Daboxin P, a phospholipase A2 of Indian Daboia russelii venom, modulates thrombin‐mediated platelet aggregation

Abstract Daboxin P, reported earlier from the venom of Daboia russellii , disturbs the blood coagulation cascade by targeting factor X and factor Xa. The present study exhibits that Daboxin P also inhibits platelet aggregation induced by various agonists. The thrombin‐induced platelet aggregation was inhibited maximum whereas inhibition of collagen‐induced platelet aggregation was found to be 50% and no inhibition of adenosine diphosphate (ADP) and arachidonic acid‐induced aggregation was observed. Daboxin P dose‐dependently inhibited the thrombin‐induced platelet aggregation with Anti‐Aggregation 50 (AD 50 ) dose of 55.166 nM and also reduced the thrombin‐mediated calcium influx. In‐silico interaction studies suggested that Daboxin P binds to thrombin and blocks its interaction with its receptor on the platelet surface. Quenching of thrombin's emission spectrum by Daboxin P and electrophoretic profiles of pull‐down assay further reveals the binding between Daboxin P and thrombin. Thus, the present study demonstrates that Daboxin P inhibits thrombin‐induced platelet aggregation by binding to thrombin.