title: Unexpected formation of etheno-2'-deoxyguanosine adducts from 5(S)-hydroperoxyeicosatetraenoic acid: evidence for a bis-hydroperoxide intermediate.
abstract: Analysis of products from the reaction between 5(S)-hydroperoxy-6,8,11,14-(E,Z,Z,Z)-eicosatetraenoic acid and 2'-deoxyguanosine in the presence of FeII, FeIII, or vitamin C by liquid chromatography/atmospheric pressure chemical ionization/mass spectrometry revealed the presence of four DNA adducts. Surprisingly, adducts I and II had mass spectral characteristics identical to those for 1,N2-etheno-2'-deoxyguanosine and heptanone-1,N2-etheno-2'-deoxyguanosine. These adducts have previously been shown to arise from the homolytic decomposition of 13(S)-hydroperoxy-9,11-(Z,E)-octadecadienoic acid. It appears that under the reaction conditions, 5(S)-hydroperoxy-6,8,11,14-(E,Z,Z,Z)-eicosatetraenoic acid was subjected to a previously unknown peroxidation reaction to give a bis-hydroperoxide intermediate that underwent a Hock rearrangement to produce 3(Z)-nonenal from the omega-terminus. The 3(Z)-nonenal was then converted to 4-hydroperoxy-2-nonenal, a precursor to the formation of 4-oxo-2-nonenal. 4-Oxo-2-nonenal forms heptanone-1,N2-etheno-adducts with 2'-deoxyguanosine, whereas 4-hydroperoxy-2-nonenal forms 1,N2-etheno-2'-deoxyguanosine. Two novel carboxylate adducts were also identified. The structure of the more abundant adduct (III) was characterized as its methyl ester derivative by NMR spectroscopy as 3-(2'-deoxy-beta-D-erythropentafuranosyl)imidazo-7-(5' '-carboxypenta-2' '-one)-9-oxo[1,2-alpha]purine (5-carboxy-2-pentanone-1,N2-etheno-2'-deoxyguanosine). This etheno adduct was formed by the reaction of 2'-deoxyguanosine with 5,8-dioxo-6(E)-octenoic acid. The bifunctional electrophile is proposed to arise from the alpha-terminus during the Hock rearrangement of bis-hydroperoxide derived from 5(S)-hydroperoxy-6,8,11,14-(E,Z,Z,Z)-eicosatetraenoic acid. 5-Carboxy-2-pentanone-1,N2-etheno-2'-deoxyguanosine may serve as a biomarker of 5-lipoxygenase-mediated oxidative stress. The less abundant carboxylate adduct IV arose from a quite different pathway and was tentatively characterized as 6-carboxy-3-hydroxy-1-hexene-1,N2-etheno-2'-deoxyguanosine.
authors.affiliation: Center for Cancer Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6160, USA.
authors.forename: Wenying
authors.initials: W
authors.lastname: Jian
authors.forename: Seon Hwa
authors.initials: SH
authors.lastname: Lee
authors.forename: Jasbir S
authors.initials: JS
authors.lastname: Arora
authors.forename: Maria V
authors.initials: MV
authors.lastname: Silva Elipe
authors.forename: Ian A
authors.initials: IA
authors.lastname: Blair
mesh_terms: D018736:DNA Adducts / Q000138:chemical synthesis*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D015289:Leukotrienes / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D018736:DNA Adducts; D015289:Leukotrienes; C054579:1,N(2)-ethenodeoxyguanosine; C025348:arachidonic acid 5-hydroperoxide; D003849:Deoxyguanosine