Antibacterial, Antiradical Potential and Phenolic Compounds of Thirty-One Polish Mushrooms

BACKGROUND Among many sources of natural bioactive substances, mushrooms constitute a huge and almost unexplored group. Fungal compounds have been repeatedly reported to exert biological effects which have prompted their use in pharmaceutical and cosmetic industry. Therefore, the aim of this study was analysis of chemical composition and biological activity of 31 wild growing mushroom species (including saprophytic and parasitic) from Poland. METHODS Qualitative and quantitative LC-ESI-MS/MS analysis of fourteen phenolic acids in the mushrooms analysed was performed. Moreover, total phenolic content was determined by the modified Folin-Ciocalteau method. Antioxidative activity of ethanolic extracts towards DPPH• free radical was examined. Antibacterial activity against Gram-positive (S. epidermidis, S. aureus, B. subtilis, M. luteus) and Gram-negative (E. coli, K. pneumoniae, P. aeruginosa, P. mirabilis) microbial strains was analyzed. RESULTS As a result, the first such broad report on polyphenolic composition, antiradical and antimicrobial potential of wild growing Polish mushrooms was developed. Mushroom extracts were found to contain both benzoic (protocatechuic, 4-OH-benzoic, vanillic, syringic) and cinnamic acid derivatives (caffeic, p-coumaric, ferulic). Total phenolic content in mushrooms ranged between 2.79 and 53.13 mg gallic acid equivalent /g of dried extract in Trichaptum fuscoviolaceum and Fomes fomentarius, respectively. Fungi showed much differentiated antiradical activity, from highly active F. fomentarius to poorly effective Russula fragilis (IC50 1.39 to 120.54 mg per mg DPPH•, respectively). A quite considerable relationship between phenolic content and antiradical activity has been demonstrated. Mushrooms varied widely in antimicrobial potential (MIC from 0.156 to 5 mg/ml). Generally, a slightly higher activity against Gram-positive than Gram-negative strains was observed. This is the first study concerning the chemical composition and biological activity of the majority of investigated species.