Potential Antimicrobial Isopropanol-Conjugated Carbazole Azoles as Dual Targeting Inhibitors of Enterococcus faecalis

A series of isopropanol-bridged carbazole azoles as potential antimicrobial agents were designed and synthesized from commercial carbazoles. Bioassay revealed that 3,6-dichlorocarbazolyl triazole 3f could effectively inhibit the growth of E. faecalis with minimal inhibitory concentration of 2 μg/mL. The active molecule 3f showed lower propensity to trigger the development of resistance in bacteria than norfloxacin and exerted rapidly bactericidal ability. Compound 3f also exhibited low cytotoxicity to normal mammalian RAW264.7 cells. Further mechanism exploration indicated that conjugate 3f was membrane active against E. faecalis and could form 3f-DNA complex by intercalating into DNA of resistant E. faecalis, which might be responsible for its antimicrobial action. Molecular docking showed an efficient binding of triazole derivative 3f with DNA gyrase enzyme through noncovalent interactions.