Ulcerative colitis is a well-known inflammatory bowel disease. Although there are drugs that are effective against this disease, the prevention and attenuation of ulcerative colitis by food rich in functional ingredients without side effects is desired because some drugs have side effects. In this study, we investigated the effects of yuzu (Citrus junos Tanaka), a citrus fruit native to northeast Asia, on a mouse dextran sulfate sodium (DSS)-induced colitis model. Mice given drinking water containing DSS showed significant weight loss, colon shortening, diarrhea, and visible fecal blood. In contrast, mice fed a diet containing 5% yuzu peel for 14 d before receiving DSS showed significant attenuation of these phenotypes. To clarify the mechanism underlying the attenuation, we investigated the anti-inflammatory and antioxidant effects of yuzu peel. We found that yuzu peel extract suppressed tumor necrosis factor-α (TNF-α) production in lipopolysaccharide (LPS)-stimulated mice and murine macrophage cell line through suppression of nuclear factor-κB (NF-κB) activation. In addition, we confirmed that yuzu peel extract had a moderate antioxidant effect. These results suggest that yuzu peel attenuates the pathologies of DSS-induced colitis by coordinately suppressing inflammation and oxidative stress against lipids in vivo.
Keywords: antioxidant against lipids; citrus flavonoid; experimental colitis; inflammation; oxidative stress; yuzu.