Purification and structural characterization of an anti-Trichophyton compound produced by Auricularia heimuer...

In this study, by screening approximately 160 mushroom extracts for anti-Trichophyton activity, significant activity was found in the culture filtrate of the Auricularia heimuer TUFC 100803 strain. To purify the active compound, the strain was cultured in 2.0 L of malt liquid medium, and the culture filtrate was extracted with ethyl acetate. The resulting crude extract was fractionated by silica-gel chromatography and preparative thin-layer chromatography, and a pure active compound, designated heimuerol A, was successfully isolated. According to IUPAC nomenclature, the compound was identified as (1R,2R,5R)-2-(prop-1-en-2-yl)-6-oxabicyclo[3.1.0]hex-3-en-2-ol. Unlike terbinafine, which is used as both a topical and oral medication for tinea, heimuerol A lacks a nitrogen and possesses a structure containing an epoxide group and a five-membered ring. The minimum inhibitory concentration (MIC) of terbinafine-resistant strains was lower than that for wild-type strains when treated with heimuerol A. Furthermore, a mixture of heimuerol A and terbinafine exhibited activity at concentrations lower than their respective MICs. These findings suggest that heimuerol A inhibits ergosterol biosynthesis through a mechanism distinct from that of terbinafine.