Antioxidative activity of oyster hydrolysates

Oyster was hydrolyzed by papain and neutral proteases and antioxidative activity of oyster hydrolysate was studied.Scavenging hydroxyl radical activities of peptide fractions analyzed by Sephadex G-15 showed considerable variations.The peptide molecular weights with highest scavenging hydroxyl radical activities hydrolyzed by papain were about 1 191 D and 826 D and their scavenging activities of hydroxyl radical were 53.6% and 66.6% respectively when the peptide concentrations were 0.184 mg/mL and 0.673 mg/mL,and the molecular weights of the peptides hydrolyzed by neutral protease were about 1 074 D and 735 D respectively and their scavenging activities were determined as 57.6% and 70.5% respectively when the peptide concentrations were 0.166 mg/mL and 0.830 mg/mL.Further isolating and purifying results made by HPLC indicated that when the concentration of the peptides with highest scavenging activities made separately by papain and neutral protease was 2.5 mg/mL,their scavenging activities were determined as 83.6%and 80.8% respectively.Study on white mice fed by papain and neutral protease hydrolysates after membrane separation(UF) showed that activities of GSH-PX,SOD and GSH in liver tissue mice were improved considerably compared with that of the white mice fed by crude oyster meat(P0.05).In contrast,enhancement of MDA content was significantly inhibited by supplement of the same hydrolysates(P0.05).The results of the white mice fed by papain and neutral protease hydrolysates without membrane separation only improved the activities of SOD significantly(P0.05).