Abstract: Objective: Cod skin collagen peptide (CSCP) has a good protective effect on liver injury, but the absorption mechanism of CSCP is still not clear. In this study, the Caco-2 cell monolayer model was used to investigate the absorption mechanism of CSCP in order to provide an experimental basis for the study of the absorption mechanism of CSCP in the animal intestine. Methods: The stability of CSCP in artificial gastric juice, artificial intestinal juice, different pH conditions, and Caco-2 cell monolayers were evaluated. Subsequently, the highest concentration of CSCP in the transport experiment was determined by using cell counting kit-8 (CCK-8) assay. The Caco-2 cell monolayer model was established, and its compactness, integrity and polarization were evaluated by measuring transepithelial electrical resistance and the activity of alkaline phosphatase. The effects of transport time, CSCP concentration, vrapamil, MK-571, phenylarsine oxide and odium deoxycholate on the transport efficiency were investigated by using reversed-phase high performance liquid chromatography to determine CSCP concentration and calculating apparent permeability coefficients and accumulated transport of CSCP. Results: CSCP was relatively stable in artificial gastric juice, artificial intestinal juice, different pH conditions and Caco-2 cell monolayers for 3 h. No polypeptides were found to be hydrolyzed during the transport process. The transport of CSCP was positively correlated to the transport time and CSCP concentration and was not affected by addition of verapamil or phenylarsine oxide. In the presence of sodium deoxycholate and MK-571, the transport of CSCP was significantly promoted (P < 0.05). Conclusion: The mechanism of CSCP transport across Caco-2 cell monolayer was related to cell bypass and CSCP efflux was mediated by multidrug resistance proteins.

Key words: cod skin, collagen peptide, gastrointestinal tract stability, Caco-2 cell, transport mechanism