Research progress in biological activities and mechanisms of theabrownin

Abstract

Tea is beneficial to human health, which is rich in tea pigments with important biological activities. Theabrownin, derived from theaflavins and thearubigins by oxidative polymerization, mainly distributes in semi-fermented oolong tea, and completely fermented black tea and dark tea. As a kind of macromolecular substance, theabrownin cannot be directly absorbed by the gut, but it can directly interact with intestinal microbiota to regulate and maintain the homeostasis of intestinal flora. Theabrownin has multiple physiological roles via modulating the gut microbiota, including inhibiting hepatic cholesterol production, promoting the catabolism of cholesterol and triglyceride, and promoting energy metabolism in adipose tissues, thereby improving lipid metabolism. Theabrownin can also directly influence the gut absorption of glucose to improve carbohydrate metabolism and maintain blood glucose homeostasis. Theabrownin plays an anti-tumor role by inducing apoptosis and regulating gene expression in tumor cells. Theabrownin also plays an anti-inflammatory role via participating in the regulation of the immune cell differentiation and the levels of inflammatory factors. This review summarizes the formation process, the extraction procedures, and the chemical structure of theabrownin, and reviews the effects and mechanisms of theabrownin on intestinal microbiota, lipid metabolism, blood glucose homeostasis, cancer and inflammation.