Substrate selectivity of human cytochrome P450 2C9: importance of residues 476, 365, and 114 in recognition of diclofenac and sulfaphenazole and in mechanism-based inactivation by tienilic acid

Melet, Armelle; Assrir, Nadine; Jean, P.; López-García, M. Pilar; Marques-Soares, Cristina; Jaouen, Maryse; Dansette, Patrick M.; Sari, Marie-Agnès; Mansuy, Daniel

doi:10.1016/s0003-9861(02)00548-9

Cited by 100 publications

(97 citation statements)

References 59 publications

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“…Studies with sulfaphenazole, a well known competitive inhibitor of CYP2C9, and a high affinity substrate of CYP2C9 exhibited a K i value of 0.3 M and IC 50 of 0.6 M (Mancy et al, 1996;Ha-Duong et al, 2001a;Melet et al, 2003). The IC 50 value (0.84 M) we obtained for the inhibition of thioether sulfoxidation of disulfoton by sulfaphenazole indicates that these thioether substrates are competing for the same catalytic site as other high affinity CYP2C9 substrates.…”

Section: In Vitro Thioether Sulfoxidation In Humansmentioning

confidence: 66%

“…Considerable interest has recently been focused on CYP2C subfamily members not only because of their involvement in the oxidation of a number of clinically used drugs but also due to the discovery of numerous polymorphic forms and substrate recognition sites within these isoforms. Molecular modeling techniques have also been employed to derive predictive models for CYP2C substrates, particularly CYP2C9 (Mancy et al, 1995;Mancy et al, 1996;Poli-Scaife et al, 1997;Ha-Duong et al, 2001b;Melet et al, 2003). The thioether compounds used in the present study were not previously known as CYP2C substrates and do not fit well within the previous predictive models for CYP2C isoform substrates.…”

Section: Ethyl] Phosphorodithioate) and Sulprofos (O-ethyl O-[4-(metmentioning

confidence: 99%

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In Vitro Sulfoxidation of Thioether Compounds by Human Cytochrome P450 and Flavin-Containing Monooxygenase Isoforms With Particular Reference to the Cyp2c Subfamily

Usmani

Karoly²,

Hodgson³

et al. 2004

Drug Metab Dispos

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This article is available online at http://dmd.aspetjournals.org ABSTRACT:Cytochrome P450 (P450) and flavin-containing monooxygenase (FMO) enzymes are major catalysts involved in the metabolism of xenobiotics. The sulfoxidation of the thioether pesticides, phorate, disulfoton, sulprofos, and methiocarb, was investigated. Using pooled human liver microsomes (HLMs), thioether compounds displayed similar affinities; however, phorate and disulfoton displayed higher intrinsic clearance rates than either sulprofos or methiocarb. The sulfoxidation of thioethers by HLMs was found to be predominantly P450-driven (85-90%) compared with FMO (10-15%). Among 16 cDNA-expressed human P450 isoforms and 3 human FMO isoforms examined, the following isoforms and their polymorphisms had the highest rates for sulfoxidation, as follows: phorate, CYP1A2, 3A4, 2B6, 2C9*1, 2C18, 2C19, 2D6*1, and FMO1; disulfoton, CYP1A2, 3A4, 2B6, 2C9*1, 2C9*2, 2C18, 2C19, 2D6*1, and FMO1; sulprofos, CYP1A1, 1A2, 3A4, 2C9*1, 2C9*2, 2C9*3, 2C18, 2C19, 2D6*1, and FMO1; methiocarb, CYP1A1, 1A2, 3A4, 2B6, 2C9*1, 2C19, 2D6*1, and FMO1. Among these isoforms, members of the CYP2C subfamily often had the highest affinities and clearance rates. Moreover, sulfaphenazole, a CYP2C9 competitive inhibitor, inhibited disulfoton sulfoxidation by CYP2C9 (IC 50 0.84 M) as well as in HLMs. Ticlopidine, a CYP2C19 mechanism-based inhibitor, inhibited disulfoton sulfoxidation by CYP2C19 (IC 50 after coincubation, 43.5 M; IC 50 after preincubation, 4.3 M) and also in HLMs. Our results indicate that current models of the substrate binding site of the CYP2C subfamily would not effectively predict thioether pesticide metabolism. Thus, the substrate specificity of CYP2Cs is more extensive than is currently believed, and some reevaluation of structure-activity relationships may be required.

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Section: In Vitro Thioether Sulfoxidation In Humansmentioning

confidence: 66%

Section: Ethyl] Phosphorodithioate) and Sulprofos (O-ethyl O-[4-(metmentioning

confidence: 99%

In Vitro Sulfoxidation of Thioether Compounds by Human Cytochrome P450 and Flavin-Containing Monooxygenase Isoforms With Particular Reference to the Cyp2c Subfamily

Usmani

Karoly²,

Hodgson³

et al. 2004

Drug Metab Dispos

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“…With the exception of ticlopidine/CYP2C19 and rotonavir/CYP3A, for those combinations where inactivation was expected the percentage of decrease in activity was at least 30%. These include furafylline and zileuton (CYP1A2) (Racha et al, 1998;Lu et al, 2003), ticlopidine, PPP, and N,NЈ,NЉ-triethylenethiophosphoramide (thioTEPA) (CYP2B6) (Chun et al, 2000;Richter et al, 2004Richter et al, , 2005, desethylamiodarone (CYP2C8) (Polasek et al, 2004), tienilic acid (CYP2C9) (Melet et al, 2003), methylenedioxymethamphetamine (MDMA) and paroxetine (CYP2D6) (Bertelsen et al, 2003;Heydari et al, 2004), and diltiazem, erythromycin, and verapamil (CYP3A) (Mayhew et al, 2000;McConn et al, 2004;Wang et al, 2004;Ernest et al, 2005). With a few exceptions (e.g., desethylamiodarone, thioTEPA), these compounds did not show appreciable inactivation for other P450 enzymes.…”

Section: Downloaded Frommentioning

confidence: 99%

Mechanism-Based Inactivation of Human Cytochrome P450 Enzymes and the Prediction of Drug-Drug Interactions

Obach¹,

Walsky²,

2006

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ABSTRACT:The ability to use vitro inactivation kinetic parameters in scaling to in vivo drug-drug interactions (DDIs) for mechanism-based inactivators of human cytochrome P450 (P450) enzymes was examined using eight human P450-selective marker activities in pooled human liver microsomes. These data were combined with other parameters (systemic C max , estimated hepatic inlet C max , fraction unbound, in vivo P450 enzyme degradation rate constants estimated from clinical pharmacokinetic data, and fraction of the affected drug cleared by the inhibited enzyme) to predict increases in exposure to drugs, and the predictions were compared with in vivo DDIs gathered from clinical studies reported in the scientific literature. In general, the use of unbound systemic C max as the inactivator concentration in vivo yielded the most accurate predictions of DDI with a mean -fold error of 1.64. Abbreviated in vitro approaches to identifying mechanism-based inactivators were developed. Testing potential inactivators at a single concentration (IC 25 ) in a 30-min preincubation with human liver microsomes in the absence and presence of NADPH followed by assessment of P450 marker activities readily identified those compounds known to be mechanism-based inactivators and represents an approach that can be used with greater throughput. Measurement of decreases in IC 50 occurring with a 30-min preincubation with liver microsomes and NADPH was also useful in identifying mechanismbased inactivators, and the IC 50 measured after such a preincubation was highly correlated with the k inact /K I ratio measured after a full characterization of inactivation. Overall, these findings support the conclusion that P450 in vitro inactivation data are valuable in predicting clinical DDIs that can occur via this mechanism.The prediction of drug-drug interactions (DDIs) using in vitro enzyme kinetic data has been an area of increasing advances and sophistication. This has proven to be a valuable endeavor because DDIs remain an important issue in clinical practice and the discovery and development of new drugs. The earlier that the potential for DDIs can be identified in new compounds being studied as potential drugs, the greater the likelihood that this deleterious property can be removed through improved design of the molecule. Also, for those compounds already undergoing clinical trials, in vitro DDI data can be leveraged in the design of adequate and appropriate clinical DDI studies. With our increased understanding of drug-metabolizing enzymes and their roles in the metabolism of specific drugs, a mechanistic approach to assessing DDIs can be taken. The results of clinical DDI studies with one drug can be extrapolated to other drugs that are cleared by the same enzyme.The alteration of drug-metabolizing enzyme activities can occur by three main mechanisms: reversible inhibition, mechanism-based inactivation, and induction. Confidence in quantitatively extrapolating in vitro results to in vivo varies with these mechanisms. For reversible inhibitio...

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“…e) 4′-Hydroxylation of diclofenac-Diclofenac hydroxylation by CYP2C9 was carried out using a previously reported protocol [46] (15 μM substrate, 20 nM CYP2C9, 10 min at 28°C…”

Section: Origins Of Recombinant Cytochromes P450mentioning

confidence: 99%

Selective, competitive and mechanism-based inhibitors of human cytochrome P450 2J2

Lafite

Dijols

Zeldin

et al. 2007

Archives of Biochemistry and Biophysics

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Twenty five derivatives of the drugs terfenadine and ebastine have been designed, synthesized, and evaluated as inhibitors of recombinant human CYP2J2. Compound 14, which has an imidazole substituent, is a good non competitive inhibitor of CYP2J2 (IC 50 = 400 nM). It is not selective towards CYP2J2 as it also efficiently inhibits the other main vascular CYPs, such as CYP2B6, 2C8, 2C9 and 3A4; however, it could be an interesting tool to inhibit all these vascular CYPs. Compounds 4, 5 and 13, which have a propyl, allyl and benzo-1,3-dioxole terminal groups, respectively, are selective CYP2J2 inhibitors. Compound 4 is a high-affinity, competitive inhibitor and alternative substrate of CYP2J2 (K i = 160 ± 50 nM). Compound 5 and 13 are efficient mechanism-based inhibitors of CYP2J2 (k inact /K I values ~3000 L.mol −1 .s −1 ). Inactivation of CYP2J2 by 13 is due to the formation of a stable iron-carbene bond which occurs upon CYP2J2-catalyzed oxidation of 13 with a partition ratio of 18 ± 3. These new selective inhibitors should be interesting tools to study the biological roles of CYP2J2.

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Substrate selectivity of human cytochrome P450 2C9: importance of residues 476, 365, and 114 in recognition of diclofenac and sulfaphenazole and in mechanism-based inactivation by tienilic acid

Cited by 100 publications

References 59 publications

In Vitro Sulfoxidation of Thioether Compounds by Human Cytochrome P450 and Flavin-Containing Monooxygenase Isoforms With Particular Reference to the Cyp2c Subfamily

In Vitro Sulfoxidation of Thioether Compounds by Human Cytochrome P450 and Flavin-Containing Monooxygenase Isoforms With Particular Reference to the Cyp2c Subfamily

Mechanism-Based Inactivation of Human Cytochrome P450 Enzymes and the Prediction of Drug-Drug Interactions

Selective, competitive and mechanism-based inhibitors of human cytochrome P450 2J2

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