Insight into structural characteristics of theabrownin from Pingwu Fuzhuan brick tea and its hypolipidemic activity based on the in vivo zebrafish and in vitro lipid digestion and absorption models

Fuzhuan brick tea (FBT) is a post-fermented dark tea preferred by consumers for its excellent hypolipidemic activity, and theabrownin (TB) is the main bioactive composition in FBT. This work explored the structural and hypolipidemic properties of TB derived from Pingwu FBT, and investigated whether it exerted hypolipidemic activity by inhibiting intestinal lipid absorption. Structural characterization revealed that TB was an amorphous polymerized phenolic compound rich in hydroxyl and carboxyl groups with good thermostability. In vivo, TB and its fractions with different molecular weights (TB-LT3k, TB-3-10k, TB-10-30k, TB-30-100k, TB-GT100k) significantly reduced the lipid levels of hyperlipidemia zebrafish (P < 0.05). Moreover, TB attenuated hyperlipidemia by inhibiting intestinal lipid absorption, as TB effectively bound to bile acids, inhibited enzymatic activity of pancreatic lipase and cholesterol esterase, influenced micelle formation, and decreased micellar cholesterol solubility. Results facilitated research on TB and offered support for its feasibility as a natural alternative to prevent hyperlipidemia.