Influence of magnolol on the secretion of alpha-toxin by Staphylococcus aureus.

In this study we investigated the antimicrobial activity of magnolol on Staphylococcus aureus. The minimal inhibitory concentrations of magnolol against 31 S. aureus strains ranged from 4-32 microg/mL. In addition, hemolysin assays, Western blotting, and real-time RT-PCR were performed to investigate the effect of magnolol on alpha-toxin secretion by both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). The results indicated that sub-inhibitory concentrations of magnolol dose-dependently inhibited the transcription of hla (the gene encoding alpha-toxin) in S. aureus, resulting in a reduction of alpha-toxin secretion and, thus, hemolytic activities.