The inlcusion behaviour of unsubstituted b-cyclodextrin (b-CyD) and (2-hydroxypropyl)-b-cyclodextrin (HP-b-CyD), in solution and solid state was studied with regards to a poorly water-soluble bioflavonoid, coumestrol (Coum), namely 7,12-dihydroxycoumestan, well-known for its anti-oxidant, anti-inflammatory, anti-fungal and anti-viral activities. Phase-solubility measurements were performed to evaluate in solution the complexation of the two cyclodextrins, i.e. b-CyD and HP-b-CyD. The stoichiometry and stability constants of the Coum/b-CyD and Coum/HP-b- CyD complexes were calculated by the phase-solubility method, after which drug–cyclodextrin solid systems were prepared by co-precipitation. In solid phase, the formation of inclusion complexes was confirmed by Fourier transform infrared spectroscopy in attenuated total reflectance (FTIRATR) geometry. In particular, complexation mechanisms were explained by the significant differences revealed in the FTIR-ATR spectra of physical mixtures with respect to those of the complexes; the use of deconvolution and curve fitting was determinant.
Physicochemical characterization of coumestrol/beta-cyclodextrins inclusion complexes by UV-vis and FTIR-ATR spectroscopies
CANNAVA', CARMELA;CRUPI, Vincenza;FICARRA, Paola;GUARDO, MARTA;MAJOLINO, Domenico;STANCANELLI, Rosanna;VENUTI, Valentina
2008-01-01
Abstract
The inlcusion behaviour of unsubstituted b-cyclodextrin (b-CyD) and (2-hydroxypropyl)-b-cyclodextrin (HP-b-CyD), in solution and solid state was studied with regards to a poorly water-soluble bioflavonoid, coumestrol (Coum), namely 7,12-dihydroxycoumestan, well-known for its anti-oxidant, anti-inflammatory, anti-fungal and anti-viral activities. Phase-solubility measurements were performed to evaluate in solution the complexation of the two cyclodextrins, i.e. b-CyD and HP-b-CyD. The stoichiometry and stability constants of the Coum/b-CyD and Coum/HP-b- CyD complexes were calculated by the phase-solubility method, after which drug–cyclodextrin solid systems were prepared by co-precipitation. In solid phase, the formation of inclusion complexes was confirmed by Fourier transform infrared spectroscopy in attenuated total reflectance (FTIRATR) geometry. In particular, complexation mechanisms were explained by the significant differences revealed in the FTIR-ATR spectra of physical mixtures with respect to those of the complexes; the use of deconvolution and curve fitting was determinant.Pubblicazioni consigliate
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