Antidermatophytic Activity of Wood Vinegars Prepared from Fraxinus formosana at Different Collection Temperatures

Wood vinegars were collected from the chimney outflow of earthen kiln at 5 different temperatures (73–80, 90–92, 100–108, 120–125 and 145–162˚C) during the charcoal preparation from branches and tree tops of Fraxinus formosana. The antidermatophytic activities of the vinegars were evaluated by the broth microdilution method, the minimum inhibitory concentration (MIC), against Epidermophyton floccosum (EF), Trichophyton mentagrophytes (TM) and Trichophyton rubrum (TR). The ether stratification of wood vinegars for three fractions (acidic, neutral and phenolic) and the ether fraction was also investigated. The active fractions in the vinegars were analyzed and identified by GC–MS. All vinegars, and the ether fraction and the phenolic fraction for neutral and phenolic materials had the inhibitory activities with MICs at 0.63–2.50, and 0.08–0.31 mg/mL against EF, TM, and TR. 2,6–dimethoxyl–phenol and 3β,11α– dihydroxy–5β–androstan–17–one were found to be the major compounds in the phenolic material and the neutral material of phenolic fraction that demonstrated strong antidermatophytic activities due to the higher contents. The wood vinegars and their fractions exhibit antidermatophytic activities, and might be considered for application on treating skin fungal infections after appropriate processing.