EFFECTS OF CHLORPROMAZINE ON THE ENZYMATIC AND TOXIC PROPERTIES OF THE MOST BASIC PHOSPHOLIPASE A(2) FROM VIPERA-RUSSELLI SNAKE-VENOM

The effect of chlorpromazine on various biological activities of phosp holipase A(2) VRV-PL-VIIIa from Vipera russelli snake venom was invest igated. The drug inhibited the in vitro phospholipase A(2) activity of the enzyme by 55%. The ID50 was found to be 1.15 mu M. Increasing sub strate concentration relieved the inhibition of phospholipase A(2) act ivity by the drug indicating probable interaction with the substrate. The drug totally quenched the fluorescence intensity of the enzyme. Ch lorpromazine increased the LD(50) Of the enzyme by 1.6 fold. The drug also inhibited hemolytic and anticoagulant potencies but failed to inh ibit edema inducing activity and myotoxicity of the enzyme.