Hamdoune M, Duclos S, Mounie J, Santona L, Lhuguenot J C, Magdalou J, Goudonnet H
Formation de Biochimie Pharmacologique, UFR de Pharmacie, Dijon, France.
Toxicol Appl Pharmacol. 1995 Apr;131(2):235-43. doi: 10.1006/taap.1995.1066.
In order to investigate the glucuronidation of 2-ethylhexanoic acid (2-EHA), a metabolite of the plasticizer di-(2-ethylhexyl) adipate, by liver microsomes of several mammalian species including man, a gas chromatography method for the quantification of the corresponding glucuronides was developed. The variation coefficients for intra- and interassay repeatability were less than 3 and 7%, respectively. The rat liver UDP-glucuronosyl-transferase (UGT) presented similar Km and Vmax toward the two enantiomers. The glucuronidation of the racemate 2-EHA or its enantiomers was strongly increased up to six times by treatment of the rats with phenobarbital and, to a lesser extent, by 3-methylcholanthrene. In contrast, the treatment of the rats clofibrate did not modify the activity. The induction was not stereoselective. The Gunn rats, which present a genetic defect in the bilirubin UGT isoforms, were able to glucuronidate the drug as well as the congenic strain. Moreover, the UGT-2B1 isoform, stably expressed in V79 cells, glucuronidated 2-EHA in an appreciable amount. Interspecies comparison indicated that the most active glucuronidation of 2-EHA occurred in the dog and the rat. The lowest activities were observed in the man and the rabbit. In all species considered, except rabbit and guinea pig which glucuronidated the R isomer faster, the R and S enantiomers were glucuronidated to a similar extent. The glucuronidation activity toward compounds chemically related to 2-EHA increased as a function of molecular weight, but was not affected by the position of the methyl or the ethyl moiety on the hydrocarbon chain. A correlation between the glucuronidation rate of 2-EHA and analogs and the activity of PCoA oxidase was observed.
为了研究增塑剂己二酸二（2-乙基己基）酯的代谢产物2-乙基己酸（2-EHA）在包括人类在内的几种哺乳动物肝脏微粒体中的葡萄糖醛酸化作用，开发了一种用于定量相应葡萄糖醛酸苷的气相色谱法。批内和批间重复性的变异系数分别小于3%和7%。大鼠肝脏UDP-葡萄糖醛酸基转移酶（UGT）对两种对映体表现出相似的Km和Vmax。用苯巴比妥处理大鼠后，外消旋体2-EHA或其对映体的葡萄糖醛酸化作用强烈增加至六倍，3-甲基胆蒽处理的增加程度较小。相比之下，用氯贝丁酯处理大鼠并没有改变其活性。诱导作用没有立体选择性。患有胆红素UGT同工型遗传缺陷的冈恩大鼠能够像同基因品系一样对药物进行葡萄糖醛酸化。此外，在V79细胞中稳定表达的UGT-2B1同工型能够大量地对2-EHA进行葡萄糖醛酸化。种间比较表明，2-EHA的葡萄糖醛酸化活性在犬和大鼠中最高。在人类和兔子中观察到的活性最低。在所有考虑的物种中，除了兔子和豚鼠对R异构体的葡萄糖醛酸化更快外，R和S对映体的葡萄糖醛酸化程度相似。对与2-EHA化学相关的化合物的葡萄糖醛酸化活性随着分子量的增加而增加，但不受甲基或乙基部分在烃链上位置的影响。观察到2-EHA及其类似物的葡萄糖醛酸化速率与PCoA氧化酶活性之间存在相关性。
