Analysis of Mammalian Carboxylesterase Inhibition by Trifluoromethylketone-Containing Compounds
作者:Randy M. Wadkins、Janice L. Hyatt、Carol C. Edwards、Lyudmila Tsurkan、Matthew R. Redinbo、Craig E. Wheelock、Paul D. Jones、Bruce D. Hammock、Philip M. Potter
DOI:10.1124/mol.105.021683
日期:2007.3
Carboxylesterases (CE) are ubiquitous enzymes that hydrolyze numerous ester-containing xenobiotics, including complex molecules, such as the anticancer drugs irinotecan (CPT-11) and capecitabine and the pyrethroid insecticides. Because of the role of CEs in the metabolism of many exogenous and endogenous ester-containing compounds, a number of studies have examined the inhibition of this class of enzymes. Trifluoromethylketone-containing (TFK) compounds have been identified as potent CE inhibitors. In this article, we present inhibition constants for 21 compounds, including a series of sulfanyl, sulfinyl, and sulfonyl TFKs with three mammalian CEs, as well as human acetyl- and butyrylcholinesterase. To examine the nature of the slow tight-binding inhibitor/enzyme interaction, assays were performed using either a 5-min or a 24-h preincubation period. Results showed that the length of the preincubation interval significantly affects the inhibition constants on a structurally dependent basis. The TFK-containing compounds were generally potent inhibitors of mammalian CEs, with K i values as low as 0.3 nM observed. In most cases, thioether-containing compounds were more potent inhibitors then their sulfinyl or sulfonyl analogs. QSAR analyses demonstrated excellent observed versus predicted values correlations ( r 2 ranging from 0.908–0.948), with cross-correlation coefficients ( q 2) of ∼0.9. In addition, pseudoreceptor models for the TKF analogs were very similar to structures and models previously obtained using benzil- or sulfonamide-based CE inhibitors. These studies indicate that more potent, selective CE inhibitors, containing long alkyl or aromatic groups attached to the thioether chemotype in TFKs, can be developed for use in in vivo enzyme inhibition.
羧酸酯酶(CE)是一种普遍存在的酶,可水解多种含酯的异生物,包括抗癌药物伊立替康(CPT-11)和卡培他滨以及拟除虫菊酯类杀虫剂等复杂分子。由于CE在许多外源性和内源性酯类化合物的新陈代谢中发挥着重要作用,因此许多研究都关注这类酶的抑制作用。含三氟甲基酮(TFK)的化合物已被确定为有效的CE抑制剂。本文中,我们给出了21种化合物的抑制常数,包括一系列硫醚、亚磺酰和磺酰TFK,以及哺乳动物CE和人类乙酰胆碱酯酶和丁酰胆碱酯酶。为了研究缓慢紧密结合抑制剂/酶相互作用的性质,我们进行了5分钟或24小时预孵育期的测定。结果表明,预孵育时间的长短在结构上显著影响抑制常数。含TFK的化合物通常是哺乳动物CE的有效抑制剂,观察到的Ki值低至0.3 nM。在大多数情况下,含硫醚的化合物比它们的亚磺酰或磺酰类似物更有效。QSAR分析表明,观察值与预测值之间存在极好的相关性(r2从0.908到0.948不等),交叉相关系数(q2)约为0.9。此外,TFK类似物的伪受