Purification and identification of a novel antidiabetic peptide from Chinese giant salamander (Andrias davidianus) protein hydrolysate against α-amylase and α-glucosidase

This study aimed to purify and identify a novel antidiabetic peptides from Chinese giant salamander (Andrias davidianus) protein hydrolysate and to evaluate its anti-diabetic properties against α-amylase and α-glucosidase. The isolation was done by gel filtration, reverse phase chromatography (RF-HLPC), and finally peptide and amino acid sequences were identified by LC/MS/MS system. Our results revealed five novel peptides that strongly inhibited α-amylase and α-glucosidase. The peptides' amino acid sequences were Cys-Ser-Ser-Val (MW = 393.99 Da), Tyr-Ser-Phe-Arg (MW = 570.99 Da), Ser-Ala-Ala-Pro (MW = 343.89 Da), Pro-Gly-Gly-Pro (MW = 325.99 Da) and Leu-Gly-Gly-Gly-Asn (MW = 415.99 Da) possessing α-amylase inhibitory activity IC50 of 13.76 × 103, 10.82 × 103, 4.46 × 103, 4.23 × 103, and 2.86 × 103 µg/mL, respectively; and for α-glucosidase with IC50 of 206.00, 162.00, 66.90, 63.50, and 42.93 µg/mL, respectively. Intriguingly, the peptide LGGGN showed higher inhibition on both α-amylase and α-glucosidase and could be considered as a potential anti-diabetic inhibitor.