Institute of Environmental Pollution and Health, School of Environmental and Chemical Engineering, Shanghai University , Shanghai 200444, People's Republic of China.
Chem Res Toxicol. 2013 Oct 21;26(10):1545-53. doi: 10.1021/tx4002435. Epub 2013 Sep 25.
1-Chloro-3-buten-2-one (CBO) is a potential metabolite of 1,3-butadiene (BD), a carcinogenic air pollutant. CBO is a bifunctional alkylating agent that readily reacts with glutathione (GSH) to form mono-GSH and di-GSH adducts. Recently, CBO and its precursor 1-chloro-2-hydroxy-3-butene (CHB) were found to be cytotoxic and genotoxic in human liver cells in culture with CBO being approximately 100-fold more potent than CHB. In the present study, CBO was shown to react readily with 2'-deoxycytidine (dC) under in vitro physiological conditions (pH 7.4, 37 °C) to form four dC adducts with the CBO moieties forming fused rings with the N3 and N(4) atoms of dC. The four products were structurally characterized as 2-hydroxy-2-hydroxymethyl-7-(2-deoxy-β-d-erythro-pentofuranosyl)-1,2,3,4-tetrahydro-6-oxo-6H,7H-pyrimido[1,6-a]pyrimidin-5-ium (dC-1 and dC-2, a pair of diastereomers), 4-chloromethyl-4-hydroxy-7-(2-deoxy-β-d-erythro-pentofuranosyl)-1,2,3,4-tetrahydro-6-oxo-6H,7H-pyrimido[1,6-a]pyrimidin-5-ium (dC-3), and 2-chloromethyl-2-hydroxy-7-(2-deoxy-β-d-erythro-pentofuranosyl)-1,2,3,4-tetrahydro-6-oxo-6H,7H-pyrimido[1,6-a]pyrimidin-5-ium (dC-4). Interestingly, dC-1 and dC-2 were stable under our experimental conditions (pH 7.4, 37 °C, and 6 h) and existed in equilibrium as indicated by HPLC analysis, whereas dC-3 and dC-4 were labile with the half-lives being 3.0 ± 0.36 and 1.7 ± 0.06 h, respectively. Decomposition of dC-4 produced both dC-1 and dC-2, whereas acid hydrolysis of dC-1/dC-2 and dC-4 in 1 M HCl at 100 °C for 30 min yielded the deribosylated adducts dC-1H/dC-2H and dC-4H, respectively. Because fused-ring dC adducts of other chemicals are mutagenic, the characterized CBO-dC adducts could be mutagenic and play a role in the cytotoxicity and genotoxicity of CBO and its precursors, CHB and BD. The CBO-dC adducts may also be used as standards to characterize CBO-DNA adducts and to develop potential biomarkers for CBO formation in vivo.
1-氯-3-丁烯-2-酮（CBO）是 1,3-丁二烯（BD）这种致癌空气污染物的一种潜在代谢物。CBO 是一种双功能烷化剂，它很容易与谷胱甘肽（GSH）反应，形成单-GSH 和二-GSH 加合物。最近，研究人员发现 CBO 及其前体 1-氯-2-羟基-3-丁烯（CHB）在培养的人肝细胞中具有细胞毒性和遗传毒性，其中 CBO 的效力大约比 CHB 强 100 倍。在本研究中，研究人员发现 CBO 很容易在体外生理条件（pH 值 7.4，37°C）下与 2'-脱氧胞苷（dC）反应，形成四个带有 CBO 部分的 dC 加合物，其中 CBO 部分与 dC 的 N3 和 N(4)原子融合形成环。四个产物的结构特征为 2-羟基-2-羟甲基-7-(2-脱氧-β-D-赤型-戊呋喃糖基)-1,2,3,4-四氢-6-氧代-6H,7H-嘧啶并[1,6-a]嘧啶-5-鎓（dC-1 和 dC-2，一对非对映异构体）、4-氯甲基-4-羟基-7-(2-脱氧-β-D-赤型-戊呋喃糖基)-1,2,3,4-四氢-6-氧代-6H,7H-嘧啶并[1,6-a]嘧啶-5-鎓（dC-3）和 2-氯甲基-2-羟基-7-(2-脱氧-β-D-赤型-戊呋喃糖基)-1,2,3,4-四氢-6-氧代-6H,7H-嘧啶并[1,6-a]嘧啶-5-鎓（dC-4）。有趣的是，在我们的实验条件下（pH 值 7.4、37°C 和 6 小时），dC-1 和 dC-2 是稳定的，这可以通过 HPLC 分析来指示，而 dC-3 和 dC-4 是不稳定的，半衰期分别为 3.0±0.36 和 1.7±0.06 小时。dC-4 的分解产生了 dC-1 和 dC-2，而在 1 M HCl 中于 100°C 加热 30 分钟对 dC-1/dC-2 和 dC-4 进行酸水解，分别生成去糖基化加合物 dC-1H/dC-2H 和 dC-4H。由于其他化学物质的融合环 dC 加合物具有致突变性，因此所鉴定的 CBO-dC 加合物可能具有致突变性，并在 CBO 及其前体 CHB 和 BD 的细胞毒性和遗传毒性中发挥作用。CBO-dC 加合物也可作为标准用于鉴定 CBO-DNA 加合物，并开发体内 CBO 形成的潜在生物标志物。
