Antioxidant Activity and Chemical Composition of Extracts from Fruiting Bodies of Xylotrophic Fungi Growing on Birch

Abstract

The search for new natural sources of biologically active substances is a major issue in pharmaceutical industry. Xylotrophic basidiomycetes are common in forests worldwide, but as a prospective raw source of biologically active compounds they have not been studied as extensively as plants and other groups of fungi. The study is aimed to determine the chemical composition and antioxidant activity of extracts from 10 species of tinder fungi growing on birch and common in the forests in Russia. The chaga muchroom (Inonotus obliquus), traditionally used in medicine, was chosen as a standard species. Extracts from fruiting bodies were obtained with water or 95 % ethanol. They contained 4 to 8 types of free amino acids including 2 to 6 essential ones. Perennial basidiocarps were shown to be richer in phenolic compounds and poorer in amino acids than annual ones. Alkaloids and saponins were found in perennial basidiocarps of two species, saponins were also found in annual basidiocarps of one species. Water and alcohol extracts differed in composition and concentration of extractives, and showed different antioxidant (inhibition of lipid peroxidation) and antiradical (ABTS-test, inhibition of NO production) activity. This way it was shown that the nature of the solvent extraction agent is important for the manifestation of biological activity. In most tests, water extracts from chaga showed better antioxidant properties; extracts from Piptoporus betulinus and Fomitopsis pinicola were also effective as antioxidants, which may be promising avenues for future research.