Antibacterial Activity of Planchonia valida Against Methicillin-Resistant Staphylococcus aureus (MRSA): Phytochemical Profiling, LC-MS Analysis, and Molecular Docking Study

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is a major antimicrobial-resistant pathogen, creating a need for alternative antibacterial agents from natural resources. This study aimed to evaluate the antibacterial activity of Planchonia valida leaf extracts against MRSA and investigate potential bioactive constituents associated with the observed activity through phytochemical profiling, LC–MS analysis, and molecular docking. Leaves of P. valida were extracted using n-hexane, ethyl acetate, and methanol, and antibacterial activity was evaluated using the disk diffusion method. The most active extract was further characterized through phytochemical screening and LC–MS analysis, while tentatively annotated metabolites were evaluated by molecular docking against penicillin-binding protein 2a (PBP2a). The ethyl acetate extract exhibited the strongest antibacterial activity, producing an inhibition zone of 14.33 ± 0.32 mm at 30% (w/v). Phytochemical screening indicated the presence of terpenoids, steroids, alkaloids, and flavonoids, with flavonoids showing the strongest qualitative response. LC–MS analysis tentatively annotated five flavonoid-related compounds, including apigenin, biochanin A, luteolin, kaempferol, and quercetin. Docking validation produced an RMSD value of 0.39 Å, and quercetin exhibited the most favorable predicted binding energy among the evaluated compounds (−7.36 kcal mol⁻¹). These findings suggest that P. valida leaf extract possesses antibacterial potential against MRSA, with flavonoid-related metabolites as promising candidates for further investigation.