Radiation-induced generation and properties of lipid hydroperoxide in liposomes

The generation of hydroxyl free radicals in 60Co gamma-irradiation of a dilute aqueous suspension of phosphatidyl choline liposomes, resulted in the rapid accumulation of lipid hydroperoxides (linearly with time), but only small concentrations of malondialdehyde. Incubation of the irradiated liposomes with ferric chloride was found to significantly increase the malondialdehyde, and evidence is presented that this resulted from iron catalysed decomposition of the lipid hydroperoxide. This suggests a role for free iron or iron chelates in the propagation of lipid peroxidation stimulated by other systems.