Garnero Claudia, Longhi Marcela
Departamento de Farmacia, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina.
J Pharm Biomed Anal. 2007 Nov 30;45(4):536-45. doi: 10.1016/j.jpba.2007.07.030. Epub 2007 Aug 6.
Complexation between ascorbic acid, hydroxypropyl-beta-cyclodextrin (HP-beta-CD) and triethanolamine (TEA), separately and in combination, was studied in solution and solid state. The freeze-drying method was used to prepare solid complexes, while physical mixtures being obtained by simple blending. These complexes were characterized in the solid state using differential scanning calorimetry (DSC) and infrared spectroscopy (IR). Nuclear magnetic resonance spectroscopy ((1)H and (13)C NMR) was used in aqueous solutions to obtain information about the mode of interaction. The degradation rate of each complex in solution was determined, and the stability constant of the complexes and the degradation rate of the ascorbic acid within the complexes were obtained. NMR studies provided clear evidence of partial inclusion into the HP-beta-CD cavity, but the stability constant value was very small indicating a weak host-guest interaction. The influence of complexation on the degradation rate of ascorbic acid was evaluated, and the data obtained showed a pronounced enhancement of aqueous stability with the TEA association complex, while this effect was lower with the HP-beta-CD inclusion complex. NMR experiments showed evidence of the formation of aggregates.
研究了抗坏血酸、羟丙基-β-环糊精（HP-β-CD）和三乙醇胺（TEA）单独及组合时在溶液和固态下的络合情况。采用冷冻干燥法制备固体络合物，通过简单混合得到物理混合物。使用差示扫描量热法（DSC）和红外光谱（IR）对这些络合物进行固态表征。在水溶液中使用核磁共振光谱（（1）H和（13）C NMR）获取有关相互作用模式的信息。测定了每种络合物在溶液中的降解速率，得到了络合物的稳定常数以及络合物中抗坏血酸的降解速率。核磁共振研究提供了抗坏血酸部分包合进入HP-β-CD空腔的明确证据，但稳定常数值非常小，表明主客体相互作用较弱。评估了络合对抗坏血酸降解速率的影响，所得数据显示TEA缔合络合物显著提高了抗坏血酸在水中的稳定性，而HP-β-CD包合络合物的这种效果较低。核磁共振实验显示了聚集体形成的证据。
