Wang Yinan, Chan Ho Wai, Chan Wan
Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong.
Chem Res Toxicol. 2016 May 16;29(5):834-40. doi: 10.1021/acs.chemrestox.6b00011. Epub 2016 Apr 21.
Mutagenic semicarbazide (SEM) is a hydrazine-containing food contaminant found in a wide variety of foods. Despite decades of research, the toxicity of SEM remains incompletely understood. In this study, we demonstrate for the first time that SEM reacts rapidly with apurinic/apyrimidinic sites in an endogenous DNA lesion to form covalently bonded DNA adducts in vitro and in bacteria. Specifically, we performed high-performance liquid chromatography with high accuracy and tandem mass spectrometry to characterize the DNA adduct formed by reacting SEM with 2'-deoxyribose and single- and double-stranded oligonucleotides containing abasic sites under physiologically relevant conditions. By analyzing the reaction mixture at different time points, the reaction kinetics of SEM with DNA was also elucidated. Moreover, by using a highly sensitive and selective liquid chromatography-tandem mass spectrometry method, we show that SEM induces the dose-dependent formation of DNA adducts in Escherichia coli. The results from our studies provide the first direct evidence suggesting that SEM may exert genotoxicity by forming covalently bonded DNA adducts.
诱变剂氨基脲（SEM）是一种含肼的食品污染物，存在于多种食品中。尽管经过了数十年的研究，但SEM的毒性仍未完全了解。在本研究中，我们首次证明SEM在体外和细菌中与内源性DNA损伤中的脱嘌呤/脱嘧啶位点迅速反应，形成共价结合的DNA加合物。具体而言，我们进行了高精度高效液相色谱和串联质谱分析，以表征在生理相关条件下SEM与2'-脱氧核糖以及含有无碱基位点的单链和双链寡核苷酸反应形成的DNA加合物。通过分析不同时间点的反应混合物，还阐明了SEM与DNA的反应动力学。此外，通过使用高灵敏度和选择性的液相色谱-串联质谱法，我们表明SEM在大肠杆菌中诱导了剂量依赖性的DNA加合物形成。我们的研究结果提供了首个直接证据，表明SEM可能通过形成共价结合的DNA加合物发挥遗传毒性。
