A liquid chromatograpy-nanoelectrospray ionization-high resolution tandem mass spectrometry (LC–NSI–HRMS/MS) method was developed for quantitation of the DNA adducts 7-(2′-carboxyethyl)guanine (7-2′-CEG) and N²-(1′-carboxyethyl)guanine (N²-1′-CEG), as their methyl esters, in human leukocyte DNA from smokers and non-smokers. 7-2′-CEG has been previously identified in all human liver samples analyzed and is formed from an unknown carboxyethylating agent while N²-1′-CEG is formed from the advanced glycation endproduct methyl glyoxal. The method was applied for the analysis of these two DNA adducts in leukocyte DNA from 20 smokers and 20 non-smokers, in part to test the hypothesis that 7-2′-CEG could be formed by endogenous nitrosation, as previously observed in rats treated with nitrosodihydrouracil and nitrite. Levels of 7-2′-CEG (mean ± S.D.) were 0.6 ± 0.2 pmol/μmol dG in smokers and 0.5 ± 0.2 pmol/μmol dG in non-smokers, while those of N²-1′-CEG were 4.5 ± 1.9 pmol/μmol dG in smokers and 4.6 ± 2 pmol/μmol dG in non-smokers. These results did not support our hypothesis that endogenous nitrosation of dihydrouracil in smokers leads to higher levels of 7-2′-CEG in leukocyte DNA than in non-smokers. However the study provides the first data on levels of these DNA adducts in human leukocyte DNA, and the LC–NSI–HRMS/MS method developed for their quantitation could be important for future studies of DNA damage by methyl glyoxal.

开发了一种液相色谱-纳电喷雾电离-高分辨率串联质谱（LC-NSI-HRMS/MS）方法，用于定量 DNA 加合物 7-(2'-羧乙基)鸟嘌呤 (7-2'-CEG) 和N ² -(1'-羧乙基)鸟嘌呤 ( N ² -1'-CEG)，以其甲酯形式存在于吸烟者和非吸烟者的人类白细胞 DNA 中。 7-2'-CEG 之前已在所有分析的人类肝脏样本中被鉴定出，并且是由未知的羧乙基化剂形成的，而N ² -1'-CEG 是由高级糖基化终产物甲基乙二醛形成的。该方法用于分析 20 名吸烟者和 20 名非吸烟者白细胞 DNA 中的这两种 DNA 加合物，部分是为了检验 7-2'-CEG 可以通过内源亚硝化形成的假设，正如之前在接受治疗的大鼠中观察到的那样。与亚硝基二氢尿嘧啶和亚硝酸盐。吸烟者的 7-2′-CEG 水平（平均值±标准差）为 0.6 ± 0.2 pmol/μmol dG，非吸烟者的水平为 0.5 ± 0.2 pmol/μmol dG，而N ² -1′-CEG 的水平为 4.5 ± 1.9吸烟者为 pmol/μmol dG，非吸烟者为 4.6 ± 2 pmol/μmol dG。这些结果并不支持我们的假设，即吸烟者中二氢尿嘧啶的内源亚硝化导致白细胞 DNA 中 7-2'-CEG 的水平高于非吸烟者。然而，这项研究提供了有关人类白细胞 DNA 中这些 DNA 加合物水平的第一批数据，并且为其定量开发的 LC-NSI-HRMS/MS 方法可能对于未来甲基乙二醛造成的 DNA 损伤的研究非常重要。