In Vitro Bioactivation of a Selective Estrogen Receptor Modulator (2S,3R)-(+)-3-(3-Hydroxyphenyl)-2-[4-(2-pyrrolidin-1-ylethoxy)phenyl]-2,3-dihydro-1,4-benzoxathiin-6-ol (I) in Liver Microsomes: Formation of Adenine Adducts
In Vitro Bioactivation of a Selective Estrogen Receptor Modulator (2S,3R)-(+)-3-(3-Hydroxyphenyl)-2-[4-(2-pyrrolidin-1-ylethoxy)phenyl]-2,3-dihydro-1,4-benzoxathiin-6-ol (I) in Liver Microsomes: Formation of Adenine Adducts
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DOI：
10.1021/tx3002466
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发表时间：
2012-11-01
影响因子：
4.1
通讯作者：
Zhang, Zhoupeng
中科院分区：
文献类型：
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作者：
Li, Ying;Doss, George A.;Zhang, Zhoupeng
作为我们开发更安全的选择性雌激素受体调节剂（SERMs）的一部分，化合物I {(2S,3R)-(+)-3-（3-羟基苯基）-2-[4-（2-吡咯烷-1-基乙氧基）-苯基]-2,3-二氢-1,4-苯并恶星-6-醇}先前被确定为进一步开发的先导化合物。随后的研究表明，化合物I对中国仓鼠卵巢（CHO）细胞和小鼠体内均具有遗传毒性。为了更好地了解所观察到的遗传毒性效应的可能机制，我们在腺嘌呤存在的情况下，将I与人、猴和小鼠的肝微粒体进行体外培养，结果检测到5种腺嘌呤加合物。这些加合物的形成是nadph依赖的，表明参与了细胞色素P450酶催化的氧化生物活化。主要腺嘌呤加合物（A1）的形成机制涉及反应性开环对苯二酚中间体的形成。另外四种腺嘌呤加合物的形成可能涉及活性环氧化物或对醌中间体的形成。此外，化合物I与人肝细胞孵育显示剂量依赖性DNA损伤在彗星测定。综上所述，化合物I通过生物活化机制形成的一些活性代谢物，在体内和体外都有可能与DNA分子发生相互作用。这可能是在体外和体内观察到的临床前遗传毒性的原因之一。本案例研究展示了一种利用体外DNA捕获法评估候选药物遗传毒性潜力的方法。
As part of our efforts to develop safer selective estrogen receptor modulators (SERMs), compound I {(2S,3R)-(+)-3-(3-hydroxyphenyl)-2-[4-(2-pyrrolidin-1-ylethoxy)-phenyl]-2,3-dihydro-1,4-benzoxathiin-6-ol} was previously identified as a lead for further development. Subsequent studies showed that compound I is genotoxic in both in vitro Chinese hamster ovary (CHO) cells and in vivo mouse studies. To better understand the possible mechanisms for the observed genetoxicity effects, in vitro incubations of I with liver microsomes of human, monkey, and mouse in the presence of adenine were performed, which led to the detection of five adenine adducts. The formation of these adducts was NADPH-dependent, suggesting the involvement of oxidative bioactivation catalyzed by cytochrome P450 enzymes. The mechanism for the formation of the major adenine adduct (A1) involves the formation of a reactive ring-opened para-quinone intermediate. The formation of four other adenine adducts may involve the formation of a reactive epoxide or ortho-quinone intermediate. Furthermore, incubations of compound I with human hepatocytes showed dose-dependent DNA damages in Comet assays. All of the above suggest that some reactive metabolites of compound I, formed through bioactivation mechanisms, have a potential to interact with DNA molecules in vitro and in vivo. This may be one of the causes of the genotoxicity observed preclinically both in vitro and in vivo. This case study demonstrated an approach using in vitro DNA trapping assays for assessing the genotoxicity potential of drug candidates.