Design, synthesis and antibacterial evaluation of some new coumarin fused oxazole derivatives

A new series of dihydro-1, 2-oxazole coumarin derivatives (SR1-SR10) was prepared using a multi-step reaction. The syntheses of intermediates coumarinyl chalcones and final compounds were characterized by IR, Mass, and 1 H NMR spectra. The final compound’s SR1-SR10 binding mode and its inhibitor susceptibility were studied by molecular docking with the receptor DNA gyrase B (PDB code: 5L3J). It is responsible for catalyzing changes during DNA replication and validated targets for antibacterial molecules. The docking score of compounds SR1-SR10 ranges from -4.18 to -2.15 kcal mol-1. Among all these compounds, chloro-substituted dihydro isoxazole chromen-2-one (SR10) showed the best docking score with -4.18 kcal mol-1. SR10 interacted with the ATP-binding site of E. coli DNA gyrase B through a hydrogen bond with GLY77 and hydrophobic bond, charged negatives and polar interaction. SR1-SR10 antibacterial inhibitory property by tube dilution method was performed, and its minimum inhibitory concentrations (MIC) were observed. The MIC values of (SR1-SR10) range from 3.12 to 25 µg mL-1. Compounds SR3 and SR10 showed significant antibacterial activity with a MIC value of 3.12 µg mL-1