Evaluation of the anti-diabetic and antihyperlipidemic effect of methanol extract of Strophanthus hispidus roots D.C. (Apocynaceae)

The objective of the study is to establish the anti-diabetic effect of the methanol root extract of Strophanthus hispidus and to examine the effects of these extracts on the lipid profile of alloxan-induced diabetic rats. The acute toxicity test was carried out using standard methods. Diabetic mellitus was induced in 25 rats by single intraperitoneal injection of alloxan (150 mg/kg body weight). Two days after induction, the hyperglycaemic (> 200 mg/dl) rats were treated orally with different doses (200, 400 and 800 mg/kg) of the extract for 14days, glibenclamide (5 mg/kg) was used as the standard drug. The lipid profile was evaluated in diabetic treated groups compared with control. Similar study as above was carried out on normal rats. The extracts were found to be relatively safe. The extract at a dose of 800 mg/kg showed the most significant (P < 0.05) reduction (69.43%) in fasting blood glucose level in the diabetic rats; for normal rats, it was 41.92%. The extract at doses of 200 and 400 mg/kg also showed reduction (64.77 and67.75%) respectively in diabetic rats; (27.5 and 34.2%) respectively in normal rats. The extract showed a dose- independent decrease in the lipid profile examined at the end of the 14 day period. Phytochemical analysis revealed the presence of carbohydrates, alkaloids, flavonoids, reducing sugars, terpenoids, saponins, proteins, resins, steroids, glycosides and tannins. It can be concluded that the methanol root extract of S. hispidus possesses anti-diabetic and hypolipidemic properties on alloxan-induced diabetic rats.