Effect of combined use of Ocimum gratissimum and Vernonia amygdalina extract on the activity of angiotensin converting enzyme, hypolipidemic and antioxidant parameters in streptozotocin-induced diabetic rats

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.