PT  - JOURNAL ARTICLE
AU  - Randy M. Wadkins
AU  - Janice L. Hyatt
AU  - Carol C. Edwards
AU  - Lyudmila Tsurkan
AU  - Matthew R. Redinbo
AU  - Craig E. Wheelock
AU  - Paul D. Jones
AU  - Bruce D. Hammock
AU  - Philip M. Potter
TI  - Analysis of Mammalian Carboxylesterase Inhibition by Trifluoromethylketone-Containing Compounds
AID  - 10.1124/mol.105.021683
DP  - 2007 Mar 01
TA  - Molecular Pharmacology
PG  - 713--723
VI  - 71
IP  - 3
4099  - http://molpharm.aspetjournals.org/content/71/3/713.short
4100  - http://molpharm.aspetjournals.org/content/71/3/713.full
SO  - Mol Pharmacol2007 Mar 01; 71
AB  - 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 Ki 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 (r2 ranging from 0.908–0.948), with cross-correlation coefficients (q2) 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. The American Society for Pharmacology and Experimental Therapeutics