Antibacterial and Antibiofilm Activity of a Chemically Characterized Cinnamomum verum Bark Methanolic Extract Against Multidrug‐Resistant Bacteria: Preliminary Antibiotic–Interaction Screening and Exploratory Molecular Docking

This study characterized the phytochemical composition of a methanolic bark extract of Cinnamomum verum and evaluated its antibacterial, bactericidal, biofilm‐biomass‐reducing, and preliminary antibiotic‐potentiating effects against reference and multidrug‐resistant bacterial strains. The extract was characterized by HPLC‐MS; MIC and MBC values were determined by broth microdilution; biofilm biomass was assessed using the crystal‐violet assay; and antibiotic‐extract interactions were screened by disk diffusion. Molecular docking was used as a hypothesis‐generating approach to investigate interactions between identified phytochemicals and GyrB, LasA, and PBP1a. Seventeen compounds were identified, with trans‐cinnamaldehyde as the predominant quantified constituent, followed by quinic acid, rutin, and protocatechuic acid. The extract inhibited all tested bacteria, with MIC and MBC values of 0.625–5 and 2.5–20 mg/mL, respectively, and MBC/MIC ratios consistent with bactericidal activity. Imipenem‐resistant Acinetobacter baumannii isolates were the most susceptible. The extract also reduced biofilm biomass in a concentration‐dependent and strain‐dependent manner. Disk‐diffusion screening identified antibiotic‐ and isolate‐dependent increases in inhibition zones, particularly for cefoxitin and fosfomycin against MRSA and for selected combinations against A. baumannii ; however, some combinations were unchanged or produced smaller zones, and pharmacological synergy was not established. Docking prioritized quercetin, 1,3‐di‐O‐caffeoylquinic acid, and quercetin‐3‐O‐rhamnoside as candidates for subsequent target‐based validation.