Kunga Mohan Ramkumar

Antidiabetic effects of scoparic acid D isolated from Scoparia dulcis in rats with streptozotocin-induced diabetes

We evaluated the antihyperglycaemic effect of scoparic acid D (SAD), a diterpenoid isolated from the ethanol extract of Scoparia dulcis in streptozotocin (STZ)-induced diabetic male Wistar rats. SAD was administered orally at a dose of 10, 20 and 40 mg kg−1 bodyweight for 15 days. At the end of the experimental period, the SAD-treated STZ diabetic rats showed decreased levels of glucose as compared with diabetic control rats. The improvement in blood glucose levels of SAD-treated rats was associated with a significant increase in plasma insulin levels. SAD at a dose of 20 mg kg−1 bodyweight exhibited a significant effect when compared with other doses. Further, the effect of SAD was tested on STZ-treated rat insulinoma cell lines (RINm5F cells) and isolated islets in vitro. SAD at a dose of 20 µg mL−1 evoked two-fold stimulation of insulin secretion from isolated islets, indicating its insulin secretagogue activity. Further, SAD protected STZ-mediated cytotoxicity and nitric oxide (NO) production in RINm5F cells. The present study thus confirms the antihyperglycaemic effect of SAD and also demonstrated the consistently strong cytoprotective properties of SAD.

MODULATION OF IMPAIRED CHOLINESTERASE ACTIVITY IN EXPERIMENTAL DIABETES: EFFECT OF Gymnema montanum LEAF EXTRACT

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.

Effect of Gymnema montanum on Blood Glucose, Plasma Insulin, and Carbohydrate Metabolic Enzymes in Alloxan-Induced Diabetic Rats

The effects of Gymnema montanum, an endangered plant used in the ancient period of India, on blood glucose, plasma insulin, and carbohydrate metabolic enzymes were studied in alloxan diabetic rats. Administration of alcoholic extract of G. montanum leaves (50, 100, 200 mg/kg body weight) to alloxan diabetic rats for 3 weeks reduced the blood glucose level. Administration of G. montanum leaf extract (GLEt) at 200 mg/kg body weight significantly decreased the blood glucose levels and significantly increased the plasma insulin levels. This clearly shows the antidiabetic efficacy of GLEt, which was better than that of glibenclamide.

Antihyperlipidaemic Effect of Gymnema montanum: A Study on Lipid Profile and Fatty Acid Composition in Experimental Diabetes

In the present study, the antihyperlipidaemic efficacy of ethanol extract of Gymnema montanum leaves was investigated in alloxan-induced diabetic rats and the effect was compared to standard hypoglycaemic drug, glibenclamide. Male adult albino Wistar rats were injected with freshly prepared solution of alloxan monohydrate (150 mg/kg body weight) to induce diabetes. After 2 weeks, the rats with moderate diabetes were administered G. montanum leaves (200 mg/kg body weight) for 21 days by gastric lavage, after which serum, liver and kidney samples were analysed for lipid profile, lipoprotein changes and fatty acid composition. While the alloxan-induced diabetic rats showed a significant increase in the levels of cholesterol, triglycerides and free fatty acids, the levels in the animals treated with G. montanum leaves were considerably reduced and restored to near normal values. Antihyperlipidaemic effects of G. montanum leaves were found to be comparable with that of glibenclamide. Similarly, G. montanum leaves treatment resulted in reversal of alterations observed in the plasma lipoproteins (high-density lipoprotein, low-density lipoprotein and very high-density lipoprotein-cholesterol) and fatty acid composition in serum, liver and kidney of alloxan-induced rats. Our study suggests that phytochemicals present in G. montanum may play an important role in suppressing the elevated lipid profile in diabetes and may be useful for the prevention and/or early treatment of diabetes-associated hyperlipidaemia.