Optimisation of hydrolysis of purple sea urchin (Strongylocentrotus nudus) gonad by response surface methodology and evaluation of in vitro antioxidant activity of the hydrolysate.
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 (EC(50) = 13.29 ± 0.33 mg mL(-1)) and hydrogen peroxide (EC(50) = 16.40 ± 0.37 mg mL(-1)), inhibit lipid peroxidation (EC(50) = 11.05 ± 0.62 mg mL(-1)), chelate Fe(2+) (EC(50) = 7.26 ± 0.44 mg mL(-1)), and protect mice macrophages against death induced by tert-butyl hydroperoxide.


CONCLUSIONS
Hydrolysates prepared from S. nudus gonad have the potential to be applied as natural antioxidant agents.
School of Food Science and Technology, Dalian Polytechnic University, Engineering Research Center of Seafood of Ministry of Education, Dalian, 116034, PR China.
Dayong
D
Zhou
Lei
L
Qin
Beiwei
B
Zhu
Dongmei
D
Li
Jingfeng
J
Yang
Xiuping
X
Dong
Yoshiyuki
Y
Murata
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001688:Biological Products / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002614:Chelating Agents / Q000494:pharmacology; D003627:Data Interpretation, Statistical; D029941:Fish Proteins / Q000494:pharmacology; D006066:Gonads / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D006868:Hydrolysis; D017665:Hydroxyl Radical / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D018384:Oxidative Stress / Q000187:drug effects*; D010206:Papain / Q000378:metabolism; D010851:Picrates / Q000378:metabolism; D011492:Protein Hydrolysates / Q000494:pharmacology*; D047269:Strongylocentrotus; D047270:Strongylocentrotus purpuratus; D020122:tert-Butylhydroperoxide
D000975:Antioxidants; D001688:Biological Products; D001713:Biphenyl Compounds; D002614:Chelating Agents; D029941:Fish Proteins; D010851:Picrates; D011492:Protein Hydrolysates; D017665:Hydroxyl Radical; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl; D007501:Iron; D010206:Papain