Orally administered aqueous extract of Inonotus obliquus ameliorates acute inflammation in dextran sulfate sodium (DSS)-induced colitis in mice

Chaga mushroom (Inonotus obliquus) has been used in folk medicine to treat several disorders duet to its various biological functions. Recent reports indicate that Chaga has potential anti-inflammatory activity but its effects on intestinal inflammation (ulcerative colitis) are clearly not known. We determined the effects and the mechanism of action of the water extract of Chaga (HCG-1) on experimental colitis in mice induced by dextran sulfate sodium (DSS). Female 5-week-C57BL/6 mice were randomized into groups differing in treatment conditions (prevention and treatment) and doses of HCG-1 (50 and 100mg/kg body weight). Mice were exposed to DSS (2%) over 7 days in the drinking-water to induce acute intestinal inflammation. We observed the histological changes in colon tissues by H&E staining, and iNOS levels by immunohistochemical staining. The mRNA expressions of pro-inflammatory mediators, TNF-α, IFN-γ, IL-1β, and IL-6, were determined by reverse-transcriptase polymerase chain reaction. Histological examinations indicated that HCG-1 suppressed edema, mucosal damage, and the loss of crypts induced by DSS. HCG-1 remarkably attenuated DSS-induced iNOS levels and MPO accumulation in colon, showing its suppressive effects on infiltrations of immune cells. In addition, HCG-1 remarkably inhibited the mRNA expressions of pro-inflammatory cytokines induced by DSS in colon tissues. Our results suggest that HCG-1 might have an anti-inflammatory effect at colorectal sites that is due to the downregulations of the expressions of inflammatory mediators, and that it might be a useful supplement in the setting of inflammatory bowel disease (IBD).