Antidiabetic Effect of Aqueous Root Extract of Strophanthus hispidus in Fructose-induced Type 2 Diabetic Sprague Dawley Rats

Abstract

Background: Strophanthus hispidus DC. (Apocynaceae) (SHP) is used in African traditional medicine in the treatment of several diseases including diabetes. Objective: The study sought to explore and scientifically validate the antidiabetic activity of Strophanthus hispidus in fructose- induced Type 2 diabetic Sprague Dawley rats. Methods: S. hispidus (50, 100 and 200 mg/kg p.o.), glibenclamide (5 mg/kg p.o.), normal saline (10 mL/kg p.o.; diabetic control) and distilled water (10 mL/kg p.o.; normal control) were administered once daily for 28 days to 12 weeks fed fructose rats with homeostatic model assessment for insulin resistance (HOMA-IR) >1.5 and fasting blood glucose (FBG) level >200 mg/dL. Measurement of FBG and body weight of the fructose-induced Type 2 diabetic rats was carried out at 7 days interval. On day 28, blood samples were collected for assessment of serum biochemical parameters, including albumin (ALB), total protein (TP), creatinine, alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), bilirubin and urea; serum insulin; and haematological (haemoglobin, Hb and glycated haemoglobin, HbA1c) parameters. The liver of rats was harvested for glycogen assay. Results: S. hispidus-treated fructose-induced Type 2 diabetic rats produced significant (p<0.05) day-dependent reduction in FBG level and significant (p<0.05) increase in HDL and TP levels compared with diabetic control rats. In addition, significant (p<0.05) decrease in TG, LDL, TC, AST, ALT, ALP, bilirubin, creatinine and urea levels was produced compared with diabetic control rats. Furthermore, significant (p<0.05) increase in serum insulin and liver glycogen levels was also observed. S. hispidus- treated diabetic rats displayed significant (p<0.05) increase in Hb and decrease in HbA1c levels. Conclusion: The findings in this study showed that S. hispidus possesses beneficial antidiabetic property in Type 2 diabetes. This validates its use in African traditional medicine in the treatment of diabetes.