EPR Study of KO2 as a Source of Superoxide and •BMPO-OH/OOH Radical That Cleaves Plasmid DNA and Detects Radical Interaction with H2S and Se-Derivatives
: Superoxide radical anion (O2
•−) and its derivatives regulate numerous physiological and
pathological processes, which are extensively studied. The aim of our work was to utilize KO2 as a
source of O2
•− and the electron paramagnetic resonance (EPR) spin trapping 5-tert-butoxycarbonyl-5-
methyl-1-pyrroline N-oxide (BMPO) technique for the preparation of •BMPO-OOH and/or •BMPOOH radicals in water solution without DMSO. The method distinguishes the interactions of various
compounds with •BMPO-OOH and/or •BMPO-OH radicals over time. Here, we show that the
addition of a buffered BMPO-HCl mixture to powdered KO2
formed relatively stable •BMPO-OOH
and •BMPO-OH radicals and H2O2
, where the •BMPO-OOH/OH ratio depended on the pH. At a
final pH of ~6.5–8.0, the concentration of •BMPO-OOH radicals was ≥20 times higher than that of
•BMPO-OH, whereas at pH 9.0–10.0, the •BMPO-OH radicals prevailed. The •BMPO-OOH/OH
radicals effectively cleaved the plasmid DNA. H2S decreased the concentration of •BMPO-OOH/OH
radicals, whereas the selenium derivatives 1-methyl-4-(3-(phenylselanyl) propyl) piperazine and
1-methyl-4-(4-(phenylselanyl) butyl) piperazine increased the proportion of •BMPO-OH over the
•BMPO-OOH radicals. In conclusion, the presented approach of using KO2 as a source of O2
•−/H2O2
and EPR spin trap BMPO for the preparation of •BMPO-OOH/OH radicals in a physiological solution
could be useful to study the biological effects of radicals and their interactions with compounds