A new class of arylsulfonamide-based 3-acetyl-2-methyl-4-phenylquinolines and in vitro evaluation of their antioxidant, antifungal, and antibacterial activities

Abstract

A series of new arylsulfonamide-based 3-acetyl-2-methyl-4-phenylquinolines were synthesized. Initially, 1-(2-methyl-6-nitro-4-phenylquinolin-3-yl)ethanone was synthesized and its nitro function reduced using zinc dust and ammonium chloride, leading to formation of 1-(6-amino-2-methyl-4-phenylquinolin-3-yl)ethanone, which in turn was converted to the corresponding arylsulfonamides by treatment with various substituted sulfonyl chlorides. The synthesized derivatives were evaluated for antibacterial activity against a series of Gram-positive and Gram-negative bacteria and for antifungal activity against Candida strains, Aspergillus niger (A. niger), and Issatchenkia hanoiensis (I. hanoiensis). Compound 5a showed prominent 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity with half-maximal effective concentration (EC50) of 9.78 ± 1.68 μg mL−1. Compound 5f exhibited considerable antifungal activity [minimum inhibitory concentration (MIC) of 0.89 µg mL−1] against A. niger MTCC1344. Compounds 5e, f showed excellent antibacterial activity (MIC 4.68 µg mL−1) against Klebsiella planticola MTCC2277.