Effect of Vernonia amygdalina on phospholipase activity from Naja Mossambica (Cobra)

Background: Phospholipases are one of the numerous enzymes found in the Naja mossambica venom. They play a major role in snakebite envenomation, and also responsible for the hydrolysis of a phospholipid, disrupting the membrane integrity. In this study, we evaluated the effect of Vernonia amygdalina on Phospholipase activity from Naja mossambica (Cobra) Results: Partially purified phospholipase had maximal velocity (V_max) and Michaelis Menten constant (K_m) of 7.6 × 10^-5 mol/min and 1.7mg/ml, while the crude phospholipase had V_max and Km of 9.4 × 10^-5mol/min and 2.5mg/ml respectively. Inhibition study of aqueous extracts of Vernonia amygdalina leaf shows that the extract is a potent inhibitor of crude phospholipase in a dose-dependent pattern. The different doses of extract 15 %, 10 % and 5% produced percentage inhibition of 74.04 %, 78.6 % and 86.63% respectively. The kinetic binding constant (K_i) values of crude phospholipase for different concentrations of extracts 5%, 10% and 15% were 0.21mg/ml, 0.29mg/ml and 0.39mg/ml, while the partially purified phospholipase for different concentrations of extracts 5%, 10% and 15% were were 0.48mg/ml, 0.42mg/ml and 0.41mg/ml respectively. It can be deduced from the results that the extract inhibits the phospholipase activity in an uncompetitive manner. Conclusion: Aqueous extract of Vernonia amygdalina leaves may contain some bioactive agents that could serve as potent inhibitors of phospholipase from Naja mossambica venom.