Hypoglycemic effect of the water extract of Piper sarmentosum in rats

The hypoglycemic effect of the water extract of the whole plant of Piper sarmentosum Roxb. (Piperaceae, Thai name: Chaplu) was examined in normal and streptozotocin-diabetic rats. In an oral glucose tolerance test, a single oral administration of the water extract at doses of 0.125 and 0.25 g/kg significantly lowered the plasma glucose level in the normal rats. A reference drug, glibenclamide, at a dose of 5 mg/kg (per os, p.o.) also showed a significant hypoglycemic effect in the normal rats. In contrast, a single oral administration of the water extract at these doses and glibenclamide did not significantly lower the plasma glucose level in the diabetic rats. However, the repeated oral administration of the water extract at a dose of 0.125 g/kg for 7 days produced a significant hypoglycemic effect in the diabetic rats. Glibenclamide (5 mg/kg, p.o.) also caused significant hypoglycemia in the diabetic rats. These results demonstrated that the water extract of whole plant of Piper sarmentosum has a hypoglycemic effect in rats.