Two p-terphenyls from mushroom Paxillus panuoides with free radical scavenging activity

As part of a continuing investigation to identify free radical scavengers from the fruit bodies of basidiomycetes, we isolated two p- terphenyl compounds, designated as PA1 and PA21, from methanolic extract of the fruit body of Paxillus panuoides. The methanolic extract was processed by ethyl acetate extraction and silica gel column chromatography to yield two active fractions. PA1 was obtained from one of the fractions through Sephadex LH-20 and silica gel column chromatographies and reverse-phase HPLC. The other fraction was purified by Sephadex LH-20 and reverse-phase column chromatographies to produce PA2. The compounds PA1 and PA2 were identified as leucomentin-4 and leucomentin-2, respectively, on the basis of various spectroscopic analyses. These compounds exhibited strong inhibitory activities against lipid peroxidation in rat liver microsomes with IC₅₀ values of 0.10 and 0.06 μg/ml, respectively.