Hypoglycemic effect of aqueous extract of Hibiscus rosa sinensis L. flowers in rats

The aqueous extract of flowers on blood glucose level was assessed in normoglycemic, glucose induced hyperglycemic and streptozotocin (STZ) induced diabetic rats. The aqueous extract (250 mgkg⁻¹) did not alter blood glucose levels in either normoglycemic or STZ-induced diabetic rats. In glucose-induced hyperglycemic, however, antidiabetic activity was seen when the extract was administered 30 min after glucose. The potency of the extract was compared with that of the reference drug tolbutamide (100 mgkg⁻¹). The glucose tolerance test was monitored afre administration of single and multiple doses (7 days). Repeated dosing of the extract caused four-fold decrease in percent glycemia in glucose-induced rats as compared to those receiving only once. The extract exhibited hypoglycemic properties, which may be due to an intestinal reduction of the absorption of glucose.