Indian Journal of Pharmacy and Pharmacology

Page: 46-51

The rise of multidrug-resistant bacteria has intensified the need for alternative therapeutic approaches that suppress pathogenicity without selecting for resistance. Disrupting quorum sensing, an intercellular signaling mechanism that coordinates virulence, is one such approach. Aqueous extracts of Moringa oleifera (drumstick), Coleus amboinicus (Indian mint), Monoon longifolium (Ashoka) and Hibiscus rosa-sinensis (Chinese hibiscus) were screened for antibacterial activity against Serratia marcescens. Among them, only M. longifolium showed antibacterial activity, with an MIC of 12.75 mg/mL. This extract was further evaluated for its anti-virulence potential. At 8.5 mg/mL, it inhibited >70% biofilm formation, >80% prodigiosin production, and showed clear inhibition of lipase activity. M. oleifera, although not antibacterial, completely inhibited prodigiosin synthesis at 3.1875 mg/mL without inhibiting growth. At sub-MIC levels, both extracts reduced biofilm formation, motility, pigment production, and secretion of lipase and protease. Phytochemical profiling confirmed the presence of several bioactive classes such as flavonoids, sterols, terpenoids and alkaloids. Overall, the findings highlight the potential of plant-derived aqueous extracts as eco-friendly agents for mitigating bacterial pathogenicity, providing support for their possible application in controlling biofilm contamination within food-processing environments.