Influence of flavonol-rich excipient food (onion peel and Dendropanax morbifera) on the bioavailability of green tea epicatechins in vitro and in vivo.

The impacts of onion peel (OP) and Dendropanax morbifera (DM), as excipient foods rich in flavonols, on the digestive recovery, intestinal absorption, and pharmacokinetics of GT epicatechins were studied via an in vitro digestion model system with Caco-2 cells and an in vivo study. The digestive stability of total epicatechins recovered from GT upon the addition of 2% DM was up to 1.12 times higher than that observed with OP. The combined effects of OP and DM, which were observed with 2% OP + DM in a ratio of 1 : 4 (w : w), significantly increased (by a factor of 1.31) the digestive recovery of total epicatechins (p < 0.05). Remarkable cellular uptakes of EC (185.36%) and ECG (188.08%) were found with 4% OP + DM (4 : 1, w : w), and those of EGC (112.30%) and EGCG (136.27%) were obtained with 2% OP + DM (4 : 1, w : w) and 1% OP + DM (1 : 1, w : w), respectively. The peak plasma concentrations of total epicatechins from GT, GT + 5% OP, GT + 5% DM, and GT + 2% OP + 2% DM were 1044.78 ± 609.10, 2267.18 ± 3734.38, 1270.35 ± 547.59, and 714.53 ± 499.27 ng mL