Hypoglycaemic effect of Melothria heterophylla in streptozotocin-induced diabetic rats

Context: In the Indian traditional system of medicine, Melothria heterophylla (Lour.) Cogn., (Cucurbitaceae) is prescribed for the treatment of diabetes mellitus. Objective: In the present study, the antidiabetic effect of ethanol extract of Melothria heterophylla (EEMH), and its active isolated constituents were investigated in streptozotocin (STZ)-induced diabetic Swiss albino rats. Method: Successive Soxhlet extraction of the dried total aerial parts with petroleum ether for defatting and then with ethanol (95%) to obtain ethanol extract, which was concentrated under reduced pressure. Hyperglycemia was induced in rats by STZ (50 mg/kg, body weight). Twenty-four hours after STZ induction, respective groups of diabetic rats received EEMH (200 and 400 mg/kg, body weight), gallic acid (GA) (2 and 4 mg/kg, body weight), and rutin (RU) (2 and 4 mg/kg, body weight), respectively, orally daily for 15 days. Glibenclamide (0.5 mg/kg, orally) served as reference. Blood glucose levels and change in body weight were measured on every 5th day during 15 days of treatment. Biochemical parameters, viz., serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), alkaline phosphatase (ALP) and serum insulin, were measured. Results: EEMH and its active constituents significantly (p < 0.01) normalized blood glucose levels and serum biochemical parameters as compared to those of STZ controls. Both GA (4 mg/kg) and RU (4 mg/kg) exhibited maximum glucose lowering effect (69.1 and 66.7%, respectively) in diabetic rats compared to the other dose (2 mg/kg) at the end of the study. EEMH, gallic acid and RU also showed significant increase in serum insulin, and body weight of STZ-induced diabetic rats. Conclusion: Therefore, ethanol extract of Melothria heterophylla, GA and RU demonstrated remarkable antidiabetic activity in STZ-induced diabetic rats.