Discovery ofN-(1-(3-fluorobenzoyl)-1H-indol-5-yl)pyrazine-2-carboxamide: a novel, selective, and competitive indole-based lead inhibitor for human monoamine oxidase B

Herein, two new series ofN-substituted indole-based analogues were rationally designed, synthesizedviamicrowave heating technology, and evaluated as noteworthy MAO-B potential inhibitors. Compared to the reported indazole-based hitsVIandVII, compounds4band4eexhibited higher inhibitory activities over MAO-B with IC(50)values of 1.65 and 0.78 mu M, respectively. When compared to the modest selectivity index of rasagiline (II, a well-known MAO-B inhibitor, SI > 50), both4band4ealso showed better selectivity indices (SI > 60 and 120, respectively). A further kinetic evaluation of the most potent derivative (4e) displayed a competitive mode of inhibition (inhibition constant (K-i)/MAO-B = 94.52 nM). Reasonable explanations of the elicited biological activities were presentedviaSAR study and molecular docking simulation. Accordingly, the remarkable MAO-B inhibitory activity of4e(N-(1-(3-fluorobenzoyl)-1H-indol-5-yl)pyrazine-2-carboxamide), with its selectivity and competitive inhibition, advocates its potential role as a promising lead worthy of further optimization.