Synthesis and Biological Evaluation of Coumarin Bearing Thiourea Derivative as Potential Antibacterial Agent

In this study, a series of thiourea-substituted coumarin was synthesized in a four-step reaction from a precursor, 2-oxo-2H-chromene-3-carboxylic acid. The structures of all synthesized compounds were confirmed using NMR and LCMS. All synthesized compounds were screened for their antibacterial activity against gram-negative (Escherichia coli, Salmonella typhimurium, and Enterobacter aerogenes) and gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria strains using well diffusion method. Most of the synthesized compounds were found to be susceptible to most of the tested bacterial strains. The structure-activity relationship showed that compounds with substituents at the ortho position had lower overall activity as compared to meta-substituted and para-substituted compounds. Compound 19 was found to be the most effective antibacterial agent against gram-positive S. aureus and B. subtilis, with minimum inhibitory concentration values of 31.25 and 62.50 µg/mL, respectively. Molecular docking performed on potential compounds revealed significant binding site interaction with S. aureus gyrase residue Asp1083 and Met1121.