Wang Hai Ming, Soica Codruta M, Wenz Gerhard
Organische Makromolekulare Chemie, Saarland University, Geb. C4.2, 66123 Saarbrücken, Germany.
Nat Prod Commun. 2012 Mar;7(3):289-91.
Betulin (BET) and betulinic acid (BA) are naturally occurring pentacyclic lupane triterpenes, exhibit great promise as bioactive agents for the treatment of many diseases. The poor solubilities of BET and BA in water have limited their applications. In the present work, BET and BA were selected as guest molecules, three hydrophilic gamma-cyclodextrin (CD) thioethers were synthesized and selected as host molecules. beta-, Hydroxypropyl-beta-CD, (HP-beta-CD), gamma-CD and HP-gamma-CD were also investigated as hosts in order to compare the solubilization abilities of these host molecules. The solubilities of BET and BA were estimated from 1H NMR measurements by comparing the relative integral areas of the proton signals between CDs and guests. gamma-CD thioethers 5-7solubilized BET and BA to much higher extends than other host molecules. The obtained maximal solubilities of BET and BA were 5.2 and 4.5 mM, respectively. The topographies of the inclusion compounds were determined by ROESY NMR spectroscopy.
桦木醇（BET）和桦木酸（BA）是天然存在的五环羽扇烷三萜，作为治疗多种疾病的生物活性剂具有巨大潜力。BET和BA在水中的低溶解度限制了它们的应用。在本工作中，选择BET和BA作为客体分子，合成并选择了三种亲水性γ-环糊精（CD）硫醚作为主体分子。还研究了β-、羟丙基-β-CD（HP-β-CD）、γ-CD和HP-γ-CD作为主体，以比较这些主体分子的增溶能力。通过比较CD与客体之间质子信号的相对积分面积，利用1H NMR测量估算BET和BA的溶解度。γ-CD硫醚5-7对BET和BA的增溶程度比其他主体分子高得多。BET和BA获得的最大溶解度分别为5.2和4.5 mM。通过ROESY NMR光谱确定包合物的拓扑结构。
