Isolation and identification of peptidic alpha-glucosidase inhibitors derived from sardine muscle hydrolyzate

We report here the isolation of alpha-glucosidase (AGH) inhibitory peptides derived from sardine muscle hydrolyzate, which was prepared by digestion w ith Bacillus licheniformis alkaline protease. AS a result of reversed-phase HPLC purification, two AGH inhibitory peptides were isolated from a DEAE-S ephadex A-25 column eluate. The peptides were identified as follows: Val-Tr p (IC50 = 22.6 mM) and Try-Tyr-Pro-Leu (IC50 = 3.7 mM). AGH inhibitory stud ies of Try-Tyr-Pro-Leu and its derivatives demonstrated the importance of t he tripeptide chain length as well as the hydrophobic aromatic amino acid t yrosine at the N-terminus, aliphatic amino acids at the C-terminus, as well as an amide proton from the peptide chain at the middle position of the tr i-peptide to develop AGH inhibition activity.