The Modulatory Effect Of Oolong Tea Polyphenols On Circadian Rhythm Of Intestinal Microbiome And Liver Genes

Tea is widely consumed around the world.Oolong tea is a semi-fermented tea,while it contains various compounds,the putative effective components have been attributed to the polyphenolic fraction.Tea polyphenols have been shown to be largely important biologically activities in the fields of medicine and food research.In this thesis,a systematic study of oolong tea polyphenols(OTP)were performed,including optimization of extraction parameters,intestinal microecology regulation,and liver clock genes regulation.Main results are listed as follows:1.Three factors: liquid/solid ratio,extraction temperature and extraction time were selected for single factor experiments.Based on a single-factor experiment,combination of extraction parameters were selected to perform a three-factor three-level central combination design(CCD)experiment.Then analyzed the data by Design-Expert Software to obtain the optimal extraction parameters of OTP: liquid/solid ratio of 17 mL/g,extracting temperature 91°C,and extracting time 42 min.Under these optimal conditions,the extraction amount of tea polyphenols was the highest,being 140.24 mg/g.2.Using the 16S rDNA sequencing technology,the effect of OTP on the intestinal flora of circadian mice was analyzed.According to the results,after OTP intervention,the intestinal microbial diversity and the number of rhythmic OTUs were improved.In addition,a significant decrease in Firmicutes of the CD-OTP mice and a relative increase of Bacteroidetes were observed,and the Firmicutes/Bacteroidetes(F/B)ratio also showed a significant decrease.Interestingly,OTP can significantly improve the suppression of Bacteroidetes,Firmicutes and Proteobacteria caused by continuous darkness.At the genus level,the relative abundance of Prevotella and Bacteroides was increased,and the relative abundance of Clostridium was reduced.Meanwhile,OTP improved the suppression of Prevotella,Bacteroides and Clostridium caused by continuous darkness.3.The effect of OTP on liver genes of circadian mice was evaluated by transcriptome sequencing.It was found that OTP increased the number of rhythmic genes and improved the expression levels of liver clock genes(Bmal1,Clock,Cry1,Cry2,Per3,and Sirt1).The differentially expressed genes(DEGs)in the CD-OTP group compared with the CD group were also analyzed.After OTP intervention,the DEGs were mainly concentrated in 'regulation of transcription,DNAtemplated','transcription,DNA-templated','cytoplasm','nucleus','protein binding',and 'metal ion binding'.In addition,Kyoto Encyclopedia of Genes and Genomes(KEGG)pathways enriched the most DEGs after OTP intervention including 'Focal adhesion'(9 DEGs)and 'PI3K-Akt signaling pathway'(9 DEGs).We also classified those genes into different categories,and the DEGs were involved in such pathways as 'steroid biosynthesis','terpenoid backbone biosynthesis',and 'adherens junction'.