In vitro antibacterial and concentration-dependent bactericidal effects of Terminalia arjuna extract against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus, with synergistic activity against methicillin-resistant Staphylococcus aureus.

Staphylococcus aureus infections, particularly methicillin-resistant S. aureus (MRSA), remain a major clinical challenge due to limited treatment options. Plant-derived compounds have gained interest as alternative or adjunct antibacterial agents. This study investigated the antibacterial, antibiofilm, and synergistic effects of Terminalia arjuna extract against S. aureus and MRSA, with high-performance liquid chromatography (HPLC) analysis. Antibacterial activity of T. arjuna extract was evaluated using microdilution, time-kill, checkerboard, and biofilm assays against S. aureus and MRSA, with chemical profiling by HPLC. Data were calculated and shown as means ± standard deviation. A Significant difference was marked when P < 0.05. The ethanolic extract of T. arjuna demonstrated bactericidal action against S. aureus and MRSA, with minimum inhibitory concentration (MIC) and minimum bactericidal concentration values of 625 μg/mL. A concentration-dependent effect was observed, with complete bacterial killing achieved at supra-MIC levels. The extract reduced biofilm biomass by more than 80% at low concentrations. Notably, a pronounced synergistic interaction with ampicillin against MRSA was observed, yielding a fractional inhibitory concentration index of 0.281. The T. arjuna extract exhibited in vitro antibacterial activity and showed concentration-dependent bactericidal effects, with a synergistic interaction with ampicillin observed against MRSA.