EFFECT OF LIPID-PEROXIDATION PRODUCTS AND ANTIOXIDANTS ON THE FORMATION OF PROBUCOL RADICAL IN LOW-DENSITY LIPOPROTEINS

Effects of antioxidants and products of lipid peroxidation on hemin-in duced formation of probucol radical in low density lipoproteins (LDL) from human plasma were studied by EPR-spectroscopy. Suppression of lip id peroxidation in LDL by probucol and other antioxidants (ascorbate, 6-O-palmitoylascorbate, and ubiquinol-10) prevents the formation of pr obucol radical. However, ubiquinol-10 stimulates the formation of prob ucol radical during advanced stages of LDL oxidation, Because the conc entration of probucol radical depends on lipid hydroperoxide contents in LDL, the interaction of lipid hydroperoxides with hemin can result in the formation of probucol-oxidizing radical intermediates and ubiqu inol-10 is a mediator of this process.