Inclusion complexes of EMPO derivatives with 2,6-di-O-methyl-beta-cyclodextrin: synthesis, NMR and EPR investigations for enhanced superoxide detection.
The free radical trapping properties of eight 5-alkoxycarbonyl-5-methyl-1-pyrroline N-oxide (EMPO) type nitrones and those of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) were evaluated for trapping of superoxide anion radicals in the presence of 2,6-di-O-methyl-beta-cyclodextrin (DM-beta-CD). (1)H-NMR titrations were performed to determine both stoichiometries and binding constants for the diamagnetic nitrone-DM-beta-CD equilibria. EPR titrations were then performed and analyzed using a two-dimensional EPR simulation program affording 1 : 1 and 1 : 2 stoichiometries for the nitroxide spin adducts with DM-beta-CD and the associated binding constants after spin trapping. The nitroxide spin adducts associate more strongly with DM-beta-CD than the nitrones. The ability of the nitrones to trap superoxide, the enhancement of the EPR signal intensity and the supramolecular protection by DM-beta-CD against sodium L-ascorbate reduction were evaluated.
Bardelang
David
D
Laboratoire SREP, UMR 6517 CNRS et Universités d'Aix-Marseille 1, France.
Rockenbauer
Antal
A
Karoui
Hakim
H
Finet
Jean-Pierre
JP
Biskupska
Inga
I
Banaszak
Karol
K
Tordo
Paul
P
D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D015394:Molecular Structure; D011758:Pyrroles / Q000737:chemistry*; D013481:Superoxides / Q000032:analysis*; D047392:beta-Cyclodextrins / Q000737:chemistry*
C406273:2-ethoxycarbonyl-2-methyl-3,4-dihydro-2H-pyrrole-1-oxide; D011758:Pyrroles; D047392:beta-Cyclodextrins; D013481:Superoxides; C038119:heptakis(2,6-O-dimethyl)beta-cyclodextrin