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Golding BT, Abelairas-Edesa M, Tilbury RD, Wilson JP, Zhang D, Henderson AP, Bleasdale C, Clegg W, Watson WP. Influence of the methyl group in isoprene epoxides on reactivity compared to butadiene epoxides: Biological significance. Chem Biol Interact 2022; 361:109949. [PMID: 35490797 DOI: 10.1016/j.cbi.2022.109949] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/29/2022] [Accepted: 04/11/2022] [Indexed: 11/28/2022]
Abstract
Reactions of the epoxides of 1,3-butadiene and isoprene (2-methyl-1,3-butadiene) with oxygen, nitrogen and sulfur nucleophiles have been compared to enable a better molecular understanding of the relative human toxicities of these epoxides. Hydrolysis of rac.-ethenyloxirane in (18O)water gave 77% (2-18O)but-3-ene-1,2-diol and 23% (1-18O)but-3-ene-1,2-diol. The R:S ratio for but-3-ene-1,2-diol from hydrolysis of (S)-ethenyloxirane was 75:25. Hence, hydrolysis of ethenyloxirane occurs by competing SN2 attack at C-2 and C-3 in 3:1 ratio, with no SN1 component. Hydrolysis of rac.-2-ethenyl-2-methyloxirane gave 2-hydroxy-2-methylbut-3-en-1-ol (73%) and 27% of a 2:1 mixture of the E- and Z-isomers of 4-hydroxy-2-methylbut-2-en-1-ol. In (18O)water (2-18O)2-hydroxy-2-methylbut-3-en-1-ol was obtained. Formation of these products occurs via SN1 ionisation to resonance-stabilised allylic cations which are captured by water. Reaction of rac.-ethenyloxirane with l-valine methyl ester gave diastereoisomeric adducts from SN2 attack of the valine amino at both C-2 (substituted position) and C-3 of the oxirane. The corresponding reaction of rac.-2-methyl-2-ethenyloxirane gave diastereoisomeric adducts, (R, S)- and (S, S)-N-(2-hydroxy-2-methyl-3-buten-1-yl)-l-valine methyl ester, from SN2 attack of the valine amino solely at C-3. Reactions of rac.-2-ethenyl-2-methyloxirane with cysteine derivatives occurred at C-2 in neutral polar media (SN1 reaction) or at C-3 in basic media (SN2), whereas for ethenyloxirane products arose from attack at both C-2 and C-3. Reaction of meso-butadiene diepoxide (meso-2,2'-bioxirane) with l-valine methyl ester gave mainly 2:1 adducts, dimethyl 2,2'-(((2R,3S)-2,3-dihydroxybutane-1,4-diyl)bis(azanediyl))-(2S,2'S)-bis(3-methyl-butanoates), whereas 2-methyl-2,2'-bioxirane gave a mixture of 1:1 [methyl 2-(3,4-dihydroxy-3-methylpyrrolidin-1-yl)-3-methylbutanoates] and 2:1 adducts. Meso-2,2'-bioxirane reacted with N-acetylcysteine methyl ester in methanol to afford meso-thiolane-3,4-diol, by elimination of N-acetyldehydroalanine methyl ester from a precursor cyclic adduct. Similarly, 2-methyl-2,2'-bioxirane gave solely 3-methylthiolane-3,4-diols. Thus, the methyl group of isoprene has a subtle effect on the reactivity of its epoxides relative to those of butadiene and therefore, in the context of their toxicology, could abrogate crosslinking of nitrogen functions in biomolecules related to mutagenicity and carcinogenicity.
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Affiliation(s)
- Bernard T Golding
- School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle Upon, Tyne, NE1 7RU, UK.
| | - Manuel Abelairas-Edesa
- NewChem Technologies, The Biosphere, Draymans Way, Newcastle Helix, Newcastle Upon, Tyne, NE4 5BX, UK
| | - Rowena D Tilbury
- School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle Upon, Tyne, NE1 7RU, UK
| | - Joanne P Wilson
- School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle Upon, Tyne, NE1 7RU, UK
| | - Daping Zhang
- School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle Upon, Tyne, NE1 7RU, UK
| | - Alistair P Henderson
- School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle Upon, Tyne, NE1 7RU, UK; NewChem Technologies, The Biosphere, Draymans Way, Newcastle Helix, Newcastle Upon, Tyne, NE4 5BX, UK
| | - Christine Bleasdale
- School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle Upon, Tyne, NE1 7RU, UK
| | - William Clegg
- School of Natural and Environmental Sciences, Bedson Building, Newcastle University, Newcastle Upon, Tyne, NE1 7RU, UK
| | - William P Watson
- Shell International Chemicals BV, Shell Research and Technology Centre Amsterdam, Toxicology Department, P.O. Box 38000, 1030BN, Amsterdam, the Netherlands; Syngenta Central Toxicology Laboratory, Alderley Park, Macclesfield, SK10 4TJ, UK
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2
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Boysen G, Arora R, Degner A, Vevang KR, Chao C, Rodriguez F, Walmsley SJ, Erber L, Tretyakova NY, Peterson LA. Effects of GSTT1 Genotype on the Detoxification of 1,3-Butadiene Derived Diepoxide and Formation of Promutagenic DNA-DNA Cross-Links in Human Hapmap Cell Lines. Chem Res Toxicol 2020; 34:119-131. [PMID: 33381973 DOI: 10.1021/acs.chemrestox.0c00376] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Smoking is a leading cause of lung cancer, accounting for 81% of lung cancer cases. Tobacco smoke contains over 5000 compounds, of which more than 70 have been classified as human carcinogens. Of the many tobacco smoke constituents, 1,3-butadiene (BD) has a high cancer risk index due to its tumorigenic potency and its abundance in cigarette smoke. The carcinogenicity of BD has been attributed to the formation of several epoxide metabolites, of which 1,2,3,4-diepoxybutane (DEB) is the most toxic and mutagenic. DEB is formed by two oxidation reactions carried out by cytochrome P450 monooxygenases, mainly CYP2E1. Glutathione-S-transferase theta 1 (GSTT1) facilitates the conjugation of DEB to glutathione as the first step of its detoxification and subsequent elimination via the mercapturic acid pathway. Human biomonitoring studies have revealed a strong association between GSTT1 copy number and urinary concentrations of BD-mercapturic acids, suggesting that it plays an important role in the metabolism of BD. To determine the extent that GSTT1 genotype affects the susceptibility of individuals to the toxic and genotoxic properties of DEB, GSTT1 negative and GSTT1 positive HapMap lymphoblastoid cell lines were treated with DEB, and the extent of apoptosis and micronuclei (MN) formation was assessed. These toxicological end points were compared to the formation of DEB-GSH conjugates and 1,4-bis-(guan-7-yl)-2,3-butanediol (bis-N7G-BD) DNA-DNA cross-links. GSTT1 negative cell lines were more sensitive to DEB-induced apoptosis as compared to GSTT1 positive cell lines. Consistent with the protective effect of GSH conjugation against DEB-derived apoptosis, GSTT1 positive cell lines formed significantly more DEB-GSH conjugate than GSTT1 negative cell lines. However, GSTT1 genotype did not affect formation of MN or bis-N7G-BD cross-links. These results indicate that GSTT1 genotype significantly influences BD metabolism and acute toxicity.
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Affiliation(s)
- Gunnar Boysen
- Department of Medicinal Chemistry, University of Minnesota Minneapolis, Minnesota 55455, United States.,Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States.,The Winthrop P Rockefeller Cancer Institute, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, United States
| | - Rashi Arora
- University of Minnesota Masonic Cancer Center, Minneapolis, Minnesota 55455, United States
| | - Amanda Degner
- Department of Medicinal Chemistry, University of Minnesota Minneapolis, Minnesota 55455, United States.,University of Minnesota Masonic Cancer Center, Minneapolis, Minnesota 55455, United States
| | - Karin R Vevang
- Division of Environmental Health Sciences, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Christopher Chao
- Department of Medicinal Chemistry, University of Minnesota Minneapolis, Minnesota 55455, United States
| | - Freddys Rodriguez
- Department of Medicinal Chemistry, University of Minnesota Minneapolis, Minnesota 55455, United States
| | - Scott J Walmsley
- University of Minnesota Masonic Cancer Center, Minneapolis, Minnesota 55455, United States.,Institute for Health Informatics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Luke Erber
- Department of Medicinal Chemistry, University of Minnesota Minneapolis, Minnesota 55455, United States
| | - Natalia Y Tretyakova
- Department of Medicinal Chemistry, University of Minnesota Minneapolis, Minnesota 55455, United States.,University of Minnesota Masonic Cancer Center, Minneapolis, Minnesota 55455, United States
| | - Lisa A Peterson
- University of Minnesota Masonic Cancer Center, Minneapolis, Minnesota 55455, United States.,Division of Environmental Health Sciences, University of Minnesota, Minneapolis, Minnesota 55455, United States
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3
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Analysis of volatile emissions from grape berries infected with Aspergillus carbonarius using hyphenated and portable mass spectrometry. Sci Rep 2020; 10:21179. [PMID: 33273624 PMCID: PMC7713432 DOI: 10.1038/s41598-020-78332-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/17/2020] [Indexed: 11/08/2022] Open
Abstract
Mycotoxins represent a serious risk for human and animal health. Οchratoxin A (OTA) is a carcinogenic mycotoxin produced by A. carbonarius that constitutes a severe problem for viticulture. In this study, we investigate the development of novel detection and on-line monitoring approaches for the detection of OTA in the field (i.e. out of the chemical laboratory) using advanced molecular sensing. Both stand-alone and hyphenated mass spectrometry (MS) based systems (e.g. Time-of-Flight ToF-MS and gas chromatography GC combined with MS) and compact portable membrane inlet MS (MIMS) have been employed for the first time to detect and monitor volatile emissions of grape berries infected by the fungus Aspergillus carbonarius. In vacuo (electron impact-EI) and ambient ionisation (electrospray ionisation-ESI) techniques were also examined. On-line measurements of the volatile emissions of grape berries, infected by various strains of A. carbonarius with different toxicity levels, were performed resulting in different olfactory chemical profiles with a common core of characteristic mass fragments, which could be eventually used for on-site detection and monitoring allowing consequent improvement in food security.
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Walker VE, Degner A, Carter EW, Nicklas JA, Walker DM, Tretyakova N, Albertini RJ. 1,3-Butadiene metabolite 1,2,3,4 diepoxybutane induces DNA adducts and micronuclei but not t(9;22) translocations in human cells. Chem Biol Interact 2019; 312:108797. [PMID: 31422076 DOI: 10.1016/j.cbi.2019.108797] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 07/26/2019] [Accepted: 08/14/2019] [Indexed: 11/26/2022]
Abstract
Epidemiological studies of 1,3-butadiene (BD) exposures have reported a possible association with chronic myelogenous leukemia (CML), which is defined by the presence of the t(9;22) translocation (Philadelphia chromosome) creating an oncogenic BCR-ABL fusion gene. Butadiene diepoxide (DEB), the most mutagenic of three epoxides resulting from BD, forms DNA-DNA crosslink adducts that can lead to DNA double-strand breaks (DSBs). Thus, a study was designed to determine if (±)-DEB exposure of HL60 cells, a promyelocytic leukemia cell line lacking the Philadelphia chromosome, can produce t(9;22) translocations. In HL60 cells exposed for 3 h to 0-10 μM DEB, overlapping dose-response curves suggested a direct relationship between 1,4-bis-(guan-7-yl)-2,3-butanediol crosslink adduct formation (R = 0.977, P = 0.03) and cytotoxicity (R = 0.961, P = 0.002). Experiments to define the relationships between cytotoxicity and the induction of micronuclei (MN), a dosimeter of DNA DSBs, showed that 24 h exposures of HL60 cells to 0-5.0 μM DEB caused significant positive correlations between the concentration and (i) the degree of cytotoxicity (R = 0.998, p = 0.002) and (ii) the frequency of MN (R = 0.984, p = 0.016) at 48 h post exposure. To determine the relative induction of MN and t(9;22) translocations following exposures to DEB, or x-rays as a positive control for formation of t(9;22) translocations, HL60 cells were exposed for 24 h to 0, 1, 2.5, or 5 μM DEB or to 0, 2.0, 3.5, or 5.0 Gy x-rays, or treatments demonstrated to yield 0, 20%, 50%, or 80% cytotoxicity. Treatments between 0 and 3.5 Gy x-rays caused significant dose-related increases in both MN (p < 0.001) and t(9;22) translocations (p = 0.01), whereas DEB exposures causing similar cytotoxicity levels did not increase translocations over background. These data indicate that, while DEB induces DNA DSBs required for formation of MN and translocations, acute DEB exposures of HL60 cells did not produce the Philadelphia chromosome obligatory for CML.
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Affiliation(s)
- Vernon E Walker
- Department of Pathology and Laboratory Medicine, University of Vermont, Burlington, VT, United States.
| | - Amanda Degner
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, United States.
| | - Elizabeth W Carter
- Department of Pathology and Laboratory Medicine, University of Vermont, Burlington, VT, United States.
| | - Janice A Nicklas
- Department of Pediatrics, University of Vermont, Burlington, VT, United States.
| | - Dale M Walker
- The Burlington HC Research Group, Inc., Jericho, VT, United States.
| | - Natalia Tretyakova
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, MN, United States.
| | - Richard J Albertini
- Department of Pathology and Laboratory Medicine, University of Vermont, Burlington, VT, United States.
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Ocular disposition of treosulfan and its active epoxy-transformers following intravenous administration in rabbits. Drug Metab Pharmacokinet 2016; 31:356-362. [PMID: 27662779 DOI: 10.1016/j.dmpk.2016.07.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 06/24/2016] [Accepted: 07/06/2016] [Indexed: 11/22/2022]
Abstract
Treosulfan (TREO) has an established position in chemotherapy of advanced ovarian cancer but has been also applied in uveal melanoma patients. Moreover, it is used as an orphan drug for a myeloablative conditioning prior to stem cell transplantation. In this paper, biodistribution of prodrug TREO and its active monoepoxide (S,S-EBDM) and diepoxide (S,S-DEB) into aqueous humor of the eye was studied for the first time. For that purpose, alone TREO and the mixture of TREO, S,S-EBDM and S,S-DEB were administered intravenously to New Zealand White rabbits. The three analytes were determined in plasma and aqueous humor by validated HPLC methods and pharmacokinetic calculations were performed in WinNonlin. After the infusion of TREO, the aqueous humor/plasma Cmax ratio and area under the curve ratio amounted 0.04 and 0.10 for TREO, and 1.1 and 2.2 for S,S-EBDM, respectively. Following the bolus injection of the mixture of the prodrug and its epoxides, the aqueous humor/plasma Cmax ratios for TREO, S,S-EBDM and S,S-DEB were 0.05, 0.66, and 4.0, respectively. The presented results indicate a poor penetration of TREO into the eye, which may impair systemic treatment of ocular tumors but is beneficial in terms of a lack of clinically relevant ophthalmic adverse effects.
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Pianalto KM, Hartman JH, Boysen G, Miller GP. Differences in butadiene adduct formation between rats and mice not due to selective inhibition of CYP2E1 by butadiene metabolites. Toxicol Lett 2013; 223:221-7. [PMID: 24021170 PMCID: PMC3831829 DOI: 10.1016/j.toxlet.2013.08.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 08/29/2013] [Accepted: 08/30/2013] [Indexed: 10/26/2022]
Abstract
CYP2E1 metabolizes 1,3-butadiene (BD) into genotoxic and possibly carcinogenic 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 1,2-epoxy-3,4-butanediol (EB-diol). The dose response of DNA and protein adducts derived from BD metabolites increases linearly at low BD exposures and then saturates at higher exposures in rats, but not mice. It was hypothesized that differences in adduct formation between rodents reflect more efficient BD oxidation in mice than rats. Herein, we assessed whether BD-derived metabolites selectively inhibit rat but not mouse CYP2E1 activity using B6C3F1 mouse and Fisher 344 rat liver microsomes. Basal CYP2E1 activities toward 4-nitrophenol were similar between rodents. Through IC50 studies, EB was the strongest inhibitor (IC50 54μM, mouse; 98μM, rat), BD-diol considerably weaker (IC50 1200μM, mouse; 1000μM, rat), and DEB inhibition nonexistent (IC50>25mM). Kinetic studies showed that in both species EB and BD-diol inhibited 4-nitrophenol oxidation through two-site mechanisms in which inhibition constants reflected trends observed in IC50 studies. None of the reactive epoxide metabolites inactivated CYP2E1 irreversibly. Thus, there was no selective inhibition or inactivation of rat CYP2E1 by BD metabolites relative to mouse Cyp2e1, and it can be inferred that CYP2E1 activity toward BD between rodent species would similarly not be impacted by the presence of BD metabolites. Inhibition of CYP2E1 by BD metabolites is then not responsible for the reported species difference in BD metabolism, formation of BD-derived DNA and protein adducts, mutagenicity and tumorigenesis.
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Affiliation(s)
- Kaila M. Pianalto
- Department of Chemistry and Biochemistry, University of Arkansas at Fayetteville, Fayetteville, AR 72701, USA
| | - Jessica H. Hartman
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Gunnar Boysen
- Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Grover P. Miller
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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7
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Swenberg JA, Bordeerat NK, Boysen G, Carro S, Georgieva NI, Nakamura J, Troutman JM, Upton PB, Albertini RJ, Vacek PM, Walker VE, Sram RJ, Goggin M, Tretyakova N. 1,3-Butadiene: Biomarkers and application to risk assessment. Chem Biol Interact 2011; 192:150-4. [PMID: 20974116 PMCID: PMC3501005 DOI: 10.1016/j.cbi.2010.10.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 10/14/2010] [Accepted: 10/15/2010] [Indexed: 10/18/2022]
Abstract
1,3-Butadiene (BD) is a known rodent and human carcinogen that is metabolized mainly by P450 2E1 to three epoxides, 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB) and 1,2-epoxy-3,4-butanediol (EB-diol). The individual epoxides vary up to 200-fold in their mutagenic potency, with DEB being the most mutagenic metabolite. It is important to understand the internal formation of the individual epoxides to assign the relative risk for each metabolite and to understand the molecular mechanisms responsible for major species differences in carcinogenicity. We have conducted extensive exposure-biomarker studies on mice, rats and humans. Using low exposures that range from current occupational levels to human exposures from tobacco smoke has provided evidence that mice are very different from humans, with mice forming ∼200 times more DEB than humans at exposures of 0.1-1.5ppm BD. While no gender differences have been noted in mice and rats for globin adducts or N-7 guanine adducts, female rats and mice had 2-3-fold higher Hprt mutations and DNA-DNA cross-links, suggesting a gender difference in DNA repair. Numerous molecular epidemiology studies have evaluated globin adducts and Hprt mutations, SCEs and chromosomal abnormalities. None of the blinded studies have shown evidence of human genotoxicity at current occupational exposures and studies of globin adducts have shown similar or lower formation of adducts in females than males. If one calculates the EB dose-equivalents for the three species, mice clearly differ from rats and humans, being ∼44 and 174 times greater than rats and humans, respectively. These data provide a scientific basis for improved risk assessment of BD.
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Affiliation(s)
- James A Swenberg
- Department of Environmental Sciences and Engineering, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27559, USA.
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Kim MY. Genotoxicity of stereoisomers of 1,2,3,4-diepoxybutane in the gpt gene of Chinese hamster ovary AS52 cells. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2011; 86:587-590. [PMID: 21516456 DOI: 10.1007/s00128-011-0280-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Accepted: 04/15/2011] [Indexed: 05/30/2023]
Abstract
Three optical isomers of 1,2,3,4-diepoxybutane, S,S-, R,R-, and meso-diepoxybutane, are produced by the metabolic processing of carcinogenic 1,3-butadiene. Our previous studies suggested that the observed differences between the biological effects of diepoxybutane optical isomers may be structural in their origin. Therefore, we examined the cytotoxicity and mutation fraction induced by three diepoxybutane stereoisomers in Chinese hamster ovary AS52 cells. All three stereoisomers reduced cell survival and increased gpt mutation fraction compared to the control; S,S-diepoxybutane exhibits the greatest cytotoxic and genotoxic potency, followed by R,R- and then meso-diepoxybutane. These results suggest that the cytotoxic and mutagenic effects of diepoxybutane are mediated by the stereochemical configurations of its isomers.
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Affiliation(s)
- Min Young Kim
- Faculty of Biotechnology, College of Applied Life Sciences, Jeju National University, Jeju 690-756, Republic of Korea.
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9
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Goggin M, Sangaraju D, Walker VE, Wickliffe J, Swenberg JA, Tretyakova N. Persistence and repair of bifunctional DNA adducts in tissues of laboratory animals exposed to 1,3-butadiene by inhalation. Chem Res Toxicol 2011; 24:809-17. [PMID: 21452897 DOI: 10.1021/tx200009b] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1,3-Butadiene (BD) is an important industrial and environmental chemical classified as a human carcinogen. The mechanism of BD-mediated cancer is of significant interest because of the widespread exposure of humans to BD from cigarette smoke and urban air. BD is metabolically activated to 1,2,3,4-diepoxybutane (DEB), which is a highly genotoxic and mutagenic bis-alkylating agent believed to be the ultimate carcinogenic species of BD. We have previously identified several types of DEB-specific DNA adducts, including bis-N7-guanine cross-links (bis-N7-BD), N(6)-adenine-N7-guanine cross-links (N(6)A-N7G-BD), and 1,N(6)-dA exocyclic adducts. These lesions were detected in tissues of laboratory rodents exposed to BD by inhalation ( Goggin et al. (2009) Cancer Res. 69 , 2479 -2486 ). In the present work, persistence and repair of bifunctional DEB-DNA adducts in tissues of mice and rats exposed to BD by inhalation were investigated. The half-lives of the most abundant cross-links, bis-N7G-BD, in mouse liver, kidney, and lungs were 2.3-2.4 days, 4.6-5.7 days, and 4.9 days, respectively. The in vitro half-lives of bis-N7G-BD were 3.5 days (S,S isomer) and 4.0 days (meso isomer) due to their spontaneous depurination. In contrast, tissue concentrations of the minor DEB adducts, N7G-N1A-BD and 1,N(6)-HMHP-dA, remained essentially unchanged during the course of the experiment, with an estimated t(1/2) of 36-42 days. No differences were observed between DEB-DNA adduct levels in BD-treated wild type mice and the corresponding animals deficient in methyl purine glycosylase or the Xpa gene. Our results indicate that DEB-induced N7G-N1A-BD and 1,N(6)-HMHP-dA adducts persist in vivo, potentially contributing to mutations and cancer observed as a result of BD exposure.
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Affiliation(s)
- Melissa Goggin
- Department of Medicinal Chemistry and Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Kirkland D, Reeve L, Gatehouse D, Vanparys P. A core in vitro genotoxicity battery comprising the Ames test plus the in vitro micronucleus test is sufficient to detect rodent carcinogens and in vivo genotoxins. Mutat Res 2011; 721:27-73. [PMID: 21238603 DOI: 10.1016/j.mrgentox.2010.12.015] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 11/12/2010] [Accepted: 12/15/2010] [Indexed: 01/27/2023]
Abstract
In vitro genotoxicity testing needs to include tests in both bacterial and mammalian cells, and be able to detect gene mutations, chromosomal damage and aneuploidy. This may be achieved by a combination of the Ames test (detects gene mutations) and the in vitro micronucleus test (MNvit), since the latter detects both chromosomal aberrations and aneuploidy. In this paper we therefore present an analysis of an existing database of rodent carcinogens and a new database of in vivo genotoxins in terms of the in vitro genotoxicity tests needed to detect their in vivo activity. Published in vitro data from at least one test system (most were from the Ames test) were available for 557 carcinogens and 405 in vivo genotoxins. Because there are fewer publications on the MNvit than for other mammalian cell tests, and because the concordance between the MNvit and the in vitro chromosomal aberration (CAvit) test is so high for clastogenic activity, positive results in the CAvit test were taken as indicative of a positive result in the MNvit where there were no, or only inadequate data for the latter. Also, because Hprt and Tk loci both detect gene-mutation activity, a positive Hprt test was taken as indicative of a mouse-lymphoma Tk assay (MLA)-positive, where there were no data for the latter. Almost all of the 962 rodent carcinogens and in vivo genotoxins were detected by an in vitro battery comprising Ames+MNvit. An additional 11 carcinogens and six in vivo genotoxins would apparently be detected by the MLA, but many of these had not been tested in the MNvit or CAvit tests. Only four chemicals emerge as potentially being more readily detected in MLA than in Ames+MNvit--benzyl acetate, toluene, morphine and thiabendazole--and none of these are convincing cases to argue for the inclusion of the MLA in addition to Ames+MNvit. Thus, there is no convincing evidence that any genotoxic rodent carcinogens or in vivo genotoxins would remain undetected in an in vitro test battery consisting of Ames+MNvit.
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Affiliation(s)
- David Kirkland
- Kirkland Consulting, PO Box 79, Tadcaster LS24 0AS, United Kingdom.
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Albertini RJ, Carson ML, Kirman CR, Gargas ML. 1,3-Butadiene: II. Genotoxicity profile. Crit Rev Toxicol 2010; 40 Suppl 1:12-73. [PMID: 20868267 DOI: 10.3109/10408444.2010.507182] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
1,3-Butadiene’s (BD’s) major electrophilic metabolites 1,2-epoxy-3-butene (EB), 1,2-dihydroxy-3,4-epoxybutane (EBD), and 1,2,3,4-diepoxybutane (DEB) are responsible for both its mutagenicity and carcinogenicity. EB, EBD, and DEB are DNA reactive, forming a variety of adducts. All three metabolites are genotoxic in vitro and in vivo, with relative mutagenic potencies of DEB >> EB > EBD. DEB also effectively produces gene deletions and chromosome aberrations. BD’s greater mutagenicity and carcinogenicity in mice over rats as well as its failure to induce chromosome-level mutations in vivo in rats appear to be due to greater production of DEB in mice. Concentrations of EB and DEB in vivo in humans are even lower than in rats. Although most studies of BD-exposed humans have failed to find increases in gene mutations, one group has reported positive findings. Reasons for these discordant results are examined. BD-related chromosome aberrations have never been demonstrated in humans except for the possible production of micronuclei in lymphocytes of workers exposed to extremely high levels of BD in the workplace. The relative potencies of the BD metabolites, their relative abundance in the different species, and the kinds of mutations they can induce are major considerations in BD’s overall genotoxicity profile.
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Affiliation(s)
- Richard J Albertini
- Pathology Department, College of Medicine, University of Vermont, Burlington, Vermont, USA
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Goggin M, Seneviratne U, Swenberg JA, Walker VE, Tretyakova N. Column switching HPLC-ESI(+)-MS/MS methods for quantitative analysis of exocyclic dA adducts in the DNA of laboratory animals exposed to 1,3-butadiene. Chem Res Toxicol 2010; 23:808-12. [PMID: 20229982 DOI: 10.1021/tx900439w] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
1,3-Butadiene (BD) is an important industrial and environmental chemical classified as a human carcinogen on the basis of epidemiological evidence for an increased incidence of leukemia in workers occupationally exposed to BD and its carcinogenicity in laboratory rats and mice. BD is metabolically activated to epoxide intermediates that can react with nucleophilic sites of cellular biomolecules. Among these, 1,2,3,4-diepoxybutane (DEB) is considered the ultimate carcinogenic species of BD due to its potent genotoxicity and mutagenicity attributed to the ability to form DNA-DNA cross-links and exocyclic nucleoside adducts. DEB mutagenesis studies suggest that adducts formed at adenine bases may be critically important, as DEB induces large numbers of A --> T transversion mutations. We have recently identified two regioisomeric exocyclic DEB-dA adducts, 1,N(6)-(2-hydroxy-3-hydroxymethylpropan-1,3-diyl)-2'-deoxyadenosine (1,N(6)-gamma-HMHP-dA) and 1,N(6)-(1-hydroxymethyl-2-hydroxypropan-1,3-diyl)-2'-deoxyadenosine (1,N(6)-alpha-HMHP-dA) ( Seneviratne et al. ( ( 2010 ) Chem. Res. Toxicol. 23 , 118 - 133 ), which were detected in DEB-treated calf thymus DNA and in tissues of BD-exposed laboratory animals. In the present work, we describe a column switching HPLC-ESI(+)-MS/MS methodology for the quantitative analysis of 1,N(6)-HMHP-dA isomers in the DNA of laboratory mice exposed to BD by inhalation. On the basis of their exocyclic structure, which prevents normal Watson-Crick base pairing, these adducts could be responsible for mutations at the A:T base pairs observed following exposure to DEB.
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Affiliation(s)
- Melissa Goggin
- Department of Medicinal Chemistry and the Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, USA
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Hemoglobin adducts in 1,3-butadiene exposed Czech workers: female-male comparisons. Chem Biol Interact 2010; 188:668-76. [PMID: 20619252 DOI: 10.1016/j.cbi.2010.06.017] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 06/28/2010] [Accepted: 06/29/2010] [Indexed: 11/22/2022]
Abstract
We previously reported results of a molecular epidemiological study of female and male 1,3-butadiene (BD) exposed Czech workers showing that females appeared to absorb or metabolize less BD per unit exposure concentration than did males, based on metabolite concentrations in urine (Chem. Biol. Interact. 166 (2007) 63-77). However, that unexpected observation could not be verified at the time because the only additional BD metabolite measurement attempted was for 1,2,3,4-diepoxybutane (DEB) as reflected in specific N,N[2,3-dihydroxy-1,4-butyl]valine (pyr-Val) hemoglobin adduct concentrations, which were not quantifiable in any subject with the method then employed. Neither somatic gene mutations nor chromosome aberrations were associated with BD exposure levels in that study, consistent with findings in an earlier Czech study of males only. We have since measured production and accumulation of the 1,2-dihydroxy-3,4-epoxybutane (EBD) metabolite as reflected in N-[2,3,4-trihydroxy-butyl]valine (THB-Val) hemoglobin adduct concentrations. The mean THB-Val concentration was significantly higher in exposed males than in control males (922.3pmol/g and 275.5pmol/g, respectively), but exposed and control females did not differ significantly (224.5pmol/g and 181.1pmol/g, respectively). In both the control and exposed groups mean THB-Val concentrations were significantly higher for males than females. THB-Val concentrations were significantly correlated with mean 8-h TWA exposures for both males and females, but the rate of increase with increasing BD exposure was significantly lower for females. THB-Val concentrations also increased with increasing urine M2 metabolite [isomeric mixture of 1-hydroxy-2-{N-actylcysteinyl}-3-butene and 2-hydroxy-1-{N-acetylcysteinyl}-3-butene] concentrations in both sexes but the rate of increase was also lower in females than in males. There were no significant correlations between THB-Val concentrations and either somatic gene mutations or chromosome aberrations in either males or females. These results using another biomarker to measure a second metabolite of BD support the original conclusion that females absorb or metabolize less BD than males per unit exposure and indicate that the size of the difference increases with exposure. This observation in humans differs from findings in rodents where at prolonged exposures to high BD levels the females form higher amounts of hemoglobin adducts than do males, a difference that disappears at shorter duration lower exposure levels, while female susceptibility to BD induced mutations and tumorgenesis in rodents appears to persist at all BD exposure levels.
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Georgieva NI, Boysen G, Bordeerat N, Walker VE, Swenberg JA. Exposure-response of 1,2:3,4-diepoxybutane-specific N-terminal valine adducts in mice and rats after inhalation exposure to 1,3-butadiene. Toxicol Sci 2010; 115:322-9. [PMID: 20176624 PMCID: PMC2871755 DOI: 10.1093/toxsci/kfq060] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Accepted: 02/17/2010] [Indexed: 12/25/2022] Open
Abstract
1,3-Butadiene (BD) is a known rodent and human carcinogen that is metabolized mainly by P450 2E1 to three epoxides, 1,2-epoxy-3-butene (EB), 1,2:3,4-diepoxybutane (DEB), and 1,2-epoxy-3,4-butanediol. The individual epoxides vary up to 200-fold in their mutagenic potency, with DEB being the most mutagenic metabolite. It is important to understand the internal formation of the individual epoxides to assign the relative risk for each metabolite and to understand the molecular mechanisms responsible for extensive species differences in carcinogenicity. This study presents a comprehensive exposure-response for the formation of the DEB-specific N,N-(2,3-dihydroxy-1,4-butadiyl)valine (pyr-Val) in mice and rats. Using nano-ultra high pressure liquid chromatography-tandem-mass spectrometry allowed analysis of pyr-Val in mice and rats exposed to BD as low as 0.1 and 0.5 ppm BD, respectively, and demonstrated significant differences in the amounts and exposure-response of pyr-Val formation. Mice formed 10- to 60-fold more pyr-Val compared to rats at similar exposures. The formation of pyr-Val increased with exposures, and the formation was most efficient with regard to formation per parts per million BD at low exposures. While formation at higher exposures appeared linear in mice, in rats formation saturated at exposures > or = 200 ppm for 10 days. In rats, amounts of pyr-Val were lower after 20 days than after 10 days of exposure, suggesting that the lifespan of rat erythrocytes may be shortened following exposure to BD. This research supports the hypothesis that the lower susceptibility of rats to BD-induced carcinogenesis results from greatly reduced formation of DEB following exposure to BD.
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Affiliation(s)
| | - Gunnar Boysen
- Department of Environmental Sciences and Engineering
- Center for Environmental Health and Susceptibility, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Department of Environmental and Occupational Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
| | | | - Vernon E. Walker
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87108
- Department of Pathology, University of Vermont, Burlington, Vermont 05405
| | - James A. Swenberg
- Department of Environmental Sciences and Engineering
- Center for Environmental Health and Susceptibility, Gillings School of Global Public Health, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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Himmelstein MW, Baan RA, Albertini RJ, Bird MG, Lewis RJ. International Symposium on the Evaluation of Butadiene and Chloroprene Health Risks. Chem Biol Interact 2007; 166:1-9. [PMID: 17336954 DOI: 10.1016/j.cbi.2007.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Revised: 02/09/2007] [Accepted: 02/12/2007] [Indexed: 11/29/2022]
Abstract
These proceedings represent nearly all the platform and poster presentations given during the International Symposium on Evaluation of Butadiene and Chloroprene Health Risks, held in Charleston, South Carolina, USA, on September 20-22, 2005. The Symposium was attended by 78 participants representing private industry (37), academia (21), government (11), not-for-profit organizations (5), and consulting (4). The program followed the format of previous symposia on butadiene, chloroprene, and isoprene in London UK (2000) and butadiene and isoprene in Blaine, Washington USA (1995). This format enabled the exchange of significant new scientific results and discussion of future research needs. Isoprene was not evaluated during the 2005 Symposium because of lack of new data. For background information, the reader is referred to the proceedings of the London 2000 meeting for a thorough historical perspective and overview of scientific and regulatory issues concerning butadiene, chloroprene, and isoprene [Chem.-Biol. Interact. (2001) 135-136:1-7]. The Symposium consisted of seven sessions: (1) Introduction and Opening Remarks, (2) Butadiene/styrene-butadiene rubber (SBR)--Process Overview, Exposure and Health Effects/Human Studies; (3) Chloroprene--Process Overview, Exposure and Health Effects/Human Studies; (4) Mode of Action/Key Events; (5) Risk Assessment; (6) Poster Presentations; and (7) Panel Discussion and Future Directions. The Symposium concluded with a discussion by all participants of issues that arose throughout the course of the Symposium. The Proceedings of the Symposium published in this Special Issue are organized according to the Sessions outlined above. The purpose of this foreword is to summarize the presentations and their key findings and recommend future research directions for each chemical.
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Affiliation(s)
- Matthew W Himmelstein
- DuPont Haskell Laboratory for Health and Environmental Sciences, Newark, DE 19714, USA.
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Swenberg JA, Boysen G, Georgieva N, Bird MG, Lewis RJ. Future directions in butadiene risk assessment and the role of cross-species internal dosimetry. Chem Biol Interact 2007; 166:78-83. [PMID: 17343837 DOI: 10.1016/j.cbi.2007.01.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 01/26/2007] [Accepted: 01/26/2007] [Indexed: 11/21/2022]
Abstract
The 2005 International Symposium on the evaluation of butadiene and chloroprene health risks provided the opportunity to consider the past, present and future state of research issues for 1,3-butadiene. Considerable advancements have been made in our knowledge of exposure, metabolism, biomarkers of exposure and effect, and epidemiology. Despite this, uncertainties remain which will impact the human health risk assessment for current worker and environmental exposures. This paper reviews key aspects of recent studies and the role that biomarkers of internal dosimetry can play in addressing low to high exposure, gender, and cross-species differences in butadiene toxicity and metabolism. Considerable information is now available on the detection and quantification of protein adducts formed from the mono-, di- and dihydroxy-epoxide metabolites of butadiene. The diepoxide metabolite appears to play a key role in mutagenesis. Species differences in production of this critical metabolite are reflected by the diepoxybutane-specific hemoglobin adduct, pry-Val. To date, the pry-Val adduct has not been quantifiable in human blood samples from workers with cumulative occupational exposures up to 6.3 ppm-weeks; whereas, the pry-Val was quantifiable in the blood of mice and rats with similar cumulative exposures. Levels in mice were much higher than in rats. Further improvements in analytical sensitivity for the pyr-Val adduct are on the horizon. Epidemiology studies are also described and ongoing efforts promise to help bridge our understanding of past and future risks.
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Affiliation(s)
- James A Swenberg
- Laboratory of Molecular Mutagenesis and Carcinogenesis, University of North Carolina, Chapel Hill, NC 27599, USA.
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