Speaker
Mr
Bartosz Michalowski
(Institute od Applied Radiation Chemistry, Lodz University of Technology, Lodz, Poland)
Description
Because of the fact that the oxidation product of hydroethidine (HE), 2-hydroxyethidium (2-OH-E+), is an unique, fluorescent marker for superoxide radical anion (O2•-), hydroethidine has become one of the most used fluorogenic probes for its intracellular detection. Although, HE can be used rather as a qualitative than quantitative probe for detection of superoxide, it is still worthwhile to examine the mechanism of its oxidation, and factors affecting formation of 2-OH-E+ [1].
Here we present results showing the reactivity of hydroethidine towards chloromethylperoxyl radicals like CH2ClO2•, CHCl2O2• and CCl3O2•, generated in oxygen saturated, water/propan-2-ol solution containing 4% (v/v) of proper halocarbon compound. We showed that chloromethylperoxyl radicals are able to oxidase HE with the second-order rate constant at pH=7.4 of k=2.74 x 108 M-1s-1, k=8.8 x 108 M-1s-1 and k=1.23 x 109 M-1s-1, for corresponding radicals, measured by pulse radiolysis. Spectral characteristic of the product formed upon one-electron oxidation of HE by RO2• radicals obtained under mentioned conditions was the same with that obtained from the irradiation of HE embedded in 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM+PF6-) low-temperature glasses and characterized as hydroethidine radical cation (HE•+).
The result were concluded by theoretical calculation using TD-DFT um052x/6-311+g(d,p) basis set. Results were depicted as an electrostatic potential and spin densities maps of hydroethidine radical cation (HE•+) and other species, which formation is highly possible under mentioned experimental conditions.
[1]. Zielonka J., Vasquez-Vivar J., Kalyanaraman B. Nat. Protoc. (2008) 3, 8
Primary author
Mr
Bartosz Michalowski
(Institute od Applied Radiation Chemistry, Lodz University of Technology, Lodz, Poland)
Co-authors
Dr
Adam Sikora
(Institute od Applied Radiation Chemistry, Lodz University of Technology, Lodz, Poland)
Ms
Karolina Gajda
(Institute od Applied Radiation Chemistry, Lodz University of Technology, Lodz, Poland)
Dr
Piotr Szajerski
(Institute od Applied Radiation Chemistry, Lodz University of Technology, Lodz, Poland)
