Susceptibility of plasma to ferrous iron/hydrogen peroxide-mediated oxidation: demonstration of a possible Fenton reaction.
The aim of our study was to evaluate a model system by using iron in the peroxidation of plasma. Lipid peroxidation was monitored by fluorometric measurement of lipid peroxides (LPO). Plasma coincubated with Fe2+ and H2O2 had a 268% increase in plasma LPO after 1 h. The optimum concentrations were 0.42 mmol/L Fe2+ and 0.73 mol/L H2O2. Coincubation of plasma with these concentrations of Fe2+ and H2O2 separately resulted in no increase in plasma LPO. The increase in plasma LPO after oxidation with Fe2+/H2O2 was paralleled by a decrease in plasma polyunsaturated fatty acids, an increase in the relative electrophoretic mobility of low-density lipoprotein (LDL), and decreases in apolipoprotein (apo) B-100 and apo A-I immunoreactivity. In vitro oxidation of LDL and high-density lipoprotein separately with this system produced increases of LPO of 246% and 128%, respectively. LPO formation in plasma was inhibited by catalase, desferrioxamine, and mannitol, but not by superoxide dismutase. Hydroxyl radical generation with Fe2+/H2O2 was evidenced by fragmentation of deoxyribose. We conclude that the Fe2+/H2O2 system, possibly by a Fenton reaction mechanism, resulted in significant plasma oxidation. This model system may be useful for examining lipid peroxidation in clinical investigations.
Agil
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Laboratory of Molecular Pathology, University of Texas Southwestern Medical Center, Dallas 75235-9052.
Fuller
C J
CJ
Jialal
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I
D000328:Adult; D016632:Apolipoprotein A-I / Q000378:metabolism; D053299:Apolipoprotein B-100; D001055:Apolipoproteins B / Q000097:blood; D002374:Catalase / Q000494:pharmacology; D003676:Deferoxamine / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated / Q000097:blood; D005296:Ferrous Compounds / Q000494:pharmacology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008077:Lipoproteins, LDL / Q000097:blood; D008353:Mannitol / Q000494:pharmacology; D008875:Middle Aged; D010084:Oxidation-Reduction
D016632:Apolipoprotein A-I; D053299:Apolipoprotein B-100; D001055:Apolipoproteins B; D005231:Fatty Acids, Unsaturated; D005296:Ferrous Compounds; D008077:Lipoproteins, LDL; D008353:Mannitol; D006861:Hydrogen Peroxide; D002374:Catalase; D003676:Deferoxamine