title: Identification and quantitation of benzo[a]pyrene-derived DNA adducts formed at low adduction level in mice lung tissue.
abstract: The two major metabolic pathways of benzo[a]pyrene (BP) that lead to DNA lesions are monooxygenation that results in diolepoxides (BPDE) and one-electron oxidation that yields a BP radical cation. These pathways result in formation of stable and depurinating DNA adducts, respectively. Most in vivo animal studies with BP, however, have employed dosage/DNA adduct levels several orders of magnitude higher than the DNA damage level expected from environmentally relevant exposures. Presented are results of experiments in which A/J strain mice were intraperitoneally exposed to 50-microg/g doses of BP. It is shown that non-line-narrowed fluorescence and fluorescence line-narrowing spectroscopies possess the selectivity and sensitivity to distinguish between helix-external, base-stacked, and intercalated conformations of DNA-BPDE adducts formed in lung tissue. Concentrations measured by 32P postlabeling 2 and 3 days after intraperitoneal injection were 420-430 and 600-830 amol BPDE-type adducts per microg DNA. The external and base-stacked conformations are attributed mainly to (+)-trans-anti-BPDE-N2dG and the intercalated conformations to (+)-cis-anti adducts. A stable adduct derived from 9-OH-BP-4,5-epoxide was also detected at a concentration about a factor of 10 lower than the above concentrations. The DNA supernatants were analyzed for the presence of depurinating BP-derived adducts by capillary electrophoresis laser-induced fluorescence and high-performance liquid chromatography mass spectrometry.
authors.affiliation: Ames Laboratory-USDOE and Department of Chemistry, Iowa State University, Ames, IA 50011, USA.
authors.forename: Marzena
authors.initials: M
authors.lastname: Banasiewicz
authors.forename: Garret
authors.initials: G
authors.lastname: Nelson
authors.forename: Adam
authors.initials: A
authors.lastname: Swank
authors.forename: Nenad
authors.initials: N
authors.lastname: Grubor
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Ross
authors.forename: Stephen
authors.initials: S
authors.lastname: Nesnow
authors.forename: Harald
authors.initials: H
authors.lastname: Köfeler
authors.forename: Gerald J
authors.initials: GJ
authors.lastname: Small
authors.forename: Ryszard
authors.initials: R
authors.lastname: Jankowiak
mesh_terms: D000818:Animals; D001564:Benzo(a)pyrene / Q000737:chemistry* / Q000494:pharmacology; D018736:DNA Adducts / Q000032:analysis* / Q000737:chemistry*; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D015394:Molecular Structure; D013050:Spectrometry, Fluorescence; D013696:Temperature
chemical_list: D018736:DNA Adducts; D001564:Benzo(a)pyrene