THE ROLE OF HIGH-DENSITY-LIPOPROTEIN AND LIPID-SOLUBLE ANTIOXIDANT VITAMINS IN INHIBITING LOW-DENSITY-LIPOPROTEIN OXIDATION

1. The oxidation of low-density lipoprotein (LDL) is believed to play a central role in atherogenesis. We have compared the effect of antiox idant vitamins and high-density lipoprotein (HDL) on the Cu2+-catalyse d oxidation of LDL. 2. Antioxidant vitamin supplementation significant ly reduced conjugated diene formation but did not affect the formation of lipid peroxides. 3. Conversely, HDL did not affect conjugated dien e formation but inhibited the formation of lipid peroxides by up to 90 %. 4. The inhibition by HDL of lipid peroxide formation in oxidized L DL was dependent on the concentration of HDL and was not due to HDL ch elating Cu2+. 5. Large interindividual variations in the inhibition of lipid peroxide formation by autologous HDL were evident, which were r elated to the rate of lipid peroxide generation in the LDL. 6. We conc lude that HDL is a powerful antioxidant or more probably inhibitor of LDL oxidation in vitro and may play an important role in vivo in preve nting atherosclerosis by inhibiting LDL oxidation in the artery wall.