2943-56-8Relevant academic research and scientific papers
Hydroxyl radical-induced cross-linking of thymine and lysine: Identification of the primary structure and mechanism
Morimoto, Syota,Hatta, Hiroshi,Fujita, Shin-Ichi,Matsuyama, Tomochika,Ueno, Toru,Nishimoto, Sei-Ichi
, p. 865 - 870 (2007/10/03)
Hydroxyl radical-induced formation of a cross-link of thymine (Thy) and lysine (Lys) in the γ-radiolysis of N2O-saturated aqueous solution was studied. A Thy-Lys cross-link (I) of the formal structure that OH radical and 4-carbon-centered Lys radical added respectively to C(5) and C(6) positions of Thy was isolated by a preparative HPLC and identified by a FAB-HRMS. The primary cross-link I was dehydrated by treatment with HCl at 120°C to yield the secondary structure (II) possessing a C(5)-C(6) double bond in the Thy moiety: the latter structure II was reported previously (Dizdaroglu, M.; Gajewski, E. Cancer Res. 1989, 49, 3463-3467). A pulse radiolysis study with a redox titration method indicated that 4-carbon centered Lys radical intermediate was of neutral redox reactivity in contrast to reducing reactivity of 5-hydroxy-5,6-dihydrothymin-6-yl radical intermediate. The cross-link I could be formed by a conventional radical recombination mechanism, but not by an ionic recombination mechanism involving a redox reaction between the radical intermediates.
Reactions of cobalt(III) complexes with free radicals derived from thymine
Chakrabarti,Mandal,Bhattacharyya
, p. 693 - 703 (2007/10/03)
The nature of interaction of Co(III) complexes such as Co(III)EDTA and Co(III)NTA with transient adducts of thymine such as TOH·, T·-, and TH· formed in the gamma radiolysis of thymine were studied. The study shows that TOH radicals do not undergo electron transfer reaction with Co(III) complexes whence no radiosensitization of thymine by Co(III) complexes was observed. Electron transfer however, takes place from T·- and TH· to Co(III) complexes. A plausible mechanism of radiolysis of thymine in presence of Co(III) complexes is discussed.
Far ultraviolet induced decomposition of thymine in deaerated and aerated aqueous solutions
Ohtani, Bunsho,Nagasaki, Hiroshi,Nishimoto, Sei-ichi,Sakano, Koichi,Kagiya, Tsutomu
, p. 2297 - 2300 (2007/10/02)
Thymine in aqueous solution was decomposed with quantum yields of 0.3 and 0.4 under N2-saturated and aerated conditions by far-ultraviolet light (>180 nm, far-uv), and quantum yields of 2E-4 and 3E-4 by near-ultraviolet light (>220 nm, near-uv), respectively.The main photolytic products by far-uv were 5,6-dihydrothymine (DHT) (selectivity: S(DHT) = 0.2) and 5-hydroxymethyluracil (HMU) (S(HMU) = 0.1) under N2-saturated conditions. cis- and trans-5,6-Dihydroxy-5,6-dihydrothymine (TG), 6(5)-hydroperoxy-5(6)-hydroxy-5,6-dihydrothymine (HTP) (S(TG) + S(HTP) = 0.2), and N1-formyl-N2-pyruvylurea (FPU) (S(FPU) = 0.4) were obtained under aerated conditions.These products were attributed to the reactions of thymine with the radical H and radical O produced by photolysis of water.
Radiation-Induced Degradation of Purine and Pyrimidine 2'-Deoxyribonucleosides in Aqueous KBr Solutions
Cadet, J.,Voituriez, L.,Berger, M.,Myers, L. S., (Jr.)
, p. 1643 - 1651 (2007/10/02)
Steady-state γ-radiolysis of 5E-4 M pyrimidine and purine 2'-deoxyribonucleosides in aqueous solutions saturated with N2, N2O and O2, respectively, have been carried out in the presence of 0.1 M KBr.The main final degradation products have been isolated and characterised by various spectroscopic measurements including 1H and 13C NMR, UV, C.D. and mass spectrometry.The radiation-induced decomposition of thymidine is mostly accounted for by an ionic mechanism involving Br2, the decay product of Br2, as the reactive oxidising specie.On the other hand the degradation of the purine ring of 2'-deoxyadenosine and 2'-deoxyguanosine may be accounted for by the action of Br2 or Br3. - Keywords: 2'-Deoxyribonucleosides, Inorganic Radical, γ-Irradiation, Radical Reactions, Thymidine Oxidation
RADIATION-INDUCED HYDROXYLATION OF THYMINE SENSITIZED BY NITRO COMPOUNDS IN N2O-SATURATED AQUEOUS SOLUTION
Wada, Takeshi,Ide, Hiroshi,Nishimoto, Sei-ichi,Kagiya, Tsutomu
, p. 1041 - 1044 (2007/10/02)
Hydroxylation of thymine (1) to give thymine glycol (3) is remarkably promoted by the addition of nitro compounds (2a-f) in the γ-radiolysis of the N2O-saturated aqueous solution, although overall decomposition of 1 is depressed to some extent.The G-value of 3 increases linearly with increasing the one-electron reduction potential of 2a-f.
Steady State Radiolysis of Aqueous Aerated Solutions of 5,6-Dihydrothymine. Identification of the Major Degradation Products
Cadet, J.
, p. 1579 - 1583 (2007/10/02)
The major radiation-induced degradation products of 5,6-dihydrothymine (1) in aqueous solutions saturated either with O2 or N2O/O2 (75/25 v/v) were identified as thymine (10), the trans- and cis-isomers of 6-hydroperoxy-5,6-dihydrothymine (5, 7), 5-hydroperoxy-5,6-dihydrothymine (9), and their corresponding hydroxy derivatives (4, 6, 8).The formation of these compounds is explained in terms of initial H-abstraction from the C(5) and C(6) carbons which gives rise respectively to the transient 5-yl and 6-yl radicals.Thymine hydroxy-hydroperoxides (11-14) and their decomposition products (17-20), which are derived from hydroxyl radical attack at the 5,6-ethylenic bond of thymine (10), were also characterized. - Keywords: 5,6-Dihydrothymine, Hydroperoxides, Dihydropyrimidyl Radicals
