1
|
Das R, Karri R, Chalana A, Rai RK, Roy G. Uncovering the Role of Methylmercury on DNA Lesions at Cytotoxic Concentrations in Glutathione-Depleted Cells: Insights from Experimental and Computational Studies. Inorg Chem 2024. [PMID: 38743433 DOI: 10.1021/acs.inorgchem.3c04579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Organomercurials (RHg+), especially methylmercury (MeHg+) and ethylmercury (EtHg+), are considered to be more neurotoxic than the inorganic counterpart (Hg2+). They cause massive DNA damage in cells, especially in neurons, where cellular glutathione (GSH) levels are significantly low. However, the mechanism by which RHg+ exerts massive DNA damage at cytotoxic concentrations in brain cells remains obscure. In this study, we investigated the effect of RHg+ on the structural and electronic properties of nucleosides and its effects on DNA damage. The direct interaction of RHg+ with the nucleoside significantly weakens N-glycosidic bonds, decreases the C-H bond energy of sugar moieties, and increases the electrophilicity of the C8-center of purine bases. As a consequence, RHg+-conjugated DNA molecules are extremely labile and highly sensitive to any nucleophiles/radicals present in GSH-depleted cells and, thus, undergo enhanced oxidative and unusual alkylative DNA damage. We also report a functional model of organomercurial lyase, which showed excellent cytoprotective effect against RHg+-induced cytotoxicity; this reverses the activity of glutathione reductase inhibited by MeHgCl and ceases oxidative and alkylating DNA damage. This intriguing finding provides new mechanistic insight into the mode of action of organomercurials in GSH-depleted cells and their adverse effects on individuals with neurodegenerative disorders associated with oxidative stress.
Collapse
Affiliation(s)
- Ranajit Das
- Department of Chemistry, School of Natural Sciences, Shiv Nadar Institution of Eminence Deemed to be University, Dadri, UP 201314, India
| | - Ramesh Karri
- Department of Chemistry, School of Natural Sciences, Shiv Nadar Institution of Eminence Deemed to be University, Dadri, UP 201314, India
- Ruhvenile Biomedical OPC Pvt. Ltd., New Delhi 110070, Delhi, India
| | - Ashish Chalana
- Centre for Development of Biomaterials, Department of Chemistry & Biochemistry, Sharda University, Greater Noida, UP 201306, India
| | - Rakesh Kumar Rai
- Department of Chemistry, Indian Institute of Technology Tirupati, Tirupati, AP 517619, India
| | - Gouriprasanna Roy
- Department of Chemistry, Indian Institute of Technology Tirupati, Tirupati, AP 517619, India
| |
Collapse
|
2
|
Yurkerwich K, Quinlivan PJ, Rong Y, Parkin G. Phenylselenolate Mercury Alkyl Compounds, PhSeHgMe and PhSeHgEt: Molecular Structures, Protolytic Hg-C Bond Cleavage and Phenylselenolate Exchange. Polyhedron 2016; 103:307-314. [PMID: 26644634 PMCID: PMC4669890 DOI: 10.1016/j.poly.2015.06.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The phenylselenolate mercury alkyl compounds, PhSeHgMe and PhSeHgEt, have been structurally characterized by X-ray diffraction, thereby demonstrating that both compounds are monomeric with approximately linear coordination geometries; the mercury centers do, nevertheless, exhibit secondary Hg•••Se intermolecular interactions that serve to increase the coordination number in the solid state. The ethyl derivative, PhSeHgEt, undergoes facile protolytic cleavage of the Hg-C bond to release ethane at room temperature, whereas PhSeHgMe exhibits little reactivity under similar conditions. Interestingly, the cleavage of the Hg-C bond of PhSeHgEt is also more facile than that of the thiolate analogue, PhSHgEt, which demonstrates that coordination by selenium promotes protolytic cleavage of the mercury-carbon bond. The phenylselenolate compounds PhSeHgR (R = Me, Et) also undergo degenerate exchange reactions with, for example, PhSHgR and RHgCl. In each case, the alkyl groups preserve coupling to the 199Hg nuclei, thereby indicating that the exchange process involves metathesis of the Hg-SePh/Hg-X groups rather than metathesis of the Hg-R/Hg-R groups.
Collapse
Affiliation(s)
- Kevin Yurkerwich
- Department of Chemistry, Columbia University, New York New York 10027,
USA
| | | | - Yi Rong
- Department of Chemistry, Columbia University, New York New York 10027,
USA
| | - Gerard Parkin
- Department of Chemistry, Columbia University, New York New York 10027,
USA
| |
Collapse
|
3
|
Dórea JG, Wimer W, Marques RC, Shade C. Automated speciation of mercury in the hair of breastfed infants exposed to ethylmercury from thimerosal-containing vaccines. Biol Trace Elem Res 2011; 140:262-71. [PMID: 20419397 DOI: 10.1007/s12011-010-8695-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 03/31/2010] [Indexed: 10/19/2022]
Abstract
A simplified thiourea-based chromatography method, originally developed for methyl and inorganic mercury, was adapted to separate methylmercury (MeHg), ethylmercury (EtHg), and inorganic mercury (Hg(II)) in infants' hair. Samples were weighed and leached with an acidic thiourea solution. Leachates were concentrated on a polymeric resin prior to analysis by Hg-thiourea liquid chromatography/cold vapor atomic fluorescence spectrometry. All but one sample showed small amounts of EtHg, and four of the six analyzed samples had proportionally higher Hg(II) as a percent of total Hg. Breastfed infants from riverine Amazonian communities are exposed to mercury in breast milk (from high levels of maternal sources that include both fish consumption and dental amalgam) and to EtHg in vaccines (from thimerosal). The method proved sensitive enough to detect and quantify acute EtHg exposure after shots of thimerosal-containing vaccines. Based on work with MeHg and Hg(II), estimated detection limits for this method are 0.050, 0.10, and 0.10 ng g⁻¹ for MeHg, Hg(II), and EtHg, respectively, for a 20-mg sample. Specific limits depend on the amount of sample extracted and the amount of extract injected.
Collapse
Affiliation(s)
- José G Dórea
- Universidade de Brasília, C.P.04322, 70919-970, Brasília, Federal District, Brasil.
| | | | | | | |
Collapse
|
4
|
Trasande L, Cortes JE, Landrigan PJ, Abercrombie MI, Bopp RF, Cifuentes E. Methylmercury exposure in a subsistence fishing community in Lake Chapala, Mexico: an ecological approach. Environ Health 2010; 9:1. [PMID: 20064246 PMCID: PMC2820022 DOI: 10.1186/1476-069x-9-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 01/11/2010] [Indexed: 05/05/2023]
Abstract
BACKGROUND Elevated concentrations of mercury have been documented in fish in Lake Chapala in central Mexico, an area that is home to a large subsistence fishing community. However, neither the extent of human mercury exposure nor its sources and routes have been elucidated. METHODS Total mercury concentrations were measured in samples of fish from Lake Chapala; in sections of sediment cores from the delta of Rio Lerma, the major tributary to the lake; and in a series of suspended-particle samples collected at sites from the mouth of the Lerma to mid-Lake. A cross-sectional survey of 92 women ranging in age from 18-45 years was conducted in three communities along the Lake to investigate the relationship between fish consumption and hair mercury concentrations among women of child-bearing age. RESULTS Highest concentrations of mercury in fish samples were found in carp (mean 0.87 ppm). Sediment data suggest a pattern of moderate ongoing contamination. Analyses of particles filtered from the water column showed highest concentrations of mercury near the mouth of the Lerma. In the human study, 27.2% of women had >1 ppm hair mercury. On multivariable analysis, carp consumption and consumption of fish purchased or captured from Lake Chapala were both associated with significantly higher mean hair mercury concentrations. CONCLUSIONS Our preliminary data indicate that, despite a moderate level of contamination in recent sediments and suspended particulate matter, carp in Lake Chapala contain mercury concentrations of concern for local fish consumers. Consumption of carp appears to contribute significantly to body burden in this population. Further studies of the consequences of prenatal exposure for child neurodevelopment are being initiated.
Collapse
Affiliation(s)
- Leonardo Trasande
- Department of Community and Preventive Medicine, Mount Sinai School of Medicine, 1 Gustave L Levy Place, Box 1057, New York, NY 10029, USA
- Department of Pediatrics, Mount Sinai School of Medicine, 1 Gustave L Levy Place, Box 1057, New York, NY 10029, USA
| | - Juanita E Cortes
- Instituto Mexicano de Tecnologia de Agua (Mexican Institute of Water Technology, IMTA), Paseo Cuauhnáhuac 8532, Colonia Progreso, CP 62550, Jiutepec, Morelos, México
| | - Philip J Landrigan
- Department of Community and Preventive Medicine, Mount Sinai School of Medicine, 1 Gustave L Levy Place, Box 1057, New York, NY 10029, USA
- Department of Pediatrics, Mount Sinai School of Medicine, 1 Gustave L Levy Place, Box 1057, New York, NY 10029, USA
| | - Mary I Abercrombie
- Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Jonsson-Rowland Science Center, 1W19, 110 8th Street, Troy, NY 12180, USA
| | - Richard F Bopp
- Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Jonsson-Rowland Science Center, 1W19, 110 8th Street, Troy, NY 12180, USA
| | - Enrique Cifuentes
- Department of Community and Preventive Medicine, Mount Sinai School of Medicine, 1 Gustave L Levy Place, Box 1057, New York, NY 10029, USA
- Environmental Health Unit, Instituto Nacional de Salud Publica (National Institute of Public Health, INSP), Universidad No 655, Col Santa María Ahuacatitlán, Cerrada Los Pinos y Caminera, Cuernavaca, Morelos CP 62100, México
| |
Collapse
|
5
|
Sattler W, Yurkerwich K, Parkin G. Molecular structures of protonated and mercurated derivatives of thimerosal. Dalton Trans 2009:4327-33. [DOI: 10.1039/b823467a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
6
|
Melnick JG, Yurkerwich K, Buccella D, Sattler W, Parkin G. Molecular structures of thimerosal (Merthiolate) and other arylthiolate mercury alkyl compounds. Inorg Chem 2008; 47:6421-6. [PMID: 18533648 DOI: 10.1021/ic8005426] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The molecular structure of sodium ethylmercury thiosalicylate (also known as thimerosal and Merthiolate) and related arylthiolate mercury alkyl compounds, namely PhSHgMe and PhSHgEt, have been determined by single crystal X-ray diffraction. (1)H NMR spectroscopic studies indicate that the appearance of the (199)Hg mercury satellites of the ethyl group of thimerosal is highly dependent on the magnetic field and the viscosity of the solvent as a consequence of relaxation due to chemical shift anisotropy.
Collapse
Affiliation(s)
- Jonathan G Melnick
- Department of Chemistry, Columbia University, New York, New York 10027, USA
| | | | | | | | | |
Collapse
|