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

• Main Authors: Ahmed Elkamhawy, Sora Paik, Hyeon Jeong Kim, Jong-Hyun Park, Ashwini M. Londhe, Kyeong Lee, Ae Nim Pae, Ki Duk Park, Eun Joo Roh
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2020-01-01
• Series: Journal of Enzyme Inhibition and Medicinal Chemistry
• Subjects: monoamine oxidase b; carboxamide; mao-b inhibitor; microwave synthesis; molecular modelling
• Online Access: http://dx.doi.org/10.1080/14756366.2020.1800666

Herein, two new series of N-substituted indole-based analogues were rationally designed, synthesized via microwave heating technology, and evaluated as noteworthy MAO-B potential inhibitors. Compared to the reported indazole-based hits VI and VII, compounds 4b and 4e exhibited higher inhibitory activities over MAO-B with IC50 values of 1.65 and 0.78 µM, respectively. When compared to the modest selectivity index of rasagiline (II, a well-known MAO-B inhibitor, SI > 50), both 4b and 4e also 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 (Ki)/MAO-B = 94.52 nM). Reasonable explanations of the elicited biological activities were presented via SAR study and molecular docking simulation. Accordingly, the remarkable MAO-B inhibitory activity of 4e (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.