Inclusion complexes of EMPO derivatives with 2,6-di-O-methyl-?-cyclodextrin: synthesis, NMR and EPR investigations for enhanced superoxide detection
ABSTRACT 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.
- 01/2012; 4(1):1-102. DOI:10.4199/C00043ED1V01Y201112ISP032
- Chemistry - A European Journal 10/2009; 15(42):11114-8. DOI:10.1002/chem.200901342 · 5.70 Impact Factor
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ABSTRACT: The reduction of the chiral, racemic nitrone MiPNO provides a secondary hydroxylamine. Its O-acylation with O,O’-dibenzoyl-l-tartaric acid anhydride gives two diastereomers, that can be easily separated by selective dissolution in orthogonal solvents. The recovery of the enantiopure nitrone is then carried out in a single step. The process allows the straightforward isolation of (R) and (S)-MiPNO in 57% and 38% yield, respectively, from rac-MiPNO.Tetrahedron Asymmetry 06/2011; 22(12):1266-1273. DOI:10.1016/j.tetasy.2011.07.002 · 2.17 Impact Factor