Syntheses and antimicrobial study of heterocyclic compounds containing quinoxaline moiety

Abstract

Heterocyclic compounds containing quinoxline moiety have received considerable attention during last two decades as they possesses different pharmacological and biological activities. This study aims to synthesize and characterize heterocyclic compounds containing quinoxaline moiety. The starting compounds 3-methylquinoxalin- 2(1H)-one was prepared from o-phenylenediamine and pyruvic acid upon refluxing in ethanol for 3 hours in single step. Then the different hydrazonomethyl Quinoxaline compounds were synthesized from the coupling reaction between different diazonium salts and 3-methylquinoxalin-2(1H)-one as the active methylated compound. The structures of all the synthesized compounds were elucidated by the spectroscopic methods such as IR, 1H NMR and 13C NMR. Then the synthesized compounds were evaluated for their in vitro antibacterial activity against one Gram-positive (G+ve) bacteria Staphylococcus aureus(+), five Gram-negative (G-ve) bacteria Bacillus subtilis(-), Escherichia coli (-), Pseudomonas aeruginosa (-), Salmonella typhimurium (-) ,Citrobacter freundii (-) and antifungal activity against two fungi Aspergillus niger and Tricodarma harzianum. All the tested compounds show moderate activity against one Gram- positive, five Gram-negative (G-ve) bacteria and two fungi. Keywords: Heterocyclic; quinoxline; diazonium salt, coupling reaction;