Abstract：
The veterinary drug nitrofurazone (5-nitro-2-furaldehyde semicarbazone) exhibits excellent antimicrobial properties but its application in food-producing animals is prohibited. The illegal use of nitrofurazone is regularly monitored by food regulatory agencies. Currently, semicarbazide (SEM) is used as a marker of nitrofurazone exposure. However, the use of SEM as a marker of nitrofurazone is under scrutiny after evidence of a high incidence of false positive tests. To overcome the current dilemma, it is necessary to identify a nitrofurazone-specific marker analyte which requires conducting nitrofurazone metabolism studies in food-producing animals. The use of carbon-14 labeled nitrofurazone would facilitate metabolism studies and structural elucidation of nitrofurazone metabolites of possible utility as a marker compound. In the present work, a synthetic method is described to procure radiolabeled nitrofurazone that incorporates 14 C- carbon at the semicarbazide moiety. The method incorporates 14 C-carbon via employing readily available and more economically affordable [14 C]-urea compared with [14 C]-semicarbazide. To the best of our knowledge, there is no report on the synthesis of 5-nitro-2-furaldehyde [14 C]-semicarbazone from 14 C-urea. The developed method involves monoamination of [14 C]-urea followed by a condensation reaction with 5-nitro-2-furaldehyde to produce 5-nitro-2-furaldehyde [14 C]-semicarbazone in 85% yield with greater than 98% radiochemical purity.
摘要：
兽药硝基呋喃嗪（5-硝基-2-糠醛氨基脲）具有出色的抗菌性能，但禁止在食品生产动物中应用。食品监管机构定期监测呋喃西林的非法使用。目前,氨基脲（SEM）用作硝基呋喃酮暴露的标记。然而,在有证据表明假阳性试验发生率很高之后，使用SEM作为呋喃嗪的标志物正在接受审查。为了克服当前的困境，有必要鉴定硝基呋喃酮特异性标记分析物，这需要在食品生产动物中进行硝基呋喃酮代谢研究。使用碳-14标记的硝基呋喃酮将促进可能用作标记化合物的硝基呋喃酮代谢物的代谢研究和结构阐明。在目前的工作中,描述了一种合成方法，以获得在氨基脲部分掺入14个C-碳的放射性标记的硝基呋喃酮。与[14C]-氨基脲相比，该方法通过使用容易获得且经济上更实惠的[14C]-脲来掺入14C-碳。据我们所知,没有关于从14C-脲合成5-硝基-2-呋喃醛[14C]-氨基脲的报道。所开发的方法涉及[14C]-脲的单胺化，然后与5-硝基-2-糠醛缩合反应，以85％的收率生产5-硝基-2-糠醛[14C]-氨基脲，放射化学纯度大于98％。
