The effect of zinc on iron-induced lipid peroxidation in different lipid systems including liposomes and micelles.
The effect of zinc on FeSO4/ascorbic acid-induced lipid peroxidation was measured by the thiobarbituric acid assay in various lipid systems including small unilamellar liposomes prepared from egg phosphatidylcholine (EPC), ionic micelles prepared from arachidonic acid (C20:4), non-ionic monocomponent micelles prepared from EPC-derived, methylated fatty acids, and an eicosatetrene emulsion. With the exception of C20:4 micelles, zinc inhibited lipid peroxidation in each of the above systems in a similar dose-related fashion, with 0.5 mM zinc having maximal effect. Gas-chromatographic fatty acid analysis too indicated a protective effect of zinc against FeCl3-induced lipid peroxidation in soybean PC vesicles, which do not contain C20:4 moieties. These findings, in particular the inhibition of lipid peroxidation in eicosatetrene emulsion, suggest that the presence of uncharged polar head groups, or packing of lipid molecules into ordered self-assemblages (membranes and micelles) have no critical influence on the antioxidant effect of zinc. The results with Fe2+ are compatible with the concept that zinc interferes with the formation of Fe2+-oxygen-enoic complexes. This mechanism, however, cannot account for the inhibition by zinc of the Fe#+-induced lipid peroxidation, suggesting the involvement of other types of zinc effects in these systems.
Szebeni
J
J
Department of Surgery, University of Arizona, Tucson 85724.
Eskelson
C D
CD
Chvapil
M
M
D001205:Ascorbic Acid; D003102:Colloids; D007501:Iron; D007700:Kinetics; D015227:Lipid Peroxidation; D008081:Liposomes; D008823:Micelles; D008954:Models, Biological; D010713:Phosphatidylcholines; D015032:Zinc
D003102:Colloids; D008081:Liposomes; D008823:Micelles; D010713:Phosphatidylcholines; D007501:Iron; D015032:Zinc; D001205:Ascorbic Acid