Cyclic Diguanylate G‑Quadruplex Inducer–Siderophore Hybrids as Bifunctional Antibiofilm Agents against Pseudomonas aeruginosa

Biofilm formation is a crucial determinant of both pathogenicity and enhanced antibiotic resistance in Pseudomonas aeruginosa. Sustainable iron utilization in the bacterial growth environments and intracellular c-di-GMP signaling molecules are key factors promoting bacterial biofilm development. Capitalizing on our previous findings that c-di-GMP G-quadruplex inducers exhibit potent antibiofilm activity and that 3-hydroxypyridin-4(1H)-ones act as effective iron chelators, we designed and synthesized dual-functional hybrid molecules incorporating both pharmacophores. The lead compound 11f, which features a benzothiazole-pyridinone scaffold, demonstrated potent biofilm inhibition against both wild-type P. aeruginosa PAO1 and the hyper-biofilm-forming PAO1-ΔwspF mutant. Mechanistic investigations revealed that 11f operates through dual pathways: facilitating c-di-GMP G-quadruplex formation and disrupting iron acquisition systems. Notably, in Galleria mellonella infection models, 11f exhibited significant synergistic effects with ciprofloxacin and tobramycin while maintaining an excellent safety profile, highlighting its potential as an antibacterial adjuvant.