Gymnema Sylvestre Extract

Gymnema Sylvestre is a plant native to the tropical forests of India, and has been long used as a treatment for diabetes. Recent scientific investigation has upheld its effectiveness in both Type I and Type II diabetes. Gymnema Sylvestre is probably the most practical herbal recommendation for improving blood sugar control in diabetics.

Furthermore, there is some evidence that it may possibly regenerate or revitalize the insulin-producing beta cells of the pancreas. It is interesting to note that Gymnema extracts are without side effects and exerts its blood sugar-lowering effects only in cases of diabetes. Gymnema extract, when given to healthy volunteers, does not produce any blood sugar lowering or hypoglycemic effects.

Clinical Studies

 

Ramkumar KM, Rajaguru P, Latha M, Ananthan R.

Department of Biotechnology, School of Engineering and Technology, Bharathidasan University, Tiruchirapalli, 620 024, Tamil Nadu, India, km_ramkumar@rediffmail.com.

The aim of the present study was to evaluate the protective effect of Gymnema montanum on red blood cell (RBC) membrane in diabetic rats during lipid peroxidation. Ethanol extract of G. montanum leaves (GLEt) was administered orally to alloxan-induced diabetic rats for 3 weeks, and the effects on blood glucose, insulin, lipid peroxidation markers, thiobarbituric acid reactive substances, hydroperoxides in plasma and antioxidant enzymes including superoxide dismutase, catalase and glutathione peroxidase activities in erythrocytes were studied. Administration of GLEt to diabetic animals at doses of 50, 100, and 200 mg/kg body weight lowered elevated blood glucose levels by 24, 35, and 66%, respectively, relative to untreated diabetic rats. In comparison, treatment with the known antidiabetic drug, glibenclamide (600 mug/kg body weight) decreased blood glucose concentrations by 51%. Plasma insulin concentrations were increased in the diabetic rat by 73% with GLEt (200 mg/kg body weight) and 45% with glibenclamide (600 mug/kg body weight). Although a significant decrease in the lipid peroxidation markers was observed in plasma on treatment with GLEt and glibenclamide, the RBC antioxidant levels were increased significantly in diabetic rats. Furthermore, erythrocytes from the GLEt-treated animals were found to be more resistant to H(2)O(2)-induced peroxidation than that of untreated diabetic animals. The chemical characterization of the polyphenolics of the extract showed the presence of gallic acid (5.29% w/w), resveratrol (2.2% w/w), and quercetin (16.6% w/w). The results of this study suggest that G. montanum may be useful for the control, management, and prevention of oxidative stress associated with diabetes.

Ramkumar KM, Latha M, Ashokkumar N, Pari L, Ananthan R.

Department of Biochemistry, Faculty of Science, Annamalai University, Annamalainagar-608 002, Tamil Nadu, India.

We reported that a leaf extract (GLEt) obtained from an anti-diabetic plant, Gymnema montanum, an endangered species endemic to India, has anti-peroxidative and antioxidant effects on diabetic brain tissue in rats. Here we examined the effect of the extract on the activity of reduced brain and retinal acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in streptozotocin (STZ)-induced diabetic male Wistar rats. Diabetic rats received GLEt orally (200 mg/kg bwt/d) for 12 wk, and changes in blood glucose, plasma insulin, the lipid peroxidation marker thiobarbituric acid-reactive substance (TBARS), and AChE and BChE activity were measured. The results confirmed prior reports that hyperglycemia significantly enhances TBARS levels in brain and retinal tissue and decreases AChE and BChE activity. Treatment with GLEt significantly reversed the impairment in enzymatic activity in addition to reducing the level of TBARS, suggesting that GLEt protects against the adverse effect of lipid peroxidation on brain and retinal cholinesterases. We suggest that GLEt could be useful for preventing the cholinergic neural and retinal complications of hyperglycemia in diabetes.

Ramkumar KM, Latha M, Venkateswaran S, Pari L, Ananthan R, Bai VN.

Department of Biochemistry, Faculty of Science, Annamalai University, Annamalainagar, India.

The effects of leaf extract from Gymnema montanum, an endangered and endemic plant, were examined on brain lipid peroxidation in experimental diabetic rats. Ethanolic extract of G. montanum leaves was administered orally (50, 100, and 200 mg/kg of body weight) for 3 weeks, and changes in blood glucose, plasma insulin, and lipid peroxidation markers such as thiobarbituric acid-reactive substances (TBARS), hydroperoxides, and levels of antioxidants, namely, superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, and glutathione-S-transferase, were examined in the brain of alloxan-induced diabetic rats. Glibenclamide was used as a standard reference drug. A significant increase in the activities of antioxidants was observed in brain on treatment with G. montanum leaf extract and glibenclamide for 3 weeks. Both the treated groups showed significant decreases in formation of TBARS and hydroperoxides in brain, suggesting a role in protective action against lipid peroxidation-mediated membrane damage. Our findings indicate that G. montanum leaf extract possesses antiperoxidative and antioxidant effects in addition to its antidiabetic activity. This report helps to create awareness on the need for conservation of medicinal plants, and G. montanum is one such plant that needs to be conserved through various propagation trials.