Study on inclusion complexation of oleanolic acid and ursolic acid with hydroxypropyl-β-cyclodextrin

ZHANG Ming-wan; QUAN Peng; HUANG Yuan; WANG Hui; HAN Bai-tao; LI Rui; XU Qun-wei

Abstract：Objective:To determine the difference in the complex formation processes of oleanolic acid (OA) and ursolic acid (UA) which are insoluble isomers with hydroxypropyl-β-cyclodextrin (HP-β-CD).Methods:The changes in the UV and 1H-NMR spectra of HP-β-CD during interacting with OA and UA were observed respectively.The influences of substitution degree of HP-β-CD,pH and temperature on the inclusion process were evaluated by phase solubility method with complexation efficiency (CE) as an indicator.Meanwhile,the thermodynamic parameters during the complexation were also calculated.Furthermore,the inclusion compounds of OA-and UA-HP-β-CD were prepared by stirring method,and DSC and X-ray were performed to identify the compounds.Results:The UV and 1H-NMR spectra showed that the interaction of HP-β-CD with OA and UA formed hydrogen bond.The CE of OA was higher than UA in the different substitution degree of HP-β-CD,pH and temperature respectively.In addition,there was significant difference between the two inclusion processes according to the thermodynamic parameters.The preparation process is simple and easy to do,and the DSC and X-ray characteristics confirmed that the complexs of OA-and UA-HP-β-CD were formed.Conclusion:HP-β-CD can form inclusion compound with OA and UA to increase the solubility of drugs although there was significant difference between the two inclusion processes due to the different structure of OA and UA.