Eugenol Alleviates Dextran Sulfate Sodium-Induced Colitis Independent of Intestinal Microbiota in Mice

The present study investigated the effect of eugenol (EUG) on dextran sulfate sodium (DSS)-induced colitis and explored the underlying mechanisms. C57BL/6 mice were intragastrically administered normal saline or EUG (20 mg/kg body weight) for 17 days, and colitis was induced by using 3% DSS from day 7. The results showed that EUG increased the body weight and reduced the disease activity index score and colon pathological scores in DSS-treated mice (P < 0.05). Further, EUG preserved the proinflammatory cytokines (interleukin (IL)-6, -12, -21, and -23), lowered (P < 0.05) colonic malondialdehyde (MDA), uncoupling protein 2 (UCP2) expression and p65 phosphorylation, and activated (P < 0.05) colonic kelch-like ECH-associated protein 1 and nuclear factor (erythroid-derived 2)-like 2 expressions but did not affect the intestinal microbiota in DSS-treated mice. Furthermore, EUG ameliorated colitis in antibiotic-treated mice, while fecal microbiota transplantation from EUG preadministered mice failed to ameliorate colitis. In conclusion, EUG could alleviate colitis by attenuating colonic inflammation and oxidative stress independent of intestinal microbiota.