Auxiliary Protective Effect of Yongchun Foshou Tea on Ulcerative Colitis in Mice and Analysis of Major Components Involved

In order to explore the protective effect of Yongchun Foshou tea extracts on ulcerative colitis (UC) and the key bioactive compounds involved, we established a mouse model of UC induced by 2,4,6-trinitrobenzenesulfonic acid (TNBS) and intragastrically the mice with the water extracts of clean-aroma, strong-aroma and aged-aroma Yongchun Foshou oolong tea (200 mg/(kg·d)). We evaluated the effects of these three tea extracts on body mass, colon mass per unit length and pathological colon tissue as well as the serum levels of interleukin (IL)-6, IL-10, IL-1β, and tumor necrosis factor α (TNF-α) in mice with ulcerative colitis. Compared with the model group, body mass, colon mass per unit length, and pathological colon tissue were improved in the mice treated with each of the three tea extracts. There was no significant difference in body mass in the mice treated with the water extracts of strong-aroma and aged-aroma oolong tea for 5-7 days after UC induction compared with those before UC induction (P > 0.05). The mice treated with clean-aroma and strongaroma tea extracts showed a significant reduction in colon mass per unit length (P < 0.05 and P < 0.01). Each of these tea extracts reduced the degree of inflammation in mouse colon tissue, significantly increasing the concentrations of the antiinflammatory cytokine IL-10 (P < 0.05 and P < 0.001). The concentrations of the pro-inflammatory cytokines IL-1β and IL-6 were significantly decreased in the mice treated with strong-aroma tea extract (P < 0.05). The correlation analysis of the major compounds in the tea extracts and inflammatory cytokines revealed that flavone glycosides and N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSF) were negatively correlated with three pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α). On the other hand, theanine, catechins, and flavone glycosides were significantly positively correlated with IL-10 (P < 0.05). In conclusion, the water extracts of the three aroma types of Yongchun Foshou oolong tea have an ameliorative effect on acute ulcerative colitis. Strong-aroma tea extract is the most effective among these extracts, and the polyphenols in the extract may play an important role.