Identification of DNA adducts of acetaldehyde.
Identification of DNA adducts of acetaldehyde.
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DOI：
10.1021/tx000118t
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发表时间：
2000-10
影响因子：
4.1
通讯作者：
Mingyao Wang;E. McIntee;G. Cheng;Yongli Shi;P. Villalta;Stephen S Hecht
中科院分区：
文献类型：
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作者：
Mingyao Wang;E. McIntee;G. Cheng;Yongli Shi;P. Villalta;Stephen S Hecht
乙醛是一种诱变剂和致癌物，广泛存在于人类环境中，有时含量相当大，但人们对其与 DNA 的反应知之甚少。在这项研究中，我们鉴定了三种新型的稳定乙醛 DNA 加合物，包括链间交联。这些是除了先前表征的 N(2)-亚乙基脱氧鸟苷之外形成的。让乙醛与小牛胸腺DNA或脱氧鸟苷反应。分离DNA并用酶法水解；在某些情况下，DNA 首先用 NaBH(3)CN 处理。通过 HPLC 分析反应混合物，并通过 UV、(1) H NMR 和 MS 分离并表征加合物。主要加合物是 N(2)-亚乙基脱氧鸟苷 (1)，用 NaBH(3)CN 处理 DNA 后，将其鉴定为 N(2)-乙基脱氧鸟苷 (7)。新的乙醛加合物为3-(2-脱氧核糖-1-基)-5,6,7,8-四氢-8-羟基-6-甲基嘧啶基[1,2-a]嘌呤-10(3H)酮(9),3-(2-脱氧核糖-1-基)-5,6,7,8-四氢-8-(N(2)-脱氧鸟苷基+++)- 6-甲基嘧啶并[1,2-a]嘌呤-10(3H)酮(12)和N(2)-(2,6-二甲基-1,3-二恶烷-4-基)脱氧鸟苷(11)。先前已在巴豆醛与 DNA 的反应中鉴定出加合物 9。然而，乙醛和巴豆醛反应中非对映异构体的分布不同，表明乙醛形成9并不通过巴豆醛进行。加合物 12 是链间交联。尽管之前的证据表明 DNA 与乙醛反应形成交联，但这是首次报道这种加合物的结构特征。这种加合物也存在于巴豆醛-脱氧鸟苷反应中，但非对映体比例与此处观察到的不同。一种常见的中间体 N(2)-(4-氧代丁-2-基)脱氧鸟苷 (6) 被认为参与加合物 9 和 12 的形成。加合物 11 最终由 3-羟基丁醛（乙醛的主要羟醛缩合产物）产生。在乙醛与 DNA 反应中，加合物 9、11 和 12 的水平低于 N(2)-亚乙基脱氧鸟苷 (1) 的 10%。作为核苷，加合物 9、11 和 12 是稳定的，而 N(2)-亚乙基脱氧鸟苷 (1) 的半衰期为 5 分钟。这些新的稳定的乙醛加合物可能参与其致突变和致癌特性的测定。
Acetaldehyde is a mutagen and carcinogen which occurs widely in the human environment, sometimes in considerable amounts, but little is known about its reactions with DNA. In this study, we identified three new types of stable acetaldehyde DNA adducts, including an interstrand cross-link. These were formed in addition to the previously characterized N(2)-ethylidenedeoxyguanosine. Acetaldehyde was allowed to react with calf thymus DNA or deoxyguanosine. The DNA was isolated and hydrolyzed enzymatically; in some cases, the DNA was first treated with NaBH(3)CN. Reaction mixtures were analyzed by HPLC, and adducts were isolated and characterized by UV, (1)H NMR, and MS. The major adduct was N(2)-ethylidenedeoxyguanosine (1), which was identified as N(2)-ethyldeoxyguanosine (7) after treatment of the DNA with NaBH(3)CN. The new acetaldehyde adducts were 3-(2-deoxyribos-1-yl)-5,6,7, 8-tetrahydro-8-hydroxy-6-methylpyrimido[1,2-a]purine-10(3H)one (9), 3-(2-deoxyribos-1-yl)-5,6,7,8-tetrahydro-8-(N(2)-deoxyguanosyl+ ++)- 6-methylpyrimido[1,2-a]purine-10(3H)one (12), and N(2)-(2, 6-dimethyl-1,3-dioxan-4-yl)deoxyguanosine (11). Adduct 9 has been previously identified in reactions of crotonaldehyde with DNA. However, the distribution of diastereomers was different in the acetaldehyde and crotonaldehyde reactions, indicating that the formation of 9 from acetaldehyde does not proceed through crotonaldehyde. Adduct 12 is an interstrand cross-link. Although previous evidence indicates the formation of cross-links in DNA reacted with acetaldehyde, this is the first reported structural characterization of such an adduct. This adduct is also found in crotonaldehyde-deoxyguanosine reactions, but in a diastereomeric ratio different than that observed here. A common intermediate, N(2)-(4-oxobut-2-yl)deoxyguanosine (6), is proposed to be involved in formation of adducts 9 and 12. Adduct 11 is produced ultimately from 3-hydroxybutanal, the major aldol condensation product of acetaldehyde. Levels of adducts 9, 11, and 12 were less than 10% of those of N(2)-ethylidenedeoxyguanosine (1) in reactions of acetaldehyde with DNA. As nucleosides, adducts 9, 11, and 12 were stable, whereas N(2)-ethylidenedeoxyguanosine (1) had a half-life of 5 min. These new stable adducts of acetaldehyde may be involved in determination of its mutagenic and carcinogenic properties.