Abstract: Crude peptides were prepared from Neptunea cumingi muscle by using acid-alcohol extraction. By using the response surface methodology, the conditions for decolorizing the crude peptides were optimized as follows: activated carbon amount 0.42%, reaction temperature 52 ℃, reaction time 50 min and pH 7.4. Under these conditions, the retention rate of peptide was (67.63 ± 0.80)% and the decolorization rate was (68.70 ± 0.54)%. Furthermore, antioxidant activities of the purified peptides were evaluated both in vitro and in vivo. The half maximal effective concentration (EC50) for 1,1-diphenyl-2-trinitrobenzene hydrazine (DPPH) radical scavenging was 170.041 μg/mL. The in vivo antioxidant tests showed that the peptides showed similar activity to the positive control VC at a concentration of 50 μg/mL in a zebrafish model. In addition, at 200 μg/mL, the peptides could inhibit oxidative damage induced by metronidazole. The total amino acid content of the peptides was 853.46 mg/g. The amino acid composition was determined by precolumn derivatization. It was found that alkaline and acidic amino acids together accounted for about 80% of the total amino acids, and arginine, alanine and proline were the most abundant amino acids.

Key words: Neptunea cumingi-derived peptide, decolorization, response surface methodology, amino acid composition, antioxidant activities, zebrafish