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Ishii H, Leung GNW, Yamashita S, Nagata SI, Kushiro A, Sakai S, Toju K, Okada J, Kawasaki K, Kusano K, Kijima-Suda I. Comprehensive metabolic study of nicotine in equine plasma and urine using liquid chromatography/high-resolution mass spectrometry for the identification of unique biomarkers for doping control. J Chromatogr B Analyt Technol Biomed Life Sci 2022; 1190:123100. [PMID: 35032890 DOI: 10.1016/j.jchromb.2022.123100] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 12/07/2021] [Accepted: 01/03/2022] [Indexed: 10/19/2022]
Abstract
Nicotine is classified as a stimulant, and its use is banned in horse racing and equestrian sports by the International Federation of Horseracing Authorities and the Fédération Équestre Internationale, respectively. Because nicotine is a major alkaloid of tobacco leaves, there is a potential risk that doping control samples may be contaminated by tobacco cigarettes or smoke during sample collection. In order to differentiate the genuine doping and sample contamination with tobacco leaves, it is necessary to monitor unique metabolites as biomarkers for nicotine administration and intake. However, little is known about the metabolic fate of nicotine in horses. This is the first report of comprehensive metabolism study of nicotine in horses. Using liquid chromatography/electrospray ionization high-resolution mass spectrometry, we identified a total of 17 metabolites, including one novel horse-specific metabolite (i.e., 4-hydroxy-4-(3-pyridyl)-N-methylbutanamide), in post-administration urine samples after nasoesophageal administration of nicotine to three thoroughbred mares; eight of these compounds were confirmed based on reference standards. Among these metabolites, N-hydroxymethylnorcotinine was the major urinary metabolite in equine, but it could only be tentatively identified by mass spectral interpretation due to the lack of reference material. In addition, we developed simultaneous quantification methods for the eight target analytes in plasma and urine, and applied them to post-administration samples to establish elimination profiles of nicotine and its metabolites. The quantification results revealed that trans-3'-hydroxycotinine could be quantified for the longest period in both plasma (72 h post-administration) and urine (96 h post-administration). Therefore, this metabolite is the most appropriate monitoring target for nicotine exposure for the purpose of doping control due to its long detection times and the availability of its reference material. Further, we identified trans-3'-hydroxycotinine as a unique biomarker allowing differentiation between nicotine administration and sample contamination with tobacco leaves.
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Affiliation(s)
- Hideaki Ishii
- Drug Analysis Department, Laboratory of Racing Chemistry, 1731-2 Tsuruta-machi, Utsunomiya, Tochigi 320-0851, Japan; Department of Pharmaceutical Sciences, Tohoku University Hospital, 1-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8574, Japan.
| | - Gary Ngai-Wa Leung
- Drug Analysis Department, Laboratory of Racing Chemistry, 1731-2 Tsuruta-machi, Utsunomiya, Tochigi 320-0851, Japan
| | - Shozo Yamashita
- Drug Analysis Department, Laboratory of Racing Chemistry, 1731-2 Tsuruta-machi, Utsunomiya, Tochigi 320-0851, Japan
| | - Shun-Ichi Nagata
- Genetic Analysis Department, Laboratory of Racing Chemistry, 1731-2 Tsuruta-machi, Utsunomiya, Tochigi 320-0851, Japan
| | - Asuka Kushiro
- Equine Research Institute, Research Planning & Coordination Division, JRA, 1400-4, Shiba, Shimotsuke, Tochigi 329-0412, Japan
| | - Satoshi Sakai
- Race Horse Hospital, Miho Training Center, JRA, 2500-2, Oaza-Mikoma, Miho-mura, Inashiki-gun, Ibaraki 300-0493, Japan
| | - Kota Toju
- Race Horse Hospital, Miho Training Center, JRA, 2500-2, Oaza-Mikoma, Miho-mura, Inashiki-gun, Ibaraki 300-0493, Japan
| | - Jun Okada
- Veterinarian Section, Equine Department, JRA, 6-11-1 Roppongi, Minato-ku, Tokyo 105-0003, Japan
| | - Kazumi Kawasaki
- Veterinarian Section, Equine Department, JRA, 6-11-1 Roppongi, Minato-ku, Tokyo 105-0003, Japan
| | - Kanichi Kusano
- Race Horse Hospital, Ritto Training Center, JRA, 1028, Misono, Ritto, Shiga 520-3085, Japan
| | - Isao Kijima-Suda
- Drug Analysis Department, Laboratory of Racing Chemistry, 1731-2 Tsuruta-machi, Utsunomiya, Tochigi 320-0851, Japan
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2
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Murphy SE. Biochemistry of nicotine metabolism and its relevance to lung cancer. J Biol Chem 2021; 296:100722. [PMID: 33932402 PMCID: PMC8167289 DOI: 10.1016/j.jbc.2021.100722] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 04/26/2021] [Accepted: 04/27/2021] [Indexed: 12/27/2022] Open
Abstract
Nicotine is the key addictive constituent of tobacco. It is not a carcinogen, but it drives smoking and the continued exposure to the many carcinogens present in tobacco. The investigation into nicotine biotransformation has been ongoing for more than 60 years. The dominant pathway of nicotine metabolism in humans is the formation of cotinine, which occurs in two steps. The first step is cytochrome P450 (P450, CYP) 2A6–catalyzed 5′-oxidation to an iminium ion, and the second step is oxidation of the iminium ion to cotinine. The half-life of nicotine is longer in individuals with low P450 2A6 activity, and smokers with low activity often decrease either the intensity of their smoking or the number of cigarettes they use compared with those with “normal” activity. The effect of P450 2A6 activity on smoking may influence one's tobacco-related disease risk. This review provides an overview of nicotine metabolism and a summary of the use of nicotine metabolite biomarkers to define smoking dose. Some more recent findings, for example, the identification of uridine 5′-diphosphoglucuronosyltransferase 2B10 as the catalyst of nicotine N-glucuronidation, are discussed. We also describe epidemiology studies that establish the contribution of nicotine metabolism and CYP2A6 genotype to lung cancer risk, particularly with respect to specific racial/ethnic groups, such as those with Japanese, African, or European ancestry. We conclude that a model of nicotine metabolism and smoking dose could be combined with other lung cancer risk variables to more accurately identify former smokers at the highest risk of lung cancer and to intervene accordingly.
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Affiliation(s)
- Sharon E Murphy
- Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA.
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Taghavi T, Novalen M, Lerman C, George TP, Tyndale RF. A Comparison of Direct and Indirect Analytical Approaches to Measuring Total Nicotine Equivalents in Urine. Cancer Epidemiol Biomarkers Prev 2018; 27:882-891. [PMID: 29853480 DOI: 10.1158/1055-9965.epi-18-0018] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/15/2018] [Accepted: 05/23/2018] [Indexed: 12/23/2022] Open
Abstract
Background: Total nicotine equivalents (TNE), the sum of nicotine and metabolites in urine, is a valuable tool for evaluating nicotine exposure. Most methods for measuring TNE involve two-step enzymatic hydrolysis for indirect quantification of glucuronide metabolites. Here, we describe a rapid, low-cost direct LC/MS assay.Methods: In 139 smokers' urine samples, Bland-Altman, correlation, and regression analyses were used to investigate differences in quantification of nicotine and metabolites, TNE, and nicotine metabolite ratio (NMR) between direct and indirect LC/MS methods. DNA from a subset (n = 97 smokers) was genotyped for UGT2B10*2 and UGT2B17*2, and the known impact of these variants was evaluated using urinary ratios determined by the direct versus indirect method.Results: The direct method showed high accuracy (0%-9% bias) and precision (3%-14% coefficient of variation) with similar distribution of nicotine metabolites to literary estimates and good agreement between the direct and indirect methods for nicotine, cotinine, and 3-hydroxycotinine (ratios 0.99-1.07), but less agreement for their respective glucuronides (ratios 1.16-4.17). The direct method identified urinary 3HC+3HC-GLUC/COT as having the highest concordance with plasma NMR and provided substantially better estimations of the established genetic impact of glucuronidation variants compared with the indirect method.Conclusions: Direct quantification of nicotine and metabolites is less time-consuming and less costly, and provides accurate estimates of nicotine intake, metabolism rate, and the impact of genetic variation in smokers.Impact: Lower cost and maintenance combined with high accuracy and reproducibility make the direct method ideal for smoking biomarker, NMR, and pharmacogenomics studies. Cancer Epidemiol Biomarkers Prev; 27(8); 882-91. ©2018 AACR.
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Affiliation(s)
- Taraneh Taghavi
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Maria Novalen
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada
| | - Caryn Lerman
- Center for Interdisciplinary Research on Nicotine Addiction, Department of Psychiatry, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Tony P George
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada.,Division of Brain and Therapeutics, Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Rachel F Tyndale
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario, Canada. .,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada.,Division of Brain and Therapeutics, Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
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4
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Hellinghausen G, Roy D, Wang Y, Lee JT, Lopez DA, Weatherly CA, Armstrong DW. A comprehensive methodology for the chiral separation of 40 tobacco alkaloids and their carcinogenic E/Z-(R,S)-tobacco-specific nitrosamine metabolites. Talanta 2018; 181:132-141. [PMID: 29426492 DOI: 10.1016/j.talanta.2017.12.060] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Revised: 12/18/2017] [Accepted: 12/19/2017] [Indexed: 11/18/2022]
Abstract
The predominant enantiomer of nicotine found in nature is (S)-nicotine and its pharmacology has been widely established. However, pharmacologic information concerning individual enantiomers of nicotine-related compounds is limited. Recently, a modified macrocyclic glycopeptide chiral selector was found to be highly stereoselective for most tobacco alkaloids and metabolites. This study examines the semi-synthetic and native known macrocyclic glycopeptides for chiral recognition, separation, and characterization of the largest group of nicotine-related compounds ever reported (tobacco alkaloids, nicotine metabolites and derivatives, and tobacco-specific nitrosamines). The enantioseparation of nicotine is accomplished in less than 20s for example. All liquid chromatography separations are mass spectrometry compatible for the tobacco alkaloids, as well as their metabolites. Ring-closed, cyclized structures were identified and separated from their ring-open, straight chain equilibrium structures. Also, E/Z-tobacco-specific nitrosamines and their enantiomers were directly separated. E/Z isomers also are known to have different physical and chemical properties and biological activities. This study provides optimal separation conditions for the analysis of nicotine-related isomers, which in the past have been reported to be ineffectively separated which can result in inaccurate results. The methodology of this study could be applied to cancer studies, and lead to more information about the role of these isomers in other diseases and as treatment for diseases.
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Affiliation(s)
- Garrett Hellinghausen
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA
| | - Daipayan Roy
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA
| | - Yadi Wang
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA
| | - Jauh T Lee
- AZYP LLC, 700 Planetarium Place, Arlington, TX 76019, USA
| | - Diego A Lopez
- AZYP LLC, 700 Planetarium Place, Arlington, TX 76019, USA
| | - Choyce A Weatherly
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA
| | - Daniel W Armstrong
- Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA; AZYP LLC, 700 Planetarium Place, Arlington, TX 76019, USA.
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El-Sherbeeny NA, Nader MA, Attia GM, Ateyya H. Agmatine protects rat liver from nicotine-induced hepatic damage via antioxidative, antiapoptotic, and antifibrotic pathways. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:1341-1351. [PMID: 27638633 DOI: 10.1007/s00210-016-1284-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 08/05/2016] [Indexed: 01/07/2023]
Abstract
Tobacco smoking with its various forms is a global problem with proved hazardous effects to human health. The present work was planned to study the defending role of agmatine (AGM) on hepatic oxidative stress and damage induced by nicotine in rats. Thirty-two rats divided into four groups were employed: control group, nicotine-only group, AGM group, and AGM-nicotine group. Measurements of serum hepatic biochemical markers, lipid profile, and vascular cell adhesion molecule-1 were done. In addition, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH) activity, and nitrate/nitrite (NOx) levels were estimated in the liver homogenates. Immunohistochemistry for Bax and transforming growth factor beta (TGF-β1) and histopathology of the liver were also included. Data of the study demonstrated that nicotine administration exhibited marked liver deterioration, an increase in liver enzymes, changes in lipid profile, and an elevation in MDA with a decline in levels of SOD, GSH, and NOx (nitrate/nitrite). Also, levels of proapoptotic Bax and profibrotic TGF-β1 showed marked elevation in the liver. AGM treatment to rats in nicotine-only group ameliorated all the previous changes. These findings indicate that AGM could successfully overcome the nicotine-evoked hepatic oxidative stress and tissue injury, apoptosis, and fibrosis.
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Affiliation(s)
- Nagla A El-Sherbeeny
- Pharmacology and Toxicology, College of Pharmacy, Taibah University, El-Madinah El-Munawarah, Saudi Arabia.,Faculty of Medicine, Suez Canal University, Ismailia Governorate, Egypt
| | - Manar A Nader
- Pharmacology and Toxicology, College of Pharmacy, Taibah University, El-Madinah El-Munawarah, Saudi Arabia.,Faculty of Pharmacy, Mansoura University, Dakahlia Governorate, Egypt
| | - Ghalia M Attia
- Department of Anatomy, Faculty of Medicine, Taibah University, El-Madinah El-Munawarah, Saudi Arabia. .,Department of Histology and Cell Biology, Faculty of Medicine, Mansoura University, Mansoura, Egypt.
| | - Hayam Ateyya
- Pharmacology and Toxicology, College of Pharmacy, Taibah University, El-Madinah El-Munawarah, Saudi Arabia.,Faculty of Medicine, Cairo University, Giza, Egypt
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6
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LeMasters GK, Khurana Hershey GK, Sivaprasad U, Martin LJ, Pilipenko V, Ericksen MB, Burkle JW, Lindsey MA, Bernstein DI, Lockey JE, Gareri J, Lubetsky A, Koren G, Biagini Myers JM. N-acetyltransferase 1 polymorphism increases cotinine levels in Caucasian children exposed to secondhand smoke: the CCAAPS birth cohort. THE PHARMACOGENOMICS JOURNAL 2015; 15:189-95. [PMID: 25156213 PMCID: PMC4342329 DOI: 10.1038/tpj.2014.44] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/13/2014] [Accepted: 06/25/2014] [Indexed: 01/21/2023]
Abstract
Cotinine is a proxy for secondhand smoke (SHS) exposure. Genetic variation along nicotine and cotinine metabolic pathways may alter the internal cotinine dose, leading to misinterpretations of exposure-health outcome associations. Caucasian children with available SHS exposure and hair cotinine data were genotyped for metabolism-related genes. SHS-exposed children had 2.4-fold higher hair cotinine (0.14±0.22 ng mg(-1)) than unexposed children (0.06±0.05 ng mg(-1), P<0.001). SHS-exposed children carrying the NAT1 minor allele had twofold higher hair cotinine (0.18 ng mg(-1) for heterozygotes and 0.17 ng mg(-1) for homozygotes) compared with major allele homozygotes (0.09 ng mg(-1), P=0.0009), even after adjustment for SHS dose. These findings support that NAT1 has a role in the metabolic pathway of nicotine/cotinine and/or their metabolites. The increased cotinine levels observed for those carrying the minor allele may lead to SHS exposure misclassification in studies utilizing cotinine as a biomarker. Additional studies are required to identify functional single-nucleotide polymorphism(s) (SNP(s)) in NAT1 and elucidate the biological consequences of the mutation(s).
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Affiliation(s)
- Grace K LeMasters
- Department of Environmental Health, University of Cincinnati, Cincinnati, OH, USA
| | - Gurjit K Khurana Hershey
- Division of Asthma Research Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Umasundari Sivaprasad
- Division of Asthma Research Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Lisa J Martin
- Division of Human Genetics Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
- Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Valentina Pilipenko
- Division of Human Genetics Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Mark B Ericksen
- Division of Asthma Research Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - Jeffrey W Burkle
- Department of Environmental Health, University of Cincinnati, Cincinnati, OH, USA
| | - Mark A Lindsey
- Division of Asthma Research Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
| | - David I Bernstein
- Department of Internal Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - James E Lockey
- Department of Environmental Health, University of Cincinnati, Cincinnati, OH, USA
| | - Joey Gareri
- Division of Clinical Pharmacology and Toxicology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Angelika Lubetsky
- Division of Clinical Pharmacology and Toxicology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Gideon Koren
- Division of Clinical Pharmacology and Toxicology, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Jocelyn M Biagini Myers
- Division of Asthma Research Cincinnati Children's Hospital Medical Center, University of Cincinnati, Cincinnati, OH, USA
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7
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Barreto GE, Iarkov A, Moran VE. Beneficial effects of nicotine, cotinine and its metabolites as potential agents for Parkinson's disease. Front Aging Neurosci 2015; 6:340. [PMID: 25620929 PMCID: PMC4288130 DOI: 10.3389/fnagi.2014.00340] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/04/2014] [Indexed: 01/10/2023] Open
Abstract
Parkinson’s disease (PD) is a progressive neurodegenerative disorder, which is characterized by neuroinflammation, dopaminergic neuronal cell death and motor dysfunction, and for which there are no proven effective treatments. The negative correlation between tobacco consumption and PD suggests that tobacco-derived compounds can be beneficial against PD. Nicotine, the more studied alkaloid derived from tobacco, is considered to be responsible for the beneficial behavioral and neurological effects of tobacco use in PD. However, several metabolites of nicotine, such as cotinine, also increase in the brain after nicotine administration. The effect of nicotine and some of its derivatives on dopaminergic neurons viability, neuroinflammation, and motor and memory functions, have been investigated using cellular and rodent models of PD. Current evidence shows that nicotine, and some of its derivatives diminish oxidative stress and neuroinflammation in the brain and improve synaptic plasticity and neuronal survival of dopaminergic neurons. In vivo these effects resulted in improvements in mood, motor skills and memory in subjects suffering from PD pathology. In this review, we discuss the potential benefits of nicotine and its derivatives for treating PD.
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Affiliation(s)
- George E Barreto
- Department of Nutrition and Biochemistry, Pontificia Universidad Javeriana Bogotá, D. C., Colombia
| | - Alexander Iarkov
- Center of Research in Biomedical Sciences, Universidad Autónoma de Chile Santiago, Chile ; Research & Development Service, Bay Pines VA Healthcare System Bay Pines, FL, USA
| | - Valentina Echeverria Moran
- Center of Research in Biomedical Sciences, Universidad Autónoma de Chile Santiago, Chile ; Research & Development Service, Bay Pines VA Healthcare System Bay Pines, FL, USA ; Research Service, James A Haley Veterans' Hospital Tampa, FL, USA ; Department of Molecular Medicine, Morsani College of Medicine, University of South Tampa, FL, USA
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8
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Li D, Huang X, Lin J, Zhan CG. Catalytic mechanism of cytochrome P450 for N-methylhydroxylation of nicotine: reaction pathways and regioselectivity of the enzymatic nicotine oxidation. Dalton Trans 2013; 42:3812-20. [PMID: 23303461 DOI: 10.1039/c2dt32106h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The fundamental reaction mechanism of cytochrome P450 2A6 (CYP2A6)-catalyzed N-methylhydroxylation of (S)-(-)-nicotine and the free energy profile have been studied by performing pseudobond first-principles quantum mechanical/molecular mechanical (QM/MM) reaction-coordinate calculations. In the CYP2A6-(S)-(-)-nicotine binding structures that allow for 5'-hydroxylation, the N-methyl group is also sufficiently close to the oxygen of Cpd I for the N-methylhydroxylation reaction to occur. It has been demonstrated that the CYP2A6-catalyzed N-methylhydroxylation reaction is a concerted process involving a hydrogen-transfer transition state on both the quartet and the doublet states. The N-methylhydroxylation reaction proceeds mainly in the doublet state, since the free energy barriers on the doublet state are lower than the corresponding ones on the quartet state. The calculated free energy barriers indicate that (S)-(-)-nicotine oxidation catalyzed by CYP2A6 proceeds with a high regioselective abstraction of the hydrogen at the 5'-position, rather than the hydrogen at the N-methyl group. The predicted regioselectivity of 93% is in agreement with the most recent experimentally reported regioselectivity of 95%. The binding mode of (S)-(-)-nicotine in the active site of CYP2A6 is an important determinant for the stereoselectivity of nicotine (S)-(-)-oxidation, whereas the regioselectivity of (S)-(-)-nicotine oxidation is determined mainly by the free energy barrier difference between the 5'-hydroxylation and N-methylhydroxylation reactions.
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Affiliation(s)
- Dongmei Li
- College of Pharmacy, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, China.
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9
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Yarnall NJ, Hughes LM, Turnbull PS, Michaud M. Evaluating the effectiveness of the US Navy and Marine Corps Tobacco Policy: an assessment of secondhand smoke exposure in US Navy submariners. Tob Control 2012; 22:e66-72. [PMID: 22871902 DOI: 10.1136/tobaccocontrol-2012-050488] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To evaluate the effectiveness of the US Navy and Marine Corps tobacco policy in protecting submariners from secondhand smoke (SHS) by determining if non-tobacco users experienced a significant increase in urinary cotinine levels at sea when compared with in port levels. METHODS From February to August 2009, 634 volunteers recruited from nine US Navy submarines completed a survey to collect demographic data, information on tobacco use and pre-deployment exposure to SHS. Non-tobacco users (n=239) were requested to provide two urine samples (pre-deployment and while at sea) to quantify exposure to SHS using urinary cotinine as a biomarker. Matched samples were analysed using liquid chromatography-tandem mass spectrometry. RESULTS Overall, deployed cotinine levels were 2.1 times the in port levels in non-tobacco using submariners (95% CI 1.8 to 2.4, p<0.001, n=197). A significant increase in deployed urinary cotinine levels was found aboard six of nine submarines (p<0.05). A subgroup of submariners (n=91) who reported no SHS exposure within 10 days prior to in port cotinine sampling had deployed cotinine levels 2.7 times the in port levels (95% CI 2.2 to 3.3, p<0.001). Applying a 4.5:1 urine cotinine to serum cotinine correction factor, submariners' deployed geometric means are similar to recent US male population values at the 75th percentile. CONCLUSIONS This study provides evidence that non-tobacco using submariners were exposed to SHS. Exposure was seen in all submarine classes and was not limited to personnel working in proximity to the smoking area. The existing policy was inadequate to protect non-smokers from exposure to SHS and required revision. As a result of a policy review, informed by this study, smoking below decks was banned aboard all US Navy submarines effective 31 December 2010.
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10
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Li D, Huang X, Han K, Zhan CG. Catalytic mechanism of cytochrome P450 for 5'-hydroxylation of nicotine: fundamental reaction pathways and stereoselectivity. J Am Chem Soc 2011; 133:7416-27. [PMID: 21513309 DOI: 10.1021/ja111657j] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A series of computational methods were used to study how cytochrome P450 2A6 (CYP2A6) interacts with (S)-(-)-nicotine, demonstrating that the dominant molecular species of (S)-(-)-nicotine in CYP2A6 active site exists in the free base state (with two conformations, SR(t) and SR(c)), despite the fact that the protonated state is dominant for the free ligand in solution. The computational results reveal that the dominant pathway of nicotine metabolism in CYP2A6 is through nicotine free base oxidation. Further, first-principles quantum mechanical/molecular mechanical free energy (QM/MM-FE) calculations were carried out to uncover the detailed reaction pathways for the CYP2A6-catalyzed nicotine 5'-hydroxylation reaction. In the determined CYP2A6-(S)-(-)-nicotine binding structures, the oxygen of Compound I (Cpd I) can abstract a hydrogen from either the trans-5'- or the cis-5'-position of (S)-(-)-nicotine. CYP2A6-catalyzed (S)-(-)-nicotine 5'-hydroxylation consists of two reaction steps, that is, the hydrogen transfer from the 5'-position of (S)-(-)-nicotine to the oxygen of Cpd I (the H-transfer step), followed by the recombination of the (S)-(-)-nicotine moiety with the iron-bound hydroxyl group to generate the 5'-hydroxynicotine product (the O-rebound step). The H-transfer step is rate-determining. The 5'-hydroxylation proceeds mainly with the stereoselective loss of the trans-5'-hydrogen, that is, the 5'-hydrogen trans to the pyridine ring. The calculated overall stereoselectivity of ∼97% favoring the trans-5'-hydroxylation is close to the observed stereoselectivity of 89-94%. This is the first time it has been demonstrated that a CYP substrate exists dominantly in one protonation state (cationic species) in solution, but uses its less-favorable protonation state (neutral free base) to perform the enzymatic reaction.
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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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11
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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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Yasmin S, Afroz B, Hyat B, D'Souza D. Occupational health hazards in women beedi rollers in Bihar, India. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2010; 85:87-91. [PMID: 20512312 DOI: 10.1007/s00128-010-0037-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Accepted: 05/12/2010] [Indexed: 05/29/2023]
Abstract
We studied the health problems of 197 female beedi rollers in Patna, Bihar, India to ascertain the effects of beedi rolling on health. The study found that more than 70% of the beedi rollers suffered from eye, gastrointestinal and nervous problems while more than 50% of the respondents suffered from respiratory problems, mostly throat burning and cough. More than 75% of the respondents faced osteological problems. Total RBC, WBC and platelet counts of the beedi rollers were significantly lower in comparison to the control subjects. Differential leucocyte count showed significantly risen lymphocytes and eosinophils and lowered neutrophils and monocytes in the beedi rollers as compared to the control group. Haemoglobin levels were lower among beedi rollers compared to the control group. SGPT (ALT) enzyme concentration, a parameter of liver dysfunction was significantly higher in the beedi rollers as compared to the control group. Thus, the study concluded that beedi rolling may cause significant health hazards.
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Affiliation(s)
- Shahla Yasmin
- Department of Zoology, Patna Women's College, Bailey Road, Patna, 800001 Bihar, India.
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Abstract
Nicotine underlies tobacco addiction, influences tobacco use patterns, and is used as a pharmacological aid to smoking cessation. The absorption, distribution and disposition characteristics of nicotine from tobacco and medicinal products are reviewed. Nicotine is metabolized primarily by the liver enzymes CYP2A6, UDPglucuronosyltransferase (UGT), and flavin-containing monooxygenase (FMO). In addition to genetic factors, nicotine metabolism is influenced by diet and meals, age, sex, use of estrogen-containing hormone preparations, pregnancy and kidney disease, other medications, and smoking itself. Substantial racial/ethnic differences are observed in nicotine metabolism, which are likely influenced by both genetic and environmental factors. The most widely used biomarker of nicotine intake is cotinine, which may be measured in blood, urine, saliva, hair, or nails. The current optimal plasma cotinine cut-point to distinguish smokers from non-smokers in the general US population is 3 ng ml(-1). This cut-point is much lower than that established 20 years ago, reflecting less secondhand smoke exposure due to clear air policies and more light or occasional smoking.
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Affiliation(s)
- Neal L Benowitz
- Division of Clinical Pharmacology and Experimental Therapeutics, University of California, San Francisco, P. O. Box 1220, San Francisco, CA 94143-1220, USA.
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Attia SM. The genotoxic and cytotoxic effects of nicotine in the mouse bone marrow. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2007; 632:29-36. [PMID: 17543574 DOI: 10.1016/j.mrgentox.2007.04.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Revised: 03/11/2007] [Accepted: 04/05/2007] [Indexed: 11/23/2022]
Abstract
The objective of the present study was to investigate the potential of nicotine to induce micronucleated polychromatic erythrocytes (MNPCE) in bone marrow of male and female mice. Cyclophosphamide at 40mg/kg was used as positive control clastogen. Single doses of 4, 8 or 16mg/kg nicotine were given via oral intubation and bone marrow was sampled at 18, 24, 30, 36 and 48h after treatment. Cyclophosphamide yielded the expected positive results. Despite the evident signs of acute toxicity shown by the animals, mainly at the 8 and 16mg/kg doses of nicotine, and the reduction in the % PCE, the results show that the MNPCE frequency in male and female mice was not affected by treatment with any of the selected doses of nicotine, in either of the sampling times 18 or 24h. However, at 30 and 36h after treatment, the MNPCE showed significant increases in both genders after doses of 8 and 16mg/kg. A sex-dependent response was recorded, with males having more MNPCE than females after treatment with 8 or 16mg/kg nicotine and sampling at 30h. However, at 36h more MNPCE were induced in females than in males, suggesting different degrees of dose interaction in the sexes under the conditions of the assay. The response was directly correlated with bone-marrow toxicity, as greater bone-marrow suppression was noted in females than in males when 36h samples were examined. By 48h recovery was observed even though the cytotoxicity was high. These findings suggest that nicotine at high doses and after prolonged time intervals is genotoxic and cytotoxic for mouse bone marrow.
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Affiliation(s)
- Sabry M Attia
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Al-Azhar University, Nasr City, Cairo, Egypt.
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Yildiz D. Nicotine, its metabolism and an overview of its biological effects. Toxicon 2004; 43:619-32. [PMID: 15109883 DOI: 10.1016/j.toxicon.2004.01.017] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2003] [Accepted: 01/05/2004] [Indexed: 10/26/2022]
Abstract
Nicotine is a naturally occurring alkaloid found in many plants. The principal sources of nicotine exposure is through the use of tobacco, nicotine containing gum and nicotine replacement therapies. Nicotine is an amine composed of pyridine and pyrrolidine rings. It has been shown that nicotine crosses biological membranes and the blood brain barrier easily. The absorbed nicotine is extensively metabolized in the liver to form a wide variety of metabolites including nicotine N'-oxide and cotinine N'-oxide. These are the products of mixed function oxidase system. Nicotine is also converted to some biologically important compounds during harvesting. Among these are the nitrosamines specific to tobacco. Nicotine has been shown to affect a wide variety of biological functions ranging from gene expression, regulation of hormone secretion and enzyme activities. The objective of this study was to overview the biological effects and metabolism of nicotine.
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Affiliation(s)
- Deniz Yildiz
- Department of Biology, Mustafa Kemal University, Antakya, Turkey.
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Hecht SS, Hochalter JB, Villalta PW, Murphy SE. 2'-Hydroxylation of nicotine by cytochrome P450 2A6 and human liver microsomes: formation of a lung carcinogen precursor. Proc Natl Acad Sci U S A 2000; 97:12493-7. [PMID: 11050152 PMCID: PMC18791 DOI: 10.1073/pnas.220207697] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Smokers or people undergoing nicotine replacement therapy excrete approximately 10% of the nicotine dose as 4-oxo-4-(3-pyridyl)butanoic acid (keto acid) and 4-hydroxy-4-(3-pyridyl)butanoic acid (hydroxy acid). Previously, these acids were thought to arise by secondary metabolism of the major nicotine metabolite cotinine, but our data did not support this mechanism. Therefore, we hypothesized that nicotine is metabolized by 2'-hydroxylation, which would ultimately yield keto acid and hydroxy acid as urinary metabolites. This pathway had not been established previously in mammalian systems and is potentially significant because the product of nicotine 2'-hydroxylation, 4-(methylamino)-1-(3-pyridyl)-1-butanone (aminoketone), can be converted to the potent tobacco-specific lung carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. Incubation of nicotine with cytochrome P450 2A6 and cofactors did indeed produce aminoketone, which was identified as its N-benzoyl derivative by GC-MS. The rate was 11% of that of cotinine production. Incubation of human liver microsomes with nicotine gave keto acid by using aminoketone as an intermediate; keto acid was not formed from cotinine. In 10 human liver samples, rates of formation of keto acid were 5.7% of those of cotinine and production of these metabolites correlated. These results provide definitive evidence for mammalian 2'-hydroxylation of nicotine and elucidate a pathway by which endogenous formation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone could occur in humans.
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Affiliation(s)
- S S Hecht
- University of Minnesota Cancer Center, Minneapolis, MN 55455, USA.
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Abstract
Nicotine affects a variety of cellular processes ranging from induction of gene expression to secretion of hormones and modulation of enzymatic activities. The objective of this study was to characterize the toxicity of nicotine enantiomers as well as their ability to induce oxidative stress in an in vitro model using Chinese hamster ovary (CHO) cells. Colony formation assay has demonstrated that (-)-nicotine is the more toxic of the enantiomers. At 6 mM concentrations, (-)-nicotine was found to be approximately 28- and 19-fold more potent than (+)-, and (+/-)-nicotine (racemic), respectively. Results also indicated that the toxicity of (+/-)-nicotine is higher than that of (+)-nicotine. (-)-Nicotine at a 10 mM concentration substantially decreased glutathione (GSH) levels (46% decrease). In addition, a 3-fold increase in malondialdehyde (MDA) level was evident in cells after exposure to 10 mM (-)-nicotine. Increased lactate dehydrogenase (LDH) activities in the media demonstrated that cellular membrane integrity was disturbed in nicotine treated cells. In the presence of superoxide dismutase (SOD) and catalase (CAT), the LDH activities returned to control value in 24 h with all concentrations of (-)-, (+)-, and (+/-)-nicotine. The decreases in LDH activities in the presence of the radical scavenging enzymes SOD and CAT suggest that membrane damage may be due to free radical generation.
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Affiliation(s)
- D Yildiz
- Department of Chemistry, University of Missouri-Rolla, 65409-0010, USA
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