Novel PHL derivatives targeting quorum sensing: A strategy to combat Pseudomonas aeruginosa infections

Pseudomonas aeruginosa (P. aeruginosa) is a common pathogenic bacterium that is widely distributed and highly pathogenic. Its pathogenicity is closely related to the formation of biofilms and virulence factors. It is well known that quorum sensing (QS) controls the formation of biofilms and the production of virulence factors in P. aeruginosa. Therefore, quorum-sensing inhibitors (QSIs) have attracted great interest as a potential therapeutic strategy against P. aeruginosa infections. This study departs from the conventional approach of screening potential QSIs through experimental synthesis and subsequent activity validation, which is typically time-consuming and labor-intensive. Instead, we integrated molecular docking, molecular dynamics simulations, and experimental synthesis with validation strategies to systematically evaluate newly designed Phenylacetanoyl homoserine lactones (PHLs) derivatives. In the computational screening phase, the binding affinity, binding sites, and binding stability between the PHL derivatives and the target protein LasR were comprehensively assessed using molecular docking and molecular dynamics simulations. Five compounds demonstrating promising potential QS inhibitory activity were selected. During the experimental phase, these five compounds underwent preliminary evaluation for their anti-biofilm activity against P. aeruginosa. Results indicated that N-(3-cyclobutyl lactone)-4-nitrobenzobutyramide (L2) exhibited the most potent biofilm inhibitory activity. Compared to previously reported QSIs, L2 effectively inhibited biofilm formation, toxin production, and motility of P. aeruginosa at lower concentrations. Notably, L2 exhibited characteristics of a partial agonist, which sheds light on its deeper mechanism of action. Furthermore, L2 showed a synergistic effect when combined with antibiotics, significantly enhancing the susceptibility of biofilm bacteria of P. aeruginosa to antibiotics, while demonstrating a favorable hemocompatibility safety profile. The proposed combination strategy offers a new potential therapeutic avenue for the clinical treatment of P. aeruginosa infections.