Stevens G J, Hitchcock K, Wang Y K, Coppola G M, Versace R W, Chin J A, Shapiro M, Suwanrumpha S, Mangold B L
Preclinical Safety Department, Novartis Pharmaceuticals Corporation, East Hanover, New Jersey 07936, USA.
Chem Res Toxicol. 1997 Jul;10(7):733-41. doi: 10.1021/tx9700230.
The in vitro metabolism of SDZ HDL 376, a thiocarbamide developed for the treatment of atherosclerosis, was investigated in rat, dog, monkey, and human liver microsomes, as well as in rat and human liver slices. [14C]SDZ HDL 376 was extensively metabolized in all the species except human. In rat liver microsomes an S-oxide was the major metabolite. In human and monkey microsomes, carbon hydroxylation was favored. The NADPH-dependent oxidation of SDZ HDL 376 resulted in covalent binding to microsomal protein. Addition of GSH to the incubations decreased protein binding in a concentration-dependent manner and resulted in a novel SDZ HDL 376-GSH adduct. Adduct formation required NADPH and was mediated predominantly by cytochrome P450. Inhibition of cytochrome P450 by 1-aminobenzotriazole resulted in a 95% decrease in adduct formation, while heat inactivation of flavin-containing monooxygenases resulted in a 10% decrease. Unlike other thiocarbamides which form disulfide adducts with GSH, the SDZ HDL 376 adduct contained a thioether linkage as characterized by LC/MS/MS and reference to a synthetic standard. Reactions performed with [35S]GSH resulted in a [35S]SDZ HDL 376-GSH adduct, demonstrating the sulfur was derived from GSH. Adduct formation was faster in rat microsomal reactions compared to human microsomes. Other structurally unrelated thiocarbamides (phenylthiourea, methimazole, 2-mercaptobenzimidazole, 2-mercaptoquinazoline, and 2-propyl-6-thiouracil) did not form similar adducts in rat liver microsomes supplemented with GSH. Therefore, the GSH adduct of SDZ HDL 376 is unique for this type of thiocarbamide. These results suggest that the bioactivation and detoxification of SDZ HDL 376 differ significantly from other thiocarbamides. Furthermore, the in vitro formation of S-oxides and GSH adducts in rat hepatic tissue, and ring hydroxylation and glucuronidation in human hepatic tissue, suggests rats may be more susceptible to the toxicity of SDZ HDL 376 compared to humans.
对一种开发用于治疗动脉粥样硬化的硫脲类药物SDZ HDL 376在大鼠、犬、猴和人肝微粒体以及大鼠和人肝切片中的体外代谢情况进行了研究。[14C]SDZ HDL 376在除人之外的所有物种中均被广泛代谢。在大鼠肝微粒体中，一种S-氧化物是主要代谢产物。在人和猴的微粒体中，碳羟基化更易发生。SDZ HDL 376的NADPH依赖性氧化导致其与微粒体蛋白共价结合。在孵育体系中添加谷胱甘肽（GSH）会以浓度依赖的方式降低蛋白结合，并产生一种新的SDZ HDL 376-GSH加合物。加合物的形成需要NADPH，且主要由细胞色素P450介导。1-氨基苯并三唑对细胞色素P450的抑制导致加合物形成减少95%，而含黄素单加氧酶的热失活导致加合物形成减少10%。与其他与GSH形成二硫键加合物的硫脲类药物不同，通过液相色谱/串联质谱（LC/MS/MS）并参照合成标准物鉴定，SDZ HDL 376加合物含有硫醚键。用[35S]GSH进行的反应产生了一种[35S]SDZ HDL 376-GSH加合物，表明硫源自GSH。与人类微粒体反应相比，大鼠微粒体反应中的加合物形成更快。其他结构不相关的硫脲类药物（苯基硫脲、甲巯咪唑、2-巯基苯并咪唑、2-巯基喹唑啉和2-丙基-6-硫脲嘧啶）在添加GSH的大鼠肝微粒体中未形成类似加合物。因此，SDZ HDL 376的GSH加合物对于这类硫脲类药物而言是独特的。这些结果表明，SDZ HDL 376的生物活化和解毒过程与其他硫脲类药物有显著差异。此外，大鼠肝组织中S-氧化物和GSH加合物的体外形成，以及人肝组织中环羟基化和葡萄糖醛酸化的情况表明，与人类相比，大鼠可能对SDZ HDL 376的毒性更敏感。
