作者:Antonín Králík、Igor Linhart、Lubomír Váňa、Alena Moulisová
DOI:10.1021/acs.chemrestox.5b00120
日期:2015.6.15
Phenylnitrenium ion (PhNH+) may bind to nucleophiles through nitrogen as well as through C2 or C4 carbons. However, only adducts of the former type have been hitherto reported after its reaction with purine nucleosides. In this study, reactions of N-acetoxyaniline (PhNHOAc), a precursor to PhNH+, with 2′-deoxyadenosine (dA), 2′-deoxyguanosine (dG), and with DNA in vitro at physiological conditions are described. The reaction of PhNHOAc with dA followed by a hydrolytic deribosylation afforded 8-phenylaminoadenine (C8-PhNHA) together with a smaller amount of N6-(4-aminophenyl)adenine (N6-4APA). A similar reaction with dG afforded 8-phenylaminoguanine (C8-PhNHG) together with traces of 7-(4-aminophenyl)guanine (N7-4APG). The same adducts were found also in the DNA treated with PhNHOAc, and all of them were identified by comparison of their HPLC retention times and MS2 spectra with a set of synthesized authentic adenine adducts at C2, C8, N7, and N6 positions and guanine adducts at C8, N7, and N2 positions. The newly identified minor adduct, N7-4APG, represents the first proof of arylnitrenium adduction at the N7 position of dG, which is the prominent site of attack by most C-electrophiles.
苯基腈离子(PhNH+)可通过氮以及 C2 或 C4 碳与亲核物结合。然而,迄今为止,只有前一种类型的加合物在与嘌呤核苷反应后被报道过。本研究描述了 PhNH+ 的前体 N-乙酰氧基苯胺(PhNHOAc)与 2′-脱氧腺苷(dA)、2′-脱氧鸟苷(dG)以及 DNA 在体外生理条件下的反应。PhNHOAc 与 dA 反应后进行水解去核糖基化,可得到 8-苯基氨基腺嘌呤(C8-PhNHA)和少量 N6-(4-氨基苯基)腺嘌呤(N6-4APA)。与 dG 的类似反应产生了 8-苯氨基鸟嘌呤(C8-PhNHG)以及微量的 7-(4-氨基苯基)鸟嘌呤(N7-4APG)。通过比较其 HPLC 保留时间和 MS2 光谱与一组合成的真实腺嘌呤加合物(C2、C8、N7 和 N6 位置)和鸟嘌呤加合物(C8、N7 和 N2 位置),可以鉴定出所有这些加合物。新发现的次要加合物 N7-4APG 首次证明了芳基腈在 dG 的 N7 位上的加成作用,而 N7 位是大多数 C-亲电体的主要攻击位点。