Inhibitory effects of Pleurotus tuber-regium mycelia and bioactive constituents on LPS-treated RAW 264.7 cells

Pleurotus tuber-regium (PTR) is an edible and medicinal mushroom found mainly in tropical and subtropical countries. In this study, we investigated the anti-inflammatory effects of PTR mycelia on RAW 264.7 macrophages. Samples of PTR mycelia were prepared by submerged fermentation. An ethanolic extract of PTR mycelia (PTRA) inhibited the production of nitric oxide (NO), TNF-α, and IL-6 in LPS-treated RAW 264.7 cells. Two compounds were purified and identified as cerevisterol (CE) and ergosta-4,6,8(14),22-tetraen-3-one (EG). Both CE and EG inhibited the production of NO, TNF-α, and PGE2 in LPS-treated RAW 264.7 cells. The expression of the iNOS and COX2 proteins was inhibited by CE and EG in a dose-dependent manner. In addition, CE and EG repressed the expression of iNOS, COX2, TNF-α, and SOCS3 mRNAs. This study revealed that an ethanolic extract of PTR mycelia exhibited anti-inflammatory activity and that CE and EG might contribute to this activity.