Pro-oxidant activity of Fe2+ in oxidation of cod phospholipids in liposomes

This work examines how different factors such as temperature, amount of injected Fe 21, lipid concentration, pH, concentration of NaCl and concentration of dissolved oxygen influenced the lipid oxidation rate of liposomes made from cod phospholipids. The rate of lipid oxidation was measured by consumption of dissolved oxygen by liposomes in a closed vessel. The rate of oxygen consumption in liposomes was proportional to the concentration of iron and the lipid concentration in the assay mixture. The oxygen consumption rate was dependent on pH, with a maximum observed between pH 4 and 5. The addition of salt (final concentration 0.04-0.8 M) decreased the rate of oxygen consumption. The rate of oxidation was independent of the concentration of dissolved oxygen (in the range of 230-5 mu M). The oxygen consumption rate followed Arrhenius kinetics, and the variation in activation energy found (60-87kJ/ moles x K) might be due to variations in the composition of raw materials used in the experiments and different susceptibility to oxidation.