Phellinus baumii ethyl acetate extract inhibits lipopolysaccharide-induced iNOS, COX-2, and proinflammatory cytokine expression in RAW264.7 cells

Mushrooms are valuable sources of biologically active compounds possessing anticancer, antiplatelet, and anti-inflammatory properties. Phellinus baumii is a mushroom used in folk medicine for a variety of human diseases. However, its potential anti-inflammatory effect has remained unclear. Therefore, we studied the effect of P. baumii ethyl acetate extract (PBEAE) on inflammatory mediator and proinflammatory cytokine protein and/or mRNA expression levels using the nitric oxide (NO) assay, enzyme immunoassay (EIA), western blot, and reverse transcription polymerase chain reaction (RT-PCR) in lipopolysaccharide (LPS)-stimulated macrophage like RAW264.7 cells. PBEAE markedly inhibited NO generation and prostaglandin E ₂ (PGE ₂) synthesis in a concentration- dependent pattern without any cytotoxic effect at the concentration range used. PBEAE also suppressed inducible nitric oxide synthase (iNOS) and cyclooxygenase- 2 (COX-2) protein expression. In addition, LPSinduced iNOS and COX-2 mRNA expression levels were dose-dependently inhibited by PBEAE pretreatment. Furthermore, PBEAE attenuated the mRNA expression levels of proinflammatory cytokines, specifically interleukin (IL)- 1β, IL-6, and granulocyte macrophage colony-stimulating factor (GM-CSF), in a concentration-dependent fashion. Our study suggests that P. baumii might exhibit antiinflammatory properties by downregulating proinflammatory mediators. Thus, further study on compounds isolated from PBEAE is warranted to investigate the associated molecular mechanisms and identify the potential therapeutic targets.