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Keywords:

  • sea urchin Strongylocentrotus nudus;
  • hydrolysis;
  • response surface methodology;
  • antioxidant activity;
  • degree of hydrolysis

Abstract

BACKGROUND: Hydrolysates prepared from sea urchin (Strongylocentrotus nudus) gonad by enzymatic treatment showed strong 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and reducing power.

RESULTS: Hydrolysis of S. nudus gonad by the commercial protease papain was optimised for maximum degree of hydrolysis (DH) and trichloroacetic acid-soluble peptide index (TCA-SPI) using response surface methodology. Results showed that the optimal conditions were the following: temperature of 48.83 °C, pH of 6.92, enzyme-to-substrate ratio of 3143 U g−1, and substrate concentration of 83.5 g L−1. Under these conditions, a DH of 27.96 ± 0.54% and a TCA-SPI of 57.32 ± 0.63% were obtained. The hydrolysate prepared in the optimal conditions was fractionated by an ultra-filtration system and the resultant fraction below 10 kDa was found to effectively scavenge hydroxyl radical (EC50 = 13.29 ± 0.33 mg mL−1) and hydrogen peroxide (EC50 = 16.40 ± 0.37 mg mL−1), inhibit lipid peroxidation (EC50 = 11.05 ± 0.62 mg mL−1), chelate Fe2+ (EC50 = 7.26 ± 0.44 mg mL−1), and protect mice macrophages against death induced by tert-butyl hydroperoxide.

CONCLUSION: Hydrolysates prepared from S. nudus gonad have the potential to be applied as natural antioxidant agents. Copyright © 2012 Society of Chemical Industry