Evaluation of the antibacterial activity of diverse coumarin [3,4]-fused Tetrahydroheterocycles

This study systematically evaluated the antibacterial activity of three classes of coumarin-fused [3,4]-tetrahydroheterocycles against two animal-derived pathogenic bacteria— Staphylococcus aureus and Escherichia coli —as well as three plant pathogens: Xanthomonas citri , Pseudomonas oryzae , and Fusarium oxysporum . The results demonstrated that coumarin-fused tetrahydrofuran derivatives (e.g., 3aa , 3 ac , and 3ae ; MIC = 2 μg/mL) exhibited pronounced and selective antibacterial activity against Staphylococcus aureus . Meanwhile, coumarin-fused tetrahydropyridazine compounds showed potent efficacy against Pseudomonas oryzae and Fusarium oxysporum , with a minimum inhibitory concentration (MIC) of 2 μg/mL (e.g., 7ae , 7ah , and 7ag ), significantly surpassing the positive control osthole. In contrast, coumarin-fused tetrahydro-1,2-oxazine analogues displayed relatively weak broad-spectrum antibacterial activity. These findings provide a robust theoretical foundation for the design and synthesis of novel coumarin-based heterocyclic antibacterial agents and offer valuable guidance for future research directions.