Absorption and plasma kinetics of collagen tripeptide after peroral or intraperitoneal administration in rats

Collagen tripeptide (CTP) is a collagen-derived compound containing a high concentration of tripeptides with a Gly-X-Y sequence. In this study, the concentrations and metabolites of CTP were monitored in rat plasma after its administration. We performed a quantitative analysis using high-performance liquid chromatography tandem mass spectrometry according to the isotopic dilution method with stable isotopes. We confirmed that the tripeptides Gly-Pro-Hyp, Gly-Pro-Ala, and Gly-Ala-Hyp were transported into the plasma. Dipeptides, which are generated by degradation of the N- or C-terminus of the tripeptides Gly-Pro-Hyp, Gly-Pro-Ala, and Gly-Ala-Hyp, were also present in plasma. The plasma kinetics for peroral and intraperitoneal administration was similar. In addition, tripeptides and dipeptides were detected in no-administration rat blood. The pharmacokinetics were monitored in rats perorally administered with Gly-[ 3 H]Pro-Hyp. Furthermore, CTP was incorporated into tissues including skin, bone, and joint tissue. Thus, administering collagen as tripeptides enables efficient absorption of tripeptides and dipeptides. Plasma kinetics of peptides in the two routes of administration, and autoradiographs after peroral administration of Gly-[ 3 H]Pro-Hyp.