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NMR spin trapping: Detection of free radical reactions using a phosphorus‐containing nitrone spin trap
Author(s) -
Khramtsov Valery,
Berliner Lawrence J.,
Clanton Thomas L.
Publication year - 1999
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/(sici)1522-2594(199908)42:2<228::aid-mrm3>3.0.co;2-t
Subject(s) - nitrone , chemistry , spin trapping , radical , hydroxylamine , adduct , electron paramagnetic resonance , quenching (fluorescence) , photochemistry , nuclear magnetic resonance , fluorescence , organic chemistry , cycloaddition , catalysis , physics , quantum mechanics
This study employs 31 P‐nuclear magnetic resonance (NMR) to probe for changes in molecular structure arising from reactions between free radicals and a phosphorus‐containing nitrone spin trap, 5‐diethoxyphosphoryl‐5‐methyl‐1‐pyrroline‐N‐oxide (DEPMPO). A number of biologically relevant free radical reactions were detected: a) reactions of DEPMPO with ⋅ OH resulted in a new 31 P‐NMR resonance at 27.05 ppm (shifted from the parent compound at 23.67 ppm); evidence suggests that this species is a diamagnetic hydroxy‐pyrrolidone reduction product; b) 31 P‐NMR spectra of DEPMPO/ ⋅ CH 3 reactions resulted in peaks at 24.54, 30.83, and 32.31 ppm, while DEPMPO/ ⋅ CH 2 OH produced peaks at 24.05, 30.80 and 32.52 ppm; in the presence of excess ascorbate, only resonances between 30 and 32 ppm were evident, which we have tentatively assigned to the hydroxylamine isomers of their respective adducts; and c) reaction of DEPMPO with O 2 ⋅− , produced by xanthine/xanthine oxidase or stimulated neutrophils, resulted in a single line, indistinguishable from DEPMPO/ ⋅ OH reaction products. We conclude that NMR spin trapping is a useful approach for detecting free radical reaction pathways. It may have future applications for human free radical biology and imaging. Magn Reson Med 42:228–234, 1999. © 1999 Wiley‐Liss, Inc.