Ethanol Extract of Sarcodon asparatus Mitigates Inflammatory Responses in Lipopolysaccharide-Challenged Mice and Murine Macrophages

A number of compounds isolated from mushrooms have exhibited disease-modifying effects. We sought to investigate the mechanisms responsible for the anti-inflammatory effects of an extract from the mushroom species Sarcodon asparatus (SAE). Male BALB/c mice (N=42; 6 weeks old) were randomly assigned to four treatment groups. Intraperitoneal administration of SAE significantly attenuated lipopolysaccharide (LPS)-mediated increases in alanine aminotransferase (ALT) activity. LPS also increased serum levels of proinflammatory cytokines, including IL-1β, IL-6, and TNF-α, which were dose-dependently and significantly attenuated by SAE. Correlative relationships between serum ALT activity and proinflammatory cytokines suggested that SAE-mediated suppression of liver injury was partly attributable to the attenuation of serum inflammatory responses. SAE significantly decreased hepatic NO^• production and subsequent 3-nitrotyrosine formation, and the hepatic NO^• production significantly correlated with serum ALT and cytokine levels, suggesting that SAE mitigates liver injury in association with inflammatory processes, likely by suppressing NO^• production. Anti-inflammatory activity and further mechanisms of SAE were evaluated using RAW264.7 with LPS challenge. Noncytotoxic levels of SAE significantly attenuated NO^• production in RAW264.7 cells and also markedly suppressed the expression of iNOS and other proinflammatory mediators, including COX-2 and IL-6, which were upregulated in the presence of LPS. SAE inhibited the phosphorylation of p65, an observation that occurred independently of IKKαβ-mediated IκBα phosphorylation. Collectively, our results demonstrate that SAE suppressed NO^•-mediated inflammation by inhibiting p65 transcriptional activation without affecting IKKαβ-mediated IκBα phosphorylation. Further studies are warranted to examine the major compounds responsible for these effects and the mechanisms responsible for the p65 phosphorylation observed.