Devanesan P D, RamaKrishna N V, Todorovic R, Rogan E G, Cavalieri E L, Jeong H, Jankowiak R, Small G J
Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha 68198-6805.
Chem Res Toxicol. 1992 Mar-Apr;5(2):302-9. doi: 10.1021/tx00026a024.
The two DNA adducts of benzo[a]pyrene (BP) previously identified in vitro and in vivo are the stable adduct formed by reaction of the bay-region diol epoxide of BP (BPDE) at C-10 with the 2-amino group of dG (BPDE-10-N2dG) and the adduct formed by reaction of BP radical cation at C-6 with the N-7 of Gua (BP-6-N7Gua), which is lost from DNA by depurination. In this paper we report identification of several new BP-DNA adducts formed by one-electron oxidation and the diol epoxide pathway, namely, BP bound at C-6 to the C-8 of Gua (BP-6-C8Gua) and the N-7 of Ade (BP-6-N7Ade) and BPDE bound at C-10 to the N-7 of Ade (BPDE-10-N7Ade). The in vitro systems used to study DNA adduct formation were BP activated by horseradish peroxidase or 3-methylcholanthrene-induced rat liver microsomes, BP 7,8-dihydrodiol activated by microsomes, and BPDE reacted with DNA. Identification of the biologically-formed depurination adducts was achieved by comparison of their retention times on high-pressure liquid chromatography in two different solvent systems and by comparison of their fluorescence line narrowing spectra with those of authentic adducts. The quantitation of BP-DNA adducts formed by rat liver microsomes showed 81% as depurination adducts: BP-6-N7Ade (58%), BP-6-N7Gua (10%), BP-6-C8Gua (12%), and BPDE-10-N7Ade (0.5%). Stable adducts (19% of total) included BPDE-10-N2dG (15%) and unidentified adducts (4%). Microsomal activation of BP 7,8-dihydrodiol yielded 80% stable adducts, with 77% as BPDE-10-N2dG and 20% of the depurination adduct BPDE-10-N7Ade. The percentage of BPDE-10-N2dG (94%) was higher when BPDE was reacted with DNA, and only 1.8% of BPDE-10-N7Ade was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)
先前在体外和体内鉴定出的苯并[a]芘（BP）的两种DNA加合物，一种是BP的湾区二醇环氧化物（BPDE）在C-10处与dG的2-氨基反应形成的稳定加合物（BPDE-10-N2dG），另一种是BP在C-6处的自由基阳离子与鸟嘌呤（Gua）的N-7反应形成的加合物（BP-6-N7Gua），后者会通过脱嘌呤作用从DNA中丢失。在本文中，我们报告了通过单电子氧化和二醇环氧化物途径形成的几种新的BP-DNA加合物的鉴定结果，即BP在C-6处与Gua的C-8结合（BP-6-C8Gua）、与腺嘌呤（Ade）的N-7结合（BP-6-N7Ade），以及BPDE在C-10处与Ade的N-7结合（BPDE-10-N7Ade）。用于研究DNA加合物形成的体外系统包括用辣根过氧化物酶激活的BP或3-甲基胆蒽诱导的大鼠肝微粒体、用微粒体激活的BP 7,8-二氢二醇，以及BPDE与DNA反应。通过比较它们在两种不同溶剂系统中的高压液相色谱保留时间，以及将它们的荧光线窄化光谱与真实加合物的光谱进行比较，实现了对生物形成的脱嘌呤加合物的鉴定。对大鼠肝微粒体形成的BP-DNA加合物的定量分析表明，81%为脱嘌呤加合物：BP-6-N7Ade（58%）、BP-6-N7Gua（10%）、BP-6-C8Gua（12%）和BPDE-10-N7Ade（0.5%）。稳定加合物（占总量的19%）包括BPDE-10-N2dG（15%）和未鉴定的加合物（4%）。BP 7,8-二氢二醇的微粒体激活产生了80%的稳定加合物，其中77%为BPDE-10-N2dG，20%为脱嘌呤加合物BPDE-10-N7Ade。当BPDE与DNA反应时，BPDE-10-N2dG的百分比更高（94%），仅获得1.8%的BPDE-10-N7Ade。（摘要截短于250字）
