ABSTRACT
A combination technique of LC/ESR, LC/MS and spin trapping was used to identify and characterize the carbon-centered free radicals formed from lipoxygenase-catalyzed peroxidation of dihomo-γ-linolenic acid(DGLA). The spin trap, α-[4-pyridyl-1-oxide]-N-tert-butyl nitrone(POBN), could react with short-lived carbon-centered radicals to form relatively stable adducts. Based on the same retention time of POBN radical adduct in LC/UV/ESR and LC/MS, molecular weight of adduct could be confirmed and the structure of adduct could be confirmed by their LC/MS2 fragment pattern. The results showed that free radicals formed in lipoxygenase-catalyzed peroxidation of DGLA, including ~·C_7H_(13)O_2, ~·C_(10)H_(17)O_2 and ~·C_5H_(11), all stemmed from β-scission of DGLA alkoxyl radicals(8-, 11-, 15-LO~·). The results were helpful for further study of biological activities of these radicals in vivo.