Collagen peptides derived from the triple helical region of sturgeon collagen improve glucose tolerance in normal mice

We prepared collagen peptides (SCP) from sturgeon by-products: the skin, fin, and bone. The materials were pretreated and hydrolyzed by papain. Finally, we obtained 85.1 g of dried SCP powder from 864 g (wet weight) of the materials. In oral glucose tolerance test (OGTT) with ICR mice, blood glucose levels of SCP group were significantly lower than those of control group. Then, we fractionated SCP by Sephadex column chromatography and all fractions showed hypoglycemic effect. Further, we separated each peptide in the fractions by reversed-phase HPLC. Most of the peptides in these peaks consisted of Gly-X-Y (X and Y are optional amino acid residues) repetitive sequences which are common to the triple helical region of the collagen molecules. Moreover, many peptides contained Pro and Ala residues, which promises to serve as a DPP-IV inhibitor. Altogether, these results suggest the hypoglycemic effect of SCP may be caused by these structural properties. Practical applications While sturgeon is famous and highly valuable for its salted egg "caviar" and meat, other parts such as skin, fin, and bone, that is, by-products are not fully utilized in seafood industry. In this study, we focused on whole utilization of a sturgeon and prepared collagen peptides (SCP) from sturgeon by-products. The yield of SCP was approximately 100 g SCP/kg wet by-products. In animal experiments, SCP showed hypoglycemic effect. Moreover, the effect is probably caused by Gly-X-Y repetitive sequences derived from the triple helical region of a collagen molecule. The mechanism might be related to DPP-IV inhibitory activity. SCP was white, odorless, and easily soluble in water and it could be advantages in using SCP as an ingredient for functional foods preventing Type 2 diabetes mellitus. The by-products of sturgeon will be a new fishery resource which could be used as a material for collagen peptides providing the hypoglycemic effect.