Rashed M S, Nelson S D
Department of Medicinal Chemistry, University of Washington, Seattle 98195.
Chem Res Toxicol. 1989 Jan-Feb;2(1):41-5. doi: 10.1021/tx00007a007.
3'-Hydroxyacetanilide (AMAP) is a nonhepatotoxic regioisomer of acetaminophen (APAP) that nonetheless does form reactive metabolites which bind to hepatic proteins. Because differences in the nature of reactive metabolites formed from AMAP and APAP may explain differences in their propensity to cause hepatotoxicity, characterization of the reactive metabolites of AMAP was undertaken. The naturally occurring sulfhydryl-containing tripeptide glutathione (GSH) was used to trap the reactive metabolites. Four mono-GSH conjugates and one di-GSH conjugate of oxidative AMAP metabolites were characterized by 1H NMR and soft ionization (LSIMS or FAB) mass spectral techniques, as well as by comparison of liquid chromatographic and spectral characteristics with synthetic standards. Two isomeric mono-GSH conjugates of 2-acetamidohydroquinone (2-AcHQ) are formed as well as a bis-GSH conjugate. A mono-GSH conjugate of 3',4'-dihydroxyacetanilide (3-OH-APAP) also was formed. Thus, these GSH conjugates most likely arise by reaction of GSH with 2-acetamido-p-benzoquinone (2-APBQ) and 4-acetamido-o-benzoquinone (4-AOBQ), respectively, as oxidation products of the known AMAP metabolites 2-AcHQ and 3-OH-APAP. Finally, a GSH conjugate of 3'-methoxy-4'-hydroxy-acetanilide (3-OMe-APAP) was detected in bile of mice administered AMAP. This conjugate probably arises by oxidation of 3-OMe-APAP, another known metabolite of AMAP. The presumed oxidation product, N-acetyl-3-methoxy-p-benzoquinone imine (MAPQI), was synthesized and found to react with GSH to give the same GSH conjugate as that detected in bile and in incubations of 3-OMe-APAP with mouse liver microsomes plus GSH.(ABSTRACT TRUNCATED AT 250 WORDS)
3'-羟基乙酰苯胺（AMAP）是对乙酰氨基酚（APAP）的一种无肝毒性的区域异构体，但其确实会形成与肝脏蛋白质结合的反应性代谢产物。由于AMAP和APAP形成的反应性代谢产物性质不同，可能解释了它们导致肝毒性倾向的差异，因此对AMAP的反应性代谢产物进行了表征。天然存在的含巯基三肽谷胱甘肽（GSH）被用于捕获反应性代谢产物。通过1H NMR和软电离（LSIMS或FAB）质谱技术，以及将液相色谱和光谱特征与合成标准品进行比较，对氧化型AMAP代谢产物的四种单GSH缀合物和一种双GSH缀合物进行了表征。形成了两种2-乙酰氨基对苯二酚（2-AcHQ）的异构体单GSH缀合物以及一种双GSH缀合物。还形成了3',4'-二羟基乙酰苯胺（3-OH-APAP）的单GSH缀合物。因此，这些GSH缀合物很可能分别是由GSH与已知AMAP代谢产物2-AcHQ和3-OH-APAP的氧化产物2-乙酰氨基对苯醌（2-APBQ）和4-乙酰氨基邻苯醌（4-AOBQ）反应形成的。最后，在给予AMAP的小鼠胆汁中检测到了3'-甲氧基-4'-羟基乙酰苯胺（3-OMe-APAP）的GSH缀合物。这种缀合物可能是由AMAP的另一种已知代谢产物3-OMe-APAP氧化形成的。合成了推测的氧化产物N-乙酰-3-甲氧基对苯醌亚胺（MAPQI），发现其与GSH反应生成的GSH缀合物与在胆汁中以及3-OMe-APAP与小鼠肝微粒体加GSH孵育时检测到的相同。（摘要截断于250字）
