The effect of Longan Arillus extract on enhancing oral absorption of bioactive peptides derived from defatted walnut meal hydrolysates

The present study aims to investigate the effect of Longan Arillus extract (ELA) on oral absorption of bioactive peptides (cationic P1: VEGNLQVLRPR, anionic P2: HNLDTQTESDV) derived from defatted walnut meal hydrolysates (DWMH). Oral co-delivery of ELA with DWMH led to a significantly higher maximum blood concentration of P2 in rats than delivering DWMH alone. Endocytosis pathway of P2 in intestinal epithelia cells was altered by ELA, probably resulting from formation of uniform microparticles by mixing of P2 and ELA. Results of isothermal calorimetry proved strong binding between molecules of P2 and ELA at a molar ratio of 1:1. On the contrary, the absorption of cationic P1 remained unchanged after co-delivery of ELA, probably resulting from the complicated patterns of binding between ELA and P1 molecules. In conclusion, we found the enhancing effect of polysaccharides on absorption of peptides by formation of microparticles, which could be predicted by molecule binding.