Phytochemical‑driven antibiofilm effects of Ruellia tuberosa L. against Escherichia coli and Klebsiella pneumoniae

Multidrug‑resistant Gram‑negative pathogens, including Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) represent major clinical concerns due to their potent biofilm‑forming ability and associated virulence traits that contribute to persistent infections and antibiotic failure. In response to the growing limitations of conventional antibiotics against biofilm‑associated infections, the present study evaluated the antibiofilm potential of the ethanolic leaf extract of Ruellia tuberosa L. (R. tuberosa L.) using in vitro assays and gas chromatography‑mass spectrometry‑guided molecular docking analysis. The extract demonstrated antibacterial activity at the minimum inhibitory concentration (MIC) level and effectively inhibited biofilm formation at sub‑MIC concentrations, achieving 55% inhibition in E. coli at 10 mg/ml and 67.81% inhibition in K. pneumoniae at 20 mg/ml, without significantly affecting planktonic growth. Phytochemical profiling revealed a diverse compound composition, with diethyl phthalate identified as the major constituent. Molecular docking demonstrated stable interactions of this compound with key biofilm‑ and virulence‑associated targets in both pathogens, suggesting interference with bacterial adhesion, biofilm development, and persistence. Overall, these findings highlight R. tuberosa L. as a promising natural source of antibiofilm agents capable of attenuating biofilm formation in multidrug‑resistan Gram‑negative pathogens. These plant‑derived compound may serve as adjunct strategies for managing biofilm‑associated infections caused by E. coli and K. pneumoniae, warranting further in vivo and molecular validation.