Effects of oxidation-based tea processing on the characteristics of the derived polysaccharide conjugates and their regulation of intestinal homeostasis in DSS-induced colitis mice

Different cultivars and processing technologies involved in producing tea result in the high heterogeneity of derived polysaccharide conjugates, which limits the understanding of their composition and structure, and biological activity. Here, raw tea leaves from the same cultivar were used to produce dried fresh tea leaves, green tea, and black tea, and three polysaccharide conjugates derived from dried fresh tea leaves (FTPS), green tea (GTPS), and black tea (BTPS) were prepared accordingly. Their physiochemical characteristics and bioactivities were investigated. The results showed that the oxidation during tea processing increased the phenolics and proteins while decreasing the GalA in the derived TPS conjugates; meanwhile, it reduced the molecular weight and particle size of BTPS but enhanced their antioxidant activity in vitro. Furthermore, all three TPS conjugates improved intestinal homeostasis by reducing TJ protein loss and inflammation and alleviated DSS-induced colitis symptoms in mice. In addition, the three TPS conjugates showed differential regulation of the intestinal microbiome and altered the produced SCFAs, which contributed to the prevention of colitis. Our findings suggest that TPS conjugates could be applied in colitis prevention in association with the regulation of gut microbiota, and their efficacy could be optimized by employing suitable tea processing technologies.