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Inclusion complexes of EMPO derivatives with 2,6-di-O-methyl-beta-cyclodextrin: synthesis, NMR and EPR investigations for enhanced superoxide detection.

Bardelang D, Rockenbauer A, Karoui H, Finet JP, Biskupska I, Banaszak K, Tordo P

Laboratoire SREP, UMR 6517 CNRS et Universités d'Aix-Marseille 1, France.

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.

Published 20 July 2006 in Org Biomol Chem, 4(15): 2874-82.
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