Isolation And Purification,Component Identification And Gastrointestinal Stability Of Proanthocyanidins From Zijuan Tea

Zijuan is a kind of tea tree with high anthocyanin content rich proanthocyanidins,whose chemical composition is different from grape seed proanthocyanidins.By studing Zijuan proanthocyanidin,this can be a new research direction for the development of proanthocyanidin.Therefore,this paper focuses on the extraction,purification,chemical composition,functional evaluation of Zihuayuan proanthocyanidins and the changes in the human digestive system.The main contents are as follows.(1)Based on the extraction rate of proanthocyanidins from Zijuan tea,the extraction process of Zijuan tea was optimized,and the extraction temperature was 25 °C,the ethanol concentration was 70%,and the ratio of material to liquid was 1:35.The extraction content of proanthocyanidins from Zijuan tea was the highest under g/mL),pH=5 and extraction time of 15 minutes.(2)The process of separation and purification of proanthocyanidins from Zijuan was studied and optimized.The adsorption capacity,desorption rate and static adsorption kinetics of the resin were compared.The AB-8 resin was selected as the adsorption material for the purification of proanthocyanidins from Zijuan,which was further optimized for optimal purification.Process: The flow rate was 1.5 BV/h,the eluent flow rate was 2 BV/h,and the elution volume was 4 BV.After desorption,the purity of proanthocyanidins in the ethanol eluate was as high as 90.07%.(3)The chemical composition of the obtained proanthocyanidins was determined by ultra performance liquid chromatography-quadrupole-time-of-flight mass spectrometry(UPLC-Q-To F/MS).The results showed that three monomers and six B-type dimers were identified in the 70% ethanol eluate of Zijuan proanthocyanidins.Compared with grape seed proanthocyanidins,Zijuan proanthocyanidins mainly consist of haploid epigallocatechin gallate(EGCG)and epicatechin gallate(EGC),and the dimer constitutes the main monomer.(4)By simulating gastrointestinal digestion,the experimental results showed that the content of phenols and proanthocyanidins decreased after the simulated digestion of Zijuan aqueous extract,and its antioxidant capacity also decreased.Phenolic substances decreased by 13.44%,flavonoids increased by 30.30%,and proanthocyanidins decreased by 46.96%.The increase of flavonoids may be attributed to the decomposition of certain flavonoid macromolecules in tea extracts into flavonoids in an alkaline environment.The molecules cause an increase in the absorbance.The proanthocyanidins in Zijuan decreased significantly in the simulated digestion,but their antioxidant activity was still stronger than that in the control group.