COVALENT BINDING OF ACETAMINOPHEN TO MOUSE HEMOGLOBIN - IDENTIFICATION OF MAJOR AND MINOR ADDUCTS FORMED INVIVO AND IMPLICATIONS FOR THE NATURE OF THE ARYLATING METABOLITES
COVALENT BINDING OF ACETAMINOPHEN TO MOUSE HEMOGLOBIN - IDENTIFICATION OF MAJOR AND MINOR ADDUCTS FORMED INVIVO AND IMPLICATIONS FOR THE NATURE OF THE ARYLATING METABOLITES
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DOI：
10.1016/0009-2797(88)90009-9
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发表时间：
1988-01-01
影响因子：
5.1
通讯作者：
BAILLIE, TA
中科院分区：
文献类型：
--
作者：
AXWORTHY, DB;HOFFMANN, KJ;BAILLIE, TA
当向小鼠给予肝毒性剂量的[环U-14 C]对乙酰氨基酚[环U-14 C]APAP）时，放射性与血红蛋白以及肝脏和肾脏中的蛋白质不可逆地结合。与血红蛋白的共价结合呈剂量依赖性，在苯巴比妥预处理的小鼠中，与肝蛋白的共价结合约为相应结合的8%。通过酸水解降解修饰的珠蛋白产生3-半胱氨酸-S-基-4-羟基乙酰苯胺作为主要的放射性产物，占约70%的蛋白结合药物残留。这一发现与以下观点一致，即APAP与蛋白质的共价结合大多数是由N-乙酰基-对苯醌亚胺（NAPQI）介导的，NAPQI是一种反应性代谢产物，优先使半胱氨酰巯基残基芳基化。然而，在对小鼠施用[乙酰基-3H]APAP后，发现与血红蛋白结合的药物中有20%失去了N-乙酰基侧链，表明存在第二种类型的APAP-蛋白质加合物。珠蛋白水解产物的一个次要组分被鉴定为S-（2，5-二羟基苯基）-半胱氨酸，其最有可能是由NAPQI的水解产物对苯醌与血红蛋白结合而产生的。报道的两种加合物代表了第一个确定的芳基化药物结合血红蛋白的例子。不同的细胞色素P-450诱导剂对药物结合血红蛋白与肝蛋白的比例的影响的实验表明，APAP的反应性代谢产物在肝脏中形成并迁移到红细胞，而不是由血红蛋白催化氧化APAP产生。这些发现意味着APAP的反应性代谢产物以某些潜伏形式从肝细胞逃逸，然后参与红细胞中蛋白硫醇的芳基化，并可能在其他远程站点。
When hepatotoxic doses of [ring-U-14C]acetaminophen [ring-U-14C]APAP) were administered to mice, radioactivity became bound irreversibly to hemoglobin as well as to proteins in the live and kidney. The covalent binding to hemoglobin was dose-dependent, and in phenobarbital-pretreated mice occurred to the extent of approximately 8% of the corresponding binding to liver proteins. Degradation of the modified globin by acid hydrolysis yielded 3-cystein-S-yl-4-hydroxyacetanilide as the major radioactive product, accounting for .apprx. 70% of protein-bound drug residues. This finding is consistent with the view that the majority of covalent binding of APAP to proteins is mediated by N-acetyl-p-benzoquinone imine (NAPQI), a reactive metabolite which preferentially arylates cysteinyl thiol residues. However, after administration of [acetyl-3H]APAP to mice, it was found that .apprx. 20% of the drug bound to hemoglobin had lost the N-acetyl side-chain, indicating the existence of a second type of APAP-protein adduct. One minor component of the globin hydrolysate was identified as S-(2,5-dihydroxyphenyl)-cysteine, which most likely arises from binding to hemoglobin of p-benzoquinone, a hydrolysis product of NAPQI. The two adducts reported represent the first identified examples of arylating drugs binding to hemoglobin. Experiments on the influence of different cytochrome P-450 inducing agents on the ratio of drug bound to hemoglobin versus hepatic proteins suggested that the reactive metabolites of APAP are formed in the liver and migrate to the erythrocyte, rather than being produced by hemoglobin-catalyzed oxidation of APAP. These findings imply that the reactive metabolites of APAP escape from hepatocytes in some latent forms, which then participate in the arylation of protein thiols in red blood cells and, possibly, at other remote sites.