n-Butanol Extract of Polygonum capitatum Targets Biofilm Formation, Motility, and Adhesion Attenuation to Combat Uropathogenic Escherichia coli

Uropathogenic Escherichia coli (UPEC) that form biofilms exhibit high-level antibiotic resistance, which poses substantial challenges to current therapeutic strategies for urinary tract infection (UTI). There is an urgent need for strategies specifically targeting UPEC biofilms. This study investigated the effects of the n-butanol extract of Polygonum capitatum (BPC) on UPEC strains, focusing on its antibacterial activity, biofilm formation, bacterial motility, adhesion capacity, and cell membrane integrity. The disk diffusion method, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays demonstrated that BPC exhibited potent antibacterial activity against both reference and clinically isolated UPEC strains. Time–kill curve assays further confirmed that BPC inhibits bacterial growth in a time-dependent manner. BPC inhibited UPEC biofilm formation in a dose-dependent manner, significantly reducing biofilm formation in both reference and clinical UPEC strains. Furthermore, BPC disrupted cell membrane integrity in UPEC strain CFT073, resulting in the leakage of alkaline phosphatase (AKP), β-galactosidase, and intracellular proteins. BPC treatment also significantly reduced bacterial surface hydrophobicity, impaired swimming and swarming motility, and diminished adhesion and invasion capabilities. A total of 32 active compounds, predominantly flavonoids, were identified in BPC by UHPLC-Q-orbitrap MS/MS. Molecular docking studies revealed that several compounds in BPC, such as quercetin-3,4′-O-di-beta-glucoside, exhibited strong binding affinity to AKP and β-galactosidase, further supporting its potential to disrupt membrane integrity and inhibit biofilm formation. Thus, BPC exerts anti-UPEC effects through biofilm disruption and multi-targeted anti-virulence mechanisms, highlighting its potential as a novel therapeutic or adjunctive agent for UTI, particularly against recalcitrant biofilm-associated infections. The mode of action of BPC provides a scientific basis for developing new anti-infective strategies as alternatives to conventional antibiotics.