In this study, we used ethanol extract of A. princeps and investigated its antibacterial effects against MRSA. Ethanol extract of A.
princeps significantly inhibited MRSA growth and organic acid production during glucose metabolism at concentrations greater
than 1 mg/mL (P < 0.05). MRSA biofilm formation was observed using scanning electron microscopy (SEM) and safranin staining.
A. princeps extract was found to inhibit MRSA biofilm formation at concentrations higher than 2 mg/mL significantly (P < 0.05).
Bactericidal effects of the A. princepswere observed using confocal laser microscopy, which showed that A. princepswas bactericidal
in a dose-dependent manner. Using real-time PCR, expression of mecA, an antibiotic-resistance gene of MRSA, was observed,
along with that of sea, agrA, and sarA. A. princeps significantly inhibited mecA, sea, agrA, and sarA, mRNA expression at the
concentrations greater than 1 mg/mL (P < 0.05). The phytochemical analysis of A. princeps showed a relatively high content of
organic acids and glycosides. The results of this study suggest that the ethanol extract of A. princeps may inhibit proliferation, acid
production, biofilm formation, and virulence gene expressions of MRSA, which may be related to organic acids and glycosides, the
major components in the extract.