title: A combination study of spin-trapping, LC/ESR and LC/MS on carbon-centred radicals formed from lipoxygenase-catalysed peroxidation of eicosapentaenoic acid.
abstract: Increased evidence from animal and in vitro cellular research indicates that the metabolism of eicosapentaenoic acid (EPA) can inhibit carcinogenesis in many cancers. Free radical-mediated peroxidation is one of many possible mechanisms to which EPA's anti-cancer activity has been attributed. However, no direct evidence has been obtained for the formation of any EPA-derived radicals. In this study, a combination of LC/ESR and LC/MS was used with alpha-[4-pyridyl 1-oxide]-N-tert-butyl nitrone to identify the carbon-centred radicals that are formed in lipoxygenase-catalysed EPA peroxidation. Of the numerous EPA-derived radicals observed, the major products were those stemming from beta-scission of 5-, 15- and 18-EPA-alkoxyl radicals. By means of an internal standard in LC/MS, this study also quantified each radical adduct in all its redox forms, including an ESR-active form and two ESR-silent forms. The comprehensive profile of EPA's radical formation provides a starting point for ongoing research in defining the biological effects of radicals generated from EPA peroxidation.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, Nursing, and Allied Sciences, North Dakota State University, Fargo, ND 58105, USA.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Shan
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Yu
authors.forename: Preeti
authors.initials: P
authors.lastname: Purwaha
authors.forename: Bin
authors.initials: B
authors.lastname: Guo
authors.forename: Steven Y
authors.initials: SY
authors.lastname: Qian
mesh_terms: D055162:Biocatalysis; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D015118:Eicosapentaenoic Acid; D004578:Electron Spin Resonance Spectroscopy; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D005609:Free Radicals / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000502:physiology*; D008084:Lipoxygenase / Q000378:metabolism*; D013058:Mass Spectrometry; D011725:Pyridines; D013025:Glycine max / Q000201:enzymology; D019097:Spin Trapping
chemical_list: D005231:Fatty Acids, Unsaturated; D005609:Free Radicals; D011725:Pyridines; C043438:alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone; D015118:Eicosapentaenoic Acid; D008084:Lipoxygenase