Isolation And Purification Of Polysaccharides From Fuzhuan Brick Tea And Its Purified Components Regulate The Composition And Metabolism Of Intestinal Microbiota In Healthy People And IBD Patients

Fuzhuan brick tea(FBT)is also called black tea,border selling tea.It is a kind of black tea and it is known as the tea of the people of all ethnic groups in Northwest China.FBT has the beneficial effects of digesting and strengthening the stomach,reducing fat and degreasing.Therefore,FBT is mostly sold in the form of pressed tea such as brick,sold to the northwestern frontier regions of China.Today it is widely accepted by people.This is not only its unique taste,but also its beneficial biological activities.FBT has a variety of health functions such as lipid-lowering,blood pressure-lowering,antioxidant,liver protection,anti-tumor,immune regulation.Studies have shown that FBT can regulate lipid metabolism,improve intestinal function and prevent metabolic syndromes such as obesity and hyperlipidemia.It was found that the polysaccharide of FBT(FBTPS)is an important biologically active component in FBT.It has strong antioxidant activity and can significantly regulate the composition and abundance of intestinal flora in vivo and in vitro.But the most researched at present is the crude FBTPS,and the research on the purified components of FBTPS is less.Therefore,the research on purified FBTPS is meaningful.Inflammatory bowel disease(IBD)is a chronic,complex intestinal inflammatory pathological state.Studies have found that probiotics and short-chain fatty acids(SCFAs)are important substances for the treatment and healthy recovery of gastrointestinal diseases including IBD.Previous studies have found that the FB TPS is used by the intestinal microorganisms in the large intestine to generate a large number of SCFAs,which promotes the production of healthy intestinal probiotics.Therefore,this article mainly investigated the separation and purification of the FBTPS,the physical and chemical properties of purified components,the antioxidant activity of purified components,the effects of purified components on the composition and metabolism of intestinal microorganisms,and the effects of crude polysaccharides and purified components on intestinal microorganisms in patients with IBD were systematically studied.The main results are summarized as follows:(1)Isolation and purification of of FBTPS and chemical properties?cytotoxicity and antioxidant activity of FBTPS-2 and FBTPS-3.FBTPS was eluted with DEAE Sepharose Fast Flow column chromatography with distilled water,0.1,0.3,and 0.5 mol/L NaCl solutions to obtain two main comonents(FBTPS-2 and FBTPS-3).The neutral sugar contents of FB TPS-2 and FB TPS-3 were 51.57 ±1.52%and 44.78 ± 2.85%,respectively,and the uronic acid contents were 17.87 ± 2.94%and 40.4 ± 2.1%,respectively.The monosaccharide composition of FBTPS-2 is mainly Man,Rha,GalA,Glc,Gal,Ara and a small amount of Rib and GlcA.The monosaccharide composition of FBTPS-3 is mainly composed of Man,Rha,GalA,Gal,and Ara.The molecular weights of FBTPS-2 and FBTPS-3 are 937 and 741 kD,respectively.Comparing the two purified components by in vitro antioxidant activity experiments and cell experiments,we found that FB TPS-3 has a superior scavenging effect.FBTPS-3 has better biological activity in the purified components of FBTPS.(2)The purified components of FBTPS regulate the composition and metabolism of gut microbiota in vitro fermentation.The present results showed that FBTPS-3 could be hydrolyzed and utilized by gut microbiota.With FBTPS-3 as the carbon resource,FBTPS-3 could significantly increase the relative abundances of Bacteroides,Prevotella,Megasphaera,Dialister,Sutterella,Paraprevotella and reduce the ratio of Firmicutes/Bacteroidetes.Moreover,the contents of SCFAs,especially acetic,propionic and n-butyric acids,were significantly increased.Based on the metagenomic sequencing analysis,FBTPS-3 could significantly enrich starch and sucrose metabolic pathways in gut microbiota.FBTPS-3 could increase the enzymes for carbohydrate metabolism,such as UDP-galactose 4-epimerase and arabinan endo-1,5-a-L-arabinosidase.The present study provided a valuable resource for investigating processes,functions and pathways of effect of FBTPS-3 on gut microbiota.(3)Study on the regulation of FBTPS and FBTPS-3 on gut microbiota composition of IBD patients.Through in vitro anaerobic fermentation experiments of feces from FBTPS and FB TPS-3 and feces from IBD patients and healthy people,the results demonstrate how different the tea polysaccharides improve the gut environment of IBD patients.With the intervention of FBTPS,the abundance of the beneficial bacteria Bacteroidetes in the stool of IBD patients decreased significantly,and the abundance of the pathogen Proteobacteria increased significantly.With the intervention of FBTPS-3,the relative abundance of the beneficial bacteria Bacteroidetes in the stool of IBD patients increased,while the relative abundance of the pathogenic bacteria Proteobacteria decreased.By comparing the experimental results of the two groups of polysaccharide intervention,we found that FBTPS-3 can regulate the gut microbiota composition of IBD,which is closer to that of healthy human.FB TPS-3 can promote the increase of SCFAs,which is beneficial to improve the gut environment of IBD patients.The purified component FBTPS-3 in the tea brick polysaccharide can be used as a regulator to improve the gut environment of IBD patients,laying a scientific foundation for the subsequent treatment of IBD.