Inclusion Performance of Different Substitution Degrees of Hydroxypropyl-β-cyclodextrin with Daidzein

Six inclusion complexes of daidzein and HP-β-CD with suitable interval degrees of substitution were prepared by the solution stirring method.The complexes were characterized by infrared spectroscopy(IR),powder X-ray diffraction(XRD),ultra-violet spectroscopy(UV).The apparent equilibrium constants(Kc) of the four inclusion complexes were determined by using phase-solubility method.The effects of the substitution degrees of HP-β-CD on preparation of the inclusion complex of HP-β-CD/daidzein were investigated.The results showed that the inclusion complexes were produced and the best inclusion was at DS=7.8.The solubility of daidzein were greatly improved by HP-β-CD with DS=7.8.