Photosensitization of thymine nucleobase by benzophenone through energy transfer, hydrogen abstraction and one-electron oxidation

Delatour, Thierry; Douki, Thierry; d'Ham, Cédric; Cadet, Jean

doi:10.1016/s1011-1344(98)00142-0

Cited by 71 publications

(91 citation statements)

References 56 publications

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“…This reaction pathway, although minor, could be of biological significance. [42] Besides, the triplet energy of the Thy base in DNA must be lower than that in the dyad; this would enhance the prospects of triplet-triplet energy transfer (and hence cyclobutane dimer formation) in the biomacromolecule.…”

Section: Resultsmentioning

confidence: 99%

“…[34][35][36][37] These photobiological properties are attributable to the benzophenone (BP) substructure, as the parent compound BP photosensitizes similar DNA reactions. [29] Indeed, previous studies have shown that there is a strong intermolecular interaction between the excited BP chromophore and thymine derivatives, [38][39][40][41] including the free thymidine nucleoside [42] and a thymidine 5'-monophosphate. [43] Fast quenching of triplet BP by thymine derivatives has been observed and attributed to the occurrence of energy or electron transfer; however, recent evidence has been obtained which suggests that this quenching is mainly associated with a Paterno-Büchi cycloaddition leading to the formation of oxetanes.…”

Section: Introductionmentioning

confidence: 99%

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Intramolecular Interactions in the Triplet Excited States of Benzophenone–Thymine Dyads

Belmadoui

Encinas

Climent

et al. 2005

Chemistry A European J

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Time-resolved and product studies on the synthesized dyads 1 and 2 have provided evidence that the benzophenone-to-thymine orientation strongly influences intramolecular photophysical and photochemical processes. The prevailing reaction mechanism has been established as a Paterno-Büchi cycloaddition to give oxetanes 3-6; however, the ability of benzophenone to achieve a formal hydrogen abstraction from the methyl group of thymidine has also been evidenced by the formation of photoproducts 7 and 8. These processes have been observed only in the case of the cisoid dyad 1. Adiabatic photochemical cycloreversion of the oxetane ring is achieved upon direct photolysis to give the starting dyad 1 in its excited triplet state. The photobiological implications of the above results are discussed with respect to benzophenone-photosensitized damage of thymidine.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intramolecular Interactions in the Triplet Excited States of Benzophenone–Thymine Dyads

Belmadoui

Encinas

Climent

et al. 2005

Chemistry A European J

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“…56,60 This is 35 the case of dCpT, TpdC and TpT, which produce mainly cissyn and trans-syn diastereomers 48,61 in proportions that may range from 7:1 (TpT) to 3:1(dCpT) or 1:1 (TpdC). Similar results are obtained when two Thy units are kept in close proximity through a polymethylene linker.…”

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confidence: 99%

Photosensitised pyrimidine dimerisation in DNA

et al. 2011

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aTriplet-mediated pyrimidine (Pyr) dimerisation is a key process in photochemical damage to DNA. 5It may occur in the presence of a photosensitiser, provided that a number of requirements are fulfilled, such as favourable intersystem crossing quantum yield and high triplet energy. The attention has been mainly focused on cyclobutane pyrimidine dimers, as they are by far the most relevant Pyr photoproducts obtained by sensitisation. The present perspective deals with the involved chemistry, not only in DNA but also in its simple building blocks. It also includes the 10 photophysical characterisation of the Pyr triplet excited states, as well as a brief discussion of the theoretical aspects.

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“…Estudos in vitro também demonstraram a formação de 5-HMdU na fotossensibilização de timina (Delatour, et al, 1998), timidina ou DNA isolado na presença de menadiona e luz UVA (Douki e Cadet, 1999). A presença de 5-HMdU também foi detectada por cromatografia líquida de alta eficiência acoplada a detecção eletroquímica (HPLC/EC) e cromatografia gasosa acoplada a espectrometria de massa (GC/MS), após exposição de DNA isolado a raios-γ (Douki, et al, 1996).…”

Section: Formação De Produtos Mutagênicos Na Decomposição De 5-(hidrounclassified

“…O hidroperóxido 5-HPMU pode ser formado na exposição do DNA a radiação UVA (Delatour, et al, 1998, na reação de timina e radical • OH , na reação de radical peroxila e timina (Martini e Termini, 1997), ou na reação de radicais 5-…”

Section: -Hpmu + Hoclunclassified

Hidroperóxido de timina como fonte biológica de oxigênio molecular singlete [O2 (1Δg)]

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Photosensitization of thymine nucleobase by benzophenone through energy transfer, hydrogen abstraction and one-electron oxidation

Cited by 71 publications

References 56 publications

Intramolecular Interactions in the Triplet Excited States of Benzophenone–Thymine Dyads

Intramolecular Interactions in the Triplet Excited States of Benzophenone–Thymine Dyads

Photosensitised pyrimidine dimerisation in DNA

Hidroperóxido de timina como fonte biológica de oxigênio molecular singlete [O2 (1Δg)]

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