Synthesis of 4-hydroxycoumarin heteroarylhybrids as potential antimicrobial agents

A new series of 4-hydroxycoumarin derivatives 3a-d was synthesized by the reaction of 3-bromo-4-hydroxy coumarin 1 with various heteroaldehydes 2a-d in good yields. The synthesized compounds were characterized on the basis of their elemental and spectral (IR, (1)H-NMR and mass spectrometry) analysis. All target compounds were evaluated for their in-vitro antimicrobial activity against Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli bacterial strains and fungal cultures of Candida albicans, Aspergillus fumigatus, Trichophyton mentagrophytes, and Penicillium marneffei by disk diffusion assay with slight modifications. The minimum inhibitory concentration (MIC) was determined for the test compounds as well as for reference standards. Among the tested compounds, 3a has shown the most potent antibacterial as well as antifungal activities.