The Relationship between Lipid Peroxidation and Microviscosity in Phosphatidylcholine Liposomes. The Effects of a Plant Antioxidant and a Protein

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Abstract—The influence of lipid peroxidation on the structure of biomembranes and liposomes has been studied for many years; however, there are still a number of unexplained issues that require additional study. In particular, there are contradictions in the assessment of the state of the structure of deep-lying membrane lipids during the development of lipid peroxidation. In this work, we carried out targeted studies of changes in the microviscosity of a lipid component by the EPR method using a spin probe (16-doxyl-stearic acid) in the process of initiated lipid peroxidation in liposomes obtained from phosphatidylcholine and phosphatidylcholine with a plant antioxidant additive and encapsulation in a protein shell at two temperatures, physiological (37°C) and elevated (60°C). It has been found that the development of lipid peroxidation in all experiments is accompanied by an increase in the microviscosity of deep-lying layers of lipids, which is directly proportional to the degree of development of the lipid peroxidation. This effect is mainly due to an increase in the relative content of saturated fatty acids in lipids of liposomes, although new structural forms of the oxidized lipids may also make some contribution to it. Using dynamic light scattering and atomic force microscopy it has been shown that lipid peroxidation causes an increase in the average diameter and volume of individual liposomes and an increase in the absolute value of their negative zeta potential. A plant antioxidant and a protein inhibit this process.