title: Characterization of 1,2,3,4-diepoxybutane-2'-deoxyguanosine cross-linking products formed at physiological and nonphysiological conditions.
abstract: 1,2,3,4-Diepoxybutane (DEB), an in vivo metabolite of 1,3-butadiene (BD), is a carcinogen and mutagen. The strong carcinogenicity/mutagenicity of DEB has been attributed to its high DNA reactivity and cross-linking ability. Recently, we have demonstrated that under in vitro physiological conditions (pH 7.4, 37 degrees C), the reaction of DEB with 2'-deoxyguanosine (dG) produced two diastereomeric pairs of the major nucleoside adducts resulting from alkylation at the N1- and N7-positions of dG, that is, 2'-deoxy-1-(2-hydroxy-2-oxiranylethyl)guanosine and 2'-deoxy-7-(2-hydroxy-2-oxiranylethyl)guanosine, respectively [Zhang, X.-Y., and Elfarra, A. A. (2005) Chem. Res. Toxicol. 18, 1316]. As each of these adducts contains an oxirane ring, the abilities of these adducts to form cross-linking products with dG under physiological conditions were investigated. Incubation of the N7 nucleoside adducts and their corresponding guanine product with dG led to formation of 7,7'-(2,3-dihydroxy-1,4-butanediyl)bis[2-amino-1,7-dihydro-6H-purin-6-one] (bis-N7G-BD), a known DEB cross-linking product. Incubation of the N1 nucleoside adducts with dG led to formation of a pair of diastereomers of 2'-deoxy-1-[4-(2-amino-1,7-dihydro-6H-purin-6-on-7-yl)-2,3-dihydroxybutyl]-guanosine (N7G-N1dG-BD), which are novel cross-linking products. Interestingly, the reaction of DEB with dG in glacial acetic acid at 60 degrees C yielded different cross-linking products, which were characterized as 2-amino-9-hydroxymethyl-4-{4-[2-amino-9- or 7-(4-acetyloxy-2,3-dihydroxybutyl)-1,7-dihydro-6H-purin-6-on-7- or 9-yl]-2,3-dihydroxybutyl}-8,9-dihydro-7H-[1,4]oxazepino[4,3,2-gh]purin-8-ol (PA2) and 9,9'-bis(4-acetyloxy-2,3-dihydroxybutyl)-7,7'-(2,3-dihydroxy-1,4-butanediyl)bis[2-amino-1,7-dihydro-6H-purin-6-one] (PA4). Collectively, these results increase our understanding of the chemical reactivity and cross-linking ability of DEB under both physiological and nonphysiological conditions.
authors.affiliation: Department of Comparative Biosciences and the Molecular and Environmental Toxicology Center, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Xin-Yu
authors.initials: XY
authors.lastname: Zhang
authors.forename: Adnan A
authors.initials: AA
authors.lastname: Elfarra
mesh_terms: D002273:Carcinogens / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003432:Cross-Linking Reagents / Q000737:chemistry*; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry; D006207:Half-Life; D013056:Spectrophotometry, Ultraviolet
chemical_list: C512051:1,2,3,4-diepoxybutane-2'-deoxyguanosine; D002273:Carcinogens; D003432:Cross-Linking Reagents; D003849:Deoxyguanosine