Evaluation of vincamine against acetylcholinesterase enzyme

The current article deals with the in-silico along with enzyme kinetics approach to search for a prominent AChE enzyme inhibitor among the known natural compounds. The computational tools were involved for this purpose and eventual vincamine, a monoterpenoid indole alkaloid, was selected based on several parameters, including free energy of binding (-10.77 kcal/mol) and ADME parameter. Computationally, it confirmed the interaction between vincamine and AChE at an indistinguishable locus from that of substrate AChI (-3.94 kcal/mol) but with much higher binding energy. Interestingly, amino acid residues Gly120, Gly121, Gly122, Glu202, Trp86, Tyr133, Ser203, Phe297, and His447 of AChE were found to be common in these interactions. Further, these findings were approved with wet lab tests where detailed kinetics was studied. It was found that vincamine inhibited AChE with the inhibition constant K_i (239 µM). The value of IC₅₀ (239 µM) and K_M (0.598 mM) was determined and further confirmed by Dixon, Lineweaver- Burk reciprocal, Hanes, and Eadie-Hofstee plots, respectively. The mode of interaction of the compound was found to be competitive for AChE. Thus, the present computational and enzyme kinetics studies conclude that vincamine can be a promising inhibitor of AChE for the effective management of AD.