18. Prooxidant and antioxidant effects of Trolox
on ferric ion-induced oxidation of erythrocyte membrane lipids.
Ko KM, Yick PK, Poon MK, Ip SP.
Department of Biochemistry,
The prooxidant and antioxidant actions of Trolox were examined in an in vitro system measuring ferric
ion-induced oxidation of erythrocyte membrane lipids. Trolox
was found to produce a concentration-dependent biphasic effect on the ferric
ion-stimulated lipid peroxidation, with the mode of
action being similar to those produced by reducing-agent antioxidants, such as
ascorbic acid and reduced glutathione, and iron chelator,
such as desferrioxamine. Phytic
acid, a potent iron chelator, could suppress the prooxidant actions of Trolox and desferrioxamine, but not those of ascorbic acid and reduced
glutathione. The ability of Trolox to stimulate
ferric ion-catalyzed ascorbate oxidation, as similar
to the action produced by ethylenediaminetetraacetic
acid, indicates the presence of iron-chelating activity. The ensemble of
results suggests the possible involvement of iron chelation
in the prooxidant action of Trolox
in ferric ion-stimulated lipid peroxidation
reactions.