SYNTHSIS, CHARACTERISATION AND ANTI MICROBIAL EVALUATION OF NOVEL 2-SUBSTITUTED QUINOXALINE DERIVATIVES

Abstract

literature survey indicates that 2-substituted quinoxaline derivatives possess different pharmacological and biological activities, of which most potent activities are anti-bacterial, anti-fungal, anti-inflammatory, and analgesic activity. In view of above literature, we planned to synthesize novel 2-Substituted quinoxaline derivatives. The final synthesised were characterized by physical (M.P, TLC) and spectral analysis (1HNMR, IR). The 2-substituted quinoxaline nucleus was constructed by condensation of o-phenylene diamine and diethy loxalate in equimolar quantities which upon heating yielded quinoxaline -2, 3-diol moiety. The quinoxaline -2,3-diol was treated with POCl3 to furnish 2,3-di chloro quinoxaline (2). Further the 2-chloro-3-hydrazinoquinoxaline (3) was synthesized by the reaction of 2,3- dichloroquinoxaline (2) and hydrazine hydrate in methanolic medium upon refluxing for 60 min. different Schiff’s bases of 2-chloro-3- hydrazine quinoxaline were obtained by refluxing the appropriate substituted benzaldehyde and 2-chloro-3-hydrazinoquinoxaline (3) in acetic medium for 3 h. All the synthesized compounds were screened for their antibacterial and antifungal activities by using cup plate method against Bacillus subtilis, Bacillus pumilus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger and Candida albicans at 100, 50 μg/mL concentration using ciprofloxacin and clotrimazole as reference standard drugs respectively. Compounds 4e and 4f showed significant activity against Pseudomonas aeruginosa, 4a and 4d showed significant activity against Bacillus subtilis, the compound 4c showed good activity against the organism Bacillus pumilus, whereas the compound 4a shown moderate antifungal activity against Candida albicans. The rest of the compounds showed weak activity when compared to the standard ciprofloxacin and clotrimazole.