INHIBITION OF OXIDATIVE MODIFICATION OF LOW-DENSITY-LIPOPROTEIN BY ANTIOXIDANTS

Oxidation of LDL induced by free radicals proceeds by a chain mechanis m to give phosphatidylcholine hydroperoxides and cholesteryl ester hyd roperoxides as the major primary products. In addition, apolipoprotein B100 is also oxidized. Various antioxidants suppress the oxidative mo dification of LDL. Water-soluble radical-scavenging antioxidants such as vitamin C and uric acid act as the first defense to suppress the ch ain initiation. Lipophilic radical-scavenging antioxidants in LDL such as vitamin E and ubiquinol scavenge radicals attacking from outside a nd also within the LDL. The overall importance and potency of antioxid ants depend not only on chemical reactivity but also on the physical f actors such as location and mobility at the microenvironment in LDL.