Novel dipeptidyl peptidase-4-inhibiting peptide derived from β-lactoglobulin

Trypsin-treated β-lactoglobulin significantly decreased the glucose level after an oral glucose tolerance test using mice. we performed the present study to identify the active peptide inhibiting dipeptidyl peptidase-4 from trypsin-treated β-lactoglobulin. trypsin-treated β-lactoglobulin showed a concentration-dependent inhibition for dipeptidyl peptidase-4,with an ic 50 value of 210 μm,although non-treated β-lactoglobulin showed no significant effect in the in vitro assay. the active peptide was isolated from trypsin-treated β-lactoglobulin and identified as the hexapeptide val-ala-gly-thr-trp-tyr (β-lactoglobulin f15-20). this hexapeptide also exhibited a concentration-dependent inhibitory effect and ic 50 value was 174 μm,suggesting that this hexapeptide is almost totally responsible for the dpp-4 inhibitory activity of trypsin-treated β-lactoglobulin. © the japanese pharmacological society.