ABSTRACT Melothria heterophylla (Lour.) Cogn. (Cucurbitaceae) widely distributed in India and used ethnically by tribal people in India for controlling blood sugar. This promotes us to undertake a study to examine the possible antidiabetic activity of the plant extracts in normal and streptozotocin induced diabetic rats. A single dose study was studied in the normal rats for 12hrs. Oral glucose tolerance test was performed in normal rats after receiving glucose orally (2gm/kg). Diabetes was induced with streptozotocin (50mg/kg, i.p.) and a dose of 300mg/kg of Petroleum ether (PEMH), Methanol (MEMH) and Aqueous (AEMH) extracts were then administered orally to experimental diabetic rats for 21 days. Glibenclamide was used as standard reference. Fasting blood glucose levels, changes in body weight and liver weight, serum albumin, serum urea, total protein, total lipid profile, haemoglobin, SOD, GSH and TBARS were evaluated. Single dose study of extracts on normal rats showed a significant decrease in the fasting blood glucose levels when compared with the normal control rats. Oral glucose tolerance test clearly indicate that MEMH and PEMH extracts shown a significant reduce in the blood glucose levels, AEMH extract showed little effect. In diabetic rats, treatment with the PEMH, MEMH and AEMH showing significant reduction in the fasting blood glucose levels, serum cholesterol, serum triglycerides, LDL-C and VLDL-C levels. A significant escalation is seen in the levels of HDL-C, haemoglobin, body weight and liver weight. Whereas the antioxidant levels of SOD, GSH and TBARS improved than the untreated diabetic rats. The study reveals that the plant extracts of Melothria heterophylla showed significant antidiabetic activity in normal fasted rats, OGTT in normal rats and in STZ induced diabetic rats
