Preparation, Characterization and Water Solubility of Inclusion Complexes of Daidzein with Amino-Modified β-Cyclodextrins

Solid inclusion complexes of daidzein with two amino-modified β-cyclodextrins, i.e., mono-6-amino-deoxy-β-cyclodextrin (NCD) and mono-6-ethylenediamino-6-deoxy-β-cyclodextrin (ENCD), were prepared and characterized. Water solubility of daidzein was dramatically raised to 15.2 and 13.2 mg mL−1 at 25 °C, increasing by 1800 and 1500-fold compared to native daidzein (8.31 μg mL−1).