Inclusion complexes of EMPO derivatives with 2,6-di-O-methyl-β-cyclodextrin: synthesis, NMR and EPR investigations for enhanced superoxide detection
作者:David Bardelang、Antal Rockenbauer、Hakim Karoui、Jean-Pierre Finet、Inga Biskupska、Karol Banaszak、Paul Tordo
DOI:10.1039/b606062e
日期:——
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-β-cyclodextrin (DM-β-CD). 1H-NMR titrations were performed to determine both stoichiometries and binding constants for the diamagnetic nitroneâDM-β-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-β-CD and the associated binding constants after spin trapping. The nitroxide spin adducts associate more strongly with DM-β-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-β-CD against sodium L-ascorbate reduction were evaluated.
评估了八种5-烷氧羰基-5-甲基-1-吡咯啉 N-氧化物(EMPO)型氮酮和5,5-二甲基-1-吡咯啉 N-氧化物(DMPO)在含有2,6-二-O-甲基-β-环糊精(DM-β-CD)存在下捕获超氧阴离子自由基的自由基捕获性质。通过1H-NMR滴定确定顺磁性氮酮-DM-β-CD平衡的化学计量和结合常数。然后进行EPR滴定,并使用二维EPR模拟程序进行分析,得到1:1和1:2的化学计量比以及自旋捕获后的氮氧自由基与DM-β-CD的结合常数。氮氧自由基与DM-β-CD的结合比氮酮更强。评估了氮酮捕获超氧的能力、EPR信号强度的增强以及DM-β-CD对L-抗坏血酸钠还原作用的超分子保护。