Antioxidant polyketide phenolic metabolites from the edible mushroom Cortinarius purpurascens

Abstract Phytochemical investigation of the ethyl acetate extract of the edible macrofungus, Cortinarius purpurascens , led to the isolation of nine anthraquinone-related pigments, citreorosein 6,8-dimethyl ether ( 1 ), physcione ( 2 ), rufoolivacin ( 3 ), rufoolivacin C ( 4 ), rufoolivacin D ( 5 ), leucorufoolivacin ( 6 ), verbindung cr11 ( 7 ), verbindung cr60 ( 8 ) and 1-Hydroxy-3-methyl-2-isopropanyl-6,8-dimethoxyanthraquinone ( 9 ). The structures of these isolated compounds were characterised by spectroscopic methods and comparison with published data. Among the tested compounds, 3 – 6 exhibited potent DPPH radical-scavenging activity with IC 50 values in the range of 3–8 μg/ml. The results indicated that the fungus is a possible source of natural products with potential antioxidant activity.