The influence of cosolvent on the complexation of HP-beta-cyclodextrins with oleanolic acid and ursolic acid.
The present work was aimed at the influence of ethanol on the complex formation of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) with oleanolic acid (OA) and ursolic acid (UA), two insoluble isomeric triterpenic acids. Phase solubility studies were carried out to evaluate the solubilizing power of HP-beta-CD, in association with ethanol, toward OA and UA. A mathematical model was applied to explain and predict the solubility of OA and UA influenced by HP-beta-CD and ethanol. The solid complexes were prepared by evaporating the filtrate of samples which was prepared in different complexing media. The solubility of OA is much higher than that of UA in all the tested aqueous solutions. The solubility of OA and UA can be increased over 900 and 200 times, respectively, by forming complex with HP-beta-CD. Ethanol (0.5%, v/v) can help the formation of OA-HP-beta-CD complex, but is harmful to the formation of UA-HP-beta-CD complex. Increasing solubility in water can be achieved by adding ethanol into the complexing media, but the concentration of ethanol should be optimized. The ring E of the chemical compounds has a great influence on the complexing process.
Li
Rui
R
Department of Pharmaceutics, School of Pharmacy, Nanjing Medical University, 140 Hanzhong Road, 210029, Nanjing, People's Republic of China.
Quan
Peng
P
Liu
Dong-Fei
DF
Wei
Fang-Di
FD
Zhang
Qing
Q
Xu
Qun-Wei
QW
D000073738:2-Hydroxypropyl-beta-cyclodextrin; D002851:Chromatography, High Pressure Liquid; D001330:Electronic Data Processing; D000431:Ethanol / Q000737:chemistry*; D009828:Oleanolic Acid / Q000737:chemistry*; D012995:Solubility; D014315:Triterpenes / Q000737:chemistry*; D047392:beta-Cyclodextrins / Q000737:chemistry*; D000097245:Ursolic Acid
D000073738:2-Hydroxypropyl-beta-cyclodextrin; D000431:Ethanol; D009828:Oleanolic Acid; D014315:Triterpenes; D047392:beta-Cyclodextrins; D000097245:Ursolic Acid