Novel 2-Substituted 3-Hydroxy-1,6-dimethylpyridin-4(1H)-ones as Dual-Acting Biofilm Inhibitors of Pseudomonas aeruginosa

2-Heptyl-3-hydroxy-4(1H)-quinolone (PQS), a compound from P. aeruginosa, functions as both a quorum sensing (QS) regulator and a potent iron chelator to induce expression of pyoverdine and pyochelin which are involved in high-affinity iron transport systems. A potential dual-acting antibiofilm strategy requires molecules designed to interfere with iron uptake and the QS system of P. aeruginosa. A series of 2-substituted 3-hydroxy-1,6-dimethylpyridin-4-ones have been designed, synthesized, and tested as biofilm inhibitors of P. aeruginosa. One compound, N-((1,3,6-trimethyl-4-oxo-1,4-dihydropyridin-2-yl)methyl)hexanamide (10d), exhibits 68.67% biofilm inhibitory activity at 20 μM. Further mechanistic studies have confirmed that this compound not only inhibits the QS systems of P. aeruginosa but also acts as an iron chelator to compete strongly with pyoverdine, causing iron deficiency in bacteria. The pyoverdine receptor FpvA was revealed as the target of 10d by the Pvds mutant strain, fpvA-overexpressed strain, and in silico studies.