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 IC90 of 125 μg/mL and an MBIC50 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 MBIC50 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.