Nonextractable Polyphenols from Fu Brick Tea Alleviates Ulcerative Colitis by Controlling Colon Microbiota-Targeted Release to Inhibit Intestinal Inflammation in Mice

This study was designed to elucidate the colon microbiota-targeted release of nonextractable bound polyphenols (NEPs) derived from Fu brick tea and to further identify the possible anti-inflammatory mechanism in dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mice. 1.5% DSS drinking water-induced C57BL/6J mice were fed rodent chow supplemented with or without 8% NEPs or dietary fibers (DFs) for 37 days. The bound p-hydroxybenzoic acid and quercetin in NEPs were liberated up to 590.5 ± 70.6 and 470.5 ± 51.6 mg/g by in vitro human gut microbiota-simulated fermentation, and released into the colon of the mice supplemented with NEPs by 4.4- and 1.5-fold higher than that of the mice supplemented without NEPs, respectively (p < 0.05). Supplementation with NEPs also enhanced the colonic microbiota-dependent production of SCFAs in vitro and in vivo (p < 0.05). Interestingly, Ingestion of NEPs in DSS-induced mice altered the gut microbiota composition, reflected by a dramatic increase in the relative abundance of Dubosiella and Enterorhabdus and a decrease in the relative abundance of Alistipes and Romboutsia (p < 0.05). Consumption of NEPs was demonstrated to be more effective in alleviating colonic inflammation and UC symptoms than DFs alone in DSS-treated mice (p < 0.05), in which the protective effects of NEPs against UC were highly correlated with the reconstruction of the gut microbiome, formation of SCFAs, and release of bound polyphenols. These findings suggest that NEPs as macromolecular carriers exhibit targeted delivery of bound polyphenols into the mouse colon to regulate gut microbiota and alleviate inflammation.