Myricetin Modulates Quorum Sensing-Associated Phenotypes, Virulence, and Biofilm Formation in Pathogenic Bacteria: In Vitro and In Silico Studies

Background/Objectives: The rapid emergence of antimicrobial resistance (AMR) among pathogenic bacteria has necessitated the development of alternative therapeutic strategies that target bacterial virulence rather than cell viability. Methods: In this study, the flavonoid myricetin was systematically evaluated for its antibacterial, QS-associated phenotypic and biofilm formation-inhibitory activities against clinically relevant bacterial pathogens. Results: Myricetin exhibited moderate antibacterial activity and significantly reduced several QS-associated phenotypes. Violacein and prodigiosin production were reduced by 74.59% and 64.32%, respectively, consistent with QS-modulatory activity under the tested conditions. Furthermore, myricetin markedly attenuated key virulence factors in Pseudomonas aeruginosa, including pyocyanin (70.44%), pyoverdine (75.84%), and rhamnolipids (48.69%). In addition, concentration-dependent reductions in biofilm formation and extracellular polymeric substance (EPS) production was observed across all tested strains. Molecular docking predicted favourable interactions of myricetin with key QS regulatory proteins, particularly CviR and LasR, which was supported by molecular dynamics simulations. Notably, the LasR–myricetin complex showed greater computational stability among the evaluated complexes, supporting its potential role as a key interaction site. Conclusions: This study provides an integrated experimental and computational evaluation of myricetin-mediated modulation of QS-associated phenotypes across multiple bacterial systems, demonstrating reductions in virulence-factor production and biofilm formation under the tested conditions. Collectively, these findings position myricetin as a promising anti-virulence candidate, although further studies are required to validate its clinical applicability.