20433-38-9Relevant articles and documents
Analysis of oxidative cytosine products in DNA exposed to ionizing radiation
Wagner, J. R.
, p. 1280 - 1286 (2007/10/02)
From ionizing radiation studies, we have previously characterized a large number of modifications of cytosine and 2'-deoxycytidine which arise by way of hydroxyl radical or base radical cation reactions.However, it remains a great challenge today to detect and quantitate these lesions in DNA.In the present work, I have developed a method for the analysis of six oxidation products of cytosine in DNA using HF acid hydrolysis and gas chromatography/mass spectrometry with isotopic dilution.The analysis of gamma-irradiated DNA indicated that uracil 5,6-glycols 5-hydroxyuracil and 5-hydroxyhydantoin are the major stable decomposition products of cytosine residues, whereas alloxane and 1-carbamoyl-2-oxo-4,5-dihydroxy-imidazolidine are formed in comparatively lower yields.These results suggest that the major pathway of OH radical induced decomposition of cytosine in DNA involves initial deamination of intermediate 5-hydroxy-6-hydroperoxides. - Keywords: Oxidative DNA damage, mass spectrometry, isotopic dilution, mutagenesis.
PROMOTION EFFECT OF 2,2,6,6-TETRAMETHYLPIPERIDINE-1-OXYLS ON THE RADIOLYTIC HYDROXYLATION OF THYMINE IN DEAERATED AQUEOUS SOLUTION
Kagiya, Tsutomu,Kimura, Ryoji,Komuro, Chikara,Sakano, Koichi,Nishimoto, Sei-ichi
, p. 1471 - 1474 (2007/10/02)
Remarkable promotion of the hydroxylation of thymine to give thymine glycol with almost complete depression of side reactions by 2,2,6,6-tetramethylpiperidine-1-oxyl (TMPO.) derivatives was observed in the γ-radiolyses of the N2- and N2O-saturated aqueous solutions.In the O2-saturated solution, TMPO. depressed the thymine conversion close to the level under N2 while promoted the formation of thymine glycol to some extent by decreasing side reactions.
The Radiolysis of Uracil in Oxygenated Aqueous Solutions. A Study by Product Analysis and Pulse Radiolysis
Schuchmann, Man Nien,Sonntag, Clemens von
, p. 1525 - 1532 (2007/10/02)
Hydroxyl radicals are generated by the radiolysis of N2O-O2 (4:1 v/v)-saturated aqueous solutions of uracil.They add to the 5,6-double bond of the substrate .These radicals are converted by oxygen into the corresponding peroxyl radicals (I) and (II), respectively.Peroxyl radical (I) undergoes a base-induced O2(1-.) elimination (kobs 8x1E3 s-1 at pH 10.5).As an intermediate 5-hydroxy-isopyrimidine is formed which rearranges into isobarbituric acid and adds water forming 5,6-dihydro-5,6-dihydroxyuracil.Competing with this base-induced reaction of radical (I) there is a bimolecular decay of radicals (I) and (II).These processes become predominant at low pH.For this reason a strong pH dependence of G (products) is observed.The major products are (G values at pH 3 and 10 in parentheses) 5,6-dihydroxy-5,6-dihydrouracil (1.1; 2.4), isobarbituric acid (0; 1.2), N-formyl-5-hydroxyhydantoin (1.6; 0.2), 5-hydroxybarbituric acid (0.9; 0.2). 5-Hydroxybarbituric acid is formed in its keto form.Its deprotonation (k 4.4 s-1) has been followed by pulse conductometry.Details of the reaction mechanism, e.g. the involvement of oxyl radicals in the bimolecular decay of (I) and (II), are discussed.
