One‐pot synthesis of novel benzimidazoles with a naphthalene moiety as antimicrobial agents and molecular docking studies

Abstract

AbstractIn an attempt to design a greener approach for the synthesis of a potent class of antimicrobials, 1,2‐phenylenediamine derivatives were reacted with various 1/2‐carboxylic acid‐substituted naphthalene derivatives to generate a series of naphthyl‐substituted benzimidazole derivatives (11–19) using polyphosphoric acid as catalyst under microwave irradiation and conventional synthesis method. This is an eco‐friendly and swift reaction method for a synthetic approach to diverse benzimidazoles. Structures of the synthesized compounds were established on the basis of spectral data and they were screened for their antimicrobial activity. Compound 18 showed maximum potency against all Gram‐positive and Gram‐negative bacterial strains with a minimum inhibitory concentration (MIC) value in the range of 7.81–62.50 μg/ml. Only compound 17 was found to be the most active against all fungal strains with a MIC value of 15.62 μg/ml. In this study, we performed molecular docking experiments to understand the interactions between compounds 17 and 18 and E. coli topoisomerase I, and we compared the results obtained with that of 2‐(3,4‐dimethoxyphenyl)‐5‐[5‐(4‐methylpiperazin−1‐yl)‐1H‐benzimidazol‐2‐yl]‐1H‐benzimidazole (DMA). Compounds 17 and 18 demonstrated strong interactions with important active site residues, similar to DMA. As a result, the compounds obtained from this study can be used in designing new potent inhibitors of E. coli topoisomerase I.