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Müller E, von Gunten U, Tolu J, Bouchet S, Winkel LHE. Reactions of hypobromous acid with dimethyl selenide, dimethyl diselenide and other organic selenium compounds: kinetics and product formation. ENVIRONMENTAL SCIENCE : WATER RESEARCH & TECHNOLOGY 2024; 10:620-630. [PMID: 38434173 PMCID: PMC10905664 DOI: 10.1039/d3ew00787a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/02/2024] [Indexed: 03/05/2024]
Abstract
Selenium (Se) is an essential micronutrient for many living organisms particularly due to its unique redox properties. We recently found that the sulfur (S) analog for dimethyl selenide (DMSe), i.e. dimethyl sulfide (DMS), reacts fast with the marine oxidant hypobromous acid (HOBr) which likely serves as a sink of marine DMS. Here we investigated the reactivity of HOBr with dimethyl selenide and dimethyl diselenide (DMDSe), which are the main volatile Se compounds biogenically produced in marine waters. In addition, the reactivity of HOBr with further organic Se compounds was tested, i.e., SeMet (as N-acetylated-SeMet), and selenocystine (SeCys2 as N-acetylated-SeCys2), as well as the phenyl-analogs of DMSe and DMDSe, respectively, diphenyl selenide (DPSe) and diphenyl diselenide (DPDSe). Apparent second-order rate constants at pH 8 for the reactions of HOBr with the studied Se compounds were (7.1 ± 0.7) × 107 M-1 s-1 for DMSe, (4.3 ± 0.4) × 107 M-1 s-1 for DMDSe, (2.8 ± 0.3) × 108 M-1 s-1 for SeMet, (3.8 ± 0.2) × 107 M-1 s-1 for SeCys2, (3.5 ± 0.1) × 107 M-1 s-1 for DPSe, and (8.0 ± 0.4) × 106 M-1 s-1 for DPDSe, indicating a very high reactivity of all selected Se compounds with HOBr. The reactivity between HOBr and DMSe is lower than for DMS and therefore this reaction is likely not relevant for marine DMSe abatement. However, the high reactivity of SeMet with HOBr suggests that SeMet may act as a relevant quencher of HOBr.
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Affiliation(s)
- Emanuel Müller
- Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water (W+T), Eawag Ueberlandstrasse 133 CH-8600 Duebendorf Switzerland +41 58 765 5601
- Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environment Systems (D-USYS), ETH Zurich Universitätsstrasse 16 8092 Zürich Switzerland
| | - Urs von Gunten
- Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water (W+T), Eawag Ueberlandstrasse 133 CH-8600 Duebendorf Switzerland +41 58 765 5601
- School of Architecture, Civil and Environmental Engineering (ENAC), École Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environment Systems (D-USYS), ETH Zurich Universitätsstrasse 16 8092 Zürich Switzerland
| | - Julie Tolu
- Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water (W+T), Eawag Ueberlandstrasse 133 CH-8600 Duebendorf Switzerland +41 58 765 5601
- Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environment Systems (D-USYS), ETH Zurich Universitätsstrasse 16 8092 Zürich Switzerland
| | - Sylvain Bouchet
- Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water (W+T), Eawag Ueberlandstrasse 133 CH-8600 Duebendorf Switzerland +41 58 765 5601
- Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environment Systems (D-USYS), ETH Zurich Universitätsstrasse 16 8092 Zürich Switzerland
| | - Lenny H E Winkel
- Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water (W+T), Eawag Ueberlandstrasse 133 CH-8600 Duebendorf Switzerland +41 58 765 5601
- Swiss Federal Institute of Technology, Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environment Systems (D-USYS), ETH Zurich Universitätsstrasse 16 8092 Zürich Switzerland
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Carroll L, Gardiner K, Ignasiak M, Holmehave J, Shimodaira S, Breitenbach T, Iwaoka M, Ogilby PR, Pattison DI, Davies MJ. Interaction kinetics of selenium-containing compounds with oxidants. Free Radic Biol Med 2020; 155:58-68. [PMID: 32439383 DOI: 10.1016/j.freeradbiomed.2020.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/07/2020] [Accepted: 05/10/2020] [Indexed: 02/03/2023]
Abstract
Selenium compounds have been identified as potential oxidant scavengers for biological applications due to the nucleophilicity of Se, and the ease of oxidation of the selenium centre. Previous studies have reported apparent second order rate constants for a number of oxidants (e.g. HOCl, ONOOH) with some selenium species, but these data are limited. Here we provide apparent second order rate constants for reaction of selenols (RSeH), selenides (RSeR') and diselenides (RSeSeR') with biologically-relevant oxidants (HOCl, H2O2, other peroxides) as well as overall consumption data for the excited state species singlet oxygen (1O2). Selenols show very high reactivity with HOCl and 1O2, with rate constants > 108 M-1 s-1, whilst selenides and diselenides typically react with rate constants one- (selenides) or two- (diselenides) orders of magnitude slower. Rate constants for reaction of diselenides with H2O2 and other hydroperoxides are much slower, with k for H2O2 being <1 M-1 s-1, and for amino acid and peptide hydroperoxides ~102 M-1 s-1. The rate constants determined for HOCl and 1O2 with these selenium species are greater than, or similar to, rate constants for amino acid side chains on proteins, including the corresponding sulfur-centered species (Cys and Met), suggesting that selenium containing compounds may be effective oxidant scavengers. Some of these reactions may be catalytic in nature due to ready recycling of the oxidized selenium species. These data may aid the development of highly efficacious, and catalytic, oxidant scavengers.
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Affiliation(s)
- Luke Carroll
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark
| | - Kelly Gardiner
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark; The Heart Research Institute, Sydney, Australia; Sydney Medical School, University of Sydney, Australia
| | - Marta Ignasiak
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark; Department of Chemistry, Adam Mickiewicz University, Poznan, Poland
| | | | - Shingo Shimodaira
- Brain Korea (BK21), Dept. of Chemistry, KAIST 373-1, Daejeon, South Korea
| | | | - Michio Iwaoka
- Department of Chemistry, Tokai University, Hiratsuka, Japan
| | - Peter R Ogilby
- Department of Chemistry, Aarhus University, Aarhus, Denmark
| | - David I Pattison
- The Heart Research Institute, Sydney, Australia; Sydney Medical School, University of Sydney, Australia; Department of Plant and Environmental Sciences, University of Copenhagen, Denmark
| | - Michael J Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Denmark; The Heart Research Institute, Sydney, Australia; Sydney Medical School, University of Sydney, Australia.
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Carroll L, Davies MJ, Pattison DI. Reaction of low-molecular-mass organoselenium compounds (and their sulphur analogues) with inflammation-associated oxidants. Free Radic Res 2015; 49:750-67. [PMID: 25854915 DOI: 10.3109/10715762.2015.1018247] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Selenium is an essential trace element in mammals, with the majority specifically encoded as seleno-L-cysteine into a range of selenoproteins. Many of these proteins play a key role in modulating oxidative stress, via either direct detoxification of biological oxidants, or repair of oxidised residues. Both selenium- and sulphur-containing residues react readily with the wide range of oxidants (including hydrogen peroxide, radicals, singlet oxygen and hypochlorous, hypobromous, hypothiocyanous and peroxynitrous acids) that are produced during inflammation and have been implicated in the development of a range of inflammatory diseases. Whilst selenium has similar properties to sulphur, it typically exhibits greater reactivity with most oxidants, and there are considerable differences in the subsequent reactivity and ease of repair of the oxidised species that are formed. This review discusses the chemistry of low-molecular-mass organoselenium compounds (e.g. selenoethers, diselenides and selenols) with inflammatory oxidants, with a particular focus on the reaction kinetics and product studies, with the differences in reactivity between selenium and sulphur analogues described in the selected examples. These data provide insight into the therapeutic potential of low-molecular-mass selenium-containing compounds to modulate the activity of both radical and molecular oxidants and provide protection against inflammation-induced damage. Progress in their therapeutic development (including modulation of potential selenium toxicity by strategic design) is demonstrated by a brief summary of some recent studies where novel organoselenium compounds have been used as wound healing or radioprotection agents and in the prevention of cardiovascular disease.
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Affiliation(s)
- L Carroll
- The Heart Research Institute , Newtown, Sydney , Australia
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Suryo Rahmanto A, Pattison DI, Davies MJ. Photo-oxidation-induced inactivation of the selenium-containing protective enzymes thioredoxin reductase and glutathione peroxidase. Free Radic Biol Med 2012; 53:1308-16. [PMID: 22884457 DOI: 10.1016/j.freeradbiomed.2012.07.016] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 07/10/2012] [Accepted: 07/17/2012] [Indexed: 10/28/2022]
Abstract
Singlet oxygen ((1)O(2)) is a reactive oxygen species generated during photo-oxidation, inflammation, and via peroxidase-catalyzed reactions (e.g., myeloperoxidase and eosinophil peroxidase). (1)O(2) oxidizes the free amino acids Trp, Tyr, His, Cys, and Met, and those species present on peptides/proteins, with this resulting in modulation of protein structure and function. Impairment of the activity of antioxidant enzymes may be of relevance to the oxidative stress observed in a number of pathologies involving either light exposure or inflammation. In this study, the effects of (1)O(2) on glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) activity, including the mechanisms of their inactivation, were investigated. Exposure of GPx or TrxR, either as purified proteins or in cell lysates, to Rose Bengal and visible light (an established source of (1)O(2)) resulted in significant, photolysis time-dependent reductions in enzyme activity (10-40%, P<0.05). More extensive inhibition (ca. 2-fold) was detected when the reactions were carried out in D(2)O, consistent with the intermediacy of (1)O(2). No additional inhibition was detected after the cessation of photolysis, eliminating a role for photo-products. Methionine, which reacts rapidly with (1)O(2) (k~10(7)M(-1) s(-1))(,) significantly reduced photo-inactivation at large molar excesses, presumably by acting as an alternative target. Reductants (NaBH(4), DTT, GSH, or NADPH) added after the cessation of (1)O(2) formation were unable to reverse enzyme inactivation, consistent with irreversible enzyme oxidation. Formation of nonreducible protein aggregates and/or fragments was detected for both photo-oxidized GPx and TrxR by SDS-PAGE. An oxidant concentration-dependent increase in protein carbonyls was detected with TrxR but not GPx. These studies thus demonstrate that the antioxidant enzymes GPx and TrxR can be irreversibly inactivated by (1)O(2).
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Collins SP, Heverly-Coulson GS, Boyd RJ. Reaction of group 16 analogues of ethoxyquin with hydrogen peroxide: A computational study. COMPUT THEOR CHEM 2012. [DOI: 10.1016/j.comptc.2011.11.047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Suryo Rahmanto A, Davies MJ. Catalytic activity of selenomethionine in removing amino acid, peptide, and protein hydroperoxides. Free Radic Biol Med 2011; 51:2288-99. [PMID: 22015433 DOI: 10.1016/j.freeradbiomed.2011.09.027] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 09/23/2011] [Accepted: 09/23/2011] [Indexed: 11/21/2022]
Abstract
Selenium is a critical trace element, with deficiency associated with numerous diseases including cardiovascular disease, diabetes, and cancer. Selenomethionine (SeMet; a selenium analogue of the amino acid methionine, Met) is a major form of organic selenium and an important dietary source of selenium for selenoprotein synthesis in vivo. As selenium compounds can be readily oxidized and reduced, and selenocysteine residues play a critical role in the catalytic activity of the key protective enzymes glutathione peroxidase and thioredoxin reductase, we investigated the ability of SeMet (and its sulfur analogue, Met) to scavenge hydroperoxides present on amino acids, peptides, and proteins, which are key intermediates in protein oxidation. We show that SeMet, but not Met, can remove these species both stoichiometrically and catalytically in the presence of glutathione (GSH) or a thioredoxin reductase (TrxR)/thioredoxin (Trx)/NADPH system. Reaction of the hydroperoxide with SeMet results in selenoxide formation as detected by HPLC. Recycling of the selenoxide back to SeMet occurs rapidly with GSH, TrxR/NADPH, or a complete TrxR/Trx/NADPH reducing system, with this resulting in an enhanced rate of peroxide removal. In the complete TrxR/Trx/NADPH system loss of peroxide is essentially stoichiometric with NADPH consumption, indicative of a highly efficient system. Similar reactions do not occur with Met under these conditions. Studies using murine macrophage-like J774A.1 cells demonstrate a greater peroxide-removing capacity in cells supplemented with SeMet, compared to nonsupplemented controls. Overall, these findings demonstrate that SeMet may play an important role in the catalytic removal of damaging peptide and protein oxidation products.
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Day BJ. Catalase and glutathione peroxidase mimics. Biochem Pharmacol 2008; 77:285-96. [PMID: 18948086 DOI: 10.1016/j.bcp.2008.09.029] [Citation(s) in RCA: 185] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Revised: 09/18/2008] [Accepted: 09/19/2008] [Indexed: 12/14/2022]
Abstract
Overproduction of the reactive oxygen species (ROS) superoxide (O(2)(-)) and hydrogen peroxide (H(2)O(2)) are increasingly implicated in human disease and aging. ROS are also being explored as important modulating agents in a number of cell signaling pathways. Earlier work has focused on development of small catalytic scavengers of O(2)(-), commonly referred to as superoxide dismutase (SOD) mimetics. Many of these compounds also have substantial abilities to catalytically scavenge H(2)O(2) and peroxynitrite (ONOO(-)). Peroxides have been increasingly shown to disrupt cell signaling cascades associated with excessive inflammation associated with a wide variety of human diseases. Early studies with enzymatic scavengers like SOD frequently reported little or no beneficial effect in biologic models unless SOD was combined with catalase or a peroxidase. Increasing attention has been devoted to developing catalase or peroxidase mimetics as a way to treat overt inflammation associated with the pathophysiology of many human disorders. This review will focus on recent development of catalytic scavengers of peroxides and their potential use as therapeutic agents for pulmonary, cardiovascular, neurodegenerative and inflammatory disorders.
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Affiliation(s)
- Brian J Day
- Department of Medicine, National Jewish Health, Departments of Medicine, Immunology & Pharmaceutical Sciences, University of Colorado Health Sciences Center, Denver, CO 80206, USA.
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Abstract
Interstitial lung disease encompasses a large group of chronic lung disorders associated with excessive tissue remodeling, scarring, and fibrosis. The evidence of a redox imbalance in lung fibrosis is substantial, and the rationale for testing antioxidants as potential new therapeutics for lung fibrosis is appealing. Current animal models of lung fibrosis have clear involvement of ROS in their pathogenesis. New classes of antioxidant agents divided into catalytic antioxidant mimetics and antioxidant scavengers are being developed. The catalytic antioxidant class is based on endogenous antioxidant enzymes and includes the manganese-containing macrocyclics, porphyrins, salens, and the non-metal-containing nitroxides. The antioxidant scavenging class is based on endogenous antioxidant molecules and includes the vitamin E analogues, thiols, lazaroids, and polyphenolic agents. Numerous studies have shown oxidative stress to be associated with many interstitial lung diseases and that these agents are effective in attenuating fibroproliferative responses in the lung of animals and humans.
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Affiliation(s)
- Brian J Day
- Division of Environmental and Occupational Health Sciences, Department of Medicine, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.
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Mishra B, Priyadarsini KI, Mohan H, Mugesh G. Horseradish peroxidase inhibition and antioxidant activity of ebselen and related organoselenium compounds. Bioorg Med Chem Lett 2006; 16:5334-8. [PMID: 16919452 DOI: 10.1016/j.bmcl.2006.07.085] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Revised: 07/10/2006] [Accepted: 07/26/2006] [Indexed: 01/01/2023]
Abstract
Horseradish peroxidase (HRP) inhibition and glutathione peroxidase (GPx) activities of ebselen and some related derivatives are described. These studies show that ebselen and ebselen ditelluride (EbTe(2)) with significant antioxidant activity, inhibit the HRP-catalyzed oxidation reactions. In addition, inhibition of lipid peroxidation and singlet oxygen quenching studies were carried out. Although the inhibition of HRP by ebselen is comparable with that of EbTe(2), the inhibitory effect on gamma-radiation induced lipid peroxidation and the GPx activity of ebselen is found to be much higher than that of EbTe(2).
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Affiliation(s)
- Beena Mishra
- Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 85, India
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Mugesh G, du Mont WW. Structure-activity correlation between natural glutathione peroxidase (GPx) and mimics: a biomimetic concept for the design and synthesis of more efficient GPx mimics. Chemistry 2001; 7:1365-70. [PMID: 11330888 DOI: 10.1002/1521-3765(20010401)7:7<1365::aid-chem1365>3.0.co;2-y] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Among the organoselenium compounds that mimic the action of the natural enzyme glutathione peroxidase (GPx), there are certain basic differences in the activity, substrate specificity and mechanism. These differences arise mainly from the nature of the substituents near the reaction center, and stability and reactivity of the intermediates. As an attempt to draw some general concepts for the development of new mimics, a structure - activity correlation between natural GPx and some existing mimics is described.
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Affiliation(s)
- G Mugesh
- Institut für Anorganische und Analytische Chemie Technische Universität, Braunschweig, Germany.
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Matsugo S, Yan LJ, Konishi T, Youn HD, Lodge JK, Ulrich H, Packer L. The lipoic acid analogue 1,2-diselenolane-3-pentanoic acid protects human low density lipoprotein against oxidative modification mediated by copper ion. Biochem Biophys Res Commun 1997; 240:819-24. [PMID: 9398652 DOI: 10.1006/bbrc.1997.7711] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1,2-Diselenolane-3-pentanoic acid, in which the sulfur atoms of alpha-lipoic acid are replaced with selenium, displayed markedly different antioxidant properties when compared to alpha-lipoic acid. 1,2-Diselenolane-3-pentanoic acid was unable to inhibit protein oxidative modification of human low density lipoprotein (LDL) and bovine serum albumin induced by copper ion or hydroxyl radical, whereas alpha-lipoic acid showed significant protection. However, 1,2-diselenolane-3-pentanoic acid was able to inhibit the formation of lipid peroxidation products in LDL after oxidation by copper, while alpha-lipoic acid did not. Hence the diselenium compound exerts its effects in a lipophilic environment whilst lipoic acid exerts its effects in a hydrophilic environment. These differences in antioxidant activities of the two compounds may be explained, at least in part, by their differing partition coefficients.
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Affiliation(s)
- S Matsugo
- Department of Molecular and Cell Biology, University of California at Berkeley 94720-3200, USA
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Serguievski P, Detty MR. Electronic Substituent Effects in Quenching of1O2by Diaryl Tellurides. Organometallics 1997. [DOI: 10.1021/om970535+] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Clennan EL. The Reactions of Sulfides and Sulfenic Acid Derivatives with Singlet Oxygen. ACTA ACUST UNITED AC 1996. [DOI: 10.1080/01961779608047906] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Kim W, Dannaldson J, Gates KS. Reactions of 3H-1,2-benzodithiol-3-one 1-oxide with amines and anilines. Tetrahedron Lett 1996. [DOI: 10.1016/0040-4039(96)01124-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Sies H, Masumoto H. Ebselen as a glutathione peroxidase mimic and as a scavenger of peroxynitrite. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1996; 38:229-46. [PMID: 8895811 DOI: 10.1016/s1054-3589(08)60986-2] [Citation(s) in RCA: 176] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- H Sies
- Institut für Physiologische Chemie I, Heinrich-Heine-Universität Düsseldorf, Germany
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Abstract
1. Ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) is a non-toxic seleno-organic drug with antiinflammatory, antiatherosclerotic and cytoprotective properties. 2. Ebselen and some of its metabolites are effective reductants of hydroperoxides including those arising in biomembranes and lipoproteins. 3. By reactions with hydroperoxides and thiols several interconversion cycles are formed which include ebselen metabolites with varying oxidation number of the selenium. 4. In the presence of thiols ebselen mimics the catalytic activities of phospholipid hydroperoxide glutathione peroxidase. 5. Ebselen inhibits at low concentrations a number of enzymes involved in inflammation such as lipoxygenases, NO synthases, NADPH, oxidase, protein kinase C and H+/K(+)-ATPase. The inhibitions are manifested on the cellular level and may contribute to the antiinflammatory potential of ebselen.
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Affiliation(s)
- T Schewe
- Institute of Biochemistry, University Clinics Charité, Humboldt University of Berlin, Germany
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Affiliation(s)
- H Sies
- Institut für Physiologische Chemie I, Heinrich-Heine-Universität, Düsseldorf, Germany
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Abstract
The selenoorganic compound ebselen, 2-phenyl-1,2-benzisoselenazol-3(2H)-one, exhibits activity as an enzyme mimic. The reaction catalyzed is that of a glutathione (GSH) peroxidase (i.e., the reduction of a hydroperoxide at the expense of thiol). The specificity for substrates ranges from hydrogen peroxide and smaller organic hydroperoxides to membrane-bound phospholipid and cholesterol hydroperoxides. In addition to glutathione, the thiol reductant cosubstrate can be dithioerythritol, N-acetylcysteine or dihydrolipoate, or other suitable thiol compounds. Ebselen also has properties such as free radical and singlet oxygen quenching. Model experiments in vitro with liposomes, microsomes, isolated cells, and organs show that the protection against oxidative challenge afforded by ebselen can be explained largely by the activity as GSH peroxidase mimic. Whether this also explains the known preliminary results in clinical settings is yet open. The metabolism and disposition of ebselen is presented in this review. The main point is that the selenium is not bioavailable, explaining the extremely low toxicity observed in animal studies. The occurrence of natural GPx mimics, ovothiol and related compounds, is briefly mentioned.
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Affiliation(s)
- H Sies
- Institut für Physiologische Chemie I, Heinrich Heine Universität Düsseldorf, Germany
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