Formation of Superoxide Anion during Ferrous Ion–Induced Decomposition of Linoleic Acid Hydroperoxide under Aerobic Conditions

• Published in: Journal of biochemistry (Tokyo) 2003-12, Vol.134 (6), p.903-909
• Main Authors: Kambayashi, Yasuhiro, Tero-Kubota, Shozo, Yamamoto, Yorihiro, Kato, Masashi, Nakano, Minoru, Yagi, Kunio, Ogino, Keiki
• Format: Article
• Language: English
• Subjects: 2-a]pyrazin-3-one; 2-methyl-6-(p-methoxyphenyl)-3; 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide; 5-dimethyl-1-pyrroline N-oxide; 7-dihydroimidazo; Aerobiosis; Argon - chemistry; Catalysis; Cyclic N-Oxides - chemistry; DEPMPO; DEPMPO-hydroxyl adduct; DEPMPO-OH; DEPMPO-OOH; DMPO; DMPO-hydroxyl adduct; DMPO-OH; DMPO-OOH; electron spin resonance; Electron Spin Resonance Spectroscopy; ESR; Ferrous Compounds - chemistry; Free Radicals - chemistry; high performance liquid chromatography; HPLC; hydrogen peroxide; hydroxyl radical; hypoxanthine; Key words: ferrous ion–induced decomposition of linoleic acid hydroperoxide; linoleic acid; linoleic acid alkoxyl radical; linoleic acid hydroperoxide; linoleic acid hydroxide; linoleic acid peroxyl radical; Linoleic Acids - chemistry; Linoleic Acids - metabolism; Lipid Peroxides - chemistry; Lipid Peroxides - metabolism; LO; LOH; LOO; LOOH; Luminescent Measurements; MCLA; SOD; Spin Labels; Spin Trapping; superoxide anion; superoxide anion adduct of DEPMPO; superoxide anion adduct of DMPO; superoxide dismutase; Superoxides - chemistry; Superoxides - metabolism; xanthine oxidase; XOD
• ISSN: 0021-924X
• DOI: 10.1093/jb/mvg217

We studied the mechanism of formation of oxygen radicals during ferrous ion-induced decomposition of linoleic acid hydroperoxide using the spin trapping and chemiluminescence methods. The formation of the superoxide anion (O2·–) was verified in the present study. The hydroxyl radical is also generated through Fenton type decomposition of hydrogen peroxide produced on disproportionation of O2·–. A carbon-centered radical was detected using 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide (DEPMPO) as a spin trap. Alkoxyl radical formation is essential for the conversion of linoleic acid hydroperoxide into the peroxyl radical by ferrous ion. It is likely that the alkoxyl radical [R1CH(O·)R2] is converted into the hydroxylcarbon radical [R1C·(OH)R2] in water, and that this carbon radical reacts with oxygen to give the α-hydroxyperoxyl radical [R1R2C(OH)OO·], which decomposes into the carbocation [R1C+(OH)R2] and O2·–.