Bardelang David, Rockenbauer Antal, Karoui Hakim, Finet Jean-Pierre, Tordo Paul
Laboratoire SREP, UMR 6517 CNRS et Universités d'Aix-Marseille 1, 2 et 3, Avenue Escadrille Normandie Niemen, Marseille 13397, France.
J Phys Chem B. 2005 May 26;109(20):10521-30. doi: 10.1021/jp0509414.
(1)H NMR and electron paramagnetic resonance (EPR) titrations were used to determine the association constants of the complexes of alpha-phenyl-N-tert-butylnitrone (PBN) analogues and their superoxide spin adducts, respectively, with methylated beta-cyclodextrins. A 1:1 stoichiometry for the nitrones with randomly methylated beta-cyclodextrin and 2,6-di-O-methyl-beta-cyclodextrin and 1:1 and 1:2 stoichiometries for the corresponding cyclodextrin-nitroxide complexes were observed. After the superoxide radical spin trapping reaction, EPR titrations afforded the association constants of the corresponding cyclodextrin-nitroxide complexes. Two-dimensional EPR simulations indicated a bimodal inclusion of the nitroxide free radical spin adducts into the cyclodextrins. For all the nitrone-cyclodextrin and nitroxide-cyclodextrin complexes, the association constants were always higher for the nitroxide complexes than for the nitrone complexes. A cooperative system concerning the complexation of the nitroxide spin adduct with a cyclodextrin was evidenced by EPR titrations. The efficiency of the cyclodextrin inclusion technique to trap superoxide and to resist bioreduction by sodium l-ascorbate was also investigated.
（1）利用核磁共振氢谱（¹H NMR）和电子顺磁共振（EPR）滴定法分别测定了α-苯基-N-叔丁基硝酮（PBN）类似物及其超氧自旋加合物与甲基化β-环糊精形成的配合物的缔合常数。观察到硝酮与随机甲基化β-环糊精和2,6-二-O-甲基-β-环糊精的化学计量比为1:1，相应的环糊精-氮氧化物配合物的化学计量比为1:1和1:2。超氧自由基自旋捕获反应后，EPR滴定得到了相应环糊精-氮氧化物配合物的缔合常数。二维EPR模拟表明，氮氧化物自由基自旋加合物以双峰形式包合在环糊精中。对于所有硝酮-环糊精和氮氧化物-环糊精配合物，氮氧化物配合物的缔合常数总是高于硝酮配合物。EPR滴定证明了氮氧化物自旋加合物与环糊精络合的协同体系。还研究了环糊精包合技术捕获超氧和抵抗L-抗坏血酸钠生物还原的效率。
