The influence of magnesium-pyridoxal-5'-phosphate-glutamate in comparison with probucol, alpha-tocopherol and trolox on copper-induced oxidation of human low density lipoprotein in vitro.

Low density lipoprotein (LDL) in the presence of magnesium-pyridoxal-5'-phosphate-glutamate (MPPG), pyridoxal-5'-phosphate (PP), alpha-tocopherol, probucol or trolox is more resistant against copper-induced oxidation as control-LDL in vitro. The efficiency of the drugs is: probucol > MPPG > trolox > alpha-tocopherol > PP. LDL oxidation is determined by its increasing negative surface charge, fragmentation of apolipoprotein B-100 and changes of the fatty acid content of LDL. The protection of the drugs depends on their concentration and incubation time. Different experiments point to the fact that copper-induced oxidation of LDL in vitro starts with the binding of copper at the apolipoprotein B-100, resulting in an increasing negative surface charge and fragmentation of the apolipoprotein B-100. Afterwards a decrease of LDL-bound linoleic acid (18:2) is measurable.