Gamboa da Costa Gonçalo, Churchwell Mona I, Hamilton L Patrice, Von Tungeln Linda S, Beland Frederick A, Marques M Matilde, Doerge Daniel R
Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.
Chem Res Toxicol. 2003 Oct;16(10):1328-37. doi: 10.1021/tx034108e.
Acrylamide (AA) is a high production volume chemical with many industrial uses; however, recent findings of ppm levels in starchy foods cooked at high temperature have refocused worldwide attention on the neurotoxicity, germ cell mutagenicity, and carcinogenicity of AA. Oxidative metabolism of AA to its epoxide metabolite, glycidamide (GA), has been observed in experimental animals and humans and may be associated with many of the toxic effects of AA exposure, including formation of N7-(2-carbamoyl-2-hydroxyethyl)guanine (N7-GA-Gua) in vivo. This paper describes the characterization of two new GA-derived DNA adducts formed in vitro, N3-(2-carbamoyl-2-hydroxyethyl)adenine (N3-GA-Ade) and N1-(2-carboxy-2-hydroxyethyl)-2'-deoxyadenosine. A sensitive method for quantification of N7-GA-Gua and N3-GA-Ade, based on LC with tandem mass spectrometry and isotope dilution, was developed and validated for use in measuring DNA adduct formation in selected tissues of adult and whole body DNA of 3 day old neonatal mice treated with AA and GA. In adult mice, DNA adduct formation was observed in liver, lung, and kidney with levels of N7-GA-Gua around 2000 adducts/10(8) nucleotides and N3-GA-Ade around 20 adducts/10(8) nucleotides. Adduct levels were modestly higher in adult mice dosed with GA as opposed to AA; however, treatment of neonatal mice with GA produced 5-7-fold higher whole body DNA adduct levels than with AA, presumably reflective of lower oxidative enzyme activity in newborn mice. DNA adduct formation from AA treatment in adult mice showed a supralinear dose-response relationship, consistent with saturation of oxidative metabolism at higher doses. These results increase our understanding of the mutagenic potential of GA and provide further evidence for a genotoxic mechanism in AA carcinogenesis.
丙烯酰胺（AA）是一种大量生产且具有多种工业用途的化学品；然而，近期发现高温烹制的淀粉类食物中含有百万分之一级别的丙烯酰胺，这使得全球范围内对丙烯酰胺的神经毒性、生殖细胞致突变性和致癌性的关注再度聚焦。在实验动物和人类中均观察到丙烯酰胺氧化代谢生成其环氧化物代谢产物缩水甘油酰胺（GA），这可能与丙烯酰胺暴露的许多毒性效应相关，包括体内形成N7-(2-氨基甲酰-2-羟乙基)鸟嘌呤（N7-GA-Gua）。本文描述了体外形成的两种新的GA衍生DNA加合物，即N3-(2-氨基甲酰-2-羟乙基)腺嘌呤（N3-GA-Ade）和N1-(2-羧基-2-羟乙基)-2'-脱氧腺苷的特性。基于液相色谱串联质谱和同位素稀释技术，开发并验证了一种灵敏的定量N7-GA-Gua和N3-GA-Ade的方法，用于测量用AA和GA处理的成年小鼠选定组织及3日龄新生小鼠全身DNA中的DNA加合物形成情况。在成年小鼠中，在肝脏、肺和肾脏中观察到DNA加合物的形成，N7-GA-Gua的水平约为2000个加合物/10(8)个核苷酸，N3-GA-Ade的水平约为20个加合物/10(8)个核苷酸。与给予AA的成年小鼠相比，给予GA的成年小鼠加合物水平略高；然而，用GA处理新生小鼠产生的全身DNA加合物水平比用AA处理高5至7倍，这可能反映出新生小鼠氧化酶活性较低。成年小鼠经AA处理后形成的DNA加合物呈现超线性剂量反应关系，这与较高剂量下氧化代谢的饱和现象一致。这些结果增进了我们对GA诱变潜力的理解，并为AA致癌作用中的遗传毒性机制提供了进一步证据。
