Design, Synthesis, and Biological Evaluation of Novel Fused Spiro-4-Pyran Derivatives as Bacterial Biofilm Disruptor.

This study aims to synthesize novel fused spiro-4-pyran derivatives under green conditions to develop agents having antimicrobial activity. The synthesized compounds were initially screened for in vitro antibacterial activity against two Gram-positive and three Gram-negative bacterial strains, and all the compounds exhibited moderate to potent antibacterial activity. However, compound showed significant inhibition toward all the bacterial strains, particularly against and with minimum inhibitory concentration values of 125 μg/mL for each. The toxicity studies of selected compounds (, , , and using human red blood cells as well as human embryonic kidney (HEK-293) cells showed nontoxic behavior at desired concentration. Growth kinetic and time-kill curve studies of against and supported its bactericidal nature. Interestingly, compound showed a synergistic effect when used in combination with ciprofloxacin against selected strains. Biofilm formation in the presence of a lead compound, as assessed by XTT assay, showed complete disruption of the bacterial biofilm visualized by scanning electron microscopy. Overall, the findings suggest to be considered as a promising lead for further development as an antibacterial agent.