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 t he peroxidation of plasma. Lipid peroxidation was monitored by fluorom etric measurement of lipid peroxides (LPO). Plasma coincubated with Fe 2+ and H2O2 had a 268% increase in plasma LPO after 1 h. The optimum c oncentrations were 0.42 mmol/L Fe2+ and 0.73 mol/L H2O2. Coincubation of plasma with these concentrations of Fe2+ and H2O2 separately result ed in no increase in plasma LPO. The increase in plasma LPO after oxid ation with Fe2+/H2O2 was paralleled by a decrease in plasma polyunsatu rated fatty acids, an increase in the relative electrophoretic mobilit y of low-density lipoprotein (LDL), and decreases in apolipoprotein (a pe) B-100 and apo A-I immunoreactivity. In vitro oxidation of LDL and high-density lipoprotein separately with this system produced increase s of LPO of 246% and 128%, respectively. LPO formation in plasma was i nhibited by catalase, desferrioxamine, and mannitol, but not by supero xide dismutase. Hydroxyl radical generation with Fe2+/H2O2 was evidenc ed by fragmentation of deoxyribose. We conclude that the Fe2+/H2O2 sys tem, possibly by a Fenton reaction mechanism, resulted in significant plasma oxidation. This model system may be useful for examining lipid peroxidation in clinical investigations.