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In vitro and In Silico Studies of Interactions of Cathinone with Human Recombinant Cytochrome P450 CYP(1A2), CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2, and CYP3A5. Toxicol Rep 2022; 9:759-768. [DOI: 10.1016/j.toxrep.2022.03.040] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 03/27/2022] [Accepted: 03/28/2022] [Indexed: 11/21/2022] Open
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Kheirkhah Rahimabad P, Anthony TM, Jones AD, Eslamimehr S, Mukherjee N, Ewart S, Holloway JW, Arshad H, Commodore S, Karmaus W. Nicotine and Its Downstream Metabolites in Maternal and Cord Sera: Biomarkers of Prenatal Smoking Exposure Associated with Offspring DNA Methylation. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17249552. [PMID: 33419350 PMCID: PMC7766890 DOI: 10.3390/ijerph17249552] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 12/14/2020] [Accepted: 12/15/2020] [Indexed: 12/14/2022]
Abstract
Nicotine is a major constituent of cigarette smoke. Its primary metabolite in maternal and cord sera, cotinine, is considered a biomarker of prenatal smoking. Nicotine and cotinine half-lives are decreased in pregnancy due to their increased rate of metabolism and conversion to downstream metabolites such as norcotinine and 3-hydroxycotinine. Hence, downstream metabolites of nicotine may provide informative biomarkers of prenatal smoking. In this study of three generations (F0-mothers, F1-offspring who became mothers, and F2-offspring), we present a biochemical assessment of prenatal smoking exposure based on maternal and cord sera levels of nicotine, cotinine, norcotinine, and 3-hydroxycotinine. As potential markers of early effects of prenatal smoking, associations with differential DNA methylation (DNAm) in the F1- and F2-offspring were assessed. All metabolites in maternal and cord sera were associated with self-reported prenatal smoking, except for nicotine. We compared maternal self-report of smoking in pregnancy to biochemical evidence of prenatal smoking exposure. Self-report of F0-mothers of F1 in 1989–1990 had more accuracy identifying prenatal smoking related to maternal metabolites in maternal serum (sensitivity = 94.6%, specificity = 86.9%) compared to self-reports of F1-mothers of F2 (2010–2016) associated with cord serum markers (sensitivity = 66.7%, specificity = 78.8%). Nicotine levels in sera showed no significant association with any DNAm site previously linked to maternal smoking. Its downstream metabolites, however, were associated with DNAm sites located on the MYO1G, AHRR, and GFI1 genes. In conclusion, cotinine, norcotinine, and 3-hydroxycotinine in maternal and cord sera provide informative biomarkers and should be considered when assessing prenatal smoking. The observed association of offspring DNAm with metabolites, except for nicotine, may imply that the toxic effects of prenatal nicotine exposure are exerted by downstream metabolites, rather than nicotine. If differential DNA methylation on the MYO1G, AHRR, and GFI1 genes transmit adverse effects of prenatal nicotine exposure to the child, there is a need to investigate whether preventing changes in DNA methylation by reducing the metabolic rate of nicotine and conversion to harmful metabolites may protect exposed children.
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Affiliation(s)
- Parnian Kheirkhah Rahimabad
- Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, University of Memphis, Memphis, TN 38152, USA; (S.E.); (N.M.); (W.K.)
- Correspondence:
| | - Thilani M. Anthony
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; (T.M.A.); (A.D.J.)
| | - A. Daniel Jones
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824, USA; (T.M.A.); (A.D.J.)
| | - Shakiba Eslamimehr
- Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, University of Memphis, Memphis, TN 38152, USA; (S.E.); (N.M.); (W.K.)
| | - Nandini Mukherjee
- Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, University of Memphis, Memphis, TN 38152, USA; (S.E.); (N.M.); (W.K.)
| | - Susan Ewart
- Department of Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824, USA;
| | - John W. Holloway
- Human Development and Health, Faculty of Medicine, University of Southampton, Southampton SO17 1BJ, UK;
| | - Hasan Arshad
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton SO17 1BJ, UK;
- The David Hide Asthma and Allergy Research Centre, Isle of Wight, Newport PO30 5TG, UK
- NIHR Southampton Biomedical Research Centre, University Hospital Southampton, Hampshire SO16 6YD, UK
| | - Sarah Commodore
- Department of Environmental and Occupational Health, Indiana University, Bloomington, IN 47405, USA;
| | - Wilfried Karmaus
- Division of Epidemiology, Biostatistics, and Environmental Health, School of Public Health, University of Memphis, Memphis, TN 38152, USA; (S.E.); (N.M.); (W.K.)
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Elfaki I, Mir R, Almutairi FM, Duhier FMA. Cytochrome P450: Polymorphisms and Roles in Cancer, Diabetes and Atherosclerosis. Asian Pac J Cancer Prev 2018; 19:2057-2070. [PMID: 30139042 PMCID: PMC6171375 DOI: 10.22034/apjcp.2018.19.8.2057] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cytochromes P450s (CYPs) constitute a superfamily of enzymes that catalyze the metabolism of drugs and other substances. Endogenous substrates of CYPs include eicosanoids, estradiol, arachidonic acids, cholesterol, vitamin D and neurotransmitters. Exogenous substrates of CYPs include the polycyclic aromatic hydrocarbons and about 80% of currently used drugs. Some isoforms can activate procarcinogens to ultimate carcinogens. Genetic polymorphisms of CYPs may affect the enzyme catalytic activity and have been reported among different populations to be associated with various diseases and adverse drug reactions. With regard of drug metabolism, phenotypes for CYP polymorphism range from ultrarapid to poor metabolizers. In this review, we discuss some of the most clinically important CYPs isoforms (CYP2D6, CYP2A6, CYP2C19, CYP2C9, CYP1B1 and CYP1A2) with respect to gene polymorphisms and drug metabolism. Moreover, we review the role of CYPs in renal, lung, breast and prostate cancers and also discuss their significance for atherosclerosis and type 2 diabetes mellitus.
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Affiliation(s)
- Imadeldin Elfaki
- Department of Biochemistry, Faculty of Science, University of Tabuk, Kingdom of Saudi Arabia.
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van de Nobelen S, Kienhuis AS, Talhout R. An Inventory of Methods for the Assessment of Additive Increased Addictiveness of Tobacco Products. Nicotine Tob Res 2016; 18:1546-55. [PMID: 26817491 PMCID: PMC4902882 DOI: 10.1093/ntr/ntw002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 12/30/2015] [Indexed: 01/01/2023]
Abstract
BACKGROUND Cigarettes and other forms of tobacco contain the addictive drug nicotine. Other components, either naturally occurring in tobacco or additives that are intentionally added during the manufacturing process, may add to the addictiveness of tobacco products. As such, these components can make cigarette smokers more easily and heavily dependent.Efforts to regulate tobacco product dependence are emerging globally. Additives that increase tobacco dependence will be prohibited under the new European Tobacco Product Directive. OBJECTIVE This article provides guidelines and recommendations for developing a regulatory strategy for assessment of increase in tobacco dependence due to additives. Relevant scientific literature is summarized and criteria and experimental studies that can define increased dependence of tobacco products are described. CONCLUSIONS Natural tobacco smoke is a very complex matrix of components, therefore analysis of the contribution of an additive or a combination of additives to the level of dependence on this product is challenging. We propose to combine different type of studies analyzing overall tobacco product dependence potential and the functioning of additives in relation to nicotine. By using a combination of techniques, changes associated with nicotine dependence such as behavioral, physiological, and neurochemical alterations can be examined to provide sufficient information.Research needs and knowledge gaps will be discussed and recommendations will be made to translate current knowledge into legislation. As such, this article aids in implementation of the Tobacco Product Directive, as well as help enable regulators and researchers worldwide to develop standards to reduce dependence on tobacco products. IMPLICATIONS This article provides an overall view on how to assess tobacco product constituents for their potential contribution to use and dependence. It provides guidelines that help enable regulators worldwide to develop standards to reduce dependence on tobacco products and guide researches to set research priorities on this topic.
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Affiliation(s)
- Suzanne van de Nobelen
- Center for Health Protection (GZB), National Institute of Public Health and Environment (RIVM), Bilthoven, The Netherlands
| | - Anne S Kienhuis
- Center for Health Protection (GZB), National Institute of Public Health and Environment (RIVM), Bilthoven, The Netherlands
| | - Reinskje Talhout
- Center for Health Protection (GZB), National Institute of Public Health and Environment (RIVM), Bilthoven, The Netherlands
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Raunio H, Kuusisto M, Juvonen RO, Pentikäinen OT. Modeling of interactions between xenobiotics and cytochrome P450 (CYP) enzymes. Front Pharmacol 2015; 6:123. [PMID: 26124721 PMCID: PMC4464169 DOI: 10.3389/fphar.2015.00123] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/29/2015] [Indexed: 01/01/2023] Open
Abstract
The adverse effects to humans and environment of only few chemicals are well known. Absorption, distribution, metabolism, and excretion (ADME) are the steps of pharmaco/toxicokinetics that determine the internal dose of chemicals to which the organism is exposed. Of all the xenobiotic-metabolizing enzymes, the cytochrome P450 (CYP) enzymes are the most important due to their abundance and versatility. Reactions catalyzed by CYPs usually turn xenobiotics to harmless and excretable metabolites, but sometimes an innocuous xenobiotic is transformed into a toxic metabolite. Data on ADME and toxicity properties of compounds are increasingly generated using in vitro and modeling (in silico) tools. Both physics-based and empirical modeling approaches are used. Numerous ligand-based and target-based as well as combined modeling methods have been employed to evaluate determinants of CYP ligand binding as well as predicting sites of metabolism and inhibition characteristics of test molecules. In silico prediction of CYP–ligand interactions have made crucial contributions in understanding (1) determinants of CYP ligand binding recognition and affinity; (2) prediction of likely metabolites from substrates; (3) prediction of inhibitors and their inhibition potency. Truly predictive models of toxic outcomes cannot be created without incorporating metabolic characteristics; in silico methods help producing such information and filling gaps in experimentally derived data. Currently modeling methods are not mature enough to replace standard in vitro and in vivo approaches, but they are already used as an important component in risk assessment of drugs and other chemicals.
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Affiliation(s)
- Hannu Raunio
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland Kuopio, Finland
| | - Mira Kuusisto
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland Kuopio, Finland ; Computational Bioscience Laboratory, Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä Jyväskylä, Finland
| | - Risto O Juvonen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland Kuopio, Finland
| | - Olli T Pentikäinen
- Computational Bioscience Laboratory, Department of Biological and Environmental Science, Nanoscience Center, University of Jyväskylä Jyväskylä, Finland
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Tani N, Juvonen RO, Raunio H, Fashe M, Leppänen J, Zhao B, Tyndale RF, Rahnasto-Rilla M. Rational design of novel CYP2A6 inhibitors. Bioorg Med Chem 2014; 22:6655-6664. [PMID: 25458499 DOI: 10.1016/j.bmc.2014.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Accepted: 10/02/2014] [Indexed: 02/06/2023]
Abstract
Inhibition of CYP2A6-mediated nicotine metabolism can reduce cigarette smoking. We sought potent and selective CYP2A6 inhibitors to be used as leads for drugs useful in smoking reduction therapy, by evaluating CYP2A6 inhibitory effect of novel formyl, alkyl amine or carbonitrile substituted aromatic core structures. The most potent CYP2A6 inhibitors were thienopyridine-2-carbaldehyde, benzothienophene-3-ylmethanamine, benzofuran-5-carbaldehyde and indole-5-carbaldehyde, with IC50 values below 0.5 μM for coumarin 7-hydroxylation. Nicotine oxidation was effectively inhibited in vitro by two alkyl amine compounds and benzofuran-5-carbonitrile. Some of these molecules could serve as potential lead molecules when designing CYP2A6 inhibitory drugs for smoking reduction therapy.
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Affiliation(s)
- Niina Tani
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland.
| | - Risto O Juvonen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
| | - Hannu Raunio
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
| | - Muluneh Fashe
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
| | - Jukka Leppänen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland
| | - Bin Zhao
- Departments of Pharmacology and Toxicology and Psychiatry, University of Toronto, Campbell Family Mental Health Research Institute, M5S 1A8 Toronto, Ontario, Canada
| | - Rachel F Tyndale
- Departments of Pharmacology and Toxicology and Psychiatry, University of Toronto, Campbell Family Mental Health Research Institute, M5S 1A8 Toronto, Ontario, Canada
| | - Minna Rahnasto-Rilla
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland.
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Martikainen LE, Rahnasto-Rilla M, Neshybova S, Lahtela-Kakkonen M, Raunio H, Juvonen RO. Interactions of inhibitor molecules with the human CYP2E1 enzyme active site. Eur J Pharm Sci 2012; 47:996-1005. [PMID: 23069620 DOI: 10.1016/j.ejps.2012.09.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 08/07/2012] [Accepted: 09/25/2012] [Indexed: 11/27/2022]
Abstract
CYP2E1 is an important enzyme oxidizing ethanol as well as several drugs and other xenobiotics in the human liver. We determined the inhibition potency of structurally diverse compounds against human CYP2E1, and analyzed their interactions with the enzyme active site by molecular docking and 3D-QSAR approaches. The IC(50) values for the tested compounds varied from 1.4 μM for γ-undecanolactone to over 46 mM for glycerol. This data set was used to create a comparative molecular field analysis (CoMFA) model. The most important interactions for binding of inhibitors were identified by docking and key features for inhibitors were characterized via the COMFA model. Since the active site of CYP2E1 is flexible, long chain lactones and alkyl alcohols fitted best into the larger open form while the other compounds fitted better in the smaller closed form of the active site. Electrostatic interactions near the Thr(303) residue proved to be important for inhibition of the enzyme activity. Thus, docking analysis and the predictive CoMFA model proved to be efficient tools for revealing interactions between inhibiting compounds and CYP2E1. These approaches can be used to analyze CYP2E1-mediated metabolism and drug interactions in the development of new chemical entities.
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Sridhar J, Liu J, Foroozesh M, Klein Stevens CL. Insights on cytochrome p450 enzymes and inhibitors obtained through QSAR studies. Molecules 2012; 17:9283-305. [PMID: 22864238 PMCID: PMC3666846 DOI: 10.3390/molecules17089283] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 07/24/2012] [Accepted: 07/26/2012] [Indexed: 11/28/2022] Open
Abstract
The cytochrome P450 (CYP) superfamily of heme enzymes play an important role in the metabolism of a large number of endogenous and exogenous compounds, including most of the drugs currently on the market. Inhibitors of CYP enzymes have important roles in the treatment of several disease conditions such as numerous cancers and fungal infections in addition to their critical role in drug-drug interactions. Structure activity relationships (SAR), and three-dimensional quantitative structure activity relationships (3D-QSAR) represent important tools in understanding the interactions of the inhibitors with the active sites of the CYP enzymes. A comprehensive account of the QSAR studies on the major human CYPs 1A1, 1A2, 1B1, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, 3A4 and a few other CYPs are detailed in this review which will provide us with an insight into the individual/common characteristics of the active sites of these enzymes and the enzyme-inhibitor interactions.
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Affiliation(s)
- Jayalakshmi Sridhar
- Department of Chemistry, Xavier University of Louisiana, 1 Drexel Dr., New Orleans, LA 70125, USA
| | - Jiawang Liu
- Department of Chemistry, Xavier University of Louisiana, 1 Drexel Dr., New Orleans, LA 70125, USA
| | - Maryam Foroozesh
- Department of Chemistry, Xavier University of Louisiana, 1 Drexel Dr., New Orleans, LA 70125, USA
- Author to whom correspondence should be addressed; ; Tel.: +1-504-520-5078; Fax: +1-504-520-7942
| | - Cheryl L. Klein Stevens
- Ogden College of Science & Engineering, Western Kentucky University, 1906 College Heights Blvd., Bowling Green, KY 42101, USA
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Stephens ES, Walsh AA, Scott EE. Evaluation of inhibition selectivity for human cytochrome P450 2A enzymes. Drug Metab Dispos 2012; 40:1797-802. [PMID: 22696418 DOI: 10.1124/dmd.112.045161] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytochrome P450 (P450) enzymes are mixed-function oxidases that catalyze the metabolism of xenobiotics and endogenous biochemicals. Selective inhibitors are needed to accurately distinguish the contributions of individual P450 enzymes in the metabolism of drugs and the activation of procarcinogens in human tissues, but very frequently these enzymes have substantial overlapping selectivity. We evaluated a chemically diverse set of nine previously identified CYP2A6 inhibitors to determine which are able to discriminate between human CYP2A enzymes CYP2A6 and the 94%-identical CYP2A13 enzyme. Inhibitor binding to recombinant purified enzyme was evaluated, and affinities were determined. K(i) values were determined for inhibition of p-nitrophenol 2-hydroxylation, a reaction accomplished by CYP2A13 and CYP2A6 with more similar catalytic efficiencies (k(cat)/K(m) 0.19 and 0.12 μM⁻¹ · min⁻¹, respectively) than hydroxylation of the classic substrate coumarin (0.11 and 0.53 μM⁻¹ · min⁻¹, respectively). Of the nine compounds assayed, only tranylcypromine and (R)-(+)-menthofuran had a greater than 10-fold preference for CYP2A6 inhibition versus CYP2A13 inhibition. Most compounds evaluated [tryptamine, 4-dimethylaminobenzaldehyde, phenethyl isothiocyanate, β-nicotyrine, (S)-nicotine, and pilocarpine] demonstrated only moderate or no preference for inhibition of one CYP2A enzyme over the other. However, 8-methoxypsoralen has a 6-fold lower K(i) for CYP2A13 than for CYP2A6. This information is useful to inform reinterpretation of previous data with these inhibitors and to guide future studies seeking to determine which human CYP2A enzyme is responsible for the in vivo metabolism of compounds in human tissues expressing both enzymes.
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Affiliation(s)
- Eva S Stephens
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas, USA
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Abu-Bakar A, Arthur DM, Wikman AS, Rahnasto M, Juvonen RO, Vepsäläinen J, Raunio H, Ng JC, Lang MA. Metabolism of bilirubin by human cytochrome P450 2A6. Toxicol Appl Pharmacol 2012; 261:50-8. [DOI: 10.1016/j.taap.2012.03.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 03/13/2012] [Accepted: 03/16/2012] [Indexed: 10/28/2022]
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Rahnasto MK, Raunio HA, Wittekindt C, Salminen KA, Leppänen J, Juvonen RO, Poso A, Lahtela-Kakkonen MK. Identification of novel CYP2A6 inhibitors by virtual screening. Bioorg Med Chem 2011; 19:7186-93. [PMID: 22019468 DOI: 10.1016/j.bmc.2011.09.054] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 09/01/2011] [Accepted: 09/28/2011] [Indexed: 11/19/2022]
Abstract
The human CYP2A6 enzyme metabolises several xenobiotics including nicotine, the addictive component in tobacco. Reduced activity of CYP2A6, either for genetic reasons or by administering inhibitors of CYP2A6, reduces tobacco smoking. The aim was to design novel inhibitors of CYP2A6 using 3D-QSAR analysis combined with virtual screening. A 3D-QSAR model was utilised to identify the most important features of the inhibitors, and this knowledge was used to design inhibitors for CYP2A6. Chemical database screening yielded several potent inhibitor candidates such as alkylamine derivatives (compound no. 5, IC(50)=0.1 μM) and 1-benzothiophene-3-carbaldehyde that can be used as lead compounds in the development of drugs for smoking reduction therapy.
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Affiliation(s)
- Minna K Rahnasto
- School of Pharmacy, University of Eastern Finland, POB 1627, 70211 Kuopio, Finland.
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García-Sosa AT, Sild S, Takkis K, Maran U. Combined Approach Using Ligand Efficiency, Cross-Docking, and Antitarget Hits for Wild-Type and Drug-Resistant Y181C HIV-1 Reverse Transcriptase. J Chem Inf Model 2011; 51:2595-611. [DOI: 10.1021/ci200203h] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - Sulev Sild
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia
| | - Kalev Takkis
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia
| | - Uko Maran
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia
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Li D, Wang Y, Han K, Zhan CG. Fundamental reaction pathways for cytochrome P450-catalyzed 5'-hydroxylation and N-demethylation of nicotine. J Phys Chem B 2010; 114:9023-30. [PMID: 20572647 DOI: 10.1021/jp102225e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reaction pathways for 5'-hydroxylation and N-demethylation of nicotine catalyzed by cytochrome P450 were investigated by performing a series of first-principle electronic structure calculations on a catalytic reaction model system. The computational results indicate that 5'-hydroxylation of nicotine occurs through a two-state stepwise process, that is, an initial hydrogen atom transfer from nicotine to Cpd I (i.e., the HAT step) followed by a recombination of the nicotine moiety with the iron-bound hydroxyl group (i.e., the rebound step) on both the high-spin (HS) quartet and low-spin (LS) doublet states. The HAT step is the rate-determining one. This finding represents the first case that exhibits genuine rebound transition state species on both the HS and the LS states for C(alpha)-H hydroxylation of amines. N-Demethylation of nicotine involves a N-methylhydroxylation to form N-(hydroxymethyl)nornicotine, followed by N-(hydroxymethyl)nornicotine decomposition to nornicotine and formaldehyde. The N-methylhydroxylation step is similar to 5'-hydroxylation, namely, a rate-determining HAT step followed by a rebound step. The decomposition process occurs on the deprotonated state of N-(hydroxymethyl)nornicotine assisted by a water molecule, and the energy barrier is significantly lower than that of the N-methylhydroxylation process. Comparison of the rate-determining free energy barriers for the two reaction pathways predicts a preponderance of 5'-hydroxylation over the N-demethylation by roughly a factor of 18:1, which is in excellent agreement with the factor of 19:1 derived from available experimental data.
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Affiliation(s)
- Dongmei Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, People's Republic of China
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14
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Ai C, Li Y, Wang Y, Li W, Dong P, Ge G, Yang L. Investigation of binding features: Effects on the interaction between CYP2A6 and inhibitors. J Comput Chem 2010; 31:1822-31. [DOI: 10.1002/jcc.21455] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Abstract
Cytochrome P450 (CYP450) enzymes are predominantly involved in the Phase I metabolism of xenobiotics. Metabolic inhibition and induction can give rise to clinically important drug-drug interactions. Metabolic stability is a prerequisite for sustaining the therapeutically relevant concentrations, and very often drug candidates are sacrificed due to poor metabolic profiles. Computational tools such as quantitative structure-activity relationships are widely used to study different metabolic end points successfully to accelerate the drug discovery process. There are a lot of computational studies on clinically important CYPs already reported in recent years. But other clinically significant families are to yet be explored computationally. Powerfulness of quantitative structure-activity relationship will drive computational chemists to develop new potent and selective inhibitors of different classes of CYPs for the treatment of different diseases with least drug-drug interactions. Furthermore, there is a need to enhance the accuracy, interpretability and confidence in the computational models in accelerating the drug discovery pathways.
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Affiliation(s)
- Kunal Roy
- Jadavpur University, Division of Medicinal and Pharmaceutical Chemistry, Department of Pharmaceutical Technology, Drug Theoretics and Cheminformatics Lab, Kolkata 700 032, India.
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Ray R, Tyndale RF, Lerman C. Nicotine dependence pharmacogenetics: role of genetic variation in nicotine-metabolizing enzymes. J Neurogenet 2009; 23:252-61. [PMID: 19169923 PMCID: PMC3772540 DOI: 10.1080/01677060802572887] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Nicotine-dependence pharmacogenetics research is an emerging field, and a number of studies have begun to characterize the clinical relevance and predictive power of genetic variation in drug-metabolizing enzymes and drug target genes for response to medication. The present paper focuses on evidence for the role of nicotine-metabolizing enzymes in smoking behavior and response to treatment. Nicotine metabolism is mediated primarily by cytochrome P450 2A6 (CYP2A6). Genetic variation in the CYP2A6 gene has been linked with several smoking behavior phenotypes. Individuals who carry null or reduced activity alleles for CYP2A6 smoke fewer cigarettes per day, are less dependent on nicotine, and may have an easier time quitting smoking. A phenotypic measure of CYP2A6 enzyme activity, defined as the ratio of the nicotine metabolites 3'hydroxycotinine/cotinine, also predicts successful quitting with the transdermal nicotine patch, and counseling alone. Faster metabolizers of nicotine respond more poorly to these treatments; however, they may be excellent candidates for non-nicotine therapies, such as bupropion. Inherited variation in the CYP2B6 enzyme is also associated with response to bupropion treatment and counseling alone for smoking cessation. Inhibition of the CYP2A6 enzyme to slow nicotine metabolism is a promising approach to increase nicotine availability and potentially reduce harm from tobacco smoking.
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Affiliation(s)
- Riju Ray
- Abramson Cancer Center and Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rachel F. Tyndale
- Centre for Addiction and Mental Health and Department of Pharmacology, Toronto, Ontario, Canada
| | - Caryn Lerman
- Abramson Cancer Center and Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Development of a New Predictive Model for Interactions with Human Cytochrome P450 2A6 Using Pharmacophore Ensemble/Support Vector Machine (PhE/SVM) Approach. Pharm Res 2008; 26:987-1000. [DOI: 10.1007/s11095-008-9807-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2008] [Accepted: 12/08/2008] [Indexed: 02/06/2023]
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