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Org. Biomol. Chem., 2006, 4, 2874 - 2882, DOI: 10.1039/b606062e
Inclusion complexes of EMPO derivatives with 2,6-di-O-methyl-
-cyclodextrin: synthesis, NMR and EPR investigations for enhanced superoxide detectionDavid Bardelang, Antal Rockenbauer, Hakim Karoui, Jean-Pierre Finet, Inga Biskupska, Karol Banaszak and Paul Tordo
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-
-cyclodextrin (DM--CD). 1H-NMR titrations were performed to determine both stoichiometries and binding constants for the diamagnetic nitrone–DM--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--CD and the associated binding constants after spin trapping. The nitroxide spin adducts associate more strongly with DM--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--CD against sodium L-ascorbate reduction were evaluated.
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