Disruption of quorum sensing and biofilm formation by lawsone in gram-negative bacteria

Antimicrobial resistance is a major global health threat, exacerbated by bacterial virulence mechanisms such as quorum sensing (QS) and biofilm formation, which enhance pathogenicity and reduce antibiotic susceptibility. Targeting QS offers a promising antivirulence strategy that may attenuate pathogenic traits without imposing selective pressure. In this study, lawsone was evaluated for anti-QS and antibiofilm activity against Chromobacterium violaceum, Pseudomonas aeruginosa, and Serratia marcescens. Lawsone significantly inhibited QS-regulated virulence factors, with reductions in violacein production in C. violaceum (90.62%) at 250 µg/mL (1.43 mM). There was also a reduction in pyocyanin and pyoverdin in P. aeruginosa (87.90% and 81.97%, respectively) and prodigiosin in S. marcescens (~83%) at 500 µg/mL (2.87 mM) lawsone. Additionally, lawsone suppressed protease and elastase activities, as well as rhamnolipid production in P. aeruginosa. Biofilm formation was inhibited in a dose-dependent manner, reaching 84.28% in C. violaceum, 76.22% in P. aeruginosa, and 56.27% in S. marcescens at respective sub-MICs. Computational analyses supported these findings; docking showed stable binding of lawsone to QS regulators, including CviR (-7.8 kcal/mol), LasR (-8.5 kcal/mol), and SmaR (-7.7 kcal/mol). Molecular dynamics simulations confirmed the stability of these complexes, with root mean square deviation values of 0.200 ± 0.016 nm (CviR-lawsone), 0.238 ± 0.036 nm (LasR-lawsone), and 0.632 ± 0.061 nm (SmaR-lawsone). Molecular Mechanics Poisson-Boltzmann Surface Area (MM-PBSA) calculations further demonstrated favorable binding. To my knowledge, this is the first study to systematically demonstrate the anti-QS and antibiofilm potential of lawsone across multiple clinically relevant gram-negative pathogens using an integrated experimental and computational approach. This work provides possible mechanistic insights into lawsone-QS regulator interactions, highlighting its potential as a broad-spectrum antivirulence agent targeting conserved QS systems.IMPORTANCEAntimicrobial resistance is a growing global threat, driven in part by bacterial virulence mechanisms such as quorum sensing (QS) and biofilm formation. Targeting QS offers an alternative strategy to reduce pathogenicity without promoting resistance. This study shows that lawsone effectively inhibits QS-regulated virulence factors and biofilm formation in gram-negative pathogens, like Pseudomonas aeruginosa, Serratia marcescens, and Chromobacterium violaceum. These findings highlight lawsone as a promising antivirulence agent that could complement existing therapies for managing biofilm-associated and drug-resistant infections.