Chemical Profile and Biological Activity of the Hymenochaetoid Mushroom Hirschioporus fuscoviolaceus (Agaricomycetes)

Hirschioporus fuscoviolaceus is a commonly distributed saprotrophic fungus across the coniferous forests of temperate regions. An in-depth chemical analysis of the methanol extract of H. fuscoviolaceus resulted in the isolation of four compounds (1-4). The four fungal metabolites were identified as ergosterol peroxide (1), 5α,8α-epidioxy-ergosta-6-en-3β-ol (2), β-sitosterol (3) and 9,11-dehydro-ergosterol peroxide (4), that latest was isolated as a mixture with its closely related compound, ergosterol peroxide (1). The structure identification of the isolated compounds was carried out by one- and two-dimensional NMR and MS analysis. The antimicrobial properties of the fungal secondary metabolites were investigated on several pathogens including Bacillus subtilis, Rhodococcus fascians, Xanthomonas euvesicatoria, and Fusarium graminearum. According to our results, among the identified ergostane-type sterols only mixture of compounds 1 and 4 exhibited moderate inhibitory activity on Bacillus subtilis and Rhodococcus fascians. For the examination of their potential α-glucosidase, lipase and acetylcholinesterase inhibition activities, dot-blot enzyme assays were performed which highlighted that compounds 1-4 have considerable α-glucosidase inhibitory property, with the most active isolates of 3 and 4, while compounds 1, 2 and 4 demonstrated notable activity against acetylcholinesterase. The current study represents the first report on the chemical profile of H. fuscoviolaceus, providing a comprehensive study on the isolation and structure elucidation of the most important secondary metabolites and their potential biological activities.