CHEMICAL TOXICOLOGY OF ISOCYANATES AND FORMAMIDES

拟议研究的中心目标是研究化学方面的 高活性高毒性试剂甲基异氰酸酯的毒理学研究 工业上用于制备氨基甲酸酯类杀虫剂，以及 其在印度博帕尔市的意外释放带来了 关于历史上最严重的工业悲剧。该项目还 目的是确定MIC和相关的亲电氨基甲酰化的作用 N-甲基甲酰胺所致肝损伤的介导物 实验性抗肿瘤药物(NMF)和N，N-二甲基甲酰胺(DMF)， 一种广泛使用的工业溶剂。有毒异氰酸酯的参与 三种抗肿瘤药物的生物学去向及其作用机制 毒品，即。1，3-二(2-氯乙基)-L-亚硝脲 NMF，也将接受调查，重点是他们的作用 谷胱甘肽(GSH)是一种活性氨基甲酰化试剂。具体的 该项目的目标如下： (A)表明在大鼠吸入MIC蒸气后， 谷胱甘肽偶联物S-(N-甲基氨基甲酰基)谷胱甘肽 在胆汁和相应的硫代尿酸中，S-(N-甲基氨基甲酰基) -N-乙酰半胱氨酸。(AMCC)，通过尿液排泄。(B)证明 SMG氨基甲酰化血清蛋白和建立的性质 生成的共价加合物。(C)建立机制基础，以便 合理开发MIC中毒解毒剂，探索MIC中毒解毒剂 N-乙酰半胱氨酸在这种用途上的用途。(D)阐明途径(S) NMF和DMF的代谢活化。(E)挑战已被接受的意见 DMF在α-碳原子上的代谢羟化反应代表着 这种化合物的解毒途径。(F)调查是否 卡拉塞米体内释放MIC，并建立MIC的来源 释放出异氰酸酯。(G)测定其体内抗肿瘤活性；以及 SMG、AMCC及相应半胱氨酸的体外致突变性 S-(N-甲基氨基甲酰基)半胱氨酸(SMC)。(H)评估能力 反应性异氰酸酯的GSH偶联物作为活性部位导向的 谷胱甘肽还原酶抑制剂。 提出了一系列全面的体外和体内实验。 它将使用大鼠和小鼠作为动物模型。对其结构的研究 感兴趣化合物及其共价化合物的极性代谢物 蛋白质的加合物，将基于最先进的使用 分析技术，包括电喷雾电离和高 性能串联质谱仪。总的来说，拟议的研究 将提供有关该物质化学毒理学的基本信息 异氰酸酯和甲酰胺，并将有助于我们理解 谷胱甘肽依赖过程在运输活性有毒化学物质中的作用 在活体内。

The central goal of the proposed research is to study chemical aspects of the toxicology of methylisocyanate (MIC), a highly reactive and toxic agent employed industrially in the preparation of carbamate pesticides, and the compound whose accidental release in the city of Bhopal, India, brought about the worst industrial tragedy recorded in history. The project also aims to define the role of MIC and related electrophilic carbamoylating species as mediators of the hepatic damage induced by N-methylformamide (NMF), an experimental antitumor agent, and N,N-dimethylformamide (DMF), a widely-used industrial solvent. The participation of toxic isocyanates in the biological fate and mechanism of action of three antineoplastic drugs, viz. 1,3-bis(2-chloroethyl)-l-nitrosourea (BCNU), caracemide and NMF, also will be investigated, with an emphasis on the role of their glutathione (GSH) conjugates as active carbamoylating agents. The specific aims of the project are as follows: (a) To show that, following inhalation exposure of rats to MIC vapor, the glutathione conjugate S-(N-methylcarbamoyl) glutathione (SMG) is present in bile and the corresponding mercapturic acid, S-(N-methylcarbamoyl) -N-acetylcysteine. (AMCC), is excreted in urine. (b) To demonstrate that SMG carbamoylates serum proteins and to establish the nature of the resulting covalent adducts. (c) To establish a mechanistic basis for the rational development of antidotes to MIC poisoning, and to explore the utility of N-acetylcysteine for such use. (d) To elucidate the pathway(s) of metabolic activation of NMF and DMF. (e) To challenge the accepted view that metabolic hydroxylation of DMF at the alpha-carbon atom represents a route of detoxification of this compound. (f) To investigate whether caracemide liberates MIC in vivo, and to establish the origin of the released isocyanate. (g) To determine the in vivo antitumor activity, and the in vitro mutagenicity, of SMG, AMCC and the corresponding cysteine conjugate, S-(N-methylcarbamoyl) cysteine (SMC). (h) To assess the ability of GSH conjugates of reactive isocyanates to serve as active site-directed inhibitors of glutathione reductase. A comprehensive series of in vitro and in vivo experiments is proposed which will employ rats and mice as animal models. Structure elucidation of polar metabolites of the compounds of interest, and of their covalent adducts to proteins, will be based on the use of state-of-the-art analytical techniques, including electrospray ionization and high performance tandem mass spectrometry. Collectively, the proposed studies will provide fundamental information on the chemical toxicology of isocyanates and formamides, and will contribute to our understanding of the role of GSH-dependent processes in the transport reactive, toxic chemicals in vivo.