Purification, characterisation and stability of an antioxidant peptide derived from sandfish (Arctoscopus japonicus) protein hydrolysates

A peptide showing antioxidant activity was purified from Arctoscopus (A.) japonicus sandfish protein. The A. japonicus protein was hydrolysed using Alcalase 2.4 L, and isolation and purification were performed using ultrafiltration (UF), prep-HPLC, and RP-HPLC. The effects of heat, pH, NaCl, and intestinal proteases on stability of the purified antioxidant peptide were determined. The sequence of the antioxidant peptide was identified as Ala-Thr-Ser-His-His (551.25 Da). The DPPH radical scavenging activity of the peptide was above 90% at a concentration 1.0 mg/mL. The antioxidant peptide maintained >66% DPPH radical scavenging activity after treatment at various temperatures with intestinal proteases. In addition, the peptide showed >79% stability at pH 4.0, 6.0, and 8.0. These results suggest that the antioxidant peptide derived from A. japonicus could be used for producing functional foods, protein supplements, and pharmaceutical agents.