Bioaccessibility and Absorption of Flavonoid C-glycosides from Abrus mollis Using Simulated Digestion, Caco-2 Cell, and In Situ Single-pass Perfusion Models

Abrus mollis is commonly used as a traditional Chinese medicine for the treatment of liver diseases due to its hepatoprotection and anti-inflammation, but the absorption properties of its main bioactive ingredients remain unclear. Our previous studies verified that the flavonoid C-glycosides, including vicenin-2 (1), isoschaftoside (2), and schaftoside (3), were the major active components in A. mollis for hepatic protection against nonalcoholic fatty liver disease, hepatitis, and hepatic fibrosis. This study investigated the bioaccessibility and transport mechanisms of total flavonoid C-glycoside, as well as vicenin-2 (1), isoschaftoside (2), and schaftoside (3), in A. mollis by simulated digestion and use of the Caco-2 cell model. Moreover, this study attempted to verify their absorption properties by in situ gastrointestinal perfusion in rats. Total flavonoid C-glycoside and 1, 2, and 3 exhibited similar bioaccessibility of 84.58%, 85.13%, 83.05%, and 81.65% respectively after simulated digestion. The transport of total flavonoid C-glycoside in the Caco-2 cell model increased with the concentration, and the transport showed saturation characteristics with the time and concentration of total flavonoid C-glycoside to a certain degree. The Papp values of total flavonoid C-glycoside and the 3 flavonoid C-glycosides were significantly improved by verapamil, probenecid, and EDTA-Na2. Their absorption properties in the gastrointestinal tract were consistent with that found in Caco-2 cells, and superior absorption rates were observed in the duodenum and jejunum. The absorption pattern of total flavonoid C-glycoside may involve multiple transport pathways, including active transport, passive diffusion, and the paracellular pathway. TFC was actively pumped out by P-glycoprotein and multidrug resistance-associated protein. These results revealed that the bioaccessibility and intestinal absorption characteristic of total flavonoid C-glycoside were consistent with the 3 major flavonoids.