1
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Dhaked DK, Nicklaus MC. What impact does tautomerism have on drug discovery and development? Expert Opin Drug Discov 2024:1-6. [PMID: 39014878 DOI: 10.1080/17460441.2024.2379873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Accepted: 07/10/2024] [Indexed: 07/18/2024]
Affiliation(s)
- Devendra K Dhaked
- Department of Pharmacoinformatics, National Institute of Pharmaceutical Education and Research (NIPER), Kolkata, India
| | - Marc C Nicklaus
- Computer-Aided Drug Design Group, Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, NIH, Frederick, MD, USA
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2
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Georgiou-Siafis SK, Tsiftsoglou AS. The Key Role of GSH in Keeping the Redox Balance in Mammalian Cells: Mechanisms and Significance of GSH in Detoxification via Formation of Conjugates. Antioxidants (Basel) 2023; 12:1953. [PMID: 38001806 PMCID: PMC10669396 DOI: 10.3390/antiox12111953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 10/18/2023] [Accepted: 10/23/2023] [Indexed: 11/26/2023] Open
Abstract
Glutathione (GSH) is a ubiquitous tripeptide that is biosynthesized in situ at high concentrations (1-5 mM) and involved in the regulation of cellular homeostasis via multiple mechanisms. The main known action of GSH is its antioxidant capacity, which aids in maintaining the redox cycle of cells. To this end, GSH peroxidases contribute to the scavenging of various forms of ROS and RNS. A generally underestimated mechanism of action of GSH is its direct nucleophilic interaction with electrophilic compounds yielding thioether GSH S-conjugates. Many compounds, including xenobiotics (such as NAPQI, simvastatin, cisplatin, and barbital) and intrinsic compounds (such as menadione, leukotrienes, prostaglandins, and dopamine), form covalent adducts with GSH leading mainly to their detoxification. In the present article, we wish to present the key role and significance of GSH in cellular redox biology. This includes an update on the formation of GSH-S conjugates or GSH adducts with emphasis given to the mechanism of reaction, the dependence on GST (GSH S-transferase), where this conjugation occurs in tissues, and its significance. The uncovering of the GSH adducts' formation enhances our knowledge of the human metabolome. GSH-hematin adducts were recently shown to have been formed spontaneously in multiples isomers at hemolysates, leading to structural destabilization of the endogenous toxin, hematin (free heme), which is derived from the released hemoglobin. Moreover, hemin (the form of oxidized heme) has been found to act through the Kelch-like ECH associated protein 1 (Keap1)-nuclear factor erythroid 2-related factor-2 (Nrf2) signaling pathway as an epigenetic modulator of GSH metabolism. Last but not least, the implications of the genetic defects in GSH metabolism, recorded in hemolytic syndromes, cancer and other pathologies, are presented and discussed under the framework of conceptualizing that GSH S-conjugates could be regarded as signatures of the cellular metabolism in the diseased state.
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Affiliation(s)
| | - Asterios S. Tsiftsoglou
- Laboratory of Pharmacology, Department of Pharmaceutical Sciences, School of Health Sciences, Aristotle University of Thessaloniki (AUTh), 54124 Thessaloniki, Greece;
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3
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Biological Assessment of Potential Exposure to Occupational Substances in Current Semiconductor Workers with at Least 5 Years of Employment. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19148737. [PMID: 35886589 PMCID: PMC9318163 DOI: 10.3390/ijerph19148737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/15/2022] [Accepted: 07/16/2022] [Indexed: 12/10/2022]
Abstract
Background: this study aimed to conduct a biological assessment of the potential exposure to carcinogenic substances in current semiconductor workers. Methods: A cross-sectional study was conducted on 306 semiconductor workers. The assessed biomarkers were as follows: (benzene) urine S-phenylmercapturic, trans,trans-muconic acid, blood benzene; (trichloroethylene) urine trichloroacetic acid; (2-ethoxyethanol) 2-ethoxyacetic acid; (arsine) urine arsenic3+, arsenic5+, monomethylarsonic, dimethylarsinic acid, arsenobetaine; (shift work) 6-hydroxymelatonin; (smoking) cotinine, and (radiation). The detection rate of these materials is defined as more than the biological exposure index (BEI) or the previous reference value. Results: Some workers exposed to trans,trans-muconic acid, trichloroacetic acid, and arsenic5+ showed high BEI levels. Generally, there was no difference according to job categories, and workers were suspected to be exposed to other sources. The melatonin concentration tended to decrease when working at night, and cotinine was identified as an excellent surrogate marker for smoking. In the case of radiation exposure, there was no significant difference in the number of stable chromosome translocation in 19 semiconductor workers. Their estimated radiation exposure level was below the limit of detection (LOD) or near the LOD level. Conclusion: In this study, most carcinogens were below the BEI level, but verification through re-measurement was needed for workers who were identified to have a high BEI level. For continuous monitoring, a prospective cohort is necessary to deal with the healthy worker effect and assess additional materials.
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4
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Sun R, Yu L, Xu K, Pu Y, Huang J, Liu M, Zhang J, Yin L, Pu Y. Evi1 involved in benzene-induced haematotoxicity via modulation of PI3K/mTOR pathway and negative regulation Serpinb2. Chem Biol Interact 2022; 354:109836. [PMID: 35092719 DOI: 10.1016/j.cbi.2022.109836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/08/2022] [Accepted: 01/24/2022] [Indexed: 12/11/2022]
Abstract
Benzene is a widely used chemical and an environmental pollutant. Exposure to benzene can cause blood diseases, but the mechanisms underlying benzene haematotoxicity have not been fully clarified. Ecotropic virus integration site-1 (Evi1), a transcription factor, plays important roles in normal haematopoiesis and haematological diseases. In this study, we investigated the role and mechanism of Evi1 in benzene-induced haematotoxicity. We found that benzene exposure significantly increased Evi1 level in white blood cells (WBCs) in occupational benzene workers as well as mouse bone marrow cells. Further in vitro results demonstrated that compared with control cells exposed to same 1,4-benzoquinone (1,4-BQ, an important active metabolite of benzene) concentration, Evi1 downregulation significantly reduced cell proliferation, and disrupted cell viability, apoptosis, erythroid and megakaryotic cell differentiation and cell cycle. Additionally, down-regulation of Evi1 suppressed phosphoinositide 3-kinase (PI3K)/mTOR signalling pathway and elevated its target gene Serpinb2 following 1,4-BQ exposure. Moreover, the PI3K activator could partially relieve the inhibitory effect of down-regulation of Evi1 on cell proliferation and increase cell arrest in in G2/M phase. What's more, downregulation of Serpinb2 could partially alleviate proliferation inhibition and reverse cell cycle changes in G0/G1 phase and S phase induced by Evi1 inhibition. In conclusion, our data revealed that Evi1 downregulation aggravated the inhibition of cell proliferation and arrested cells in the G0/G1 phase when exposed to 1,4-BQ, potentially by inactivating the PI3K/mTOR pathway and upregulating downstream target gene Serpinb2. Our study provides novel insights on mechanism by which Evi1 participates in benzene-induced haematotoxicity.
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Affiliation(s)
- Rongli Sun
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China.
| | - Linling Yu
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Kai Xu
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Yunqiu Pu
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Jiawei Huang
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Manman Liu
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Juan Zhang
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Lihong Yin
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China
| | - Yuepu Pu
- Key Laboratory of Environmental Medicine Engineering, Ministry of Education, School of Public Health, Southeast University, Nanjing, 210009, Jiangsu, China.
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5
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Monooxygenase- and Dioxygenase-Catalyzed Oxidative Dearomatization of Thiophenes by Sulfoxidation, cis-Dihydroxylation and Epoxidation. Int J Mol Sci 2022; 23:ijms23020909. [PMID: 35055091 PMCID: PMC8777831 DOI: 10.3390/ijms23020909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/31/2021] [Accepted: 01/05/2022] [Indexed: 11/17/2022] Open
Abstract
Enzymatic oxidations of thiophenes, including thiophene-containing drugs, are important for biodesulfurization of crude oil and drug metabolism of mono- and poly-cyclic thiophenes. Thiophene oxidative dearomatization pathways involve reactive metabolites, whose detection is important in the pharmaceutical industry, and are catalyzed by monooxygenase (sulfoxidation, epoxidation) and dioxygenase (sulfoxidation, dihydroxylation) enzymes. Sulfoxide and epoxide metabolites of thiophene substrates are often unstable, and, while cis-dihydrodiol metabolites are more stable, significant challenges are presented by both types of metabolite. Prediction of the structure, relative and absolute configuration, and enantiopurity of chiral metabolites obtained from thiophene enzymatic oxidation depends on the substrate, type of oxygenase selected, and molecular docking results. The racemization and dimerization of sulfoxides, cis/trans epimerization of dihydrodiol metabolites, and aromatization of epoxides are all factors associated with the mono- and di-oxygenase-catalyzed metabolism of thiophenes and thiophene-containing drugs and their applications in chemoenzymatic synthesis and medicine.
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6
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Golabi-Habashi N, Salimi A, Malekinejad H. Quercetin attenuated the Benzene-induced hemato- and hepatotoxicity in mice. Toxicol Rep 2021; 8:1569-1575. [PMID: 34430219 PMCID: PMC8367781 DOI: 10.1016/j.toxrep.2021.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2021] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 11/29/2022] Open
Abstract
The protective effects of Quercetin (QCN) on Benzene (BNZ)-induced hemato- and hepatotoxicy were investigated. To reach this goal, 36 adult male mice were divided into 6 groups (n = 6). The control group was not exposed to BNZ, while animals in BNZ group were exposed to BNZ (30 ppm) and the animals of QCN group were received QCN (50 mg/kg, orally), the fourth, fifth and sixth groups were exposed to 30 ppm BNZ and received 10, 50 and 100 mg/kg QCN one h before the BNZ exposure, for 28 days. The day after the last exposure following anesthesia and the blood collection, the liver and femur tissues were collected. The bone marrow samples were extracted and subjected to micronucleus assay. The blood samples were processed for hematological and biochemical analyses. Histopathological examinations were performed on the liver samples. QCN reduced significantly (p < 0.05) the BNZ-elevated hepatic enzymes and ameliorated the BNZ-induced WBC and RBC reduction. The BNZ-elevated micronucleus percentage both in the bone marrow and peripheral blood was remarkably declined in the QCN-received groups. QCN improved the BNZ-induced histopathological changes and oxidative status in the liver and serum. Our results suggest that QCN could be a protective supplement to reduce the BNZ-induced hemato- and hepatotoxicities.
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Affiliation(s)
- Nayyer Golabi-Habashi
- Department of Pharmacology & Toxicology, School of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Ahmad Salimi
- Department of Pharmacology & Toxicology, School of Pharmacy, Ardabil University of Medical Sciences, Ardabil, Iran
- Traditional Medicine and Hydrotherapy Research Center, Ardabil University of Medical Sciences, Ardabil, Iran
| | - Hassan Malekinejad
- Department of Pharmacology & Toxicology, School of Pharmacy, Urmia University of Medical Sciences, Urmia, Iran
- Experimental and Applied Pharmaceutical Sciences Research Center, Urmia University of Medical Sciences, Urmia, Iran
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7
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Méausoone C, Landkocz Y, Cazier F, Seigneur M, Courcot D, Billet S. Toxicological responses of BEAS-2B cells to repeated exposures to benzene, toluene, m-xylene, and mesitylene using air-liquid interface method. J Appl Toxicol 2020; 41:1262-1274. [PMID: 33269480 DOI: 10.1002/jat.4113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/16/2020] [Accepted: 11/02/2020] [Indexed: 12/27/2022]
Abstract
In order to reduce exposure to toxic chemicals, the European REACH regulation (1907/2006) recommends substituting toxic molecules with compounds that are less harmful to human health and the environment. Toluene is one of the most frequently used solvents in industries despite its toxicity. The objective of this study is to better understand and compare the toxicity of toluene and its homologues in a bronchial cell model. Thus, human bronchial BEAS-2B cells were exposed to steams of toluene, m-xylene, mesitylene (1,3,5-trimethylbenzene), and benzene (20 and 100 ppm). Exposure was carried out using an air-liquid interface (ALI) system (Vitrocell) during 1 h/day for 1, 3, or 5 days. Cytotoxicity, xenobiotic metabolism enzyme gene expression, and inflammatory response were evaluated following cell exposures. BEAS-2B cell exposure to toluene and its homologues revealed the involvement of major (CYP2E1) and minor metabolic pathways (CYP1A1). A late induction of genes (EPHX1, DHDH, ALDH2, and ALDH3B1) was measured from Day 3 and can be linked to the formation of metabolites. An increase in the secretion level of inflammatory markers (TNF-α, IL-6, IL-8, MCP-1, and GM-CSF) was also observed. In parallel, regulation between inflammatory mediators and the expression of transmembrane glycoprotein mucin MUC1 was also studied. This in vitro approach with ALI system points out the relevance of conducting repeated exposures to detect potential late effects. The difference recorded after cell exposure to toluene and its homologues highlights the importance of substitution principle.
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Affiliation(s)
- Clémence Méausoone
- Unité de Chimie Environnementale et Interactions sur le Vivant, SFR Condorcet FR CNRS 3417, Université du Littoral Côte d'Opale, Dunkirk, France
| | - Yann Landkocz
- Unité de Chimie Environnementale et Interactions sur le Vivant, SFR Condorcet FR CNRS 3417, Université du Littoral Côte d'Opale, Dunkirk, France
| | - Fabrice Cazier
- Centre Commun de Mesures, Université du Littoral Côte d'Opale, Dunkirk, France
| | - Marianne Seigneur
- Unité de Chimie Environnementale et Interactions sur le Vivant, SFR Condorcet FR CNRS 3417, Université du Littoral Côte d'Opale, Dunkirk, France
| | - Dominique Courcot
- Unité de Chimie Environnementale et Interactions sur le Vivant, SFR Condorcet FR CNRS 3417, Université du Littoral Côte d'Opale, Dunkirk, France
| | - Sylvain Billet
- Unité de Chimie Environnementale et Interactions sur le Vivant, SFR Condorcet FR CNRS 3417, Université du Littoral Côte d'Opale, Dunkirk, France
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8
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Schleif T, Prado Merini M, Sander W. The Mystery of the Benzene-Oxide/Oxepin Equilibrium-Heavy-Atom Tunneling Reversed by Solvent Interactions. Angew Chem Int Ed Engl 2020; 59:20318-20322. [PMID: 32816382 PMCID: PMC7702039 DOI: 10.1002/anie.202010452] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Indexed: 11/24/2022]
Abstract
The equilibrium between benzene oxide (1) and oxepin (2) is of large importance for understanding the degradation of benzene in biological systems and in the troposphere. Our studies reveal that at cryogenic temperatures, this equilibration is governed by rare heavy-atom tunneling. In solid argon at 3 K, 1 rearranges to 2 via tunneling with a rate constant of approximately 5.3×10-5 s-1 . Thus, in a nonpolar environment, 2 is slightly more stable than 1, in agreement with calculations at the CCSD(T) level of theory. However, if the argon is doped with 1 % of H2 O or CF3 I as typical hydrogen or halogen bond donors, respectively, weak complexes of 1 and 2 are formed, and now 2 is tunneling back to form 1. Thus, by forming non-covalent complexes, 1 becomes slightly more stable than 2 and the direction of the heavy-atom tunneling is reversed.
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Affiliation(s)
- Tim Schleif
- Lehrstuhl für Organische Chemie IIRuhr-Universität BochumUniversitätsstraße 15044801BochumGermany
| | - Melania Prado Merini
- Lehrstuhl für Organische Chemie IIRuhr-Universität BochumUniversitätsstraße 15044801BochumGermany
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie IIRuhr-Universität BochumUniversitätsstraße 15044801BochumGermany
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9
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Schleif T, Prado Merini M, Sander W. The Mystery of the Benzene‐Oxide/Oxepin Equilibrium—Heavy‐Atom Tunneling Reversed by Solvent Interactions. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202010452] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Tim Schleif
- Lehrstuhl für Organische Chemie II Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
| | - Melania Prado Merini
- Lehrstuhl für Organische Chemie II Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie II Ruhr-Universität Bochum Universitätsstraße 150 44801 Bochum Germany
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10
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Cytochrome P450 Can Epoxidize an Oxepin to a Reactive 2,3-Epoxyoxepin Intermediate: Potential Insights into Metabolic Ring-Opening of Benzene. MOLECULES (BASEL, SWITZERLAND) 2020; 25:molecules25194542. [PMID: 33023027 PMCID: PMC7582548 DOI: 10.3390/molecules25194542] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 11/16/2022]
Abstract
Dimethyldioxirane epoxidizes 4,5-benzoxepin to form the reactive 2,3-epoxyoxepin intermediate followed by very rapid ring-opening to an o-xylylene that immediately isomerizes to the stable product 1H-2-benzopyran-1-carboxaldehyde. The present study demonstrates that separate incubations of 4,5-benzoxepin with three cytochrome P450 isoforms (2E1, 1A2, and 3A4) as well as pooled human liver microsomes (pHLM) also produce 1H-2-benzopyran-1-carboxaldehyde as the major product, likely via the 2,3-epoxyoxepin. The reaction of 4,5-benzoxepin with cerium (IV) ammonium nitrate (CAN) yields a dimeric oxidized molecule that is also a lesser product of the P450 oxidation of 4,5-benzoxepin. The observation that P450 enzymes epoxidize 4,5-benzoxepin suggests that the 2,3-epoxidation of oxepin is a major pathway for the ring-opening metabolism of benzene to muconaldehyde.
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11
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Álvarez JM, Jorge ZD, Massanet GM. Study of the Oxidative Cleavage Proposed in the Biogenesis of Transtaganolides/Basiliolides: Pyran-2-one Aromaticity-Mediated Regioselective Control and Biogenetic Implications. European J Org Chem 2020. [DOI: 10.1002/ejoc.201901894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- José María Álvarez
- Department of Organic Chemistry; University of Cádiz; 11510 Puerto Real Spain
| | - Zacarías D. Jorge
- Department of Organic Chemistry; University of Cádiz; 11510 Puerto Real Spain
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12
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Chu S, Letcher RJ. In vitro metabolic activation of triphenyl phosphate leading to the formation of glutathione conjugates by rat liver microsomes. CHEMOSPHERE 2019; 237:124474. [PMID: 31377596 DOI: 10.1016/j.chemosphere.2019.124474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 07/17/2019] [Accepted: 07/26/2019] [Indexed: 06/10/2023]
Abstract
The present study investigated the metabolism of the flame retardant and plasticizer chemical, triphenyl phosphate (TPHP), in a rat liver microsome-based in vitro assay with glutathione (GSH) in order to elucidate metabolic pathways leading to formation of conjugates. A highly sensitive and efficient method was developed for the detection and characterization of GSH reactive metabolites using LC-Q-TOF-MS/MS both in the negative and positive electrospray ionization modes. Seven GSH conjugates formed as a result of microsomal incubation, which were identified as S-conjugates based on MS/MS spectra, and confirmed by subsequent time-dependent incubation assays. With the exception of hydrolysis reactions leading to formation of a diester metabolite, diphenyl phosphate (DPHP), the results demonstrated that Phase I epoxidation on phenyl ring of TPHP leading to mono- and di-hydroxylated TPHP metabolites, which can further conjugate with GSH. Depending on hydroxylated TPHP formation, an o-hydroquinone intermediate formed in vitro via Phase I metabolism, and the o-benzoquinone form reacted with GSH and also formed GSH conjugates. The present study showed that via hydroxylated TPHP Phase I formation that GSH conjugates are important Phase II metabolites for TPHP metabolism in vitro. Some GSH conjugates may be valuable candidate biomarkers for monitoring TPHP exposure in biota.
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Affiliation(s)
- Shaogang Chu
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Carleton University, Ottawa, ON, K1A 0H3, Canada
| | - Robert J Letcher
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Environment and Climate Change Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Carleton University, Ottawa, ON, K1A 0H3, Canada.
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13
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McNally K, Sams C, Loizou GD, Jones K. Evidence for non-linear metabolism at low benzene exposures? A reanalysis of data. Chem Biol Interact 2017; 278:256-268. [PMID: 28899792 DOI: 10.1016/j.cbi.2017.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 08/30/2017] [Accepted: 09/01/2017] [Indexed: 12/17/2022]
Abstract
The presence of a high-affinity metabolic pathway for low level benzene exposures of less than one part per million (ppm) has been proposed although a pathway has not been identified. The variation of metabolite molar fractions with increasing air benzene concentrations was suggested as evidence of significantly more efficient benzene metabolism at concentrations <0.1 ppm The evidence for this pathway is predicated on a rich data set from a study of Chinese shoe workers exposed to a wide range of benzene concentrations (not just "low level"). In this work we undertake a further independent re-analysis of this data with a focus on the evidence for an increase in the rate of metabolism of benzene exposures of less than 1 ppm. The analysis dataset consisted of measurements of benzene and toluene from personal air samplers, and measurements of unmetabolised benzene and toluene and five metabolites (phenol hydroquinone, catechol, trans, trans-muconic acid and s-phenylmercapturic acid) from post-shift urine samples for 213 workers with an occupational exposure to benzene (and toluene) and 139 controls. Measurements from control subjects were used to estimate metabolite concentrations resulting from non-occupational sources, including environmental sources of benzene. Data from occupationally exposed subjects were used to estimate metabolite concentrations as a function of benzene exposure. Correction for background (environmental exposure) sources of metabolites was achieved through a comparison of geometric means in occupationally exposed and control populations. The molar fractions of the five metabolites as a function of benzene exposure were computed. A supra-linear relationship between metabolite concentrations and benzene exposure was observed over the range 0.1-10 ppm benzene, however over the range benzene exposures of between 0.1 and 1 ppm only a modest departure from linearity was observed. The molar fractions estimated in this work were near constant over the range 0.1-10 ppm. No evidence of high affinity metabolism at these low level exposures was observed. Our reanalysis brings in to question the appropriateness of the dataset for commenting on low dose exposures and the use of a purely statistical approach to the analysis.
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Affiliation(s)
- K McNally
- Health & Safety Laboratory, Harpur Hill, Buxton, SK17 9JN, UK
| | - C Sams
- Health & Safety Laboratory, Harpur Hill, Buxton, SK17 9JN, UK
| | - G D Loizou
- Health & Safety Laboratory, Harpur Hill, Buxton, SK17 9JN, UK
| | - K Jones
- Health & Safety Laboratory, Harpur Hill, Buxton, SK17 9JN, UK.
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14
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Sabbioni G, Turesky RJ. Biomonitoring Human Albumin Adducts: The Past, the Present, and the Future. Chem Res Toxicol 2017; 30:332-366. [PMID: 27989119 PMCID: PMC5241710 DOI: 10.1021/acs.chemrestox.6b00366] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Indexed: 12/21/2022]
Abstract
Serum albumin (Alb) is the most abundant protein in blood plasma. Alb reacts with many carcinogens and/or their electrophilic metabolites. Studies conducted over 20 years ago showed that Alb forms adducts with the human carcinogens aflatoxin B1 and benzene, which were successfully used as biomarkers in molecular epidemiology studies designed to address the role of these chemicals in cancer risk. Alb forms adducts with many therapeutic drugs or their reactive metabolites such as β-lactam antibiotics, acetylsalicylic acid, acetaminophen, nonsteroidal anti-inflammatory drugs, chemotherapeutic agents, and antiretroviral therapy drugs. The identification and characterization of the adduct structures formed with Alb have served to understand the generation of reactive metabolites and to predict idiosyncratic drug reactions and toxicities. The reaction of candidate drugs with Alb is now exploited as part of the battery of screening tools to assess the potential toxicities of drugs. The use of gas chromatography-mass spectrometry, liquid chromatography, or liquid chromatography-mass spectrometry (LC-MS) enabled the identification and quantification of multiple types of Alb xenobiotic adducts in animals and humans during the past three decades. In this perspective, we highlight the history of Alb as a target protein for adduction to environmental and dietary genotoxicants, pesticides, and herbicides, common classes of medicinal drugs, and endogenous electrophiles, and the emerging analytical mass spectrometry technologies to identify Alb-toxicant adducts in humans.
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Affiliation(s)
- Gabriele Sabbioni
- Institute of Environmental and Occupational Toxicology, CH-6780 Airolo, Switzerland
- Alpine Institute of Chemistry and Toxicology, CH-6718 Olivone, Switzerland
- Walther-Straub-Institut für Pharmakologie
und Toxikologie, Ludwig-Maximilians-Universität München, D-80336 München, Germany
| | - Robert J. Turesky
- Masonic Cancer Center and Department of
Medicinal Chemistry, College of Pharmacy, University of Minnesota, 2231 Sixth Street SE, Minneapolis, Minnesota 55455, United States
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15
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Haiman CA, Patel YM, Stram DO, Carmella SG, Chen M, Wilkens LR, Le Marchand L, Hecht SS. Benzene Uptake and Glutathione S-transferase T1 Status as Determinants of S-Phenylmercapturic Acid in Cigarette Smokers in the Multiethnic Cohort. PLoS One 2016; 11:e0150641. [PMID: 26959369 PMCID: PMC4784986 DOI: 10.1371/journal.pone.0150641] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 02/16/2016] [Indexed: 12/17/2022] Open
Abstract
Research from the Multiethnic Cohort (MEC) demonstrated that, for the same quantity of cigarette smoking, African Americans and Native Hawaiians have a higher lung cancer risk than Whites, while Latinos and Japanese Americans are less susceptible. We collected urine samples from 2,239 cigarette smokers from five different ethnic groups in the MEC and analyzed each sample for S-phenylmercapturic acid (SPMA), a specific biomarker of benzene uptake. African Americans had significantly higher (geometric mean [SE] 3.69 [0.2], p<0.005) SPMA/ml urine than Whites (2.67 [0.13]) while Japanese Americans had significantly lower levels than Whites (1.65 [0.07], p<0.005). SPMA levels in Native Hawaiians and Latinos were not significantly different from those of Whites. We also conducted a genome-wide association study in search of genetic risk factors related to benzene exposure. The glutathione S-transferase T1 (GSTT1) deletion explained between 14.2-31.6% (p = 5.4x10-157) and the GSTM1 deletion explained between 0.2%-2.4% of the variance (p = 1.1x10-9) of SPMA levels in these populations. Ethnic differences in levels of SPMA remained strong even after controlling for the effects of these two deletions. These results demonstrate the powerful effect of GSTT1 status on SPMA levels in urine and show that uptake of benzene in African American, White, and Japanese American cigarette smokers is consistent with their lung cancer risk in the MEC. While benzene is not generally considered a cause of lung cancer, its metabolite SPMA could be a biomarker for other volatile lung carcinogens in cigarette smoke.
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Affiliation(s)
- Christopher A. Haiman
- Department of Preventive Medicine and Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90032, United States of America
| | - Yesha M. Patel
- Department of Preventive Medicine and Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90032, United States of America
| | - Daniel O. Stram
- Department of Preventive Medicine and Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90032, United States of America
| | - Steven G. Carmella
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55105, United States of America
| | - Menglan Chen
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55105, United States of America
| | - Lynne R. Wilkens
- Epidemiology Program, Cancer Research Center of Hawai’i, University of Hawai’i, Honolulu, HI, 96813, United States of America
| | - Loic Le Marchand
- Epidemiology Program, Cancer Research Center of Hawai’i, University of Hawai’i, Honolulu, HI, 96813, United States of America
| | - Stephen S. Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, 55105, United States of America
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Xue Y, Dong W, Wang X, Bi W, Zhai P, Li H, Nie M. Degradation of sunscreen agent p-aminobenzoic acid using a combination system of UV irradiation, persulphate and iron(II). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016; 23:4561-4568. [PMID: 26517998 DOI: 10.1007/s11356-015-5631-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/18/2015] [Indexed: 06/05/2023]
Abstract
Increased usage and discharge of sunscreens have led to ecological safety crisis, and people are developing the advanced oxidation processes (AOPs) to treat them. The present study aimed to determine the degradation efficiency and mechanism of the sunscreen agent p-aminobenzoic acid (PABA) using the UV/Fe(2+)/persulphate (PS) method. A series of irradiation experiments were conducted to optimise the system conditions and to study the impacts of the natural anion. Free radicals and degradation products were identified in order to clarify the degradation mechanism. Initial PS and Fe(2+) concentrations showed significant impacts on PABA degradation. Natural anions, such as Cl(-), NO3 (-), H2PO4 (-) and HCO3 (-), impeded PABA degradation because of ion (Fe(2+)) capture, radical scavenging or pH effects. Hydroxyl (HO·) and sulphate (SO4 (·-)) radicals were two main radicals observed in the UV/Fe(2+)/PS system; of these, SO4 (·-) showed greater effects on PABA degradation. Over 99 % of the available PABA was completely degraded into carbon dioxide (CO2) and water (H2O) by the UV/Fe(2+)/PS system, and the remaining PABA participated in complex radical reactions. By-products were identified by total ion chromatography and mass spectrometry. Our research provides a treatment process for PABA with high degradation efficiency and environmental safety and introduces a new strategy for sunscreen degradation.
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Affiliation(s)
- Yicen Xue
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
| | - Wenbo Dong
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China.
| | - Xiaoning Wang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
| | - Wenlong Bi
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
| | - Pingping Zhai
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
| | - Hongjing Li
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China.
| | - Minghua Nie
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science and Engineering, Fudan University, Shanghai, 200433, China
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Gaugg MT, Gomez DG, Barrios-Collado C, Vidal-de-Miguel G, Kohler M, Zenobi R, Martinez-Lozano Sinues P. Expanding metabolite coverage of real-time breath analysis by coupling a universal secondary electrospray ionization source and high resolution mass spectrometry—a pilot study on tobacco smokers. J Breath Res 2016; 10:016010. [DOI: 10.1088/1752-7155/10/1/016010] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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18
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Wiwanitkit V. Benzene, cytochrome, carcinogenesis: A topic in preventive toxicology. Indian J Occup Environ Med 2015; 18:97-9. [PMID: 25568606 PMCID: PMC4280785 DOI: 10.4103/0019-5278.146900] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Benzene is a common chemical substance with confirmed toxicity to human beings. The benzene toxicity can be in either acute or chronic. Also, the carcinogenicity of benzene is confirmed. Hence, the control of benzene usage is a topic in preventive toxicology; however, this substance is still problematic in many industrialized settings. In this article, the author discusses benzene and cytochrome focusing on the carcinogenesis process. A further extrapolation on the aspects on preventive toxicology is also included.
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Barata-Silva C, Mitri S, Pavesi T, Saggioro E, Moreira JC. Benzeno: reflexos sobre a saúde pública, presença ambiental e indicadores biológicos utilizados para a determinação da exposição. ACTA ACUST UNITED AC 2014. [DOI: 10.1590/1414-462x201400040006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
O uso indiscriminado de um número cada vez maior de substâncias químicas vem aumentando e a contaminação ambiental associada tem trazido sérias consequências para o sistema público de saúde devido à elevação de danos para a saúde humana. Uma das substâncias que desperta grande interesse devido à contaminação contemporânea é o benzeno, composto aromático classificado pela International Agency for Research on Cancer como reconhecidamente carcinogênico para humanos. O objetivo do presente estudo foi elaborar e discutir um panorama sobre a contaminação por benzeno, seu metabolismo, consequências para a saúde e sua determinação ambiental e biológica a partir de informações existentes na literatura científica. O levantamento de dados possibilitou o acesso a mais de 200 artigos científicos tanto de âmbito nacional quanto internacional, demonstrando a atualidade do tema e a necessidade de minimização da exposição humana a essa substância. A maioria preocupa-se em explorar o metabolismo e investigar indicadores de exposição, muitos já amplamente estudados e com sérias limitações. Contudo, um crescente número de pesquisadores estão empenhados em elucidar fatores relacionados à suscetibilidade e à interferência da exposição no material genético e proteico. Indicadores de exposição inovadores têm sido propostos com o objetivo de complementar as lacunas de informações anteriormente obtidas, contribuindo para o delineamento da estrutura da biologia de sistemas orgânicos frente à exposição ao benzeno.
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De Palma G, Manno M. Metabolic polymorphisms and biomarkers of effect in the biomonitoring of occupational exposure to low-levels of benzene: state of the art. Toxicol Lett 2014; 231:194-204. [PMID: 25447454 DOI: 10.1016/j.toxlet.2014.10.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Revised: 10/07/2014] [Accepted: 10/09/2014] [Indexed: 12/21/2022]
Abstract
Current levels of occupational exposure to benzene, a genotoxic human carcinogen, in Western countries are reduced by two-three orders of magnitude (from ppm to ppb) as compared to the past. However, as benzene toxicity is strongly dependent on biotransformation and recent evidence underlines a higher efficiency of bio-activation pathways at lower levels of exposure, toxic effects at low doses could be higher than expected, particularly in susceptible individuals. Currently, biological monitoring can allow accurate exposure assessment, relying on sensitive and specific enough biomarkers of internal dose. The availability of similarly reliable biomarkers of early effect or susceptibility could greatly improve the risk assessment process to such an extent that risk could even be assessed at the individual level. As to susceptibility biomarkers, functional genetic polymorphisms of relevant biotransformation enzymes may modulate the risk of adverse effects (NQO1) and the levels of biomarkers of internal dose, in particular S-phenylmercapturic acid (GSTM1, GSTT1, GSTA1). Among biomarkers of early effect, genotoxicity indicators, although sensitive in some cases, are too aspecific for routine use in occupational health surveillance programmes. Currently only the periodical blood cell count seems suitable enough to be applied in the longitudinal monitoring of effects from benzene exposure. Novel biomarkers of early effect are expected from higher collaboration among toxicologists and clinicians, also using advanced "omics" techniques.
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Affiliation(s)
- G De Palma
- Department of Medical and Surgical Specialties, Radiological Sciences and Public Health, Section of Public Health and Human Sciences, University of Brescia, Piazzale Spedali Civili 1, 25123 Brescia, Italy.
| | - M Manno
- Department of Public Health, Section of Occupational Medicine and Toxicology, University of Napoli Federico II, Via S. Pansini, 5, 80131 Napoli, Italy
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21
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Zarth AT, Cheng G, Zhang Z, Wang M, Villalta PW, Balbo S, Hecht SS. Analysis of the benzene oxide-DNA adduct 7-phenylguanine by liquid chromatography-nanoelectrospray ionization-high resolution tandem mass spectrometry-parallel reaction monitoring: application to DNA from exposed mice and humans. Chem Biol Interact 2014; 215:40-5. [PMID: 24632417 PMCID: PMC4022132 DOI: 10.1016/j.cbi.2014.03.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 02/06/2014] [Accepted: 03/04/2014] [Indexed: 01/19/2023]
Abstract
Benzene oxide, the initial metabolite of the human carcinogen benzene, reacts with DNA producing 7-phenylguanine (7-PhG) and other products. We developed a highly sensitive liquid chromatography-nanoelectrospray ionization-high resolution tandem mass spectrometry-parallel reaction monitoring method for the analysis of 7-PhG in DNA. Accuracy and precision of the method were established and the detection limit was about 8amol of 7-PhG injected on the column and less than 1 adduct per 10(9) nucleotides in DNA. 7-PhG was detected in calf thymus DNA reacted with 1μM to 10mM benzene oxide. The method was applied for the analysis of DNA isolated from bone marrow, lung, and liver of B6C3F1 mice treated by gavage with 50mg/kg benzene in corn oil 5 times weekly for 4weeks. 7-PhG was not detected in any of these DNA samples. The method was applied to DNA from mouse hepatocytes exposed to 100μM benzene oxide and human TK-6 lymphoblasts exposed to 100μM, 1, and 10mM benzene oxide. 7-PhG was only detected in TK-6 cell DNA from the 10mM exposure. The method was also applied to leukocyte DNA from 10 smokers and 10 nonsmokers. 7-PhG was detected in only one DNA sample, from a nonsmoker. The results of this study do not support the hypothesis that the benzene oxide-DNA adduct 7-PhG is involved in carcinogenesis by benzene.
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Affiliation(s)
- Adam T Zarth
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - Guang Cheng
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - Zhaobin Zhang
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - Mingyao Wang
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - Peter W Villalta
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - Silvia Balbo
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, United States
| | - Stephen S Hecht
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, United States.
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22
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Knutsen JS, Kerger BD, Finley B, Paustenbach DJ. A calibrated human PBPK model for benzene inhalation with urinary bladder and bone marrow compartments. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2013; 33:1237-1251. [PMID: 23278103 DOI: 10.1111/j.1539-6924.2012.01927.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A physiologically-based pharmacokinetic (PBPK) model of benzene inhalation based on a recent mouse model was adapted to include bone marrow (target organ) and urinary bladder compartments. Empirical data on human liver microsomal protein levels and linked CYP2E1 activities were incorporated into the model, and metabolite-specific conversion rate parameters were estimated by fitting to human biomonitoring data and adjusting for background levels of urinary metabolites. Human studies of benzene levels in blood and breath, and phenol levels in urine were used to validate the rate of human conversion of benzene to benzene oxide, and urinary benzene metabolites from Chinese benzene worker populations provided model validation for rates of human conversion of benzene to muconic acid (MA) and phenylmercapturic acid (PMA), phenol (PH), catechol (CA), hydroquinone (HQ), and benzenetriol (BT). The calibrated human model reveals that while liver microsomal protein and CYP2E1 activities are lower on average in humans compared to mice, the mouse also shows far lower rates of benzene conversion to MA and PMA, and far higher conversion of benzene to BO/PH, and of BO/PH to CA, HQ, and BT. The model also differed substantially from existing human PBPK models with respect to several metabolic rate parameters of importance to interpreting benzene metabolism and health risks in human populations associated with bone marrow doses. The model provides a new methodological paradigm focused on integrating linked human liver metabolism data and calibration using biomonitoring data, thus allowing for model uncertainty analysis and more rigorous validation.
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23
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Arnold SM, Angerer J, Boogaard PJ, Hughes MF, O'Lone RB, Robison SH, Schnatter AR. The use of biomonitoring data in exposure and human health risk assessment: benzene case study. Crit Rev Toxicol 2013; 43:119-53. [PMID: 23346981 PMCID: PMC3585443 DOI: 10.3109/10408444.2012.756455] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 11/30/2012] [Accepted: 12/04/2012] [Indexed: 01/08/2023]
Abstract
Abstract A framework of "Common Criteria" (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of the Common Criteria and allowed for a risk-based evaluation of the benzene biomonitoring data. In general, biomarker (blood benzene, urinary benzene and urinary S-phenylmercapturic acid) central tendency (i.e. mean, median and geometric mean) concentrations for non-smokers are at or below the predicted blood or urine concentrations that would correspond to exposure at the US Environmental Protection Agency reference concentration (30 µg/m(3)), but greater than blood or urine concentrations relating to the air concentration at the 1 × 10(-5) excess cancer risk (2.9 µg/m(3)). Smokers clearly have higher levels of benzene exposure, and biomarker levels of benzene for non-smokers are generally consistent with ambient air monitoring results. While some biomarkers of benzene are specific indicators of exposure, the interpretation of benzene biomonitoring levels in a health-risk context are complicated by issues associated with short half-lives and gaps in knowledge regarding the relationship between the biomarkers and subsequent toxic effects.
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25
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Spatari G, Saitta S, Cimino F, Sapienza D, Quattrocchi P, Carrieri M, Barbaro M, Saija A, Gangemi S. Increased serum levels of advanced oxidation protein products and glycation end products in subjects exposed to low-dose benzene. Int J Hyg Environ Health 2012; 215:389-92. [DOI: 10.1016/j.ijheh.2011.11.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 10/22/2011] [Accepted: 11/08/2011] [Indexed: 11/17/2022]
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26
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Djurhuus R, Nossum V, Øvrebø S, Skaug V. Proposal on limits for chemical exposure in saturation divers' working atmosphere: the case of benzene. Crit Rev Toxicol 2012; 42:211-29. [PMID: 22304480 DOI: 10.3109/10408444.2011.650791] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Saturation diving is performed under extreme environmental conditions. The divers are confined to a limited space for several weeks under high environmental pressure and elevated oxygen partial pressure. At present, divers are protected against chemical exposure by standard exposure limits only adjusted for the increased exposure length, i.e. from 8 to 24 hours a day and from 5 to 7 days a week. The objective of the present study was to indicate a procedure for derivation of occupational exposure limits for saturation diving, termed hyperbaric exposure limits (HEL). Using benzene as an example, a procedure is described that includes identification of the latest key documents, extensive literature search with defined exclusion criteria for the literature retrieved. Hematotoxicity and leukemia were defined as the critical effects, and exposure limits based upon concentration and cumulative exposure data and corresponding risks of leukemia were calculated. Possible interactions of high pressure, elevated pO₂, and continuous exposure have been assessed, and incorporated in a final suggestion of a HEL for benzene. The procedure should be applicable for other relevant chemicals in the divers' breathing atmosphere. It is emphasized that the lack of interactions from pressure and oxygen indicated for benzene may be completely different for other chemicals.
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Affiliation(s)
- Rune Djurhuus
- Norwegian Underwater Intervention AS (NUI AS), Bergen, Norway.
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27
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McHale CM, Zhang L, Smith MT. Current understanding of the mechanism of benzene-induced leukemia in humans: implications for risk assessment. Carcinogenesis 2012; 33:240-52. [PMID: 22166497 PMCID: PMC3271273 DOI: 10.1093/carcin/bgr297] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 11/21/2011] [Accepted: 12/07/2011] [Indexed: 01/01/2023] Open
Abstract
Benzene causes acute myeloid leukemia and probably other hematological malignancies. As benzene also causes hematotoxicity even in workers exposed to levels below the US permissible occupational exposure limit of 1 part per million, further assessment of the health risks associated with its exposure, particularly at low levels, is needed. Here, we describe the probable mechanism by which benzene induces leukemia involving the targeting of critical genes and pathways through the induction of genetic, chromosomal or epigenetic abnormalities and genomic instability, in a hematopoietic stem cell (HSC); stromal cell dysregulation; apoptosis of HSCs and stromal cells and altered proliferation and differentiation of HSCs. These effects modulated by benzene-induced oxidative stress, aryl hydrocarbon receptor dysregulation and reduced immunosurveillance, lead to the generation of leukemic stem cells and subsequent clonal evolution to leukemia. A mode of action (MOA) approach to the risk assessment of benzene was recently proposed. This approach is limited, however, by the challenges of defining a simple stochastic MOA of benzene-induced leukemogenesis and of identifying relevant and quantifiable parameters associated with potential key events. An alternative risk assessment approach is the application of toxicogenomics and systems biology in human populations, animals and in vitro models of the HSC stem cell niche, exposed to a range of levels of benzene. These approaches will inform our understanding of the mechanisms of benzene toxicity and identify additional biomarkers of exposure, early effect and susceptibility useful for risk assessment.
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Affiliation(s)
| | | | - Martyn T. Smith
- Division of Environmental Health Sciences, Genes and Environment Laboratory, School of Public Health, University of California, Berkeley, CA 94720-7356, USA
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28
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Peng D, Jiaxing W, Chunhui H, Weiyi P, Xiaomin W. Study on the cytogenetic changes induced by benzene and hydroquinone in human lymphocytes. Hum Exp Toxicol 2012; 31:322-35. [DOI: 10.1177/0960327111433900] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Benzene (BN) is a prototypical hematotoxicant, genotoxic carcinogen, and ubiquitous environmental pollutant. Although the molecular mechanisms of BN-induced cytotoxicity and genotoxic damage are poorly understood in humans, previous studies suggested that bioactivated BN metabolites are capable of oxidative stress, cell cycle arrest, apoptosis, and DNA damage. The objective of the current study was to investigate the BN-induced cytogenetic changes and underlying mechanisms based on these hypotheses. Peripheral blood lymphocytes (PBLs) might be the targets for BN-induced cytotoxicity and genotoxicity, and therefore DNA damage responses of PBLs after exposure to different concentrations of BN (0.25, 3.5, 50 μmol/L) or BN metabolite, hydroquinone (HQ; 50, 150, 450 μmol/L) were studied in vitro. Microculture tetrazolium assay, flow cytometry, 2′,7′-dichlorodihydrofluorescein-diacetate assay, comet assay, micronuclei assay, and attenuated total reflectance microspectroscope were chosen for this study. Based on the results, we reached the conclusion that different concentrations of BN or HQ significantly inhibited cell growth, induced the arrest of S phase and G2/M phase, and increased late apoptosis in a concentration-dependent manner. Furthermore, evidence was also provided to support the conclusion that BN and HQ induced DNA strand breaks and chromosomal mutations in PBL, which indicated the genotoxicity of BN and HQ. Current evidence has indicated that multiple mechanisms including dysfunction of cell cycle, programmed cell death, oxidative stress, and DNA lesions are likely to contribute to BN-induced cytogenetic changes.
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Affiliation(s)
- D Peng
- Department of Public Health, School of Basic Medical, Hubei University of Medicine, Shiyan, Hubei, PR China
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, PR China
| | - W Jiaxing
- School of Chemical Project, Beijing University of Chemical Technology, Beijing, PR China
| | - H Chunhui
- Department of Clinical Laboratories, the Affiliated Taihe Hospital, Hubei University of Medicine, Hubei Shiyan, PR China
| | - P Weiyi
- Department of Health Statistics and Environmental Health, School of Public Health, Guangxi Medical University, Nanning, Guangxi, PR China
| | - W Xiaomin
- Department of Toxicology, School of Public Health, Guangxi Medical University, Nanning, Guangxi, PR China
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29
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Linhart I, Mikeš P, Králík A, Mráz J, Frantík E. Metabolism of N2-(4-hydroxyphenyl)guanine, a DNA adduct formed from p-benzoquinone, in rat. Toxicol Lett 2011; 205:273-8. [DOI: 10.1016/j.toxlet.2011.06.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 06/10/2011] [Accepted: 06/14/2011] [Indexed: 10/18/2022]
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30
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Zhou YY, Chen DZ, Zhu RY, Chen JM. Substrate interactions during the biodegradation of BTEX and THF mixtures by Pseudomonas oleovorans DT4. BIORESOURCE TECHNOLOGY 2011; 102:6644-6649. [PMID: 21511464 DOI: 10.1016/j.biortech.2011.03.076] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 03/22/2011] [Accepted: 03/23/2011] [Indexed: 05/30/2023]
Abstract
The efficient tetrahydrofuran (THF)-degrading bacterium, Pseudomonas oleovorans DT4 was used to investigate the substrate interactions during the aerobic biotransformation of THF and BTEX mixtures. Benzene and toluene could be utilized as growth substrates by DT4, whereas cometabolism of m-xylene, p-xylene and ethylbenzene occurred with THF. In binary mixtures, THF degradation was delayed by xylene, ethylbenzene, toluene and benzene in descending order of inhibitory effects. Conversely, benzene (or toluene) degradation was greatly enhanced by THF leading to a higher degradation rate of 39.68 mg/(h g dry weight) and a shorter complete degradation time about 21 h, possibly because THF acted as an "energy generator". Additionally, the induction experiments suggested that BTEX and THF degradation was initiated by independent and inducible enzymes. The transient intermediate hydroquinone was detected in benzene biodegradation with THF while catechol in the process without THF, suggesting that P. oleovorans DT4 possessed two distinguished benzene pathways.
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Affiliation(s)
- Yu-Yang Zhou
- College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China
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31
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Wu XR, Xue M, Li XF, Wang Y, Wang J, Han QL, Yi ZC. Phenolic metabolites of benzene inhibited the erythroid differentiation of K562 cells. Toxicol Lett 2011; 203:190-9. [PMID: 21414390 DOI: 10.1016/j.toxlet.2011.03.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 03/06/2011] [Accepted: 03/07/2011] [Indexed: 01/27/2023]
Abstract
Benzene is a common occupational hazard and a ubiquitous environmental pollutant. Benzene exposure at the levels even below 1ppm still showed hematotoxicity. It is widely accepted that the metabolites of benzene play important roles in the benzene toxicity to the hematopoietic system, but little is known about the effects of benzene metabolites on erythropoiesis. In present study, erythroid progenitor-like K562 cells were used to determine the effects of phenolic metabolites of benzene, including phenol, hydroquinone and 1,2,4-benzenetriol, on the erythroid differentiation. After the treatment with these benzene metabolites at the concentrations with no obvious cytotoxicity, the hemin-induced hemoglobin synthesis in K562 cells decreased in a concentration- and time-dependent manner, and the expression of CD71 and GPA protein on the surface of K562 cells was also inhibited. The reverse transcription-PCR was used to determine the mRNA level of the erythroid related genes in the K562 cells that were treated with benzene metabolites. The hemin-induced expression of globin genes, including α-, β- and γ-globin genes, and the gene encoding the heme synthesis enzyme porphobilinogen deaminase was inhibited by benzene metabolites. When the K562 cells were pretreated with benzene metabolites, the hemin-induced expression of two transcription factor genes GATA-1 and NF-E2 was distinctly reduced, and the pre-treatment with benzene metabolites promoted the decrease of the mRNA level of transcription factor gene GATA-2 by hemin. These results indicated that benzene metabolites inhibited the hemin-induced erythroid differentiation through affecting the transcription of the erythroid related genes.
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Affiliation(s)
- Xiao-Rong Wu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
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Bacterial phenylalanine and phenylacetate catabolic pathway revealed. Proc Natl Acad Sci U S A 2010; 107:14390-5. [PMID: 20660314 DOI: 10.1073/pnas.1005399107] [Citation(s) in RCA: 267] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Aromatic compounds constitute the second most abundant class of organic substrates and environmental pollutants, a substantial part of which (e.g., phenylalanine or styrene) is metabolized by bacteria via phenylacetate. Surprisingly, the bacterial catabolism of phenylalanine and phenylacetate remained an unsolved problem. Although a phenylacetate metabolic gene cluster had been identified, the underlying biochemistry remained largely unknown. Here we elucidate the catabolic pathway functioning in 16% of all bacteria whose genome has been sequenced, including Escherichia coli and Pseudomonas putida. This strategy is exceptional in several aspects. Intermediates are processed as CoA thioesters, and the aromatic ring of phenylacetyl-CoA becomes activated to a ring 1,2-epoxide by a distinct multicomponent oxygenase. The reactive nonaromatic epoxide is isomerized to a seven-member O-heterocyclic enol ether, an oxepin. This isomerization is followed by hydrolytic ring cleavage and beta-oxidation steps, leading to acetyl-CoA and succinyl-CoA. This widespread paradigm differs significantly from the established chemistry of aerobic aromatic catabolism, thus widening our view of how organisms exploit such inert substrates. It provides insight into the natural remediation of man-made environmental contaminants such as styrene. Furthermore, this pathway occurs in various pathogens, where its reactive early intermediates may contribute to virulence.
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Morgan J, Greenberg A. Insights into the formation and isomerization of the benzene metabolite muconaldehyde and related molecules: comparison of computational and experimental studies of simple, benzo-annelated, and bridged 2,3-epoxyoxepins. J Org Chem 2010; 75:4761-8. [PMID: 20560653 DOI: 10.1021/jo100610g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
2,8-Dioxabicyclo[5.1.0]octa-3,5-diene ("2,3-epoxyoxepin") has been postulated as an intermediate in ring-opening metabolism of benzene. Density functional theory (B3LYP/6-31G*) is employed to study the activation and reaction energies for ring-opening isomerization of 2,3-epoxyoxepin, its 4,5-benzo derivative, and its 3,6-hexamethylene derivative. The results are compared with published experimental data. The markedly different fates of these three molecules suggest a means for testing the postulated metabolic pathway.
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Affiliation(s)
- Jessica Morgan
- Department of Chemistry University of New Hampshire Durham, New Hampshire 03824, USA
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Josephy PD. Genetic variations in human glutathione transferase enzymes: significance for pharmacology and toxicology. HUMAN GENOMICS AND PROTEOMICS : HGP 2010; 2010:876940. [PMID: 20981235 PMCID: PMC2958679 DOI: 10.4061/2010/876940] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Accepted: 03/22/2010] [Indexed: 01/21/2023]
Abstract
Glutathione transferase enzymes (GSTs) catalyze reactions in which electrophiles are conjugated to the tripeptide thiol glutathione. While many GST-catalyzed transformations result in the detoxication of xenobiotics, a few substrates, such as dihaloalkanes, undergo bioactivation to reactive intermediates. Many molecular epidemiological studies have tested associations between polymorphisms (especially, deletions) of human GST genes and disease susceptibility or response to therapy. This review presents a discussion of the biochemistry of GSTs, the sources-both genetic and environmental-of interindividual variation in GST activities, and their implications for pharmaco- and toxicogenetics; particular attention is paid to the Theta class GSTs.
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Affiliation(s)
- P David Josephy
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada N1G 2W1
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