Exploring the binding mechanism and kinetics of Piperine with snake venom secretory Phospholipase A<sub>2</sub>

<p>Secreted venom Phospholipase A<sub>2</sub> is highly responsible for pharmacological effects like neurotoxicity, myotoxicity, hemolytic, anti-coagulation, and platelet aggregation. Neutralization of these pharmacological behaviors is one of the challenges existing for many decades and a potent drug compound for this is very much needed to control local effects of venom sPLA<sub>2</sub>. In this study, we investigated binding mechanism and kinetics of inhibition of Piperine (major constitute of <i>Piper nigrum)</i> with sPLA<sub>2</sub> using DFT, MD simulation, MM-PBSA, and SPR method. Frontier MO properties were suggested that it procured better chemical reactivity and druglikeness and binding mode of Piperine with <i>Ec</i>PLA<sub>2</sub> defined that it occupied well in N-terminal hydrophobic cleft. The persistence of Piperine interactions with and without calcium ion was analyzed and confirmed by MD simulation analysis. The dPCA-based FEL shows the nature of apo- and Piperine-bound conformational behavior of <i>Ec</i>PLA<sub>2</sub> including intermediate forms. Further, binding energy of Piperine was calculated by high-throughput MM-PBSA which states that calcium ion presence enhances the Piperine binding by additional electrostatic interactions. Finally, kinetics of inhibition between Piperine and <i>Ec</i>PLA<sub>2</sub> implied that it secured better binding affinity (<i>K</i><sub><i>D</i></sub>: as 1.708 pM) and the result gives clear evidence for the binding mechanism and binding energy calculated. In conclusion, Piperine was authenticated with better drug ability, entrenched binding interaction, and robust kinetics of inhibition with <i>Ec</i>PLA<sub>2</sub> through which it can become an exceeding drug candidate for pharmacological as well as catalytic activity of sPLA<sub>2</sub>.</p>