Abstract: The body wall of Isostichopus badionotus was hydrolyzed with flavourzyme.Two fractions with different molecular weights I₁ (6kD<Mr<10kD) and I₂ (Mr<6kD) were obtained by ultrafiltration.The protective effects of I₁ and I₂ on H₂O₂-induced damage in PC12 cells were investigated.Results showed that all doses of I₁ and I₂ can promote the growth of PC12 injured by H₂O₂ obviously (P<0.05,P<0.01).The intracellular ROS,LDH release and the content of MDA decreased significantly (P<0.05, P<0.01).The activities of SOD,CAT and GSH-Px were stimulated remarkably (P<0.05,P<0.01).The caspase-3 activities decreased significantly (P<0.01).The collagen peptide with low molecular weight showed a better cytoprotective activity.These results demonstrated that collagen polypeptides from I.badionotus had remarkable antioxidant activity and can play a neuroprotective role in PC12 cells oxidative damaged by H₂O₂.

Key words: Isostichopus badionotus, collagen peptides, hydrogen peroxide, PC12 cells, reactive oxygen species, antioxidase