Study of DNA damage with a new system for irradiation of samples in a nuclear reactor

In this paper, we report results of a quantitative analysis of the effects of neutrons on DNA, and, specifically, the production of simple and double breaks of plasmid DNA in aqueous solutions with different concentrations of free-radical scavengers. The radiation damage to DNA was evaluated by electrophoresis through agarose gels. The neutron and gamma doses were measured separately with thermoluminescent detectors. In this work, we have also demonstrated usefulness of a new system for positioning and removing samples in channel BH#3 of the IEA-R1 reactor at the Instituto de Pesquisas Energeticas e Nucleares (Brazil) without necessity of interrupting the reactor operation. (C) 2010 Elsevier Ltd. All rights reserved.

Effect of flavonoids on 2 `-deoxyguanosine and DNA oxidation caused by singlet molecular oxygen

Antioxidant potential is generally investigated by assaying the ability of a compound to protect biological systems from free radicals. However, non-radical reactive oxygen species can also be harmful. Singlet molecular oxygen ((1)O(2)) is generated by energy transfer to molecular oxygen. The resulting (1)O(2) is able to oxidize the nucleoside 2`-deoxyguanosine (dGuo), which leads to the formation of 8-oxo-7,8-dihydro-2`-deoxyguanosine (8-oxodGuo) and spiroiminodihydantoin 2`-deoxyribonucleoside diastereomers (dSp) in an aqueous solution. The main objective of the present study was to verify whether the presence of flavonoids (flavone, apigenin, quercetin, morin and catechin) at different concentrations could protect dGuo from (1)O(2) damage. Of the tested flavonoids, flavone possessed antioxidant activity, as determined by a decrease in the formation of both products. Apigenin, morin, quercetin and catechin all increased the formation of 8-oxodGuo at a concentration of 100 mu M. The quantification of plasmid strand breaks after treatment with formamidopyrimidine-DNA glycosylase showed that flavone protected and quercetin and catechin enhanced DNA oxidation. Our results show that compounds, such as flavonoids, may affect the product distribution of (1)O(2)-mediated oxidation of dGuo, and, in particular, high concentrations of flavonoids with hydroxyl groups in their structure lead to an increase in the formation of the mutagenic lesion 8-oxodGuo. (C) 2010 Elsevier Ltd. All rights reserved.