Quenching of nucleotide-derived radicals by bisbenzimidazole derivative Hoechst-33258 in aqueous solution

Citation
H. Mohan et al., Quenching of nucleotide-derived radicals by bisbenzimidazole derivative Hoechst-33258 in aqueous solution, P I A S-CH, 112(4), 2000, pp. 487-496
Citations number
19
Categorie Soggetti
Chemistry
Journal title
PROCEEDINGS OF THE INDIAN ACADEMY OF SCIENCES-CHEMICAL SCIENCES
ISSN journal
02534134 → ACNP
Volume
112
Issue
4
Year of publication
2000
Pages
487 - 496
Database
ISI
SICI code
0253-4134(200008)112:4<487:QONRBB>2.0.ZU;2-G
Abstract
The pulse radiolysis technique has been employed to investigate the reactio n of DNA-minor-groove ligand bisbenzimidazole Hoechst 33258 with pyrimidine and purine nucleotide-derived radicals. Formation of an N-centred Hoechst- 33258 radical is observed. Bimolecular rate constants and the yields of Hoe chst-33258 radical have been evaluated. While the rate constant for the rea ction of pyrimidine-derived radicals with Hoechst-33258 remained the same ( 1-2) x 10(9) dm(3) mol(-1) s(-1), th, yields of the Hoechst-33258 radical v aried from 25% (5'-cytidine monophosphate) to 75% (5'-guanosine monophospha te) under anoxic conditions. The rate constant values for the reaction of p urine-derived radicals with Hoechst-33258, under oxic and anoxic conditions , remained the same whereas with pyrimidine-derived radicals, the rate cons tant value under oxic conditions was about two orders of magnitude lower th an under anoxic conditions. The difference in the yields of Hoechst-33258 r adical with various nucleotide-derived radicals suggest the formation of di fferent types of radicals and that the reaction mainly occurs by electron t ransfer from Hoechst-33258 to the nucleotide radicals.