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Shchukin PV, Muftakhov MV, Khatymov RV, Tuktarov RF. Resonant electron capture by 5-Br-2′-deoxyuridine. J Chem Phys 2022; 156:104304. [DOI: 10.1063/5.0077009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The results of the study of resonant electron capture by molecules of 5-Br-2′-deoxyuridine (BrdUrd) over the range of electron energies from near zero to 14 eV are described. In the thermal energy range, long-lived molecular negative ions, unstable with respect to autoneutralization and dehalogenation, have been registered. Examination of the kinetics of these decay processes led us to the conclusion that the most probable structure for molecular negative ions is that with an extended C–Br bond, which was predicted earlier using quantum-chemical calculations. Estimates have shown that the BrdUrd molecule owns a significant electronic affinity of 0.93–1.38 eV. The most intense fragmentation channel leads to the abundant formation of Br− ions. The dissociative electron attachment cross section for Br− ions formation was estimated to amount to no less than 1.65 × 10−15 cm2, indirectly implying a fairly intense formation of complementary highly reactive deoxyuridine-5-yl particles. These particles are known to be responsible for the radiosensitizing properties of BrdUrd.
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Affiliation(s)
- P. V. Shchukin
- Institute of Molecule and Crystal Physics–Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - M. V. Muftakhov
- Institute of Molecule and Crystal Physics–Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
| | - R. V. Khatymov
- Mendeleev University of Chemical Technology of Russia, Miusskaya square, 9, Moscow 125047, Russia
| | - R. F. Tuktarov
- Institute of Molecule and Crystal Physics–Subdivision of the Ufa Federal Research Centre of the Russian Academy of Sciences, Prospekt Oktyabrya 151, Ufa 450075, Russia
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Sedmidubská B, Luxford TFM, Kočišek J. Electron attachment to isolated and microhydrated favipiravir. Phys Chem Chem Phys 2021; 23:21501-21511. [PMID: 34382983 DOI: 10.1039/d1cp02686k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Electron attachment and its equivalent in complex environments, single-electron reduction, are important in many biological processes. Here, we experimentally study the electron attachment to favipiravir, a well-known antiviral agent. Electron attachment spectroscopy is used to explore the energetics of associative (AEA) and dissociative (DEA) electron attachment to isolated favipiravir. AEA dominates the interaction and the yields of the fragment anions after DEA are an order of magnitude lower than that of the parent anion. DEA primary proceeds via decomposition of the CONH2 functional group, which is supported by reaction threshold calculations using ab initio methods. Mass spectrometry of small favipiravir-water clusters demonstrates that a lot of energy is transferred to the solvent upon electron attachment. The energy gained upon electron attachment, and the high stability of the parent anion were previously suggested as important properties for the action of several electron-affinic radiosensitizers. If any of these mechanisms cause synergism in chemo-radiation therapy, favipiravir could be repurposed as a radiosensitizer.
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Affiliation(s)
- Barbora Sedmidubská
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic. and Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Břehová 7, 11519 Prague, Czech Republic
| | - Thomas F M Luxford
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic.
| | - Jaroslav Kočišek
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences, Dolejškova 3, 18223 Prague, Czech Republic.
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Muftakhov M, Shchukin P, Khatymov R. Thymidine and stavudine molecules in reactions with low-energy electrons. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2021.109464] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Bocková J, Rebelo A, Ryszka M, Pandey R, Mészáros D, Limão-Vieira P, Papp P, Mason NJ, Townsend D, Nixon KL, Vizcaino V, Poully JC, Eden S. Thermal desorption effects on fragment ion production from multi-photon ionized uridine and selected analogues. RSC Adv 2021; 11:20612-20621. [PMID: 35479354 PMCID: PMC9033967 DOI: 10.1039/d1ra01873f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/09/2021] [Indexed: 12/22/2022] Open
Abstract
Experiments on neutral gas-phase nucleosides are often complicated by thermal lability. Previous mass spectrometry studies of nucleosides have identified enhanced relative production of nucleobase ions (e.g. uracil+ from uridine) as a function of desorption temperature to be the critical indicator of thermal decomposition. On this basis, the present multi-photon ionization (MPI) experiments demonstrate that laser-based thermal desorption is effective for producing uridine, 5-methyluridine, and 2′-deoxyuridine targets without thermal decomposition. Our experiments also revealed one notable thermal dependence: the relative production of the sugar ion C5H9O4+ from intact uridine increased substantially with the desorption laser power and this only occurred at MPI wavelengths below 250 nm (full range studied 222–265 nm). We argue that this effect can only be rationalized plausibly in terms of changing populations of different isomers, tautomers, or conformers in the target as a function of the thermal desorption conditions. Furthermore, the wavelength threshold behavior of this thermally-sensitive MPI channel indicates a critical dependence on neutral excited state dynamics between the absorption of the first and second photons. The experimental results are complemented by density functional theory (DFT) optimizations of the lowest-energy structure of uridine and two further conformers distinguished by different orientations of the hydroxymethyl group on the sugar part of the molecule. The energies of the transitions states between these three conformers are low compared with the energy required for decomposition. This work reveals the first experimental evidence supporting isomer-dependence in the radiation response of a nucleoside.![]()
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Affiliation(s)
- J Bocková
- School of Physical Sciences, The Open University Walton Hall Milton Keynes MK7 6AA UK
| | - A Rebelo
- School of Physical Sciences, The Open University Walton Hall Milton Keynes MK7 6AA UK .,Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, FCT - Universidade NOVA de Lisboa P-2829-516 Caparica Portugal
| | - M Ryszka
- School of Physical Sciences, The Open University Walton Hall Milton Keynes MK7 6AA UK
| | - R Pandey
- School of Physical Sciences, The Open University Walton Hall Milton Keynes MK7 6AA UK
| | - D Mészáros
- Department of Experimental Physics, Comenius University in Bratislava Mlynská dolina F2 84248 Bratislava Slovakia
| | - P Limão-Vieira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, FCT - Universidade NOVA de Lisboa P-2829-516 Caparica Portugal
| | - P Papp
- Department of Experimental Physics, Comenius University in Bratislava Mlynská dolina F2 84248 Bratislava Slovakia
| | - N J Mason
- School of Physical Sciences, The Open University Walton Hall Milton Keynes MK7 6AA UK .,School of Physical Sciences, Ingram Building, University of Kent Canterbury CT2 7NH UK
| | - D Townsend
- Institute of Photonics and Quantum Sciences, Heriot-Watt University Edinburgh EH14 4AS UK.,Institute of Chemical Sciences, Heriot-Watt University Edinburgh EH14 4AS UK
| | - K L Nixon
- School of Life, Health, and Chemical Sciences, The Open University Walton Hall Milton Keynes MK7 6AA UK.,School of Sciences, University of Wolverhampton Wulfruna Street Wolverhampton WV1 1LY UK
| | - V Vizcaino
- CIMAP UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Normandie, GANIL Bd Becquerel BP 5133 14070 Caen France
| | - J-C Poully
- CIMAP UMR 6252, CEA/CNRS/ENSICAEN/Université de Caen Normandie, GANIL Bd Becquerel BP 5133 14070 Caen France
| | - S Eden
- School of Physical Sciences, The Open University Walton Hall Milton Keynes MK7 6AA UK
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Khatymov RV, Terentyev AG. Resonant electron capture negative ion mass spectrometry: the state of the art and the potential for solving analytical problems. Russ Chem Bull 2021. [DOI: 10.1007/s11172-021-3132-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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