34973-29-0Relevant articles and documents
Expanded analysis of benzo[a]pyrene-DNA adducts formed in vitro and in mouse skin: Their significance in tumor initiation
Chen,Devanesan,Higginbotham,Ariese,Jankowiak,Small,Rogan,Cavalieri
, p. 897 - 903 (2007/10/03)
This paper reports expanded analyses of benzo[a]pyrene (BP)-DNA adducts formed in vitro by activation with horseradish peroxidase (HRP) or 3- methylcholanthrene-induced rat liver microsomes and in vivo in mouse skin. The adducts formed by BP are compared to those formed by BP-7,8-dihydrodiol and anti-BP diol epoxide (BPDE). First, activation of BP by HRP produced 61% depurinating adducts: 7-(benzo[a]pyrene-6-yl)guanine (BP-6-N7Gua), BP-6- C8Gua, BP-6-N7Ade, and the newly identified BP-6-N3Ade. As a standard, the last adduct was synthesized along with BP-6-N1Ade by electrochemical oxidation of BP in the presence of adenine. Second, identification and quantitation of BP-DNA adducts formed by microsomal activation of BP showed 68% depurinating adducts: BP-6-N7Ade, BP-6-N7Gua, BP-6-C8Gua, BPDE-10-N7Ade, and the newly detected BPDE-10-N7Gua. The stable adducts were mostly BPDE- 10-N2dG (26%), with 6% unidentified. BPDE-10-N7Ade and BPDE-10-N7Gua were the depurinating adducts identified after microsomal activation of BP-7,8- dihydrodiol or direct reaction of anti-BPDE with DNA. In both cases, the predominant adduct was BPDE-10-N2dG (90% and 96%, respectively). Third, when mouse skin was treated with BP for 4 h, 71% of the total adducts were the depurinating adducts BP-6-N7Gua, BP-6-C8Gua, BP-6-N7Ade, and small amounts of BPDE-10-N7Ade and BPDE-10-N7Gua. These newly detected depurinating diol epoxide adducts were found in larger amounts when mouse skin was treated with BP-7,8-dihydrodiol or anti-BPDE. The stable adduct BPDE-10-N2dG was predominant, especially with anti-BPDE. Comparison of the profiles of DNA adducts formed by BP, BP-7,8-dihydrodiol, and anti-BPDE with their carcinogenic potency indicates that tumor initiation correlates with the levels of depurinating adducts, but not with stable adducts. Furthermore, the levels of depurinating adducts of BP correlate with mutations in the Harvey- ras oncogene in DNA isolated from mouse skin papillomas initiated by this compound [Chakravarti et al. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 10422- 10426]. The depurinating adducts formed by BP in mouse skin appear to be the key adducts leading to tumor initiation.
Synthesis an Identification of Benzopyrene-Guanine Nucleoside Adducts Formed by Electrochemical Oxidation and by Horseradish Peroxidase Catalyzed Reaction of Benzopyrene with DNA
Rogan, E. G.,Cavalieri, E. L.,Tibbels, S. R.,Cremonesi, P.,Warner, C. D.,et al.
, p. 4023 - 4029 (2007/10/02)
One-electron oxidation plays an important role in the metabolism of many substrates and their covalent binding to macromolecules.This mechanism of activation can be demonstrated by elucidation of the structure of DNA adducts.In this paper, we report the synthesis of adducts by anodic oxydation of benzolpyrene (BP) in the presence of deoxyguanosine (dG) or guanosine (G).By using 1H and two-dimensional NMR spectroscopy as well as fast atom bombardment and collisionally activated decomposition (CAD) mass spectroscopy, adducts were identified as BP bound at C-6-C-8 of guanine (Gua), dG and G and to N-7 of Gua.Loss of deoxyribose from the N-7 adduct was anticipated, but it was unexpectedly found that about 30percent of the C-8 adduct with dG lost the deoxyribose moiety.The C-8 adduct of G almost entirely retained the ribose moiety.These compounds were used as markers for high pressure liquid chromatography (HPLC) to identify adducts formed in the horseradish peroxidase catalysed binding of BP to DNA.By use of HPLC in two solvent systems, adducts were identified in the supernatant fraction obtained after ethanol precipitation of the DNA and in an enzymatic digest of the DNA.The supernatant, containing adducts lost by depurination, afforded 95percent of the N-7 adduct and about half of the C-8 adduct.The major adduct identified in the DNA digest was the C-8 of dG.The structure of the N-7 adduct in the supernatant was confirmed by CAD mass spectroscopy.These results demonstrate that horseradish peroxidase catalyzes binding of BP to DNA by one-electron oxidation.
