Quality Analysis Of Aged Wuyi Rock Tea And Its Alleviation Of Ulcerative Colitis In Mice

Inflammatory bowel disease(IBD)is a non-specific,recurrent,chronic inflammatory disease of the intestinal tract with an unknown cause,the cause and pathogenesis of which are still not fully understood.Wuyi rock tea,an oolong tea with the quality characteristic of "rocky bones and floral aroma" made through a unique processing process,is stored for a certain period of time and becomes aged rock tea,which not only has a more characteristic flavour,but is also rich in a variety of bioactive ingredients and has great potential in disease prevention and alleviation.In this study,aged Wuyi rock [Oolong] tea(AOT)of Shuixian species with different storage times(0,5,10,15,20,25 and 30 years)were used as materials to firstly investigate the dynamic changes of taste and aroma quality of AOT at different storage periods.Secondly,the inflammation model was constructed by Dextran Sulfate Sodium Salt(DSS)to investigate the alleviating effect of AOT extract on colitis in mice.Finally,based on FMT technique,the mechanism of action of AOT extract in alleviating colitis through regulating intestinal microbiota and its metabolites in mice was investigated in depth.In order to provide scientific basis for the quality change and pharmacological efficacy of AOT,it has research significance and practical value.The main findings are as follows:1.Storage time has a significant effect on the flavour quality of aged Wuyi rock tea.The effects of storage time on the flavor quality of AOT were investigated by multivariate analysis using sensory evaluation,detection of non-volatile and volatile substances,and seven AOTs with different storage periods.The results showed that the taste gradually changed to aged alcohol with the extension of storage time,and the acidic taste appeared in the middle of storage and gradually faded away in the later stage.The significant decrease of tea polyphenols and catechins and the increase of soluble sugar and flavonoid contents were the main reasons for the taste differences.The changes in the content of characteristic volatile substances with VIP values >1,such as indole、trans-nerolidol,dihydroactinidiolide,hotrienol,alpha-terpineol,methyl salicylate,β-ionone,phytone and 3-hexenylbutyrate,The changes in the content of the above characteristic volatile substances are the key factors for the transformation of AOT aroma from floral and fruity to aged,woody and medicinal aromas.2.AOT extract has good anti-inflammatory effects in vitro.AOT extract showed good anti-inflammatory and antioxidant effects on lipopolysaccharide(LPS)-induced inflammation in RAW264.7macrophages.aot significantly reduced the expression of pro-inflammatory factors and lnducible nitric oxide synthase(i NOS)at AOT significantly reduced the expression of pro-inflammatory factors and i NOS at the m RNA level.3.The AOT extract exhibited prebiotic effect on mice and acted as a reliever of colitis.The alleviating effect of AOT extract on colitis in mice at different storage periods was investigated by drinking 3%(w/v)DSS induced colitis model in mice.The results showed that mock human longterm intake of AOT extract(200 mg/kg/day)exhibited beneficial bacterial enrichment in C57BL/6 mice.AOT improved the symptoms of DSSinduced colitis in mice,and the effect of AOT-10 extract was superior to other storage periods of AOT.physically,AOT extract reduced the increase of disease activity index and the shortening of colon length in mice;downregulated the pro-inflammatory down-regulated the expression of proinflammatory factors(IL-1β,IL-6 and TNF-α)and regulated the activity of oxidative stress factors to alleviate the symptoms of colitis in mice;restored the integrity of the intestinal barrier by up-regulating the expression of tight junction proteins(Occludin,Claudin-1,ZO-1 and MUC2);alleviated the intestinal microbiota disorders in mice with colitis.4.Fecal microbiota transplantation treatment revealed the mechanism by which AOT extract alleviates colitis in mice by modulating the intestinal microbiota and its metabolites.Fresh fecal microbiota from donor mice were transplanted to 3%(w/v)DSS-induced colitis recipient mice for treatment.The results showed that fresh faecal microbiota from both Control and AOT-10 donor mice significantly improved inflammation in colitis recipient mice.16 S r RNA microbial sequencing showed that fecal microbiota transplantation treatment significantly altered the composition and abundance of the intestinal microbiota and reduced the expression of potentially harmful bacteria(e.g.Mucispirillum,Sutterella,Clostridiaceae＿Clostridium and Allobaculum)and increased the relative abundance of beneficial bacteria(e.g.Oscillospira,Ruminococcus and Coprococcus),and the fecal bacteria of donor mice in the AOT group achieved significantly better results than those of donor mice in the Control group.mice.Targeted metabolomics showed that fecal microbiota transplantation treatment significantly restored microbial metabolite levels and modulated metabolite-related pathways(e.g.,TCA cycle,glycine,serine and threonine metabolism,linoleic acid metabolism and amino acid biosynthesis)in mice with colitis.Finally,correlation results showed that pro-inflammatory factors were significantly positively correlated with most amino acid and fatty acid metabolites and negatively correlated with bile acid metabolites.Thus,the regulation of intestinal microbiota and its metabolites by AOT is one of the important mechanisms for the relief of colitis and has great potential for future adjuvant therapy.