Abstract: Aim To prepare and characterize the QURC-HP-β-CD inclusion complexes and investigate the thermodynamic parameters of the process. Methods QURC-HP-β-CD inclusion complexes were prepared by the grinding method. The equilibrium inclusion constants and thermodynamic parameters were determinated by phase solubility analysis. Dissolution tests were performed to study the dissolution rate of inclusion complexes. The formation of inclusion complexes was confirmed by differential scanning calorimetry (DSC), infrared spectroscopy (IR), powder X-ray diffractometry (PXRD) and scanning electron microscopy (SEM). Results The aqueous solubility of quercetin was greatly increased (about 37 folds) by inclusion technique, and the initial dissolution rate was markedly improved (10 folds) in the first 5 min. The results of DSC and SEM photographs showed that quercetin crystal disappeared in inclusion complexes, which indicated the formation of new phase. FT-IR spectra showed that the carbonyl absorption band of quercetin was shifted. PXRD showed that the diffraction peak of quercetin crystal disappeared. Conclusion QURC-HP-β-CD inclusion complexes are produced by the grinding method. The solubility of quercetin is improved by the inclusion technique.

Key words: quercetin, quercetin, hydroxypropyl-β-cyclodextrin, hydroxypropyl-β-cyclodextrin, inclusion complex, inclusion complex, inclusion constant, inclusion constant, Phase behavior, Phase behavior