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Datta M, Szczyrba A, Zdrowowicz M, Wyrzykowski D, Ciupak O, Demkowicz S, Izadi F, Denifl S, Rak J. Surprising Radiolytic Stability of 8-Thiomethyladenine in an Aqueous Solution. J Phys Chem B 2024; 128:3621-3630. [PMID: 38578255 PMCID: PMC11033863 DOI: 10.1021/acs.jpcb.4c01033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2024] [Revised: 03/18/2024] [Accepted: 03/20/2024] [Indexed: 04/06/2024]
Abstract
8-Thiomethyladenine (ASCH3), a potentially radiosensitizing modified nucleobase, has been synthesized in a reaction between 8-thioadenine and methyl iodide. Despite favorable dissociative electron attachment (DEA) characteristics, the radiolysis of an aqueous solution of ASCH3 with a dose of X-ray amounting to as much as 300 Gy leads to no effects. Nevertheless, crossed electron-molecule beam experiments in the gas phase on ASCH3 confirm the theoretical findings regarding the stability of its radical anion, namely, the most abundant reaction channel is related to the dissociation of the S-CH3 bond in the respective anion. Furthermore, electron-induced degradation of ASCH3 has been observed in aprotic acetonitrile, which is strong evidence for the involvement of proton transfer (PT) in stabilizing the radical anion in an aqueous solution. These findings demonstrate that PT in water can be the main player in deciding the radiosensitizing properties of modified nucleobases/nucleosides.
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Affiliation(s)
- Magdalena Datta
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Adrian Szczyrba
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Magdalena Zdrowowicz
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Dariusz Wyrzykowski
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Olga Ciupak
- Department
of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Sebastian Demkowicz
- Department
of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Farhad Izadi
- Institut
für Ionenphysik und Angewandte Physik and Center for Biomolecular
Sciences Innsbruck, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Stephan Denifl
- Institut
für Ionenphysik und Angewandte Physik and Center for Biomolecular
Sciences Innsbruck, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Janusz Rak
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
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Saqib M, Arthur-Baidoo E, Izadi F, Szczyrba A, Datta M, Demkowicz S, Rak J, Denifl S. Dissociative Electron Attachment to 5-Iodo-4-thio-2'-deoxyuridine: A Potential Radiosensitizer of Hypoxic Cells. J Phys Chem Lett 2023; 14:8948-8955. [PMID: 37769041 PMCID: PMC10578351 DOI: 10.1021/acs.jpclett.3c02219] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/20/2023] [Indexed: 09/30/2023]
Abstract
In the search for effective radiosensitizers for tumor cells, halogenated uracils have attracted more attention due to their large cross section for dissociation upon the attachment of low-energy electrons. In this study, we investigated dissociative electron attachment (DEA) to 5-iodo-4-thio-2'-deoxyuridine, a potential radiosensitizer using a crossed electron-molecule beam experiment coupled with quadrupole mass spectrometry. The experimental results were supported by calculations on the threshold energies of formed anions and transition state calculations. We show that low-energy electrons with kinetic energies near 0 eV may effectively decompose the molecule upon DEA. The by far most abundant anion observed corresponds to the iodine anion (I-). Due to the associated bond cleavage, a radical site is formed at the C5 position, which may initiate strand break formation if the molecule is incorporated into a DNA strand. Our results reflect the conclusion from previous radiolysis studies with the title compound, suggesting its potential as a radiosensitizer.
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Affiliation(s)
- Muhammad Saqib
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
- Center
for Molecular Biosciences Innsbruck, Universität
Innsbruck, Technikerstraße
25, A-6020 Innsbruck, Austria
| | - Eugene Arthur-Baidoo
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
- Center
for Molecular Biosciences Innsbruck, Universität
Innsbruck, Technikerstraße
25, A-6020 Innsbruck, Austria
| | - Farhad Izadi
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
- Center
for Molecular Biosciences Innsbruck, Universität
Innsbruck, Technikerstraße
25, A-6020 Innsbruck, Austria
| | - Adrian Szczyrba
- Laboratory
of Biological Sensitizers, Department of Physical Chemistry, Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Magdalena Datta
- Laboratory
of Biological Sensitizers, Department of Physical Chemistry, Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Sebastian Demkowicz
- Department
of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Janusz Rak
- Laboratory
of Biological Sensitizers, Department of Physical Chemistry, Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Stephan Denifl
- Institut
für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstraße 25, A-6020 Innsbruck, Austria
- Center
for Molecular Biosciences Innsbruck, Universität
Innsbruck, Technikerstraße
25, A-6020 Innsbruck, Austria
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Izadi F, Szczyrba A, Datta M, Ciupak O, Demkowicz S, Rak J, Denifl S. Electron-Induced Decomposition of 5-Bromo-4-thiouracil and 5-Bromo-4-thio-2'-deoxyuridine: The Effect of the Deoxyribose Moiety on Dissociative Electron Attachment. Int J Mol Sci 2023; 24:ijms24108706. [PMID: 37240053 DOI: 10.3390/ijms24108706] [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] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 04/28/2023] [Accepted: 05/08/2023] [Indexed: 05/28/2023] Open
Abstract
When modified uridine derivatives are incorporated into DNA, radical species may form that cause DNA damage. This category of molecules has been proposed as radiosensitizers and is currently being researched. Here, we study electron attachment to 5-bromo-4-thiouracil (BrSU), a uracil derivative, and 5-bromo-4-thio-2'-deoxyuridine (BrSdU), with an attached deoxyribose moiety via the N-glycosidic (N1-C) bond. Quadrupole mass spectrometry was used to detect the anionic products of dissociative electron attachment (DEA), and the experimental results were supported by quantum chemical calculations performed at the M062X/aug-cc-pVTZ level of theory. Experimentally, we found that BrSU predominantly captures low-energy electrons with kinetic energies near 0 eV, though the abundance of bromine anions was rather low compared to a similar experiment with bromouracil. We suggest that, for this reaction channel, proton-transfer reactions in the transient negative ions limit the release of bromine anions.
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Affiliation(s)
- Farhad Izadi
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Center for Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
| | - Adrian Szczyrba
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Magdalena Datta
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Olga Ciupak
- Department of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Sebastian Demkowicz
- Department of Organic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12, 80-233 Gdańsk, Poland
| | - Janusz Rak
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
- Center for Molecular Biosciences Innsbruck, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria
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