Design, synthesis, antibacterial activity evaluation, and mechanism of action study of novel pyrrolidine derivatives...

Bacterial biofilms serve as innate protective frameworks, sheltering embedded microbes to sustain their survival while potentially enhancing antimicrobial resistance by blocking bactericide penetration. While extensive research has focused on planktonic bacteria, biofilm recalcitrance remains understudied, leaving conventional antimicrobials often ineffective against these sessile communities. This underscores an urgent need for next-generation agents with specialized biofilm-inhibiting properties to enabling effective antibacterial therapy; in this study, we used pyrrolidine-3-carboxylic acid as a starting material to synthesize a series of sulfonamide-containing pyrrolidine derivatives via an active coupling reaction. Compound A14 exhibited the strongest activity, with an EC₅₀ value of 38.33 μg/mL against Xanthomonas oryzae pv. oryzae (Xoo). Mechanistic investigations revealed that A14 suppresses extracellular polymeric substance (EPS) biosynthesis and bacterial motility-key drivers of pathogenicity, biofilm development, and plant cell wall degradation. Conductivity measurements and protein leakage assays confirmed that A14 disrupts multiple Xoo physiological functions, positioning it as a promising antimicrobial candidate targeting core mechanisms of bacterial plant diseases.