Abstract

This study was aimed at investigating the angiotensin converting enzyme (ACE) inhibitory effect, hypolidemic and antioxidant properties of combined extract of Occimum gratissimum andVernonia amygdalina in streptozotocin-induced diabetic rats. Thirty (30) apparently healthy male Wistar rats were grouped into: control, diabetic, diabetic + insulin, diabetic + 100 mg/kg and diabetic + 250 mg/kg extract groups. All rats except those in the control group were made diabetic using a single intraperitoneal injection of 60 mg/kg streptozotocin. Administration of extract began four days after induction of diabetes and lasted for four weeks. Results show a significant (P<0.05) increase in serum and liver triacyglycerol, total cholesterol and low density lipoprotein levels upon induction of diabetes, which reduced significantly (P<0.05) in rats given insulin and the extract. HDL-C levels remained unchanged in both liver and serum of diabetic rats when compared to control rats. The serum levels of sulfuroxide dismutase (SOD) and catalase increased significantly (P<0.05) in rats given insulin and the extract, while thiobarbituric acid reactive substances decreased significantly (P<0.05) compared to diabetic rats. Theangiotensin converting enzyme (ACE) activity in lungs, kidney and heart of diabetic rats were significantly (P<0.05) higher than that of control rats. Also kidney and liver functions were affected on induction of diabetes with a significant increase in levels of urea and aspartate aminotransferase (AST). All of the above factors reduced significantly (P<0.05) when rats were given either insulin or the extract. In conclusion, this study has shown that a combination of the aqueous leaf extracts of Vernonia amygdalina and Ocimum gratissimum inhibits ACE activity, lowers blood glucose and lipid levels; and is a good antioxidant.

Key words: Angiotensin converting enzyme (ACE), Ocimum gratissimum and Vernonia amygdalina, diabetes.