Tabriz University of Medical Sciences Pharmaceutical Sciences 1735-403X 32 3 2026 07 31 Exploring the Phytopharmaceutical Potential of Passiflora incarnata L. in Combating Biofilm Formation and Virulence of Clinical Acinetobacter baumannii Isolates 430 440 10.34172/ps.43311 EN Kamali Srilakshmi Ravichandran https://orcid.org/0009-0000-4513-6217 Naji Naseef Pathoor Pitchaipillai Sankar Ganesh https://orcid.org/0000-0003-0954-5966 Geetha Royapuram Veeraragavan Journal Article 10.34172/ps.43311 2025 09 30 2026 02 23 Introduction: Biofilm-associated infections caused by multidrug-resistant (MDR) Acinetobacter baumannii (A. baumannii) pose a major therapeutic challenge due to persistent colonization and limited treatment options. Natural products are increasingly investigated as antivirulence agents capable of disrupting biofilm formation and motility without imposing strong bactericidal pressure. Passiflora incarnata (P. incarnata), a flavonoid-rich medicinal plant, has shown promising antimicrobial potential. This study examined the ability of P. incarnata extract to modulate biofilm formation, virulence traits, and quorum sensing (QS) related targets in clinical A. baumannii isolates. Methods: Clinical A. baumannii isolates (CUAB-01–CUAB-04) were confirmed by MALDI-TOF and tested for antibiotic susceptibility. Antibacterial activity of P. incarnata extract was evaluated by well-diffusion and broth microdilution assays to determine MIC. Sub-MIC levels were used to assess biofilm inhibition, alginate production, growth kinetics, swarming and twitching motility, and H2 O2 sensitivity. Biofilm architecture was examined on coverslips using light microscopy. Furthermore, molecular docking of orientin and vitexin with QS related targets (7ZL4, 5HM6) was carried out using AutoDock Vina to predict binding affinities and key interactions. Results: P. incarnata extract demonstrated clear antibacterial activity with a MIC of 0.625 mg/mL, A sub-MIC of 0.312 mg/mL significantly reduced biofilm biomass without affecting planktonic growth. Sub-inhibitory treatment also led to reduced alginate production, impaired swarming and twitching motility, and heightened susceptibility to oxidative stress. Microscopy revealed disrupted, sparse biofilm architecture in treated samples. Docking analysis revealed favorable binding affinities of orientin and vitexin toward 7ZL4 and 5HM6, suggesting potential targeting of QS and biofilm regulatory proteins. Conclusion: P. incarnata exhibits strong antibacterial, antibiofilm, and antivirulence effects against clinical MDR A. baumannii, particularly at sub-MIC levels by suppressing the pathogenic traits. These findings highlight its potential as a natural therapeutic candidate for managing persistent A. baumannii biofilm infections and warrant further in-vivo and mechanistic investigations.