.Cr > Tfg.Cr > Gs.Cr ≅ POL4. Against phenylephrine (P.E) contractions, Ci.Cr and Tfg.Cr exhibited complete relaxation, while POL4.Cr, Gs.Cr and Ns.Cr showed vasomodulatory effect. The Ca++ antagonist activity was confirmed when POL4 and its ingredients shifted Ca++ concentrations-response curves to the right in a manner similar to that of verapamil. On baseline of rat aorta, the parent formulation and its ingredients (except Tfg.Cr) exhibited partially phentolamine (1 μM)-sensitive vasoconstriction.

CONCLUSION

These data show that POL4 and its constituents possess blood pressure lowering activity mediated through inhibition of Ca++ influx via membranous Ca++ channels and receptor (α-adrenergic) operated pathways. Thus, this study provides a rationale to the medicinal use of POL4 and its constituents in hypertension.

The Effects of Gymnema sylvestre in High-Fat Diet-Induced Metabolic Disorders

This study used an integrated approach to investigate the effects of Gymnema sylvestre (GS) extract as a functional dietary supplement with a high-fat diet. This approach examined insulin resistance, the dysfunction of adipose tissue, and liver steatosis. Male C57BL/6J mice were fed a normal chow or high-fat diet (HFD) for the acute and chronic study, in addition to GS in different doses (100, 250 and 500[Formula: see text]mg/kg body weight). Their body composition changes, serum lipid and glucose parameters, adipose and liver tissue histology, and gene expression were measured. It was found that GS significantly suppressed the increase of body weight, serum levels of lipid, insulin and leptin, and adipose tissue, and liver inflammation. GS also demonstrated hypoglycemic effects due to the amylase inhibition activity. Our results support the existence of a relationship between the HFD induced insulin resistance, adipose dysfunction and liver steatosis. In conclusion, GS works as a functional dietary supplement with preventative effects against metabolic disorder.

Herbal Medicines for Treating Metabolic Syndrome: A Systematic Review of Randomized Controlled Trials

Objective. The aim of this systematic review is to evaluate the efficacy and safety of herbal medicines in the management of metabolic syndrome. Materials and Methods. On December 9, 2015, we searched PubMed, EMBASE, Cochrane Library, SCOPUS, AMED, CNKI, KoreaMed, KMBASE, OASIS, and J-STAGE with no restriction on language or published year. We selected randomized controlled trials that involved patients with metabolic syndrome being treated with herbal medicines as intervention. The main keywords were “Chinese herbal medicines”, “metabolic syndrome”, and “randomized controlled trials”. Herbal substances which were not based on East Asian medical theory, combination therapy with western medicines, and concurrent diseases other than metabolic syndrome were excluded. The risk of bias was assessed by Cochrane's “Risk of Bias” tool. The protocol or review was registered in PROSPERO (an international prospective register of systematic reviews) (CRD42014006842). Results. From 1,098 articles, 12 RCTs were included in this review: five trials studied herbal medicines versus a placebo or no treatment, and seven trials studied herbal medicines versus western medicines. Herbal medicines were effective on decreasing waist circumference, blood glucose, blood lipids, and blood pressure. Conclusion. This study suggests the possibility that herbal medicines can be complementary and alternative medicines for metabolic syndrome.

Plant secondary metabolism linked glycosyltransferases: An update on expanding knowledge and scopes

The multigene family of enzymes known as glycosyltransferases or popularly known as GTs catalyze the addition of carbohydrate moiety to a variety of synthetic as well as natural compounds. Glycosylation of plant secondary metabolites is an emerging area of research in drug designing and development. The unsurpassing complexity and diversity among natural products arising due to glycosylation type of alterations including glycodiversification and glycorandomization are emerging as the promising approaches in pharmacological studies. While, some GTs with broad spectrum of substrate specificity are promising candidates for glycoengineering while others with stringent specificity pose limitations in accepting molecules and performing catalysis. With the rising trends in diseases and the efficacy/potential of natural products in their treatment, glycosylation of plant secondary metabolites constitutes a key mechanism in biogeneration of their glycoconjugates possessing medicinal properties. The present review highlights the role of glycosyltransferases in plant secondary metabolism with an overview of their identification strategies, catalytic mechanism and structural studies on plant GTs. Furthermore, the article discusses the biotechnological and biomedical application of GTs ranging from detoxification of xenobiotics and hormone homeostasis to the synthesis of glycoconjugates and crop engineering. The future directions in glycosyltransferase research should focus on the synthesis of bioactive glycoconjugates via metabolic engineering and manipulation of enzyme's active site leading to improved/desirable catalytic properties. The multiple advantages of glycosylation in plant secondary metabolomics highlight the increasing significance of the GTs, and in near future, the enzyme superfamily may serve as promising path for progress in expanding drug targets for pharmacophore discovery and development.

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.

Effects of feeding a diet containing Gymnema sylvestre extract: Attenuating progression of obesity in C57BL/6J mice

OBJECTIVE

To investigate the effect of Gymnema sylvestre extract (GS) on initial anti-obesity, liver injury, and glucose homeostasis induced by a high-fat diet (HFD).

METHODS

The dry powder of GS was extracted with methanol, and gymnemic acid was identified by high performance liquid chromatography as deacyl gymnemic acid. Male C57BL/6J mice that fed on either a normal diet, normal diet containing 1 g/kg GS (CON+GS), HFD, or HFD containing 1.0 g/kg GS (HFD + GS) for 4 weeks were used to test the initial anti-obesity effect of GS. Body weight gain and food intake, and serum levels about lipid and liver injury markers were measured. Histopathology of adipose tissue and liver stained with hematoxylin and eosin (H&E) and oil-red O were analyzed. After 4 weeks of GS extract feeding, intraperitoneal glucose tolerance test (IPGTT) was performed.

RESULTS

The methanol extracts of GS exerted significant anti-obesity effects in HFD + GS group. They decreased body weight gain, a lower food and energy efficiency ratio, and showed lower serum levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL)-cholesterol, very-low density lipoprotein (VLDL)-cholesterol and leptin compared with the HFD group. The decreases of abdominal as well as epididymal fat weight and adipocyte hypertrophy, lipid droplets in liver, and serum levels of aspartate aminotransferase (AST) and alanine transaminase (ALT) were also observed. The CON + GS group showed an effect of glucose homeostasis compared to the CON group.

CONCLUSIONS

This study shows that GS provide the possibility as a key role in an initial anti-obesity effects feeding with a HFD.

Human Cytochrome P450 Enzyme Modulation by Gymnema sylvestre: A Predictive Safety Evaluation by LC-MS/MS

BACKGROUND

Traditionally GS is used to treat diabetes mellitus. Drug-herb interaction of GS via cytochrome P450 enzyme system by substrate cocktail method using HLM has not been reported.

OBJECTIVE

To evaluate the in-vitro modulatory effects of GS extracts (aqueous, methanol, ethyl acetate, chloroform and n-hexane) and deacylgymnemic acid (DGA) on human CYP1A2, 2C8, 2C9, 2D6 and 3A4 activities in HLM.

MATERIAL AND METHODS

Probe substrate-based LCMS/MS method was established for all CYPs. The metabolite formations were examined after incubation of probe substrates with HLM in the presence or absence of extracts and DGA. The inhibitory effects of GS extracts and DGA were characterized with kinetic parameters IC50 and Ki values.

RESULTS

GS extracts showed differential effect on CYP activities in the following order of inhibitory potency: ethyl acetate > Chloroform > methanol > n-hexane > aqueous > DGA. This differential effect was observed against CYP1A2, 2C9 and less on CYP3A4 and 2C8 but all CYPs were unaffected by aqueous extract and DGA. The ethyl acetate and chloroform extract exhibited moderate inhibition towards CYP1A2 and 3A4. The aqueous extract and DGA however showed negligible inhibition towards all five major human CYPs with very high IC50 values (>90μg/ml).

CONCLUSION

The results of our study revealed that phytoconstituents contained in GS, particularly in ethyl acetate and chloroform extracts, were able to inhibit CYP1A2, 3A4 and 2C9. The presence of relatively small, lipophillic yet slightly polar compounds within the GS extracts may be attributed for inhibition activities. These suggest that the herb or its extracts should be examined for potential pharmacokinetic drug interactions in vivo. Abbreviations used: GS: Gymnema sylvestre, GSE: Gymnema sylvestre extract, DGA: deacyl gymnemic acid, CYP: cytochrome P450, DMSO: dimethylsulphoxide, HLM: human liver microsomes, LC-MS/MS: liquid chromatography tandem mass spectroscopy, NADPH: reduced nicotinamide adeninedinucleotide phosphate, NRS: nicotinamide adeninedinucleotide phosphate regenerating system, CHE: chloroform extract, EAE: ethyl acetate extract, NHE- n-hexane extract, AE: aqueous extract, ME: methanol extract.

Recent Trends in Therapeutic Approaches for Diabetes Management: A Comprehensive Update

Diabetes highlights a growing epidemic imposing serious social economic crisis to the countries around the globe. Despite scientific breakthroughs, better healthcare facilities, and improved literacy rate, the disease continues to burden several sections, especially middle and low income countries. The present trends indicate the rise in premature death, posing a major threat to global development. Scientific and technological advances have witnessed the development of newer generation of drugs like sulphonylureas, biguanides, alpha glucosidase inhibitors, and thiazolidinediones with significant efficacy in reducing hyperglycemia. Recent approaches in drug discovery have contributed to the development of new class of therapeutics like Incretin mimetics, Amylin analogues, GIP analogs, Peroxisome proliferator activated receptors, and dipeptidyl peptidase-4 inhibitor as targets for potential drugs in diabetes treatment. Subsequently, the identification and clinical investigation of bioactive substances from plants have revolutionized the research on drug discovery and lead identification for diabetes management. With a focus on the emerging trends, the review article explores the current statistical prevalence of the disease, discussing the benefits and limitations of the commercially available drugs. Additionally, the critical areas in clinical diabetology are discussed, with respect to prospects of statins, nanotechnology, and stem cell technology as next generation therapeutics and why the herbal formulations are consistently popular choice for diabetes medication and management.

Molecular decodification of gymnemic acids from Gymnema sylvestre. Discovery of a new class of liver X receptor antagonists

The individual chemical components of commercial extract of Gymnema sylvestre, a medicinal plant used in the traditional systems of the Indian medicine for its antidiabetic and hypolipidemic properties, were isolated and evaluated for their capability to act as modulators of nuclear and membrane receptors involved in glucose and lipid homeostasis. The study disclosed for the first time that individual gymnemic acids are potent and selective antagonists for the β isoform of LXR. Indeed the above activity was shared by the most abundant aglycone gymnemagenin (10) whereas gymnestrogenin (11) was endowed with a dual LXRα/β antagonistic profile. Deep pharmacological investigation demonstrated that gymnestrogenin, reducing the expression of SREBP1c and ABCA1 in vitro, is able to decrease lipid accumulation in HepG2 cells. The results of this study substantiate the use of G. sylvestre extract in LXR mediated dislypidemic diseases.

Molecular cloning and biochemical characterization of a recombinant sterol 3-O-glucosyltransferase from Gymnema sylvestre R.Br. catalyzing biosynthesis of steryl glucosides

Gymnema sylvestre R.Br., a pharmacologically important herb vernacularly called Gur-Mar (sugar eliminator), is widely known for its antidiabetic action. This property of the herb has been attributed to the presence of bioactive triterpene glycosides. Although some information regarding pharmacology and phytochemical profiles of the plant are available, no attempts have been made so far to decipher the biosynthetic pathway and key enzymes involved in biosynthesis of steryl glucosides. The present report deals with the identification and catalytic characterization of a glucosyltransferase, catalyzing biosynthesis of steryl glycosides. The full length cDNA (2572 bp) contained an open reading frame of 2106 nucleotides that encoded a 701 amino acid protein, falling into GT-B subfamily of glycosyltransferases. The GsSGT was expressed in Escherichia coli and biochemical characterization of the recombinant enzyme suggested its key role in the biosynthesis of steryl glucosides with catalytic preference for C-3 hydroxyl group of sterols. To our knowledge, this pertains to be the first report on cloning and biochemical characterization of a sterol metabolism gene from G. sylvestre R.Br. catalyzing glucosylation of a variety of sterols of biological origin from diverse organisms such as bacteria, fungi, and plants.