Abstract: Caco-2 cell model was established and verified to analyze the transport capacity of ACE inhibitory peptides LL and LPEW and to explore their transport mechanism across intestinal epithelial cells. Morphology, transepithelial electrical resistance and alkaline phosphatase activity were measured to verify the validity of the Caco-2 cell model. Apparent permeability coefficient (Papp) of LL and LPEW were (275.17 ± 8.28) × 10-7 and (5.13 ± 1.49) × 10-7cm/s, respectively in Caco-2 transport experiments, suggesting that LL displayed much better intestinal absorption than LPEW. The transportation route of LL may be endocytosis, as demonstrated by comparing the transport capacity of LL with and without transport inhibitors including the paracellular transport accelerator sodium deoxycholate, the endocytosis inhibitor Wortmannin, and the competitive inhibitor of the peptide transports Gly-Pro. LL had no efflux activity, as suggested by comparing the transport capacity with and without efflux inhibitor including the P-glycoprotein inhibitor verapamil, the multidrug resistance protein inhibitor MK-571, and the ATPase inhibitor sodium azide. In conclusion, LL showed good intestinal absorption.

Key words: angiotensin-I converting enzyme (ACE) inhibitory peptides, Caco-2 cell model, intestinal absorption