Effect of Monoon longifolium extract on quorum-sensing-regulated production of virulence factors in Serratia marcescens
Authors: SANGEETA RAJESH SHETTY, Phileo Abraham
Keywords: Antibiotic resistance, Quorum sensing, Anti-virulence, Monoon longifolium, Moringa oleifera, Coleus amboinicus, Hibiscus × rosa-sinensis, Chromobacterium violaceum.
Abstract:
The growing emergence of multidrug-resistant pathogens presents a critical health challenge worldwide, urging the development of novel therapies that can reduce bacterial virulence without promoting resistance. One promising strategy involves targeting quorum sensing, a bacterial cell-to-cell communication system that regulates the expression of virulence factors. This study evaluated the quorum quenching potential of aqueous leaf extracts of Moringa oleifera, Coleus amboinicus, Monoon longifolium, and Hibiscus rosa-sinensis against Chromobacterium violaceum MTCC 2656. Antibacterial activity was observed at 3.1875 mg/mL for M. oleifera, 25.5 mg/mL for C. amboinicus, and 8.5 mg/mL for both H. rosa-sinensis and M. longifolium. Moringa showed the most potent antibacterial action. Further, all four aqueous extracts, at sub-MIC concentrations, inhibited biofilm formation and production of violacein, lipase, and protease without affecting bacterial viability. Phytochemical screening revealed the presence of flavonoids, sterols, terpenoids, alkaloids, and phenols in all extracts, with Moringa showing higher sterol and phenolic content. Bioautography of C. amboinicus extract showed two active bands, which inhibited violacein production in the overlaid C. violaceum culture. These results suggest that plant extracts offer a sustainable, natural strategy to combat bacterial infections, including MDR strains, and can also serve to control biofilm formation in the food processing industry.
