Determinations of the inclusion complex between gossypol and β-cyclodextrin

Features of the inclusion complex between gossypol (Gos) and β-cyclodextrin (CD), such as its aqueous solubility, association constant, characteristics in the solid state and crystalline morphology, as well as the stoichiometry of this complex have been determined. The phase–solubility diagram drawn using UV detections belongs to an AN-type. Fluorescence detection and calculation with the modified Benesi–Hidebrond equation provide an 1:2 stoichiometry for the complex. Its apparent stability constant has been determined to be 3203 M−1 by fluorescence technique and confirmed by the calculation from UV spectroscopy. X-ray powder diffractions (XRD) and Scanning Electron Microscopy (SEM) observations showed a clear difference in the crystal morphology of the complex from those of both Gos and β-CD.