Absorption and transport of myofibrillar protein-bound N^ɛ-(carboxymethyl)lysine in Caco-2 cells after simulated gastrointestinal digestion

This study aimed to investigate the absorption and transport of myofibrillar protein-bound N^ɛ-(carboxymethyl)lysine (MP-bound CML) in Caco-2 cells after simulated gastrointestinal digestion. Four kinds of MP-bound CML hydrolysates with molecular weights (MWs) less than 1 kDa, 1-3 kDa, 3-5 kDa and greater than 5 kDa, were obtained by ultrafiltration; their absorption and transport were studied in Caco-2 cells. Peptide-bound CML in hydrolysates with MWs less than 1 kDa was absorbed by 6.58 % and might transport across Caco-2 cells monolayer through paracellular pathway; peptide-bound CML in hydrolysates with MWs 1-3 kDa was absorbed by 12.8 % and might transport across Caco-2 cells monolayer through paracellular pathway and transcytosis route; peptide-bound CML in hydrolysates with MWs 3-5 kDa was absorbed by 14.66 % and might be through active route via PepT-1 transport across Caco-2 cells monolayer; whereas protein-bound CML in hydrolysates with MWs greater than 5 kDa was only absorbed by 1.02 %, which was hardly transported into Caco-2 cells. In conclusion, MP-bound CML could be absorbed by 35.06 % into Caco-2 cells after simulated gastrointestinal digestion and is transported across Caco-2 cells through paracellular pathway, transcytosis route and active route via PepT-1.