Design and Synthesis of N-Benzyl-Quinoxaline Derivatives Linked with Quinoline Moiety for Antimicrobial Activity

Abstract

In the present study, a novel series of N-benzyl-quinoxaline derivatives linked with a quinoline moiety through a thioether bridge were designed and synthesized with the objective of exploring their antimicrobial potential. The synthetic strategy involved the condensation of 2,3-dichloroquinoxaline with benzylamine to afford N-benzyl-3-chloroquinoxalin-2-amine, which was subsequently coupled with 2-chloroquinolin-3-ylmethyl intermediates to yield the target compounds. The structures of the synthesized derivatives were confirmed by spectroscopic techniques (¹H NMR, ¹³C NMR). All the compounds were evaluated for their in vitro antimicrobial activity against selected Gram-positive and Gram-negative bacterial strains as well as fungal pathogens using the agar disc diffusion method, with gatifloxacin and clotrimazole as reference drugs. Several derivatives demonstrated promising antibacterial and antifungal activity, with some compounds exhibiting comparable or superior efficacy to the standard drugs. The findings suggest that molecular hybridization of quinoline and quinoxaline frameworks represents a valuable approach in the development of potent antimicrobial agents.