Anti-dermatophytic activity of bakuchiol: in vitro mechanistic studies and in vivo tinea pedis-inhibiting activity in a guinea pig model.

Bakuchiol was an active antifungal compound isolated from Psoraleae Fructus by means of bioassay-guided fractionation in our previous study. The present work aimed to investigate the underlying mechanisms and the therapeutic effect of bakuchiol in Trichophyton mentagrophytes-induced tinea pedis. After exposure to bakuchiol at 0.25-fold, 0.5-fold and 1-fold of minimum inhibitory concentration (MIC) (3.91 μg/ml) for 24h, the fungal conidia of T. mentagrophytes demonstrated a significant dose-dependent increase in membrane permeability. Moreover, bakuchiol at 1-fold MIC elicited a 187% elevation in reactive oxygen species (ROS) level in fungal cells after a 3-h incubation. However, bakuchiol did not induce DNA fragmentation. In a guinea pig model of tinea pedis, bakuchiol at 1%, 5% or 10% (w/w) concentration in aqueous cream could significantly reduce the fungal burden of infected feet (p<0.01-0.05). In conclusion, this is the first report to demonstrate that bakuchiol is effective in relieving tinea pedis and in inhibiting the growth of the dermatophyte T. mentagrophytes by increasing fungal membrane permeability and ROS generation, but not via induction of DNA fragmentation.