Demonstration of the hypoglycemic action of Momordica charantia in a validated animal model of diabetes

In an effort to establish and document the hypoglycaemic activity of Momordica charantia in validated models of diabetes, the alcoholic extract of the pulp was studied. In the normal glucose primed rat model, M. charantia fruit extract, 500 mg kg(-1), depressed the plasma glucose levels by 10-15% at 1 h. Under similar conditions, tolbutamide (100 mg kg(-1)) caused approximately 40% reductions in plasma glucose both at 1 and 2 h. At 500 mg kg(-1), the efficacy of M. charantia was 25-30% of tolbutamide. The reduction in plasma glucose in normal glucose primed rat was not accompanied by increased insulin secretion. There was no evidence of tachyphylaxis to the effect of M. charantia extract on repeated dosing. In streptozotocin diabetes rats, it improved the oral glucose tolerance causing significant (P< 0.002) reduction in plasma glucose of 26% at 3.5 h while metformin caused 40-50% reduction at 1, 2 and 3.5 h. M. charantia extract (500 mg kg(-1)) caused a 4-5-fold increase in the rate of glycogen synthesis from U-C-14-glucose in the liver of normally fed rats. These data suggest that the mechanism of action of M. charantia could be partly attributed to increased glucose utilization in the liver rather than an insulin secretion effect. This is the first report on the effect of M. charantia in characterized and validated animal model systems known to respond to oral hypoglycaemic drugs. (C) 1996 The Italian Pharmacological Society