Chemical Profile, In Vitro Enzyme Inhibitory, and Antioxidant Properties of Stereum Species (Agaricomycetes) from Turkey

Recently, mushroom species have been the focus of researchers' interest because of several bioactivities. The aim of this study was to investigate the chemical profile and biological activities of various extracts of two Stereum species (S. rugosum and S. sanguinolentum). Antioxidant activity was tested using beta-carotene-linoleic acid, DPPH center dot scavenging, ABTS(center dot)(+) scavenging, cupric-reducing antioxidant capacity (CUPRAC), and metal chelating assays. The extracts were also tested for their enzyme inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinestemse (BChE). HPLC-DAD was applied for the analysis of phenolic compounds, and fatty acid compositions were determined using GC and GC-MS. When ftunaric acid and catechin hydrate were found as the most abundant phenolic compounds in both Stereum species, oleic acid and palrnitic acid were identified as major fatty acids. Both of the studied Stereum methanol extracts were determined as the most active in beta-carotene-linoleic acid, DPPH center dot, ABTS(center dot)(+), and CUPRAC assays; the n-hexane extracts were found to be most active in metal chelating and AChE inhibitory activity assays. In addition, the methanol extract of S. sanguinolentum (IC50: 34.26 +/- 0.31 mu g/mL) showed higher ABTS(center dot+) scavenging activity than alpha-tocopherol (IC50: 38.51 +/- 0.54 mu g/mL). The acetone extracts were found as potent inhibitors against BChE. These results suggest that Stereum species could be an antioxidant source and cholinesterase agent in pharmaceutic, food, and cosmetics industries.