Citrus junos Tanaka peel extract attenuates experimental colitis and inhibits tumour growth in a mouse xenograft model

The inhibitory effects of yuja peel extract (Citrus junos Tanaka) on experimental colitis and colorectal cancer cells were evaluated. Yuja peel extracted with 70% ethanol (YPEE) reduced LPS-induced secretion of nitric oxide (NO), tumour necrosis factor-alpha (TNF-α), monocyte chemotactic protein-1 (MCP-1), and interleukin-6 (IL-6) by reduction of cyclooxygenase-2 (COX-2), nitric oxide synthase (NOS), and p38 phosphorylation in RAW264.7 cells. YPEE at 100 mg/(kg·day) also reduced both disease activity index (DAI) and colon shortening induced by Dextran sulphate sodium (DSS) in mice. COX-2 expression was decreased in colon tissue by YPEE. In addition, YPEE induced apoptotic body appearance in HT-29 colorectal cancer cells via decreasing COX-2. Furthermore, YPEE at 100 mg/(kg·day) inhibited tumour growth in tumour xenografts, which was accompanied by reduced COX-2 expression in colon tissue. Taken together, Yuja may be useful in preventing colitis and colorectal cancer via reduction of COX-2 expression.