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Petronek MS, Allen BG, Luthe G, Stolwijk JM. Polyoxometalate Nanoparticles as a Potential Glioblastoma Therapeutic via Lipid-Mediated Cell Death. Int J Mol Sci 2022; 23:ijms23158263. [PMID: 35897839 PMCID: PMC9332768 DOI: 10.3390/ijms23158263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/22/2022] [Accepted: 07/23/2022] [Indexed: 12/04/2022] Open
Abstract
Polyoxometalate nanoparticles (POMs) are a class of compounds made up of multiple transition metals linked together using oxygen atoms. POMs commonly include group 6 transition metals, with two of the most common forms using molybdenum and tungsten. POMs are suggested to exhibit antimicrobial effects. In this study, we developed two POM preparations to study anti-cancer activity. We found that Mo-POM (NH4)Mo7O24) and W-POM (H3PW12O40) have anti-cancer effects on glioblastoma cells. Both POMs induced morphological changes marked by membrane swelling and the presence of multinucleated cells that may indicate apoptosis induction along with impaired cell division. We also observed significant increases in lipid oxidation events, suggesting that POMs are redox-active and can catalyze detrimental oxidation events in glioblastoma cells. Here, we present preliminary indications that molybdenum polyoxometalate nanoparticles may act like ferrous iron to catalyze the oxidation of phospholipids. These preliminary results suggest that Mo-POMs (NH4)Mo7O24) and W-POMs (H3PW12O40) may warrant further investigation into their utility as adjunct cancer therapies.
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Affiliation(s)
- Michael S. Petronek
- Department of Radiation Oncology, Division of Free Radical and Radiation Biology, The University of Iowa, Iowa City, IA 52242-1181, USA
- Correspondence: (M.S.P.); (J.M.S.); Tel.: +1-(319)-356-8019 (M.S.P.)
| | - Bryan G. Allen
- Spheres4Life B.V., 7521 Enschede, The Netherlands; (B.G.A.); (G.L.)
| | - Gregor Luthe
- Spheres4Life B.V., 7521 Enschede, The Netherlands; (B.G.A.); (G.L.)
| | - Jeffrey M. Stolwijk
- Department of Radiation Oncology, Division of Free Radical and Radiation Biology, The University of Iowa, Iowa City, IA 52242-1181, USA
- Spheres4Life B.V., 7521 Enschede, The Netherlands; (B.G.A.); (G.L.)
- Correspondence: (M.S.P.); (J.M.S.); Tel.: +1-(319)-356-8019 (M.S.P.)
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Schön P, Ctistis G, Bakker W, Luthe G. Nanoparticular surface-bound PCBs, PCDDs, and PCDFs-a novel class of potentially higher toxic POPs. Environ Sci Pollut Res Int 2017; 24:12758-12766. [PMID: 26939687 DOI: 10.1007/s11356-016-6211-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 01/31/2016] [Indexed: 06/05/2023]
Abstract
In a previous study, Env Sci Poll Res:1-7, 2015 showed that polychlorinated biphenyls (PCBs), polychlorinated dibenzo dioxins (PCDDs), and polychlorinated dibenzo furanes (PCDFs) are found in commercially available (nano) particular titanium dioxide as a result of the fabrication. Here, we give a brief perspective and reason the toxicity of these new classes of persistent organic pollutants (POPs) by reviewing also their nanoparticular properties, such as surface-to-volume ratio, photocatalytic activity, polarity shifts, and stealth effect. These insights point towards a new class of POPs and toxicologic effects, which are related to the size but not a result of nanotechnology itself. We pave the way to the understanding of until now unresolved very complex phenomena, such as the indoor exposure, formation, and transformation of POP and sick-building syndrome. This is a fundamental message for nanotoxicology and kinetics and should be taken into account when determining the toxicity of nanomaterials and POPs separately and as a combination.
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Affiliation(s)
- Peter Schön
- NanoBioInterface Research Group, School of Life Science, Engineering, and Design, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
- Materials Science and Technology of Polymers, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands
| | - Georgios Ctistis
- NanoBioInterface Research Group, School of Life Science, Engineering, and Design, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
- Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands
| | - Wouter Bakker
- NanoBioInterface Research Group, School of Life Science, Engineering, and Design, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
| | - Gregor Luthe
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA.
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA.
- Luthe Pharma, Fabrikstrasse 2, 48599, Gronau, Germany.
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Ctistis G, Schön P, Bakker W, Luthe G. PCDDs, PCDFs, and PCBs co-occurrence in TiO2 nanoparticles. Environ Sci Pollut Res Int 2016; 23:4837-4843. [PMID: 26545886 DOI: 10.1007/s11356-015-5628-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/15/2015] [Indexed: 06/05/2023]
Abstract
In the present study, we report on the co-occurrence of persistent organic pollutants (POPs) adsorbed on nanoparticular titanium dioxide (TiO2). We report on the finding of polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) on the surface of commercially available TiO2 nanoparticles, being formed during the fabrication process of the TiO2. Thereby, the samples comprise PCBs with higher congener numbers or, in the absence of PCBs, a high concentration of PCDDs and PCDFs. This new class of POPs on an active catalytic surface and the great range of applications of nanoparticular TiO2, such as in color pigments, cosmetics, and inks, give rise to great concern due to their potential toxicity.
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Affiliation(s)
- Georgios Ctistis
- NanoBioInterface Research Group, School of Life Science and Technology, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
- Complex Photonic Systems (COPS), MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands
| | - Peter Schön
- NanoBioInterface Research Group, School of Life Science and Technology, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
- Materials Science and Technology of Polymers, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE, Enschede, The Netherlands
| | - Wouter Bakker
- NanoBioInterface Research Group, School of Life Science and Technology, Saxion University of Applied Sciences, M.H. Tromplaan 28, P.O. Box 70.000, 7500 KB, Enschede, The Netherlands
| | - Gregor Luthe
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA.
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA.
- Luthe Pharma®, Fabrikstrasse 2, 48599, Gronau, Germany.
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Wangpradit O, Adamcakova-Dodd A, Heitz K, Robertson L, Thorne PS, Luthe G. PAMAM dendrimers as nano carriers to investigate inflammatory responses induced by pulmonary exposure of PCB metabolites in Sprague-Dawley rats. Environ Sci Pollut Res Int 2016; 23:2128-2137. [PMID: 26400242 PMCID: PMC4803647 DOI: 10.1007/s11356-015-5022-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 07/02/2015] [Indexed: 05/29/2023]
Abstract
Polychlorinated biphenyls (PCBs) persist and accumulate in the ecosystem depending upon the degree of chlorination of the biphenyl rings. Airborne PCBs are especially susceptible to oxidative metabolism, yielding mono- and di-hydroxy metabolites. We have previously demonstrated that 4-chlorobiphenyl hydroquinones (4-CB-HQs) acted as cosubstrates for arachidonic acid metabolism by prostaglandin H synthase (PGHS) and resulted in an increase of prostaglandin production in vitro. In the present study, we tested the capability of 4-CB-HQ to act as a co-substrate for PGHS catalysis in vivo. BQ and 4-CB-2',5'-HQ were administered intratracheally to male Sprague-Dawley rats (2.5 μmol/kg body weight) using nanosized polyamidoamine (PAMAM) dendrimers as carriers. We found that 24 h post application, PGE2 metabolites in kidney of rats treated with 4-CB-2',5'-HQ were significantly increased compared to the controls. The increase of PGE2 metabolites was correlated with increased alveolar macrophages in lung lavage fluid. The elevation of PGE2 synthesis is of great interest since it plays a crucial role in balancing homeostasis and inflammation where a chronic disturbance may increase risk of cancer. PAMAM dentrimers proved to be an effective transport medium and did not stimulate an inflammatory response themselves.
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Affiliation(s)
- Orarat Wangpradit
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA
- Department of Occupational and Environmental Health, The University of Iowa, UI Research Park, Iowa City, IA, 52242, USA
- Sirindhorn College of Public Health, Bansuan, Muang, Chonburi, 20000, Thailand
| | - Andrea Adamcakova-Dodd
- Department of Occupational and Environmental Health, The University of Iowa, UI Research Park, Iowa City, IA, 52242, USA
- Pulmonary Toxicology Facility, Environmental Health Science Research Center, The University of Iowa, UI Research Park, Iowa City, IA, 52242, USA
| | - Katharina Heitz
- Department of Occupational and Environmental Health, The University of Iowa, UI Research Park, Iowa City, IA, 52242, USA
| | - Larry Robertson
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA
- Department of Occupational and Environmental Health, The University of Iowa, UI Research Park, Iowa City, IA, 52242, USA
| | - Peter S Thorne
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA
- Department of Occupational and Environmental Health, The University of Iowa, UI Research Park, Iowa City, IA, 52242, USA
- Pulmonary Toxicology Facility, Environmental Health Science Research Center, The University of Iowa, UI Research Park, Iowa City, IA, 52242, USA
| | - Gregor Luthe
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA, 52242, USA.
- Department of Occupational and Environmental Health, The University of Iowa, UI Research Park, Iowa City, IA, 52242, USA.
- Saxion University of Applied Sciences, Institute for Life Science and Technology, Enschede, The Netherlands.
- Luthe-Pharma, Fabrikstrasse 3, 48599, Gronau, Germany.
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Wangpradit O, Rahaman A, Mariappan SVS, Buettner GR, Robertson LW, Luthe G. Breaking the dogma: PCB-derived semiquinone free radicals do not form covalent adducts with DNA, GSH, and amino acids. Environ Sci Pollut Res Int 2016; 23:2138-2147. [PMID: 26396011 PMCID: PMC4767158 DOI: 10.1007/s11356-015-5007-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 07/01/2015] [Indexed: 06/05/2023]
Abstract
Covalent bond formations of free radical metabolites with biomolecules like DNA and proteins are thought to constitute a major mechanism of toxicity and carcinogenesis. Glutathione (GSH) is generally accepted as a radical scavenger protecting the cell. In the present study, we investigated a semiquinone radical (SQ(●-)) metabolite of the semivolatile 4-chlorobiphenyl, using electron paramagnetic resonance spectroscopy, and oxygen consumption. Proton nuclear magnetic resonance ((1)H NMR) and liquid chromatography-mass spectrometry (LC-MS) were also employed to elucidate the radical interaction with DNA, amino acids, and GSH. We found that DNA and oligonucleotides stabilized SQ(●-) by electron delocalization in the π-stacking system, resulting in persistent radical intercalated, rather than forming a covalent bond with SQ(●-). This finding was strongly supported by the semiempirical calculation of the semioccupied molecular orbital and the linear combination of the atomic orbitals, indicating 9.8 kcal mol(-1) energy gain. The insertion of SQ(●-) into the DNA strand may result in DNA strand breaks and interruption of DNA replication process or even activate radical mediated secondary reactions. The presence of amino acids resulted in a decrease of the electron paramagnetic resonance (EPR) signal of SQ(●-) and correlated with their isoelectric points. The pH shifts the equilibrium of the dianions of hydroquinone and influenced indirectly the formation of SQ(●-). Similar findings were observed with GSH and Cys. GSH and Cys functioned as indirect radical scavengers; their activities depend on their chemical equilibria with the corresponding quinones, and their further reaction via Michael addition. The generally accepted role of GSH as radical scavenger in biological systems should be reconsidered based upon these findings, questioning the generally accepted view of radical interaction of semiquinones with biologically active compounds, like DNA, amino acids, proteins, and radical scavengers like GSH.
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Affiliation(s)
- Orarat Wangpradit
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
- Sirindhorn College of Public Health, BanSuan, Muang, Chonburi, 2000, Thailand
| | - Asif Rahaman
- Department of Chemistry, City College of New York, Convent Avenue at 138th St., New York, NY, 10031, USA
| | - S V Santhana Mariappan
- Central High-Field NMR Research Facility, Department of Chemistry, The University of Iowa, Iowa, IA, 52242, USA
| | - Garry R Buettner
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
- Free Radical and Radiation Biology Program, The University of Iowa, Iowa, IA, 52242, USA
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA
| | - Gregor Luthe
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa, IA, 52242, USA.
- School of Life Science, Engineering & Design, Saxion University of Applied Sciences, Enschede, Netherlands.
- Luthe-Pharma, Fabrikstrasse 3, 48599, Gronau.
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Ekuase EJ, van 't Erve TJ, Rahaman A, Robertson LW, Duffel MW, Luthe G. Mechanistic insights into the specificity of human cytosolic sulfotransferase 2A1 (hSULT2A1) for hydroxylated polychlorinated biphenyls through the use of fluoro-tagged probes. Environ Sci Pollut Res Int 2016; 23:2119-2127. [PMID: 26165989 PMCID: PMC4713379 DOI: 10.1007/s11356-015-4886-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 06/15/2015] [Indexed: 06/04/2023]
Abstract
Determining the relationships between the structures of substrates and inhibitors and their interactions with drug-metabolizing enzymes is of prime importance in predicting the toxic potential of new and legacy xenobiotics. Traditionally, quantitative structure activity relationship (QSAR) studies are performed with many distinct compounds. Based on the chemical properties of the tested compounds, complex relationships can be established so that models can be developed to predict toxicity of novel compounds. In this study, the use of fluorinated analogues as supplemental QSAR compounds was investigated. Substituting fluorine induces changes in electronic and steric properties of the substrate without substantially changing the chemical backbone of the substrate. In vitro assays were performed using purified human cytosolic sulfotransferase hSULT2A1 as a model enzyme. A mono-hydroxylated polychlorinated biphenyl (4-OH PCB 14) and its four possible mono-fluoro analogues were used as test compounds. Remarkable similarities were found between this approach and previously published QSAR studies for hSULT2A1. Both studies implicate the importance of dipole moment and dihedral angle as being important to PCB structure in respect to being substrates for hSULT2A1. We conclude that mono-fluorinated analogues of a target substrate can be a useful tool to study the structure activity relationships for enzyme specificity.
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Affiliation(s)
- E J Ekuase
- Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, IA, USA
| | - T J van 't Erve
- Department of Occupational and Environmental Health, The University of Iowa, Iowa City, IA, USA.
- Institute of Life Sciences, Saxion University of Applied Sciences, Enschede, The Netherlands.
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA, USA.
- Immunity, Inflammation and Disease Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, 27709, NC, USA.
| | - A Rahaman
- Department of Chemistry, The University of Iowa, Iowa City, IA, USA
| | - L W Robertson
- Department of Occupational and Environmental Health, The University of Iowa, Iowa City, IA, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA, USA
| | - M W Duffel
- Department of Pharmaceutical Sciences and Experimental Therapeutics, The University of Iowa, Iowa City, IA, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA, USA
| | - G Luthe
- Department of Occupational and Environmental Health, The University of Iowa, Iowa City, IA, USA
- Institute of Life Sciences, Saxion University of Applied Sciences, Enschede, The Netherlands
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA, USA
- LuthePharma, Fabrikstrasse 2, 48599, Gronau, Germany
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Kim JS, Klösener J, Flor S, Peters TM, Ludewig G, Thorne PS, Robertson LW, Luthe G. Toxicity assessment of air-delivered particle-bound polybrominated diphenyl ethers. Toxicology 2014; 317:31-9. [PMID: 24451063 DOI: 10.1016/j.tox.2014.01.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 12/17/2013] [Accepted: 01/09/2014] [Indexed: 11/29/2022]
Abstract
Human exposure to polybrominated diphenyl ethers (PBDEs) can occur via ingestion of indoor dust, inhalation of PBDE-contaminated air and dust-bound PBDEs. However, few studies have examined the pulmonary toxicity of particle-bound PBDEs, mainly due to the lack of an appropriate particle-cell exposure system. In this study we developed an in vitro exposure system capable of generating particle-bound PBDEs mimicking dusts containing PBDE congeners (BDEs 35, 47 and 99) and delivering them directly onto lung cells grown at an air-liquid interface (ALI). The silica particles and particles-coated with PBDEs ranged in diameter from 4.3 to 4.5 μm and were delivered to cells with no apparent aggregation. This experimental set up demonstrated high reproducibility and sensitivity for dosing control and distribution of particles. ALI exposure of cells to PBDE-bound particles significantly decreased cell viability and induced reactive oxygen species generation in A549 and NCI-H358 cells. In male Sprague-Dawley rats exposed via intratracheal insufflation (0.6 mg/rat), particle-bound PBDE exposures induced inflammatory responses with increased recruitment of neutrophils to the lungs compared to sham-exposed rats. The present study clearly indicates the potential of our exposure system for studying the toxicity of particle-bound compounds.
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Affiliation(s)
- Jong Sung Kim
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA.
| | - Johannes Klösener
- Department of Occupational and Environmental Health, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA
| | - Susanne Flor
- Department of Occupational and Environmental Health, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA
| | - Thomas M Peters
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA; Department of Occupational and Environmental Health, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA
| | - Gabriele Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA; Department of Occupational and Environmental Health, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA
| | - Peter S Thorne
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA; Department of Occupational and Environmental Health, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA; Department of Occupational and Environmental Health, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA.
| | - Gregor Luthe
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA; Department of Occupational and Environmental Health, University of Iowa, UI Research Park, Iowa City, IA 52242-5000, USA.
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Wangpradit O, Moman E, Nolan KB, Buettner GR, Robertson LW, Luthe G. Observation of an unusual electronically distorted semiquinone radical of PCB metabolites in the active site of prostaglandin H synthase-2. Chemosphere 2010; 81:1501-1508. [PMID: 20843536 PMCID: PMC3622869 DOI: 10.1016/j.chemosphere.2010.08.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2010] [Revised: 08/18/2010] [Accepted: 08/20/2010] [Indexed: 05/29/2023]
Abstract
The activation of the metabolites of airborne polychlorinated biphenyls (PCBs) into highly reactive radicals is of fundamental importance. We found that human recombinant prostaglandin H synthase-2 (hPGHS-2) biotransforms dihydroxy-PCBs, such as 4-chlorobiphenyl-2',5'-hydroquinone (4-CB-2',5'-H(2)Q), into semiquinone radicals via one-electron oxidation. Using electron paramagnetic resonance (EPR) spectroscopy, we observed the formation of the symmetric quartet spectrum (1:3:3:1 by area) of 4-chlorobiphenyl-2',5'-semiquinone radical (4-CB-2',5'-SQ()(-)) from 4-CB-2',5'-H(2)Q. This spectrum changed to an asymmetric spectrum with time: the change can be explained as the overlap of two different semiquinone radical species. Hindered rotation of the 4-CB-2',5'-SQ()(-) appears not to be a major factor for the change in lineshape because increasing the viscosity of the medium with glycerol produced no significant change in lineshape. Introduction of a fluorine, which increases the steric hindrance for rotation of the dihydroxy-PCB studied, also produced no significant changes. An in silico molecular docking model of 4-CB-2',5'-H(2)Q in the peroxidase site of hPGHS-2 together with ab initio quantum mechanical studies indicate that the close proximity of a negatively charged carboxylic acid in the peroxidase active site may be responsible for the observed perturbation in the spectrum. This study provides new insights into the formation of semiquinones from PCB metabolites and underscores the potential role of PGHS-2 in the metabolic activation of PCBs.
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Affiliation(s)
- Orarat Wangpradit
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
| | - Edelmiro Moman
- ProSciens, Computing & Molecular Sciences, 2-4 rue du Palais de Justice, L-1841, Luxembourg
| | - Kevin B. Nolan
- Department of Pharmaceutical & Medicinal Chemistry, Royal College of Surgeons in Ireland (RCSI), Dublin 2, Ireland
| | - Garry R. Buettner
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
- Free Radical and Radiation Biology Program, The University of Iowa, Iowa City, IA, 52242-1181, USA
| | - Larry W. Robertson
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
| | - Gregor Luthe
- Department of Occupational and Environmental Health, The University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
- Saxion University of Applied Sciences, Institute for Life Science and Technology, Enschede, The Netherlands
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van 't Erve TJ, Rautiainen R, Robertson L, Luthe G. Trimethylsilyldiazomethane: a safe non-explosive, cost effective and less-toxic reagent for phenol derivatization in GC applications. Environ Int 2010; 36:835-842. [PMID: 20385409 PMCID: PMC4090112 DOI: 10.1016/j.envint.2010.02.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Revised: 01/27/2010] [Accepted: 02/25/2010] [Indexed: 05/29/2023]
Abstract
Diazomethane is a highly explosive and toxic gas routinely employed for the quantitative and clean derivatization of phenols. We investigated the commercially available trimethylsilyldiazomethane in the presence of diisopropylethylamine as a safe, non-explosive and less-toxic alternative using six phenolic polychlorinated biphenyls as model analytes and fluoro-tagged analogues as internal standards. We compared yields and derivatization times of each method employing a liver microsomal extract as a real matrix. Steric hindrance and electronic properties of the analytes were also investigated. The alternative method afforded equal to higher derivatization yields with increased reaction times, up to 100 min, while explosion and toxic exposure risks were minimized and cost efficiency was increased above 25%. These findings demonstrate that non-explosive trimethylsilyl diazomethane produces comparable derivatization results to the dangerous diazomethane under the conditions studied.
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Affiliation(s)
- T. J. van 't Erve
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA
- Institute of Life Sciences, Saxion University of Applied Sciences, Enschede, The Netherlands
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA
| | - R.H. Rautiainen
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA
| | - L.W. Robertson
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA
| | - G. Luthe
- Department of Occupational and Environmental Health, University of Iowa, Iowa City, IA
- Institute of Life Sciences, Saxion University of Applied Sciences, Enschede, The Netherlands
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA
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Lai I, Chai Y, Simmons D, Luthe G, Coleman MC, Spitz D, Haschek WM, Ludewig G, Robertson LW. Acute toxicity of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) in male Sprague-Dawley rats: effects on hepatic oxidative stress, glutathione and metals status. Environ Int 2010; 36:918-23. [PMID: 19969354 PMCID: PMC2891598 DOI: 10.1016/j.envint.2009.11.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2009] [Revised: 10/18/2009] [Accepted: 11/12/2009] [Indexed: 05/02/2023]
Abstract
Although polychlorinated biphenyl (PCBs) production, and new uses for PCBs, was halted in the 1970s in the United States, PCBs continue to be used in closed systems and persist in the environment, accumulating in fatty tissues. PCBs are efficacious inducers of drug metabolism and may increase oxidative events and alter many other biochemical and morphologic parameters within cells and tissues. The goal of the present study was to evaluate the effects of a single, very low dose of PCB 126 (3,3',4,4',5-pentachlorobiphenyl), a coplanar, dioxin-like PCB congener and aryl hydrocarbon receptor (AhR) agonist, on redox status, metals homeostasis, antioxidant enzymes, and cellular morphology. To examine these parameters, male Sprague-Dawley rats were fed a purified AIN-93 basal diet containing 0.2 ppm selenium for two weeks, then administered a single i.p. injection of corn oil (5 ml/kg body weight) or 1µmol PCB 126/kg body weight (326µg/kg body weight) in corn oil. Rats were maintained on the diet for an additional two weeks before being euthanized. This dose of PCB 126 did not alter feed intake or growth, but significantly increased liver weight (42%) and hepatic microsomal cytochrome P-450 (CYP1A) enzyme activities (10-40-fold increase). Hepatic zinc, selenium, and glutathione levels were significantly decreased 15%, 30%, and 20%, respectively, by PCB 126. These changes were accompanied by a 60% decrease in selenium-dependent glutathione peroxidase activity. In contrast, hepatic copper levels were increased 40% by PCB 126. PCB 126-induced pathology was characterized by hepatocellular hypertrophy and mild steatosis in the liver and a mild decrease in cortical T-cells in the thymus. This controlled study in rats fed a purified diet shows that even a single, very low dose of PCB 126 that did not alter feed intake or growth, significantly perturbed redox and metals homeostasis and antioxidant and enzyme levels in rodent liver.
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Affiliation(s)
- Ian Lai
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
- Department of Occupational & Environmental Health, University of Iowa
| | - Yingtao Chai
- University Hygienic Laboratory, University of Iowa
| | - Don Simmons
- University Hygienic Laboratory, University of Iowa
| | - Gregor Luthe
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
- Department of Occupational & Environmental Health, University of Iowa
| | - Mitchell C. Coleman
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, University of Iowa
| | - Douglas Spitz
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, University of Iowa
| | - Wanda M. Haschek
- Department of Pathobiology, University of Illinois, Urbana, IL 61802
| | - Gabriele Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
- Department of Occupational & Environmental Health, University of Iowa
| | - Larry W. Robertson
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa
- Department of Occupational & Environmental Health, University of Iowa
- Free Radical and Radiation Biology Program, Department of Radiation Oncology, University of Iowa
- Address Correspondence to Larry W. Robertson: Larry W. Robertson, Ph.D., M.P.H., Professor, Department of Occupational and Environmental Health, The University of Iowa, College of Public Health, 100 Oakdale Campus #219 IREH, Iowa City, Iowa 52242-5000, Phone: 319-335-4554, Fax: 319-335-4290,
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Klösener J, Peters TM, Adamcakova-Dodd A, Teesch LM, Thorne PS, Robertson LW, Luthe G. Innovative application of fluoro tagging to trace airborne particulate and gas-phase polybrominated diphenyl ether exposures. Chem Res Toxicol 2009; 22:179-86. [PMID: 19111055 DOI: 10.1021/tx8003032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Polybrominated diphenyl ethers (PBDEs) are flame retardants applied as coatings to many consumer products, including household items. PBDEs are released and produce airborne vapors and dusts. Inhalation of particle-phase and/or gas-phase PBDEs is therefore a major route of exposure. In an attempt to mimic realistic airborne exposures, actual uptake, and deposition of particles and vapors, we prepared and characterized particles for future animal exposure studies. To trace the particles in environmental and biological systems, we employed fluoro tagging. We synthesized, characterized, and employed three PBDE congeners, 35, 47, and 99, and five fluoro-substituted PBDEs (F-PBDEs), 17-F5' 25-F5', 28-F3', 35-F5', 47-F3, and 99-F3', for this study. The PBDE congeners were selected because they are commonly found in house dust. For that reason, we coated spherical silica particles of 3 microm and C18 endcapped silica as representative and inert support materials, with 20, 30, and 40% PBDEs. We determined the particle size distributions by aerodynamic particle size spectrometry and the morphology by scanning electron microscopy. The suitability of the fluoro-tagged tracers to mimic their corresponding parent PBDEs was investigated by extraction studies from spiked blood serum. Our study is of fundamental importance to the development of xenobiotic tracers for monitoring routes of human exposure to PBDEs and understanding uptake of PBDEs from particles and vapors.
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Affiliation(s)
- Johannes Klösener
- Department of Occupational and Environmental Health, High Resolution Mass Spectrometry Facility, and Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, 100 Oakdale Campus, Iowa City, Iowa 52242, USA
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Wangpradit O, Teesch LM, Mariappan SVS, Duffel MW, Norstrom K, Robertson LW, Luthe G. Oxidation of 4-chlorobiphenyl metabolites to electrophilic species by prostaglandin H synthase. Chem Res Toxicol 2009; 22:64-71. [PMID: 19105592 DOI: 10.1021/tx800300t] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hormonally sensitive tissues, like the prostate, ovary, and breast, increasingly studied as targets of environmental chemicals, are sources of an enzyme potentially capable of transforming and activating xenobiotics to highly reactive metabolites. Our study specifically addresses the question of whether prostaglandin H synthase (PGHS) can activate phenolic metabolites of polychlorinated biphenyls (PCBs). We found that human recombinant PGHS-2 catalyzed the oxidation of ortho (2',3'- and 3',4'-) and para (2',5'-) dihydroxy 4-chlorobiphenyl metabolites to their corresponding quinones. These were trapped in situ with N-acetyl cysteine, and the reaction products were isolated and characterized by liquid chromatography coupled mass spectrometry and (1)H and heteronuclear ((1)H-(13)C) nuclear magnetic resonance spectroscopy. Both mono- and di-N-acetyl cysteine Michael addition adducts were identified, with the 2',3'- and 2',5'-dihydroxy metabolites predominantly forming mono-N-acetyl cysteine adducts, while the 3',4'-dihydroxy predominantly formed disubstituted N-acetyl cysteine adducts. These studies clearly demonstrate that the phenolic metabolites of these environmental pollutants are activated by PGHS, as cosubstrates, to highly reactive electrophilic PCB quinones, with a potential for protein and DNA damage, especially in nonhepatic tissues where the enzyme is found.
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Affiliation(s)
- Orarat Wangpradit
- Department of Occupational and Environmental Health, Interdisciplinary Graduate Program in Human Toxicology, College of Pharmacy, and Seamans Center for the Engineering Art and Sciences, University of Iowa, Iowa City, Iowa 52242, USA
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Luthe G, Garcia Boy R, Jacobus J, Smith BJ, Rahaman A, Robertson LW, Ludewig G. Xenobiotic geometry and media pH determine cytotoxicity through solubility. Chem Res Toxicol 2008; 21:1017-27. [PMID: 18402468 DOI: 10.1021/tx700214p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polychlorinated biphenyls (PCBs), a class of 209 individual congeners, have become persistent and ubiquitous environmental contaminants. The health impacts of PCBs, such as cancer, cardiovascular disease, developmental toxicity, and neurotoxicity, have been widely reported, but for many of these, the mechanisms of toxicity are still poorly understood. Many mechanistic studies involve cultured cells where the biological activity is dependent upon the solubility of the xenobiotic. In the present study, we investigated the factors that determine solubility as measured by diffraction spectroscopy and have modeled, with semiempirical and ab initio molecular orbital methods, the dihedral angle and calculated the dipole moment of a series of monofluorinated analogues (F-PCBs 3) of 4-chlorobiphenyl (PCB 3) as model compounds in vacuum and in water. We found a strong positive correlation between the dihedral angle, the rotation energy, the cavitation energy, the solubility, and the cytotoxicity in three human cell lines. The dipole moment was of minor influence. We also determined the influence of pH changes in a medium containing 10% fetal bovine serum (FBS), changes that could be expected when cells in culture are removed from a CO 2 incubator even for a short time. We found that the solubility is strongly affected by the pH and that this effect is not reversed by subsequent pH readjustment. In a study examining cytotoxicity, we showed that the actual pH and the pH history of a medium containing FBS were of major influence. We suggest that pH-driven changes in the tertiary and quaternary structure of albumin are responsible. These observations have implications for studies of the biological activity of semisoluble compounds, like PCBs and related compounds.
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Affiliation(s)
- Gregor Luthe
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus, Iowa City, Iowa 52242-5000, USA.
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Luthe G, Jacobus J, Robertson L. Receptor interactions by polybrominated diphenyl ethers versus polychlorinated biphenyls: a theoretical Structure-activity assessment. Environ Toxicol Pharmacol 2008; 25:202-10. [PMID: 19768137 PMCID: PMC2746664 DOI: 10.1016/j.etap.2007.10.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The extensive body of literature regarding the interaction of polychlorinated biphenyls (PCBs) with transcription factors (receptors) has great value to understand similarities and distinctions and in formulating hypotheses regarding the activity of polybrominated diphenyl ethers (PBDEs) toward those same receptors. Our goal is to present the most comprehensive overview of PBDE effects on AhR, CAR, PXR, ER, AR, PR, DHT, TH, T3, T4 and IGF, as well as hypothetical biological activities of PPAR, RyR, GR and GABA. Aside the influence of the conformation of the ligand, we discuss its constitution influencing the binding affinity: size and polarizability, hydrophilicity, Gibbs free energy of solvation, inductive and mesomeric effects. We evaluate the techniques to determine the biologically relevant conformation of these halogenated hydrocarbons, including computation methods, X-ray and microwave spectroscopy. A novel fluoro-tagged ligand approach holds promise as tools for illuminating the steric and electronic effects in ligand-receptor interaction. Based on our assessment, we predict that PBDEs do not exhibit AhR activity themselves, but impurities are responsible for these effects.
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Affiliation(s)
- G. Luthe
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
| | - J.A. Jacobus
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
- Institute for Life Science and Technology, Saxion University of Applied Sciences, Enschede, The Netherlands
| | - L.W. Robertson
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
- Institute for Life Science and Technology, Saxion University of Applied Sciences, Enschede, The Netherlands
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Klösener J, Swenson DC, Robertson LW, Luthe G. Effects of fluoro substitution on 4-bromodiphenyl ether (PBDE 3). Acta Crystallogr B 2008; 64:108-19. [PMID: 18204217 PMCID: PMC3120100 DOI: 10.1107/s0108768107067079] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2007] [Accepted: 12/15/2007] [Indexed: 11/10/2022]
Abstract
It is our hypothesis that fluoro substitution provides a powerful tool to modulate the desired characteristics and to increase the specificity of studies of structure-activity relationships. 4-Bromodiphenyl ether (PBDE 3) and its five corresponding monofluorinated analogues (F-PBDEs 3) have been synthesized and fully characterized (using (1)H, (13)C and (19)F NMR spectroscopy, and mass spectrometry). The accurate structure from X-ray crystal analysis was compared with iterative calculations using semi-empirical self-consistent field molecular-orbital (SCF-MO) models. The compounds studied were 4-bromodiphenyl ether (PBDE 3), the (13)C(6)-isotopically labeled PBDE 3 ((13)C(6)-PBDE 3) and 2-fluoro-4-bromodiphenyl ether (3-2F), 2'-fluoro-4-bromodiphenyl ether (3-2'F), 3-fluoro-4-bromodiphenyl ether (3-3F), 3'-fluoro-4-bromodiphenyl ether (3-3'F), and 4'-fluoro-4-bromodiphenyl ether (3-4'F). Solid-state intermolecular interactions for PBDE 3 and the F-PBDEs 3 isomers are dominated by weak C-H(F,Br)...pi and C-H...F interactions. The C-F bond lengths varied between 1.347 (2) and 1.362 (2) A, and the C4-Br bond length between 1.880 (3) and 1.904 (2) A. These bond lengths are correlated with electron-density differences, as determined by (13)C shifts, but not with the strength of the C-F couplings. The interior ring angles of ipso-fluoro substitution increased (121.9-124.0 degrees ) as a result of hyperconjugation, a phenomenon also predicted by the calculation models. An attraction between the vicinal fluoro and halo substituents (observed in fluoro substituted chlorobiphenyls) was not observed for the bromo substituted F-PBDEs. The influence of a fluoro substituent on the conformation was only observable in PBDEs with di-ortho substitution. Calculated and observed torsion angles showed a positive correlation with increasing van der Waals radii and/or the degree of substitution for mono- to tetra-fluoro, chloro, bromo and methyl substitutions in the ortho positions of diphenyl ether. These findings utilizing F-tagged analogues presented here may prove fundamental to the interpretation of the biological effects and toxicities of these persistent environmental pollutants.
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Affiliation(s)
- J. Klösener
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
- Institute for Life Science and Technology, Saxion University of Applied Sciences, Enschede, The Netherlands
| | - D. C. Swenson
- Department of Chemistry, University of Iowa, Iowa City, IA, USA
| | - L. W. Robertson
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
| | - G. Luthe
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
- Institute for Life Science and Technology, Saxion University of Applied Sciences, Enschede, The Netherlands
- University of Bremen, Institute for Inorganic & Physical Chemistry, Bremen, Germany
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16
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Shaikh NS, Parkin S, Luthe G, Lehmler HJ. The three-dimensional structure of 3,3',4,4'-tetrachlorobiphenyl, a dioxin-like polychlorinated biphenyl (PCB). Chemosphere 2008; 70:1694-8. [PMID: 17723240 PMCID: PMC2430941 DOI: 10.1016/j.chemosphere.2007.07.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2006] [Revised: 07/09/2007] [Accepted: 07/13/2007] [Indexed: 05/02/2023]
Abstract
The crystal structure of PCB 77 (3,3',4,4'-tetrachlorobiphenyl, C(12)H(6)Cl(4)), a dioxin-like PCB congener, is described. The dihedral angle of PCB 77 is 43.94(6) degrees, which is slightly larger than calculated or experimental dihedral angles of biphenyl derivatives in solution but smaller than experimental dihedral angles in the gas phase.
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Affiliation(s)
- Nadim S. Shaikh
- The University of Iowa, Department of Occupational and Environmental Health, 100 Oakdale Campus, 124 IREH, Iowa City, IA 52242-5000, USA
| | - Sean Parkin
- University of Kentucky, Department of Chemistry, Lexington, KY 40506-0055, USA
| | - Gregor Luthe
- The University of Iowa, Department of Occupational and Environmental Health, 100 Oakdale Campus, 124 IREH, Iowa City, IA 52242-5000, USA
- University of Bremen, Institute for Inorganic and Physical Chemistry, Leobener Strasse, NW2, C2350, D-28334 Bremen, Germany
- Institute of Life Science and Technology, Saxion University of Applied Sciences, Enschede, The Netherland
| | - Hans-Joachim Lehmler
- The University of Iowa, Department of Occupational and Environmental Health, 100 Oakdale Campus, 124 IREH, Iowa City, IA 52242-5000, USA
- * Corresponding author. Tel.: +1-319-335-4211, Fax: + 1-319-335-4290, (H.-J. Lehmler)
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Luthe G, Swenson DC, Robertson LW. Influence of fluoro-substitution on the planarity of 4-chlorobiphenyl (PCB 3). Acta Crystallogr B 2007; 63:319-27. [PMID: 17374943 DOI: 10.1107/s0108768106054255] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Accepted: 12/13/2006] [Indexed: 11/10/2022]
Abstract
Accurate structure determinations by X-ray crystal analysis and computation using semi-empirical self-consistent field molecular orbital calculations are described and compared for five monofluorinated analogues of 4-chlorobiphenyl, i.e. 2-fluoro-4-chlorobiphenyl, 2'-fluoro-4-chlorobiphenyl, 3-fluoro-4-chlorobiphenyl, 3'-fluoro-4-chlorobiphenyl and 4'-fluoro-4-chlorobiphenyl. Intermolecular interactions for all monofluorinated isomers are dominated by phenyl-phenyl stacking and C-H-phenyl interactions. C-F bond lengths varied between 1.341 and 1.374 A, C-Cl between 1.733 and 1.765 A, and both correlate with electron-density differences as determined by (13)C NMR shifts. The interior ring angles at ipso-fluoro substitution increase up to 122.2-124.2 degrees due to hyperconjugation by 2p-pi-orbital overlapping, a phenomenon that was also reflected in the computer calculation. The angles of C-F and C-Cl relative to the aromatic ring for vicinal fluoro- and chloro substituents show an attraction, not a repulsion, between the adjacent F and Cl substituents. This finding is explained on the basis of electron donor and acceptor properties. The dihedral angles of ortho-substituted biphenyls show that monofluoro substitution results in slightly smaller increases compared with chlorine, while additional ortho-fluorination results in little further change in the dihedral angle. In contrast, ortho-chlorination strongly decreases the co-planarity. This is likely to be due to interior ring-angle distortion and the size of the halogen substituent. Fluoro substitution does indeed affect the planarity of the PCB3 analogues, but these effects are minor compared with chloro substitution. Fluorine tagging offers promise for use in in vitro and in vivo studies. Differences in computational versus measured data emphasize the need to use a variety of methods to ascertain the true nature of the physical properties of a compound.
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Affiliation(s)
- G Luthe
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA.
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Liu H, Skålvoll A, Reijerink GS, Luthe G, Johansen JE. Synthesis of fluorinated polybrominated diphenyl ethers (F-PBDEs) as internal standards for environmental analysis. Chemosphere 2006; 64:250-5. [PMID: 16480757 DOI: 10.1016/j.chemosphere.2005.12.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs) have become widely distributed as environmental contaminants due to their wide-spread use as flame retardants. Their structural similarity to other halogenated organic pollutants, for example polychlorinated biphenyls (PCBs), has led to speculation that they may have similar toxicological properties and effects. Recent focus on PBDEs as possible priority pollutants has also led to an increasing need for reference standards of PBDEs for toxicological studies and for environmental analysis. In this work we synthesized a series of fluorinated PBDEs (F-PBDEs) which can be used as possible internal standards, as an alternative to high-cost alternatives, such as the (13)C-labelled analogues. F-PBDEs have been synthesized by using different coupling reactions and by bromination of fluorinated starting materials.
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Affiliation(s)
- Huiling Liu
- Chiron AS, Stiklestadveien 1, N-7041 Trondheim, Norway.
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Luthe G, Leonards PEG, Reijerink GS, Liu H, Johansen JE, Robertson LW. Monofluorinated analogues of polybrominated diphenyl ethers as analytical standards: synthesis, NMR, and GC-MS characterization and molecular orbital studies. Environ Sci Technol 2006; 40:3023-9. [PMID: 16719106 DOI: 10.1021/es052410z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Polybrominated diphenyl ethers (PBDEs), a group of 209 individual congeners distinguishable by the number and position of bromines, are produced for use as flame retardants in consumer goods. PBDEs have become ubiquitous environmental contaminants, present in increasing levels in the environment and humans. In the present study, 10 individual monofluorinated analogues of PBDEs (F-PBDEs) and one difluorinated PBDE (FF-PBDE) were synthesized and characterized, and their gas chromatographic (GC) and mass spectrometric (MS) characteristics determined. The synthesis method utilized a nucleophilic reaction of bromophenols with diphenyliodonium salts and the perbromination of fluorosubstituted diphenyl ethers. Reaction yields were between 10% and 59% with > or = 98% purity. Apart from the aromatic ring carrying the fluorine atom, only minor chemical nuclear magnetic resonance (NMR) shift changes were observed in comparison to the corresponding parent PBDEs, with the exception that the J(F,H) coupling was stronger. Our preliminary data show that F-PBDEs and PBDEs have comparable retention times in gas chromatography with F-PBDEs demonstrating in general shorter or identical retention times, depending on the pattern of fluorine substitution. We also calculated the torsion angles and the dipole moments for both and report that there is a good correlation between GC retention times and the torsion angles but not with dipole moments. In MS, the difference of the ion peaks of the F-PBDE/ PBDE pairs is m/z 19 (F), which allows a simultaneous MS detection without separation. On the basis of GC separation, simultaneous MS detection, and the stability of fluorine due to its generally resistance to nucleophilic displacement, we propose that F-PBDEs may function as valuable potential standards, markers, and tracers in environmental analysis.
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Affiliation(s)
- Gregor Luthe
- Institute of Chemistry, Norwegian University of Science and Technology, N-7041 Trondheim, Norway.
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Lutnaes BF, Luthe G, Brinkman UAT, Johansen JE, Krane J. Characterization of monofluorinated polycyclic aromatic compounds by 1H, 13C and 19F NMR spectroscopy. Magn Reson Chem 2005; 43:588-594. [PMID: 15809969 DOI: 10.1002/mrc.1584] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Monofluorinated polycyclic aromatic hydrocarbons (F-PAHs) have attracted much attention in analytical, environmental, toxicological and mechanistic studies because of their physico-chemical properties, which are closely similar to those of the parent PAHs. Because of this, full NMR characterization has become of interest. Complete 1H, 13C and 19F NMR chemical shifts, and also 1J(H,C), (n)J(C,F), (n)J(H,F) and (n)J(H,H) coupling constants, have been assigned for the F-PAHs 1-fluoronaphthalene, 2-fluorofluorene, 5-fluoroacenaphthylene, 2-fluorophenanthrene, 3-fluorophenanthrene, 3-fluorofluoranthene, 1-fluoropyrene, 1-fluorochrysene, 2-fluorochrysene, 3-fluorochrysene and 9-fluorobenzo[k]fluoranthene. To allow comparison with the corresponding parent PAHs, the 1H and 13C chemical shifts of acenaphthylene, phenanthrene, fluoranthene, pyrene and benzo[k]fluoranthene were determined. Chemical shift increments and the effects on the coupling constants from the fluorine substitution are discussed.
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Affiliation(s)
- Bjart Frode Lutnaes
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim, Norway.
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Luthe G, Wiersum UE, Brinkman UAT. SYNTHESIS AND THERMAL INTERCONVERSION OF 5-FLUOROACENAPHTHYLENE BY FLASH VACUUM THERMOLYSIS. Polycycl Aromat Compd 2005. [DOI: 10.1080/10406630590909756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Luthe G, Stroomberg GJ, Ariese F, Brinkman UAT, van Straalen NM. Metabolism of 1-fluoropyrene and pyrene in marine flatfish and terrestrial isopods. Environ Toxicol Pharmacol 2002; 12:221-229. [PMID: 21782641 DOI: 10.1016/s1382-6689(02)00093-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2002] [Revised: 06/06/2002] [Accepted: 06/07/2002] [Indexed: 05/31/2023]
Abstract
Monofluorinated polycyclic aromatic hydrocarbons (F-PAHs) are useful reference compounds for a broad spectrum of PAH studies. The pyrene metabolite 1-hydroxypyrene is often used as a biomarker of PAH exposure. Two species, isopod (Porcellio scaber) and flatfish (Platichthys flesus), that produce 1-hydroxypyrene as the major intermediary metabolite and have distinct phase-II conjugates, were selected to investigate the cytochrome P450 catalyzed metabolism of 1-fluoropyrene. The fluorine atom blocks one of the four most favored carbon atoms, yielding different metabolite patterns and the results obtained in the selected species were compared with metabolite profiles obtained for unsubstituted pyrene. Charge densities in 1-fluoropyrene measured with (13)C-NMR were used to predict possible positions of hydroxylation, which were confirmed by (19)F-NMR. Additionally, the retention behaviour of conjugated 1-fluoropyrene metabolite isomers in reversed-phase liquid chromatography on a polymeric alkyl-bonded phase was interpreted based on the slot model. Whereas three phase-I metabolites were found in isopod hepatopancreas, only two were observed in flatfish bile. Phase-II metabolism appeared unaffected by the fluorine substituent. It was concluded that the phase-I enzyme cytochrome P450 is non-regioselective in the isopod: the activation is mostly influenced by the electron density distribution. In contrast, the enzymatic oxidation in the flounder is more selective. These differences will affect to what extent pyrene metabolite measurements can be used to assess the impact of PAHs to different species.
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Affiliation(s)
- Gregor Luthe
- Department of Analytical Chemistry and Applied Spectroscopy, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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Luthe G, Broeders J, Brinkman UA. Monofluorinated polycyclic aromatic hydrocarbons as internal standards to monitor trace enrichment and desorption of their parent compounds during solid-phase extraction. J Chromatogr A 2001; 933:27-35. [PMID: 11758744 DOI: 10.1016/s0021-9673(01)01265-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Solid-phase extraction (SPE) is an established sample-preparation technique for clean-up procedures of polycyclic aromatic hydrocarbons (PAHs). The suitability of monofluorinated polycyclic aromatic hydrocarbons (F-PAHs) as a novel set of internal standards, was tested for two widely used SPE sorbents, octyl-bonded silica and styrene-divinylbenzene copolymer. The elution profiles of eight F-PAHs and their parent PAHs, taken from the priority pollutant list of the US-Environmental Protection Agency, were compared for demineralized water and waste water. In both instances, the match of the elution profiles was exceptionally close. The eight F-PAHs and the corresponding PAHs were determined by reversed-phase liquid chromatography using acetonitrile-water gradient elution with UV detection at 254 nm. The UV spectra of the F-PAHs show a small bathochromic shift compared with the parent PAHs.
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Affiliation(s)
- G Luthe
- Free University, Department of Analytical Chemistry and Applied Spectroscopy, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. .
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Abstract
First studies of a series of eight monofluorinated polycyclic aromatic hydrocarbons indicate that they are a promising set of internal standards and markers in the trace-level environmental analysis of their parent polycyclic aromatic hydrocarbons. The selected examples deal with solid-phase extraction, LC separation, Shpolśkii spectroscopy and metabolic study.
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Affiliation(s)
- G Luthe
- Free University, Department of Analytical Chemistry and Applied Spectroscopy, Amsterdam, The Netherlands
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