Design, synthesis and in vitro antimicrobial activity of novel phenylbenzamido-aminothiazole-based azasterol mimics

Abstract

Phenylbenzamide framework as a mimic of the azasterol structure was investigated by synthesizing 4-phenylbenzamido-2-aminothiazole 4, and evaluating its MIC against Escherichia coli, Enterobacter cloacae, Bacillus licheniformis and Mycobacterium tuberculosis (MTB) H₃₇Rv as well as antifungal activity against three test phytopathogenic fungi. Further, the bioisosterism strategy was implemented to synthesize a series of azo-derivatives of 4 (6a–6j). All the azo-compounds were screened for their antibacterial and antifungal activity. The electronic (UV–vis) absorption characteristics of the final compounds were examined. Resazurin-mediated microtitre plate-antibacterial assay was implemented for first time on these azo-derivatives. Compounds 4 and 6b had significant antibacterial activity. For the compound 4, MIC against Escherichia coli is 7.8 × 10⁻³ mg/mL and MIC against Mycobacterium tuberculosis (MTB) H₃₇Rv is 16 μg/mL were identified. Compounds 4, 6d, 6g and 6h showed excellent antifungal activity, when compared to the standard nistatin, against three test phytopathogenic fungi.