Azelaic Acid Exhibits Dual Antimicrobial and Quorum Sensing Inhibitory Activities Against Pathogens: In Vitro Evaluation and Molecular Docking Insights
Pseudomonas aeruginosa is an opportunistic pathogen whose virulence is largely regulated by quorum sensing (QS), making this system an attractive target for anti-virulence therapies. Azelaic acid (AzA), a naturally occurring dicarboxylic acid widely used in dermatology, has not previously been investigated as a QS inhibitor. This study evaluated the antibacterial and anti-virulence activities of AzA against reference strains and multidrug-resistant clinical isolates of P. aeruginosa, together with its preliminary safety profile and potential molecular interactions with key QS proteins. Minimum inhibitory concentrations (MICs) ranged from 250 to 1000 {micro}g/mL. At sub-inhibitory concentrations, AzA significantly reduced the production of pyocyanin, elastase, protease and alginate in a dose-dependent manner without affecting bacterial viability. Molecular docking predicted favorable interactions of AzA with LasI, LasR, PqsD and PqsR, supporting a potential modulation of QS-associated pathways. Chemoinformatic analyses predicted favorable drug-likeness and safety characteristics, while PBMC viability remained above 90% and hemolysis below 4% within the anti-virulence concentration range. In the Tenebrio molitor infection model, AzA significantly increased larval survival and reduced in vivo pyocyanin production in both the reference strain Pa14 and a multidrug-resistant clinical isolate. Collectively, these findings provide the first evidence that AzA attenuates QS-regulated virulence in P. aeruginosa through complementary in vitro, in silico and in vivo approaches while exhibiting a favorable preliminary safety profile. These results support the repositioning of AzA as a promising anti-virulence candidate for the development of adjunctive therapeutic strategies against multidrug-resistant P. aeruginosa infections.