68509-78-4Relevant academic research and scientific papers
Sonochemical transformation of thymidine: A mass spectrometric study
Chandran, Jisha,Aravind, Usha K.,Aravindakumar
, p. 178 - 186 (2015/06/02)
Abstract Ultrasound is extensively used in medical field for a number of applications including targeted killing of cancer cells. DNA is one of the most susceptible entities in any kind of free radical induced reactions in living systems. In the present work, the transformation of thymidine (dT) induced by ultrasound (US) was investigated using high resolution mass spectrometry (LC-Q-ToF-MS). dT was subjected to sonolysis under four different frequencies (200, 350, 620 and 1000 kHz) and at three power densities (10.5, 24.5 and 42 W/mL) in aerated as well as argon saturated conditions. A total of twenty modified nucleosides including non-fully characterized dT dimeric compounds were detected by LC-Q-ToF-MS. Out of these products, seven were obtained only in the argon atmosphere and two only in the aerated conditions. Among the identified products, there were base modified products and sugar modified products. The products were formed by the reaction of hydroxyl radical and hydrogen atom. Under aerated conditions, the reactions proceed via the formation of hydroperoxides, while in argon atmosphere disproportionation and radical recombinations predominate. The study provides a complete picture of sonochemical transformation pathways of dT which has relevance in DNA damage under ultrasound exposure.
Photoinduced reductive repair of thymine glycol: Implications for excess electron transfer through DNA containing modified bases
Ito, Takeo,Kondo, Akiko,Terada, Satoru,Nishimoto, Sei-Ichi
, p. 10934 - 10942 (2007/10/03)
Photoinduced reduction of thymine glycol in oligodeoxynucleotides was investigated using either a reduced form of flavin adenine dinucleotide (FADH-) as an intermolecular electron donor or covalently linked phenothiazine (PTZ) as an intramolecular electron donor. Intermolecular electron donation from photoexcited flavin (*FADH-) to free thymidine glycol generated thymidine in high yield, along with a small amount of 6-hydroxy-5,6-dihydrothymidine. In the case of photoreduction of 4-mer long single-stranded oligodeoxynucleotides containing thymine glycol by *FADH-, the restoration yield of thymine was varied depending on the sequence of oligodeoxynucleotides. Time-resolved spectroscopic study on the photo-reduction by laser-excited N,N-dimethylaniline (DMA) suggested elimination of a hydroxyl ion from the radical anion of thymidine glycol with a rate constant of ～104 s-1 generates 6-hydroxy-5,6-dihydrothymidine (6-HOT?) as a key intermediate, followed by further reduction of 6-HOT? to thymidine or 6-hydroxy-5,6-dihydrothymdine (6-HOT). On the other hand, an excess electron injected into double-stranded DNA containing thymine glycol was not trapped at the lesion but was further transported along the duplex. Considering redox properties of the nucleobases and PTZ, competitive excess electron trapping at pyrimidine bases (thymine, T and cytosine, C) which leads to protonation of the radical anion (T-?, C-?) or rapid back electron transfer to the radical cation of PTZ (PTZ-?), is presumably faster than elimination of the hydroxyl ion from the radical anion of thymine glycol in DNA.
Reactions des radicaux 6-hydroxy-5,6-dihydrothymid-5-yles en solution aqueuse
Berger, M.,Sarrazin, F.,Cadet, J.
, p. 853 - 862 (2007/10/02)
The main reactions of 6-hydroxy-5,6-dihydrothymid-5-yl radicals, specifically obtained by electron capture dissociation of the trans diastereomers of 5-bromo-6-hydroxy-5,6-dihydrothymidine, were determined in aqueous solutions on the basis of final product analysis.In oxygen-free aqueous solutions a complex mixture of both monomeric and dimeric decomposition products was produced.It is worth mentioning the radiation-induced formation of modified nucleosides which involves the transient generation of 5-(2'-deoxyuridyl)methyl radical.This may be explained in terms of initial formation of 6-hydroxy-5,6-dihydrothymid-5-yl radicals, followed by dehydration and subsequent deprotonation.
