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

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BSTRACT

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.