Evaluation of Solubility Characteristics of a Hybrid Complex of Components of Soy

The purpose of this study was to evaluate the solubilities and physicochemical properties of solid dispersions of daidzein (DDZ) and genistein (GST) (the major isoflavones in soybeans) in gamma-cyclodextrin (gamma CD). Dispersions were prepared in distilled water using a three-dimensional ball mill (3DGMw). Phase solubility diagrams confirmed that DDZ/gamma CD and GST/gamma CD formed A(L) type inclusion complexes with a molar ratio of 1:1. A new peak due to inclusion complexes was observed in the results of powder Xray diffraction (3DGMw(DDZ/gamma CD = 1:1) and 3DGMw-(GST/gamma CD = 1:1)). Dissolution tests using distilled water found that solubilities of 3DGMw-(DDZ/gamma CD = 1:1) and 3DGMw-(GST/gamma CD = 1:1) were approximately 37- and 51-fold higher, respectively, than the solubilities of pure DDZ and GST. These observations are expected to expand the usefulness of cogrinding of DDZ or GST with gamma CD using a three-dimensional ball mill.