Fast kinetics of the reactions of hydroxyl radicals with nitrone spin traps |
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Authors: | R Sridhar P C Beaumont E L Powers |
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Institution: | (1) Biomembrane Research Laboratory, Oklahoma Medical Research Foundation, 73104 Oklahoma City, Oklahoma, (USA);(2) Labortory of Radiation Biology, Patterson Labs 131, The University of Texas at Austin, 78712, Texas, (USA) |
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Abstract: | The technique of spin trapping with nitrone spin traps nas gained wide acceptance as a method for estimating·OH yields in ESR studies. In our study, fast optical kinetic techniques applied to a series of these traps (PBN, 2-PyBN, 3-PyBN, 4-PyBN, 3-PyOBN and 4-PyOBN) reveal relaxation spectra that indicate two absorption maxima with different time constants, with all except 4-PyOBN showing second order behavior. These two spectral regions show different kinetics. Thus, two reaction sites are indicated, only one of which is necessarily a measure of initial · OH when ESR methods are used. One other trap (DMPO) after · OH reaction decays in one mode suggesting that its final product might be useful as a measure of initial · OH. Also, our ESR evidence shows that OH detection can be improved significantly by spin trapping -hydroxyalkyl radicals formed by · OH attack on alcohols. |
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