Discovery of Dual-Acting Biofilm Inhibitors against Pseudomonas aeruginosa by the Coupling of 3-Hydroxypyridin-4(1H)-ones with N-Phenylamide QS Inhibitors

Pseudomonas aeruginosa (P. aeruginosa) is prevalent in hospital infections and strongly complicates the treatment for its propensity to cause biofilm-associated resistance. Herein, a series of novel dual-acting biofilm inhibitors were designed and synthesized by coupling 3-hydroxypyridin-4(1H)-ones with N-phenylamides quorum sensing inhibitors. The hit compound 19l (IC₅₀ = 0.33 ± 0.06 μM) demonstrated significant biofilm inhibition compared to previously reported 3-hydroxypyridin-4(1H)-one derivatives in vitro. Mechanistic studies revealed that there was a decreased production of virulence regulated by quorum sensing system and a lack of iron acquisition under the treatment of 19l, which led to the inhibition of biofilm. More importantly, 19l demonstrated significant antibacterial synergistic effects in the mice wound infection model, enhancing the antibacterial activity of ciprofloxacin and tobramycin by 1000-fold and 200-fold, respectively. Therefore, our study highlighted the clinical application potential of dual-acting biofilm inhibitory strategies and 19l may be a potent antibacterial synergist to combat P. aeruginosa infections.