Objectives: Inflammatory bowel disease (IBD) is chronic inflammatory disorders of the intestines. Although several therapeutic agents, including steroids, are available for treatment of IBD, these agents have limited use. Therefore, herbal medications or natural products have emerged as possible interventions for IBD. The purpose of the current study was to investigate the effects and mechanisms of the water extract of Zostera marina (ZME) on dextran sulfate sodium (DSS)-induced colitis which have been popularly used as inflammatory bowel disease models.

Materials and methods: Colitis was induced by DSS in BALB/c mice. ZME 100, 300 and 1000 mg/kg were orally administered twice a day for 7 or 14 days in DSS model. In this experiment, ZME were administered before colitis induction (pre-treatment) and with DSS administration (co-treatment). Mice weight and clinical findings were measured daily. Colon length, macroscopic findings and histological damages were assessed at day 7 in DSS model. In histological analysis, we checked the inflammatory cell infiltration and the severity of ulceration, and scored degree of inflammatory cell damage by modified histological scoring. We also measured the levels of cytokine concentrations on colonic mucosa including TNF-α, IFN-γ, IL-1β, IL-6, IL-10 and IL-17 by Biometric Multiplex Cytokine Profiling method.

Results: ZME showed the dose-dependent beneficial effects on colitis mice model. It significantly inhibited colon shortening, improved macroscopic score and histological score. It inhibited weight loss and improved clinical score without significance. There were no difference between co-treatment and pre-treatment of ZME on DSS-induced colitis. Particularly, ZME 300 and 1000 mg/kg administration significantly inhibited IFN-γ expression, and ZME 1000 mg/kg administration significantly inhibited TNF-α, IL-1γ, and IL-6 expression.

Conclusion: The current results demonstrate that the clinical utility of ZME in traditional Korean medicine and indicate the possibility of potent drug development of IBD from natural products. Further investigations for exact mechanisms will be needed.