Peroxidation of phospholipid unilamellar vesicles containing vitamin E: A comparison with low-density lipoprotein.

Abstract

Oxidative degeneration of human low-density lipoprotein (LDL) is implicated in the initiation of atherosclerosis, a degeneration of the arterial wall that very commonly leads to heart attack or stroke. The high incidence of this disease in developed societies has aroused an increasing interest in antioxidants with particular attention on alpha-tocopherol (alpha-TocH), the most powerful naturally occurring antioxidant. The potential of liposomes as a suitable synthetic model of LDL with standard and modifiable composition, no risk of infection and high availability was investigated. It was found that unilamellar vesicles with similar composition and diameter as LDL behave as a homogeneous system where alpha-tocopherol behaves as an antioxidant. The cause of this unexpected kinetics may lay in the lack of a lipid core in liposomes. Rather than being hidden within an LDL particle, the alpha-Toc• is forced to reside on the surface of the vesicles where it can be immediately trapped and prevented from performing the much slower chain-carrying reaction. (Abstract shortened by UMI.)