OXIDATIVE ACTIVATION OF THE THIOPHENE RING BY HEPATIC-ENZYMES - HYDROXYLATION AND FORMATION OF ELECTROPHILIC METABOLITES DURING METABOLISM OF TIENILIC ACID AND ITS ISOMER BY RAT-LIVER MICROSOMES
OXIDATIVE ACTIVATION OF THE THIOPHENE RING BY HEPATIC-ENZYMES - HYDROXYLATION AND FORMATION OF ELECTROPHILIC METABOLITES DURING METABOLISM OF TIENILIC ACID AND ITS ISOMER BY RAT-LIVER MICROSOMES
复制标题
DOI：
10.1016/0006-2952(90)90207-2
复制
发表时间：
1990-03-01
影响因子：
5.8
通讯作者：
MANSUY, D
中科院分区：
文献类型：
--
作者：
DANSETTE, PM;AMAR, C;MANSUY, D
苯巴比妥处理的大鼠肝微粒体在NADPH存在下代谢替尼酸（TA），主要形成5-羟基替尼酸（5-OHTA），其来源于TA噻吩环的区域选择性羟基化。在TA的体外代谢过程中，形成了与微粒体蛋白不可逆结合的反应性亲电中间体，TA的5-羟基化和TA活化为与蛋白共价结合的反应性代谢物都需要完整的微粒体、NADPH和O2，并被甲吡酮和SKF 525 A抑制，表明它们依赖于使用细胞色素P-450的单加氧酶。噻吩环3位（而非2位）上带有芳酰基取代基的噻吩酸（TAI）异构体的微粒体氧化也导致能够共价结合微粒体蛋白的反应性中间体。TAI的共价结合与TA的共价结合一样，依赖于细胞色素P-450依赖性单加氧酶，并且在含硫亲核试剂（如谷胱甘肽、半胱氨酸或半胱胺）存在下几乎完全被抑制。这些结果表明，5-OHTA（已报告为TA在人体内的主要代谢产物）通过细胞色素P-450依赖性反应由肝微粒体形成。他们还表明，两种噻吩衍生物TA和TAI在体外代谢物活化后与微粒体蛋白结合，TAI产生比TA高得多的共价结合水平（约高5倍）和高得多的共价结合：稳定代谢物比率（4而不是0.5）。
Tienilic acid (TA) is metabolized by liver microsomes from phenobarbital-treated rats in the presence of NADPH with the major formation of 5-hydroxytienilic acid (5-OHTA) which is derived from the regioselective hydroxylation of the thiophene ring of TA. During this in vitro metabolism of TA, reactive electrophilic intermediates which bind irreversibly to microsomal proteins are formed, 5-Hydroxylation of TA and activation of TA to reactive metabolites which covalently bind to proteins both required intact microsomes, NADPH and O2 and are inhibited by metyrapone and SKF 525A, indicating that they are dependent on a monooxygenases using cytochromes P-450. Microsomal oxidation of an isomer of tienilic acid (TAI) bearing the aroyl substitutent on position 3 (instead of 2) of the thiophene ring also leads to reactive intermediates able to bind covalently to microsomal proteins. Covalent binding of TAI, as that of TA, depends on cytochrome P-450-dependent monooxygenase and is almost completely inhibited in the presence of sulfur containing nucleophiles such as glutathione, cysteine or cyteamine. These results show that 5-OHTA, which has been reported as the major metabolite of TA in vivo in humans, is formed by liver microsomes by a cytochrome P-450-dependent reaction. They also show that two thiophene derivatives, TA and TAI , bind to microsomal proteins after in vitro metabolite activation, TAI giving a much higher level of covalent binding than TA (about 5-fold higher) and a much higher covalent binding: stable metabolites ratio (4 instead of 0.5).