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.
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Oolong teas made with different tea cultivars have a great difference in flavor and chemical components. In this study, non-targeted metabolomics, absolute quantitative analysis, and multivariate statistics analysis were used to investigate the chemical differences among Yongchun Foshou (YCFS), Tieguanyin (TGY) and Shuixian (SX) oolong tea and to screen characteristic chemical components of YCFS oolong tea, as well as to study the influence of tea cultivars on chemical components and sensory quality of oolong tea.
Camellia sinensis cv. Foshou was used as the main research sample and Camellia sinensis cv. Tieguanyin and Camellia sinensis cv. Shuixian were used as the controls. Three tea cultivars were manufactured into fresh-scent, strong-scent and aged-scent oolong teas. Ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) was used for non-targeted metabolomics analysis to screen differential compounds in the oolong teas made from different cultivars. In addition, ultra-high performance liquid chromatograph, amino acid analyzer and ultra-high performance liquid chromatography-quadrupole-orbitrap-mass spectrometry (UHPLC-Q-Orbitrap-MS) was applied for absolute quantifications of main chemical constituents and differential compounds in oolong teas made from different tea cultivars.
Compared with the control oolong teas of same scent type, YCFS oolong tea had relatively higher contents in total amino acid and theanine. The contents of total catechins and caffeine were not significantly different among the 3 cultivars in fresh-scent and strong-scent oolong teas, which were the highest in YCFS in aged-scent oolong teas. The content of gallic acid was SX>YCFS>TGY in 3 scent types oolong teas. Metabolomics analysis combined with multivariate statistics analysis showed that the compound patterns in oolong teas made from different tea cultivars were significantly different. In fresh-scent, strong-scent and aged-scent oolong teas, there were 50, 59 and 47 differential compounds between YCFS and control cultivar, respectively. Among them, 23 differential compounds were common, including 14 flavone (flavonol) glycosides, 5 catechins and their derivatives, 1 lipid, 1 alkaloid, 1 organic acid and 1 amino acid. Further quantitative analysis of 20 main flavone (flavonol) glycosides showed that the contents of 14 flavone (flavonol) glycosides were the highest in YCFS oolong teas, whose contents were 1.4 to 14.6-fold of that in TGY oolong teas and were 1.3 to 18.0-fold of that in SX oolong teas. Among four kinds of flavone (flavonol) glycosides, quercetin glycosides were the main flavone (flavonol) glycosides with higher contents than glycosides of kaempferol, myricetin and apigenin. Sensory evaluation combined with chemical composition results showed that the higher contents of flavone (flavonol) glycosides did not significantly enhance the astringency of YCFS oolong tea infusions.
The metabolomics method effectively characterized the component differences in oolong teas made from different tea cultivars in this study. There were obvious differences in compound patterns among YCFS, TGY and SX oolong teas. Flavone (flavonol) glycosides were the most significantly differential compounds. The higher content of flavone (flavonol) glycosides was a major chemical feature of YCFS oolong tea and was expected to be used as a discriminant index for the identification of oolong tea cultivar in the future.
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