Styrene 7,8-oxide (SO), a reactive epoxide that has been classified as a probable human carcinogen, was allowed to react under alkaline conditions with 2′-deoxyguanosine and thymidine monophosphates as well as with the dinucleotide dGpdT. The reaction products were separated by high-performance liquid chromatography and were characterised by UV and electrospray mass spectroscopy, the latter showing the ability to differentiate the isomerism of the hydroxyphenylethyl moiety of the adduct. The main alkylation products of the deoxyguanosine monophosphates at high pH were those reacted at the 1- (through the β-carbon of the epoxide), N2- (α-carbon) and 7-positions (β- and α-carbons) of guanine followed by alkylation of the phosphate group. The formation of a novel diastereomeric pair of N
2-guanine adducts connected to the β-carbon of SO was identified and characterised. Furthermore, two different geometrical isomers of 1-guanine were detected. For thymidine nucleotide, base alkylation under neutral conditions was almost negligible, but at pH 10.5, alkylation at the 3-position was very prominent. The same base-adducts and the pH-effects were observed in the case of dGpdT alkylation. However, no phosphate alkylation was detected in the case of the dinucleotide.
苯乙烯 7,8-氧化物(SO)是一种活性
环氧化物,已被归类为可能的人类致癌物,它可在碱性条件下与 2′-脱氧
鸟苷和
胸苷单
磷酸盐以及二核苷酸 dGpdT 发生反应。反应产物通过高效
液相色谱法分离,并通过紫外光谱和电喷雾质谱进行表征,后者显示了区分加合物中羟基苯乙基分子异构体的能力。在高 pH 值条件下,脱氧
鸟苷单
磷酸酯的主要烷基化产物是
鸟嘌呤的 1-位(通过
环氧化物的 β-碳)、N2-位(α-碳)和 7-位(β-和 α-碳)发生反应,然后
磷酸基发生烷基化。结果发现并表征了与 SO 的 β 碳相连的 N 2-
鸟嘌呤加合物形成的一对新型非对映异构体。此外,还检测到了 1-
鸟嘌呤的两种不同几何异构体。
胸苷核苷酸在中性条件下的碱基烷基化几乎可以忽略不计,但在 pH 值为 10.5 时,3 位的烷基化非常明显。在 dGpdT 烷基化的情况下,也观察到了同样的碱基加成和 pH 值效应。不过,在二核苷酸中没有检测到
磷酸烷基化。