Zheng Yan, Dong Li-Na, Liu Min, Chen Aiju, Feng Shangcai, Wang Bingquan, Sun Dezhi
School of Chemistry and Chemical Engineering, Liaocheng University , Liaocheng, 252059 China.
J Agric Food Chem. 2014 Jan 8;62(1):244-50. doi: 10.1021/jf404320w. Epub 2013 Dec 19.
The utilization of kaempferol and its glycosides in food and pharmaceutical industries could be improved by the formation of inclusion complexes with cyclodextrins at different pH. This study explores the complexation of kaempferol-4'-glucoside with sulfobutyl ether-β-cyclodextrin (SBE-β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and methylated-β-cyclodextrin (M-β-CD) in phosphate buffer solutions of different pH using isothermal titration calorimetry, UV-vis absorption and proton nuclear magnetic resonance spectroscopy at 298.2 K. Experimental results showed that kaempferol-4'-glucoside binds with the three β- cyclodextrins in the same 1:1 stoichiometry. The rank order of stability constants is SBE-β-CD > HP-β-CD > M-β-CD at the same pH level and pH 6.0 > pH 7.4 > pH 9.0 for the same cyclodextrin. The binding of kaempferol-4'-glucoside with the three β-cyclodextrin derivatives is synergistically driven by enthalpy and entropy at pH 6.0 and enthalpy-driven at pH 7.4 and 9.0. The possible inclusion mode was that in the cavity of β-CD is included the planar benzopyranic-4-one part of the kaempferol-4'-glucoside.
通过在不同pH值下与环糊精形成包合物，可以提高山奈酚及其糖苷在食品和制药工业中的利用率。本研究采用等温滴定量热法、紫外可见吸收光谱和质子核磁共振光谱，在298.2 K下，研究了山奈酚-4'-葡萄糖苷在不同pH值的磷酸盐缓冲溶液中与磺丁基醚-β-环糊精（SBE-β-CD）、羟丙基-β-环糊精（HP-β-CD）和甲基化-β-环糊精（M-β-CD）的络合作用。实验结果表明，山奈酚-4'-葡萄糖苷与三种β-环糊精以相同的1:1化学计量比结合。在相同pH值下，稳定常数的顺序为SBE-β-CD > HP-β-CD > M-β-CD；对于相同的环糊精，pH 6.0 > pH 7.4 > pH 9.0。在pH 6.0时，山奈酚-4'-葡萄糖苷与三种β-环糊精衍生物的结合由焓和熵协同驱动，在pH 7.4和9.0时由焓驱动。可能的包合模式是β-环糊精的腔内包含山奈酚-4'-葡萄糖苷的平面苯并吡喃-4-酮部分。
