Lipid oxidation induced by oxymyoglobin and metmyoglobin with involvement of H2O2 and superoxide anion

The role of oxymyoglobin oxidation in lipid oxidation was studied in a myoglobin-liposome system. The pro-oxidant effect of oxymyoglobin towards lipid oxidation was concentration-dependent. At equimolar concentrations, oxymyoglobin showed higher prooxidative activity towards lipid than metmyoglobin (p < 0.05). These results suggested that the process of oxymyoglobin oxidation is involved in catalyzing lipid oxidation. The addition of catalase into the oxymyoglobin-liposome system resulted in significantly decreased oxidation of oxymyoglobin and lipid (p < 0.05) suggesting a role for H2O2 in the interaction between oxymyoglobin and lipid. The addition of superoxide diismutase was without effect (p > 0.05) suggesting that superoxide anion was not directly involved in mediating oxirlation of oxymyoglobin and lipid. Albumin was added as a control for a nonspecific protein antioxidant; it did not affect oxymyoglobin or lipid oxidation (p > 0.05). Our in vitro results support the hypothesis that the actual process of oxymyoglobin oxidation is a catalyst of lipid oxidation with H2O2 a major factor. (C) 1997 Elsevier Science Ltd.