Aqueous Root Extract of Strophanthus hispidus Demonstrates Antidiabetic Effect in Fructose-Streptozotocin-Induced Diabetic Rats

Background and Purpose: This investigation evaluated the antidiabetic activity of the aqueous leaf extract of Strophanthus hispidus (SHP) in fructose/low-dose streptozotocin-induced type 2 diabetic rats due to the folkloric use of the root in traditional medicine for the treatment of both type 1 and type 2 diabetes mellitus. Methods: Fructose/low-dose streptozotocin-induced diabetic rats were allotted into five groups of eight rats each and administered S. hispidus root extract at doses of 50, 100 and 200 mg/kg; glibenclamide 5 mg/kg; and normal saline 10 mL/kg respectively. A sixth group that consisted of non-diabetic rats were given distilled water (10 mL/kg). Treatment was by the oral route for 28 consecutive days.  Fasting blood glucose (FBG) level was checked at intervals of 7 days. Blood samples were collected on day 28 an hour after the administration of the last dose, for the assay of serum levels of enzymes, lipids, insulin, haemoglobin (Hb), and glycosylated haemoglobin (HbA1c). Results: The aqueous root extract of SHP demonstrated a significant (P<0.05) reduction in FBG compared with diabetic non-treated control. The doses of 50, 100, 200 mg/kg of aqueous SHP and 5 mg /kg of glibenclamide elicited 82.07%, 88.83%, 88.03% and 78.01% reduction in FBG level respectively at day 28. The extract treated rats displayed significant (P<0.05) decrease in urea, ALT, AST, ALP, LDL, TC, TG and HbA1c levels and significant (P<0.05) increase in HDL and Hb levels. Significant (P<0.05) dose-independent upsurge in serum insulin level was equally observed. Conclusion: The aqueous root extract of SHP has blood glucose lowering potential and improves some of the imbalances that occur in diabetes.