di(1H-Indol-3-yl)methane: A promising antibiofilm and anti-virulence agent against Vibrio cholerae

Cholera is a pandemic diarrheal illness caused by infection with Vibrio cholerae . Cholera remains persistent and poses a major health burden in the human population due to a lack of proper sanitation and clean potable drinking water. The spread of multidrug-resistant Vibrio cholerae strains makes conventional antibiotics ineffective and enhances cholera infectivity. Virulence gene expression and biofilm formation via quorum-sensing cascades are the major pathogenicity of Vibrio cholerae . In this research work, eight Bis(indolyl)methane derivatives were tested for their antimicrobial and antibiofilm activities against the clinical isolates. Among the various compounds tested, di(1H-indol-3-yl)methane exhibited the strongest activity. It exhibited an IC 90 of 125 μg/mL and an MBIC 50 of 31.25 μg/mL against HYR14. Although no significant growth inhibition was observed for MTCC 3906, the compound demonstrated strong antibiofilm activity with an MBIC 50 as low as 7.9 μg/mL. Further assays conducted at sub-inhibitory concentrations, including crystal violet staining, fluorescence microscopy, and motility assay, confirmed its ability to disrupt biofilm. Gene expression analysis through qRT-PCR confirmed the downregulation of all the genes responsible for biofilm formation, strengthening these findings. Overall, the study highlights di(1H-indol-3-yl)methane as a promising anti-virulent agent with strain-specific effects.