Abstract: In this study, we optimized the conditions for the enzymatic preparation of iron-chelating peptides from the fruiting bodies of Grifola frondosa and evaluated their antioxidant capacities. Six commercial proteases were screened for their suitability to hydrolyze Grifola frondosa protein, which was evaluated according to iron-chelating activity. One-factor-at-a-time and orthogonal array designs were employed to optimize the hydrolysis conditions based on iron-chelating activity. Meanwhile, the antioxidant capacity was studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radical scavenging assays. The results showed that peptides with the highest iron-chelating activity were obtained with alkaline protease. The optimal hydrolysis conditions were determined as follows: pH value, 9; alkaline protease dose, 1 800 U/g; temperature, 55 ℃; substrate concentration, 0.5 g/100 mL; and hydrolysis time, 2.5 h. Under these conditions, the iron-chelating activity and the degree of hydrolysis were 1.854 mg/g and 6.14%, respectively. The prepared peptides showed scavenging activity against DPPH and hydroxyl radicals in a concentration-dependent manner. In addition, the peptides possessed good iron-chelating ability and antioxidant activities, and could thus hold promise as a novel dietary supplement.

Key words: Grifola frondosa, hydrolisis, peptides, iron-chelating activity, antioxidant activity