Efficient Oxidation of 2‘-Deoxyguanosine by Mn-TMPyP/KHSO<sub>5</sub> to Imidazolone dIz without Formation of 8-Oxo-dG

Vialas, Corine; Pratviel, Geneviève; Claparols, and Catherine; Meunier, Bernard

doi:10.1021/ja981597+

Cited by 91 publications

(135 citation statements)

References 36 publications

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“…This involves the opening of the pyrimidine at the C5-C6 bond with subsequent decarboxylation that is accompanied by hydration of the 7,8 double bond. Then, the carbinolamine thus generated, is likely to undergo ring-chain tautomerism that leads to opening of the imidazole ring with the release of formylamine [19]. Subsequent intramolecular cyclization of the guanidine substituent of the resulting intermediate would give rise to Iz.…”

Section: One-electron Oxidation Reactionsmentioning

confidence: 99%

UVB and UVA radiation-mediated damage to isolated and cellular DNA

Cadet

Courdavault

Ravanat

et al. 2005

Pure and Applied Chemistry

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Abstract:The effects of solar light on cellular DNA are mostly explained by both direct excitation of nucleobases and photosensitized reactions that are mediated by UVB and UVA radiation, respectively. A large body of information is now available on the main photodynamic reactions to DNA, which involve guanine as the preferential target of both one-electron oxidation and singlet oxygen oxidation, as the result of type I and type II mechanisms. Most of the final products of the photosensitized reactions of guanine base in isolated DNA have been characterized, and comprehensive mechanisms for their formation have been proposed. Further insights into the mechanisms of solar radiation-induced modifications within cellular DNA have been gained from accurate measurement of the main photoproducts using recently designed sensitive chromatographic and biochemical methods. Thus, the distribution pattern of the 12 possible bipyrimidine photoproducts has been shown to be similar in the DNA of UVB-irradiated rodent and human cells. Cyclobutyl pyrimidine dimers are also generated at di-thymine and thymine-cytosine sites within nuclear DNA upon exposure to UVA radiation as the likely result of triplet energy transfer. In addition, oxidative reactions that involved mostly singlet oxygen, and to a lesser extent, ؒ OH radicals are also implicated, although less efficiently.

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Section: One-electron Oxidation Reactionsmentioning

confidence: 99%

UVB and UVA radiation-mediated damage to isolated and cellular DNA

Cadet

Courdavault

Ravanat

et al. 2005

Pure and Applied Chemistry

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“…That is the reason why Abs at the irradiation wavelength decreased exponentially with time. I t abs can be expressed by: (3) where I 0 is the incident energy (in J s -1 ) and k is the photodegradation rate constant (in s -1 ) obtained from the slope of a plot of In (A 0 /A t ) versus the elapsed time in seconds.…”

Section: Dyementioning

confidence: 99%

“…They are capable of catalyzing a wide range of oxidation reactions: from hydroxylation of alkanes and epoxidation of alkenes to drug oxidation and DNA cleavage. [1][2][3] More recently, porphyrins have attracted even more attention from researchers in various fields due to their phototherapeutic properties. [4][5][6] Photodynamic therapy (PDT) is a form of neoplastic diseases treatment using a photosensitizer, oxygen and light.…”

Section: Introductionmentioning

confidence: 99%

A novel chlorin derivative of Meso-tris(pentafluorophenyl)-4-pyridylporphyrin: synthesis, photophysics and photochemical properties

Maestrin¹,

Ribeiro²,

Tedesco³

et al. 2004

J. Braz. Chem. Soc.

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A terapia fotodinâmica (TFD) está baseada na administração e no acúmulo de fotossensibilizador, por exemplo, de tipo porfirina ou clorina, em tecidos doentes. As clorinas apresentam propriedades fotofísicas semelhantes àquelas das porfirinas, mas com intensificação e deslocamento das bandas Q, o que faz com que sejam bons candidatos para TFD. Neste trabalho relata-se a síntese da 5,10,15-tris(pentafluorofenil)-20-(4-piridil)porfirina, (2), e das clorinas isômeras 4, (5,10,20-tris(pentafluorofenil)-15-(4-piridil)-tetra-hidro-1H-N-metil-pirrolo[3,4-b]porfirina e 5, (5,10,15-tris(pentafluorofenil)-20-(4-piridil)-tetra-hidro-1H-N-metil-pirrolo[3,4-b]porfirina, obtidas a partir de 2, por reação de cicloadição 1,3-dipolar com um ileto azometínico, e respectivas caracterizações estruturais por UV-Vis, RMN e EM-FAB. Foram avaliadas as propriedades fotofísicas, fotoquímicas e fotodegradativas para a nova clorina 4, obtida com melhor rendimento que o seu isômero 5. O rendimento quântico de fotodegradação (φ Fd , mol Einstein -1 ) foi de 0,047±0,014. Foram ainda realizados testes com ácido úrico para demonstrar a capacidade do fotossensibilizador na produção de 1 O 2 . Os resultados mostraram que a nova clorina 4 pode ser considerada como um bom fotossensibilizador para TFD.Photodynamic therapy (PDT) is based on the accumulation of a photosensitizer, such as a porphyrin or a chlorin, in a malignant tissue after its administration. Chlorins exhibit photophysical properties similar to those of the porphyrin macrocycles, but with intensified and red-shifted Q bands, making chlorin-containing systems even better candidates for PDT. In this contribution, we report the synthesis of 5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)porphyrin, (2) and its transformation to the novel chlorin derivatives 4, (5,10,20-tris(pentafluorophenyl)-15-(4-pyridyl)-tetrahydro-1H-N-methyl-pyrrolo [3,4-b]porphyrin and 5, (5,10,15-tris(pentafluorophenyl)-20-(4-pyridyl)-tetrahydro-1H-N-methyl-pyrrolo[3,4-b]porphyrin) by 1,3-dipolar cycloaddition with an azomethine ylide. The new products have been characterized by UV-Vis, 1 H NMR and FAB-MS. The photophysics, photochemical and photobleaching properties of chlorin 4 have been evaluated. Its quantum yield of photobleaching (φ Pb , mol Einstein -1 ) was 0.047±0.014. In order to demonstrate the production of 1 O 2 when 4 is used as a photosensitizer, uric acid tests have been carried out. The results indicate that chlorin 4 can be considered a promising photosensitizer in PDT.

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“…On the other hand, HOCl is a strong two-electron oxidant, having an E°Ј of ϩ1.08 V, and might oxidize guanosine, resulting in guanosine ϩ via a two-electron oxidation. However, it has been reported that 8-oxo-dGuo is not formed from 2Ј-deoxyguanosine by another two-electron oxidant, an artificial nuclease MnTMPyP/KHSO 5 (34). On the basis of these biophysical data, we propose that 8-oxo-(d)Guo formation by HOCl is not mediated by a two-electron oxidation reaction but can be mediated through formation of an N-7 chlorine adduct cation from guanosine and Cl ϩ and a further reaction with H 2 O (Fig.…”

Section: Table I Effect Of Ferrous and Ferric Ions On Hocl-mediated Fmentioning

confidence: 99%

Chlorination of Guanosine and Other Nucleosides by Hypochlorous Acid and Myeloperoxidase of Activated Human Neutrophils

Masuda¹,

Suzuki²,

Friesen³

et al. 2001

Journal of Biological Chemistry

133

119

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Activated human neutrophils secrete myeloperoxidase, which generates HOCl from H 2 O 2 and Cl ؊ . We have found that various (2-deoxy)nucleosides react with HOCl to form chlorinated (2-deoxy)nucleosides, including novel 8-chloro(2-deoxy)guanosine, 5-chloro(2-deoxy)cytidine, and 8-chloro(2-deoxy)adenosine formed in yields of 1.6, 1.6, and 0.2%, respectively, when 0.5 mM nucleoside reacted with 0.5 mM HOCl at pH 7.4. The relative chlorination, oxidation, and nitration activities of HOCl, myeloperoxidase, and activated human neutrophils in the presence and absence of nitrite were studied by analyzing 8-chloro-, 8-oxo-7,8-dihydro-, and 8-nitroguanosine, respectively, using guanosine as a probe. 8-Chloroguanosine was always more easily formed than 8-oxo-7,8-dihydro-or 8-nitro-guanosine. Using electrospray ionization tandem mass spectrometry, we show that several chlorinated nucleosides including 8-chloro(2-deoxy)guanosine are formed following exposure of isolated DNA or RNA to HOCl. Micromolar concentrations of tertiary amines such as nicotine and trimethylamine dramatically enhanced chlorination of free (2-deoxy)nucleosides and nucleosides in RNA by HOCl. As the G؊463A polymorphism of the MPO gene, which strongly reduces myeloproxidase mRNA expression, is associated with a reduced risk of lung cancer, chlorination damage of DNA /RNA and nucleosides by myeloperoxidase and its enhancement by nicotine may be important in the pathophysiology of human diseases associated with tobacco habits.

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Efficient Oxidation of 2‘-Deoxyguanosine by Mn-TMPyP/KHSO₅ to Imidazolone dIz without Formation of 8-Oxo-dG

Cited by 91 publications

References 36 publications

UVB and UVA radiation-mediated damage to isolated and cellular DNA

UVB and UVA radiation-mediated damage to isolated and cellular DNA

A novel chlorin derivative of Meso-tris(pentafluorophenyl)-4-pyridylporphyrin: synthesis, photophysics and photochemical properties

Chlorination of Guanosine and Other Nucleosides by Hypochlorous Acid and Myeloperoxidase of Activated Human Neutrophils

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Efficient Oxidation of 2‘-Deoxyguanosine by Mn-TMPyP/KHSO5 to Imidazolone dIz without Formation of 8-Oxo-dG

Cited by 91 publications

References 36 publications

UVB and UVA radiation-mediated damage to isolated and cellular DNA

UVB and UVA radiation-mediated damage to isolated and cellular DNA

A novel chlorin derivative of Meso-tris(pentafluorophenyl)-4-pyridylporphyrin: synthesis, photophysics and photochemical properties

Chlorination of Guanosine and Other Nucleosides by Hypochlorous Acid and Myeloperoxidase of Activated Human Neutrophils

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Efficient Oxidation of 2‘-Deoxyguanosine by Mn-TMPyP/KHSO₅ to Imidazolone dIz without Formation of 8-Oxo-dG