Menthol diminishes Staphylococcus aureus virulence-associated extracellular proteins expression

Staphylococcus aureus is a significant human pathogen that is the major cause of a broad spectrum of illnesses, ranging from minor skin infections to life-threatening deep tissue infections and toxinosis. The ability of the organism to cause such a broad range of infections is, to a great extent, attributed to the secretion of a myriad of virulence-related extracellular proteins. Therefore, virulence as a target for antimicrobial chemotherapy has gained great interest. Menthol is a monocyclic terpene alcohol that occurs naturally in plants of the Mentha species lacking anti-S. aureus activity. In this paper, we demonstrate via hemolytic activity assays, tumor necrosis factor release assays, Western blot assays, and real-time reverse transcription-PCR assays that low concentrations of menthol can markedly inhibit the expression of α-hemolysin, enterotoxins A and B, and toxic shock syndrome toxin 1 in S. aureus. Our results indicate that menthol may be useful in managing S. aureus infections when used in combination with β-lactam antibiotics, which can often increase S. aureus toxin secretion when used at subinhibitory concentrations. In addition, the menthol basic structure has potential applications in the development of new anti-virulence drugs.