2-Hydroxypropylated Cyclodextrins as a Sustained-Release Carrier for Fragrance Materials

The potential use of three kinds of 2-hydroxypropylated cyclodextrins [HP-CyDs : 2-hydroxypropyl-α-cyclodextrin (HP-α-CyD), 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD) and 2-hydroxypropyl-γ-cyclodextrin(HP-γ-CyD)] in the solubilizing of fragrance materials and the retarding of their release rates was examined. Of the HP-CyDs, HP-β-CyD significantly increased the solubility of six fragrance materials in water, and the apparent 1 : 1 stability constant of the HP-β-CyD complexes was higher than those of the HP-α-CyD and HP-γ-CyD complexes. Ultraviolet, circular dichroism and unclear magnetic resonance spectroscopic studies suggested that the inclusion mode of eugenol is different between the HP-β-CyD complex and the HP-α- or HP-γ-CyD complexes. The release rates of d-camphor and 3-l-methoxypropane 1, 2-diol from water were remarkably decreased by the addition of HP-CyDs, where the rate of decrease was in agreement with that of the stability constant ranking of the complexes, i.e., fragrance materials alone