Fluorescence enhancement of curcumin upon inclusion into parent and modified cyclodextrins
Fluorescence enhancement of curcumin upon inclusion into parent and modified cyclodextrins
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DOI：
10.1016/j.jphotochem.2005.04.002
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发表时间：
2005-07-15
影响因子：
4.3
通讯作者：
Wagner, BD
中科院分区：
文献类型：
--
作者：
Baglole, KN;Boland, PG;Wagner, BD
研究了α-、β-和γ-环糊精（CD）及其羟基化（HP）衍生物对化合物姜黄素的溶解度和荧光的影响。姜黄素是印度香料姜黄的主要成分，由于其广泛的药用特性而受到越来越多的关注。所有这六种环糊精都显着增加了姜黄素的水溶性，其中 HP-gamma-CD 的溶解度最大。姜黄素与这些环糊精形成 2:1 的主客体包合物，其中 HP-β-CD 形成的复合物最强。假定当环糊精主体封装姜黄素分子末端的两个苯环时，就会形成这些 2:1 复合物。在每种情况下，第二环糊精主体包封的平衡常数均显着小于第一环糊精主体的平衡常数，这可能是由于第一环糊精的空间体积以及姜黄素分子的深度包含，阻碍了第二环糊精主体的包封。事实上，就 beta-CD 而言，1:1 主机：访客模型与 2:1 模型一样，甚至更好地拟合数据。对于 γ-CD 和 HP-γ-CD，发现最初形成的 1:1 复合物的荧光性低于游离姜黄素；据推测，这是由于包含了折叠的姜黄素分子，该分子破坏了分子长度上的共轭，从而大大降低了其荧光量子产率。 (c) 2005 Elsevier B.V. 保留所有权利。
The effect of alpha-, beta-, and gamma-cyclodextrin (CD) and their hydroxygropylated (HP) derivatives on the solubility and fluorescence of the compound curcumin has been studied. Curcumin, the main constituent of the Indian spice turmeric, is of growing interest due to its wide-ranging pharmaceutical properties. All of these six cyclodextrins significantly increase the aqueous solubility of curcumin, with the greatest solubility observed in HP-gamma-CD. Curcumin forms 2:1 host-guest inclusion complexes with these cyclodextrins, with the strongest complexes formed in the case of HP-beta-CD. These 2:1 complexes are postulated to form when a cyclodextrin host encapsulates each of the two phenyl rings at the ends of the curcumin molecule. The equilibrium constant for encapsulation by the second cyclodextrin host is significantly smaller than that for the first in each case, probably a result of steric bulk of the first cyclodextrin, with deep inclusion of the curcumin molecule, hindering encapsulation by the second cyclodextrin host. In fact, in the case of beta-CD, a 1: 1 host:guest model fit the data just as well, or better than, the 2:1 model. In the case of gamma-CD and HP-gamma-CD, the initial 1:1 complex formed was found to be less fluorescent than the free curcumin; this is postulated to be a result of inclusion of a folded curcumin molecule, which breaks the conjugation along the length of the molecule and hence greatly reduces its fluorescence quantum yield. (c) 2005 Elsevier B.V. All rights reserved.