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
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.