代谢
此前,已经证明大鼠中的强烈肝致癌物——二级硝基烷2-硝基丙烷,可以通过磺基转移酶介导的途径诱导大鼠肝脏DNA和RNA中8-氨基鸟嘌呤的形成。这一途径假设将致癌物转化为氨基化物种。为了进一步检验这一假设,我们检查了用2-硝基丙烷、其他致癌二级硝基烷或相关的大鼠肝肿瘤原剂乙酰氧基亚胺处理的鼠肝蛋白中是否存在3-氨基酪氨酸,这是酪氨酸氨基化的预期产物。使用离子对和/或阳离子交换高效液相色谱与电化学检测,我们发现这些动物肝脏细胞质蛋白中含有0.1-1.5摩尔/每1000摩尔酪氨酸的3-氨基酪氨酸。用非致癌的一级硝基烷1-硝基丙烷或其他一级硝基烷处理并未产生类似的氨基化氨基酸增加(检测水平估计大约为0.01摩尔/每1000摩尔酪氨酸)。
体外研究中,乙酰氧基亚胺-O-磺酸和羟胺-O-磺酸显示出这些作为2-硝基丙烷活化途径中假设的中间体与鸟苷反应生成8-氨基鸟苷、N1-氨基鸟苷和8-氧鸟苷,并且也与酪氨酸反应生成3-氨基酪氨酸和3-羟基酪氨酸。鸟苷在C8位置的氨基化和氧化也可以由乙酰苯氧基亚胺-O-磺酸和2-庚氧基亚胺-O-磺酸产生。这些结果为2-硝基丙烷和其他致癌二级硝基烷通过涉及亚胺和羟胺-O-磺酸作为中间体的途径产生能够氨基化核酸和蛋白的反应性物种提供了额外的证据。
Previously, the secondary nitroalkane 2-nitropropane, a strong hepatocarcinogen in rats, had been shown to induce the formation of 8-aminoguanine in both DNA and RNA of rat liver through a sulfotransferase-mediated pathway. This pathway was postulated to convert the carcinogen into an aminating species. To submit this postulate to further test, we examined liver proteins of rats treated with 2-nitropropane, other carcinogenic secondary nitroalkanes, or the related rat liver tumorigen acetoxime for the presence of 3-aminotyrosine, the expected product of tyrosine amination. Using ion-pair and/or cation-exchange high-performance liquid chromatography with electrochemical detection, we found that the liver cytosolic proteins of these animals contained 0.1-1.5 mol of 3-aminotyrosine/10(3) mol of tyrosine. Treatment with the noncarcinogenic primary nitroalkane 1-nitropropane or with other primary nitroalkanes did not produce an analogous increase in the aminated amino acid (level of detection estimated at approximately 0.01 mol/10(3) mol of tyrosine). ... In vitro studies with acetoxime-O-sulfonate and hydroxylamine-O-sulfonate showed that these proposed intermediates in the activation pathway of 2-nitropropane react with guanosine to give 8-aminoguanosine, N1-aminoguanosine, and 8-oxoguanosine and also react with tyrosine to give 3-aminotyrosine and 3-hydroxytyrosine. The in vitro amination and oxidation of guanosine at C8 were also produced by acetophenoxime-O-sulfonate and 2-heptanoxime-O-sulfonate. These results provide additional evidence for the production of a reactive species capable of aminating nucleic acids and proteins from 2-nitropropane and other carcinogenic secondary nitroalkanes by a pathway involving oxime- and hydroxylamine-O-sulfonates as intermediates.
来源:Hazardous Substances Data Bank (HSDB)