Vitamin E or probucol as donors for oxidation of human low-density lipoprotein by peroxidases/H2O2.

Horseradish peroxidase or myeloperoxidase and H2O2 oxidize human low-density lipoprotein (LDL) in the presence or absence of a xenobiotic donor without an essential lag phase as revealed by an increase in the absorption at 234 nm. In the latter case, natural antioxidants like vitamin E and congeners serve as donor; radical formation by the action of peroxidase has been described before. Otherwise trolox C or probucol have donor function in this system. After oxidation by peroxidase/H2O2 LDL showed the expected reduced antioxidant capacity against vitamin-E-consuming radicals.