linoleic-acid and tetradecyltrimethylammonium

We investigated the lipid peroxidation in linoleic acid micells caused by H2O2 in the presence of metmyoglobin by monitoring the oxygen consumption. O2 consumption usually consisted of two phases. In the first phase, it occurred slowly and linearly until the concentration of linoleic acid hydroperoxide reached a certain value, rapid consumption, presumably by a chain reaction, then followed in the second phase. No effects of diethylenetriaminepentaacetic acid (DTPA) on the induction period (the period during the first phase) and the maximum oxygen consumption rate (MOCR) in the second phase indicate that free ferric ions liberated from myoglobin had no role in any phases during the lipid peroxidation. The differing dose effects of ascorbic acid, alpha-tocopherol, and sodium nitrite on the induction period and MOCR reflect their respective antioxidative mechanisms during lipid peroxidation.

Topics: Antioxidants; Ferric Compounds; Hydrogen Peroxide; Iron Chelating Agents; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Metmyoglobin; Micelles; Myoglobin; Oxygen Consumption; Pentetic Acid; Quaternary Ammonium Compounds; Sodium Nitrite; Trimethyl Ammonium Compounds

Peroxidation of linoleic acid (LA) was catalyzed by Fenton reagent (H2O2 and Fe2+) in positively charged tetradecyltrimethylammonium bromide (TTAB) micelles, but not in negatively charged sodium dodecylsulfate (SDS) micelles. However, more hydroxyl radicals formed via the Fenton reaction were trapped by N-t-butyl-alpha-phenyl-nitrone (PBN) in SDS micelles than in TTAB micelles. Generation of linoleic acid alkoxy (LO) radicals by Fe2+ via reductive cleavage of linoleic acid hydroperoxide (LOOH) resulted in peroxidation of LA and formation of PBN-LO. adducts in SDS micelles, but not in TTAB micelles. This LOOH dependent lipid peroxidation could be catalyzed in TTAB micelles in the presence of a negatively charged iron chelator, nitrilotriacetic acid (NTA). LO radicals formed by the LOOH dependent Fenton reaction were also trapped by PBN at the surface of TTAB micelles in the presence of NTA, but not in its absence. The consumption of a spin probe, 16-(N-oxyl-4,4'-dimethyloxazolidin-2-yl)stearic acid (16-NS) during the LOOH dependent Fenton reaction in the presence of NTA was higher in TTAB micelles of LA than in those of lauric acid (LauA), although the rates and amounts of LO radicals formed in the two types of fatty acid micelles were similar. The rates of 5-NS consumption in LA and LauA micelles were almost the same, and were lower than the rate of 16-NS in LA micelles. NTA-Fe2+ initiated peroxidation of LA in TTAB micelles without a lag time in the presence of LOOH, but after a lag period, peroxidation occurred without LOOH.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Electron Spin Resonance Spectroscopy; Free Radicals; Indicators and Reagents; Iron; Iron Chelating Agents; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Micelles; Nitrilotriacetic Acid; Quaternary Ammonium Compounds; Trimethyl Ammonium Compounds; Vitamin E

Oxidation of linoleic acid (LA) in tetradecyltrimethylammonium bromide micelles was induced by ferrous- and ferric-chelates in the presence of linoleic acid hydroperoxide (LOOH). Ferrous-chelates also induced lipid peroxidation in the presence of H2O2, but ferric-chelates did not, thought they could generate OH-radicals in the presence of H2O2, resulting in deoxyribose degradation. Of the chelators tested, nitrilotriacetic acid (NTA) chelated with iron showed the highest activity for induction of H2O2- and LOOH-dependent lipid peroxidations and H2O2-dependent deoxyribose degradation. NTA with ferrous ion, but not with ferric ion, also initiated oxidation of LA after a short lag period in the absence of peroxides such as H2O2 and LOOH, but other chelators with ferrous ion did not. The peroxide-independent lipid peroxidation and associated oxidation of ferrous-NTA to ferric-NTA progressed in two steps: an induction step in a lag period and then a propagation step. Ferrous ion complexed with NTA was autoxidized pH-dependently and synchronously with oxygen uptake. The rates of both reactions increased with increase of pH, but were not related to the length of the lag period, which was also dependent on pH, and was shortest at pH 4.2. The EPR spectrum of the ferric-NTA complex prepared directly from ferric salt was different from that of the complex prepared from ferrous salt, confirming that some ferric-type active oxygen participated in induction of peroxide-independent lipid peroxidation. From these results, we propose a possible mechanism of lipid peroxidation induced by ferrous-NTA without peroxides. The finding that iron-NTA had the highest activity for induction of the oxidations of LA and deoxyribose is discussed in relation to the carcinogenic and nephrotoxic effects of this chelating agent.

Topics: Catalysis; Electron Spin Resonance Spectroscopy; Hydrogen-Ion Concentration; Hydrolysis; Iron Chelating Agents; Linoleic Acid; Linoleic Acids; Lipid Peroxidation; Lipid Peroxides; Micelles; Nitrilotriacetic Acid; Oxidation-Reduction; Quaternary Ammonium Compounds; Trimethyl Ammonium Compounds