NMR spin trapping: detection of free radical reactions using a phosphorus-containing nitrone spin trap.
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 ( small middle dot)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/( small middle dot)CH(3) reactions resulted in peaks at 24.54, 30.83, and 32.31 ppm, while DEPMPO/( small middle dot)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)( small middle dot-), produced by xanthine/xanthine oxidase or stimulated neutrophils, resulted in a single line, indistinguishable from DEPMPO/( small middle dot)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.
Khramtsov
V
V
Department of Internal Medicine, Pulmonary and Critical Care Medicine, The Ohio State University, Columbus, Ohio 43210, USA.
Berliner
L J
LJ
Clanton
T L
TL
D003497:Cyclic N-Oxides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D009504:Neutrophils / Q000378:metabolism; D019097:Spin Trapping
D003497:Cyclic N-Oxides; D005609:Free Radicals; C098505:5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide