Hypoglycemic and hypolipidemic activity of Hibiscus rosa sinensis Linn on streptozotocin–induced diabetic rats

To investigate the hypoglycemic activity of an aqueous extract of the flower of Hibiscus rosa sinensis on blood glucose in normal and streptozotocin (STZ) -induced diabetic rats, serum triglyceride and cholesterol levels and the effect of the flower extract on insulin secretion. Effect of H. rosa sinensis flower extract on blood glucose was studied with fed, fasted and glucose-loaded diabetic and nondiabetic rats. Glycosylated hemoglobin, serum insulin levels and lipid profile were also determined. Student’s t test was used for statistical analysis. In normal rats, the aqueous extract of the flower of H. rosa sinensis (250 and 500 mg/kg body weight) significantly (P < 0.001) reduced the blood glucose levels after an oral glucose load from 127.9 ± 5.6 to 80.6 ± 3.9 mg/dl 2 h after oral administration of the flower extract. It also significantly lowered the blood glucose in STZ diabetic rats from 241.0 ± 6.6 to 90.8 ± 5.7 mg/dl after 21 days of oral administration of the extract (P < 0.001). Serum insulin levels were not stimulated in the animals treated with the extract. Glycosylated hemoglobin and serum lipid profiles were significantly lowered by the administration of the extract. From the studies, it can be concluded that the aqueous extract of the flowers of H. rosa sinensis at a dosage of 500 mg/kg/day exhibits significant hypoglycemic and hypolipidemic activities. A marked reduction in glycosylated hemoglobin was also observed while insulin levels did not show any significant change.