Identification of a radical formed in the reaction mixtures of oxidized phosphatidylcholine with ferrous ions using HPLC-ESR and HPLC-ESR-MS.

Identification of free radicals was performed for the reaction mixtures of autoxidized 1,2-dilinoleoylphosphatidylcholine (DLPC) with ferrous ions (or DLPC hydroperoxide with ferrous ions) and of DLPC with soybean lipoxygenase using electron spin resonance (ESR), high performance liquid chromatography (HPLC)--ESR and HPLC--ESR-mass spectrometry (MS) combined use of spin trapping technique. ESR measurements of the reaction mixtures showed prominent signals with hyperfine coupling constants (a(N)=1.58 mT and a(H)beta=0.26 mT). Outstanding peaks with almost same retention times (autoxidized DLPC, 36.9 min; DLPC hydroperoxide, 35.0 min; DLPC with soybean lipoxygenase, 37.1 min) were observed on the elution profile of the HPLC--ESR analyses of the reaction mixtures. HPLC--ESR--MS analyses of the reaction mixtures gave two ions at m/z 266 and 179, suggesting that 4-POBN/pentyl radical adduct forms in these reaction mixtures.