Selective Carboxylesterase Inhibitors Research Articles

Synthesis of new efficient and selective carboxylesterase inhibitors based on adamantyl and citronellyl 4,4,4-trifluoro-2-arylhydrazonylidene-3-oxobutanoates

A series of new adamantyl and citronellyl 4,4,4-trifluoro-2-arylhydrazinylidene-3-oxo-butanoates was synthesized. The synthesized compounds in nanomolar concentrations selectively inhibit carboxylesterase, while their activity is independent of the nature and position of the substituent in the aryl fragment, which is consistent with the molecular docking results.

Synthesis of 2-arylhydrazinylidene-3-oxo-4,4,4-trifluorobutanoic acids as new selective carboxylesterase inhibitors and radical scavengers.

A series of 2-arylhydrazinylidene-3-oxo-4,4,4-trifluorobutanoic acids was synthesized via dealkylation of ethyl 2-arylhydrazinylidene-3-oxo-4,4,4-trifluorobutanoates under the action of a Lewis acid. Under the same conditions, ethyl 2-arylhydrazinylidene-3-oxobutanoates were also found to undergo dealkylation rather than the previously described cyclization into cinnolones. Study of the esterase profile of these compounds showed that trifluoromethyl-containing acids, in contrast to non-fluorinated analogs, were effective and selective inhibitors of carboxylesterase (CES), without substantially inhibiting structurally related cholinesterases (acetylcholinesterase and butyrylcholinesterase). Moreover, both 3-oxo-4,4,4-trifluorobutanoic and 3-oxobutanoic acids having methyl or methoxy substituent in the arylhydrazinylidene fragment showed high antioxidant activity in the ABTS test. Thus, 2-arylhydrazinylidene-3-oxo-4,4,4-trifluorobutanoic acids were found to constitute a new class of effective and selective CES inhibitors that also possess high radical-scavenging activity.

Synthesis, molecular docking, and biological evaluation of 3-oxo-2-tolylhydrazinylidene-4,4,4-trifluorobutanoates bearing higher and natural alcohol moieties as new selective carboxylesterase inhibitors

To search for effective and selective inhibitors of carboxylesterase (CES), a series of 3-oxo-2-tolylhydrazinylidene-4,4,4-trifluorobutanoates bearing higher or natural alcohol moieties was synthesized via pre-transesterification of ethyl trifluoroacetylacetate with alcohols to isolate transesterificated oxoesters as lithium salts, which were then subjected to azo coupling with tolyldiazonium chloride. Inhibitory activity against porcine liver CES, along with two structurally related serine hydrolases, acetylcholinesterase and butyrylcholinesterase, were investigated using enzyme kinetics and molecular docking. Kinetics studies demonstrated that the tested keto-esters are reversible and selective mixed-type CES inhibitors. Analysis of X-ray crystallographic data together with our IR and NMR spectra and QM calculations indicated that the Z-isomers were the most stable. The kinetic data were well explained by the molecular docking results of the Z-isomers, which showed specific binding of the compounds in the CES catalytic active site with carbonyl oxygen atoms in the oxyanion hole and non-specific binding outside it. Some compounds were studied as inhibitors of the main human isozymes involved in biotransformation of ester-containing drugs, hCES1 and hCES2. Esters of geraniol (3d) and adamantol (3e) proved to be highly active and selective inhibitors of hCES2, inhibiting the enzyme in the nanomolar range, whereas esters of borneol (3f) and isoborneol (3g) were more active and selective against hCES1. Computational ADMET studies revealed that all test compounds had excellent intestinal absorption, medium blood-brain barrier permeability, and low hERG liability risks. Moreover, all test compounds possessed radical-scavenging properties and low acute toxicity. Overall, the results indicate that members of this novel series of esters have the potential to be good candidates as hCES1 or hCES2 inhibitors for biomedicinal applications.

Phosphorylated flavonoids as selective carboxylesterase inhibitors

A series of phosphorylated flavonoids has been synthesized and evaluated in vitro for inhibitory activity against carboxylesterase, acetylcholinesterase and butyrylcholinesterase as well as for their cytotoxicity towards human adenocarcinoma A549 and human glioblastoma U251 cell lines. Diethylphosphoryl derivatives of chrysin and 7-hydroxyflavone were found to be the most effective with bimolecular rate constants for carboxylesterase inhibition ki = 2.0 × 106 and 5.7 × 106 dm3 mol−1 min−1, respectively.

Carboxylesterase Inhibitors: An Update.

Mammalian carboxylesterases are key serine hydrolases that catalyze the hydrolysis of a wide variety of ester compounds in the corresponding carboxylic acids and alcohols. In human, two major carboxylesterases, CES1 and CES2, have been identified and well-studied over the past decade. CES1 inhibitors have potential applications in the treatment of hypertriglyceridaemia, obesity and type 2 diabetes, owing to that this enzyme plays prominent role in the metabolism of cholesteryl esters. CES2 plays crucial roles in the metabolic activation of many prodrugs including anticancer agents capecitabine and CPT-11. Co-administration with CES2 inhibitors may ameliorate CPT-11 associated lifethreatening diarrhea or improve the half-lives of CES2-substrate drugs. The important roles of carboxylesterases in both endogenous and xenobiotic metabolism arouse great interest in the discovery and development of potent and selective inhibitors against these enzymes. This review is focused on the application potentials and recent advances in the discovery and development of carboxylesterases inhibitors. The inhibitory capacities and inhibition mechanism of a variety of carboxylesterases inhibitors including synthetic, semi-synthetic and natural compounds are comprehensively summarized. Furthermore, the key structural features and structure-activity relationships (SARs) of different classes of CES1 and CES2 inhibitors are discussed. All information and knowledge summarized in this review will be very helpful for the medicinal chemists to design and develop more potent and highly selective carboxylesterases inhibitors for potential biomedical applications.

Selective Carboxylesterase Inhibitors for Improving Efficacy, Safety and Rational use of Ester-Containing Drugs

In clinical practice, a large number of prodrugs and active drugs containing an ester, carbamate or amide moiety are used. Carboxylesterase (CaE, EC 3.1.1.1) is the key enzyme of hydrolytic metabolism of such drugs in the body, it largely determines their pharmacokinetics, bioavailability, efficacy and possible toxic effects. Using CaE selective inhibitors as components of combined drug therapy it is possible us to regulate the rate of hydrolytic transformation of ester-containing drugs and opens the possibility of their rational use. The development of effective and selective CaE inhibitors suitable for in vivo application is a new promising approach in medicinal chemistry and pharmacology that allows to improve the efficacy, bioavailability and reduce the side effects of ester-containing drugs.

Synthesis, molecular docking, and biological activity of polyfluoroalkyl dihydroazolo[5,1-c][1,2,4]triazines as selective carboxylesterase inhibitors

To search for effective and selective inhibitors of carboxylesterase (CaE), a series of 7-hydroxy-7-polyfluoroalkyl-4,7-dihydroazolo[5,1-c][1,2,4]triazines has been synthesized. Their inhibitory activity against acetylcholinesterase, butyrylcholinesterase, and CaE were investigated using the methods of enzyme kinetics and molecular docking. It was shown that the tested compounds are reversible selective CaE inhibitors of mixed type. Elongation of the polyfluoroalkyl substituent and the presence of an ester, preferably the ethoxycarbonyl group, enhance inhibitory activity toward CaE. Furthermore, the compounds with a tetrazole ring are more active against CaE than their triazole analogues. The obtained kinetic data are well explained by the results of molecular docking, according to which there is a similar orientation of triazolo- and tetrazolotriazines in the active site of CaE and the opposite one for pyrazolotriazines. In the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assay, all of the studied tetrazolotriazines and some pyrazolotriazines demonstrated good antiradical activity comparable with a standard antioxidant, Trolox. The leading compounds were nonafluorobutyl substituted tetrazolo- and 7-phenylpyrazolotriazines, which possess effective and selective CaE inhibitory activity as well as additional useful radical-scavenging properties.

Molecular design of N,N-disubstituted 2-aminothiazolines as selective carboxylesterase inhibitors

Selective carboxylesterase inhibitors are employed as modulators of hydrolytic metabolism of ester or amide-containing drugs. Using the Molecular Field Topology Analysis (MFTA), the models for the relationships between the structures and inhibitory activities of 5-halomethyl-2-aminothiazolines against acetylcholinesterase, butyrylcholinesterase, and carboxylesterase were built, the molecular design was performed, and a focused library of potentially active and selective carboxylesterase inhibitors was proposed.

Analysis of Mammalian Carboxylesterase Inhibition by Trifluoromethylketone-Containing Compounds

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 approximately 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.