Characterization of sesquiterpene polygodial-beta cyclodextrin inclusion complex

Polygodial is a sesquiterpene drimane isolated from the genus Drimys, which exhibits anti-asthmatic, anti-allergic, anti-inflammatory and antinociceptive effects. We have prepared a polygodial-beta-cyclodextrin inclusion complex for further pharmacological studies. The inclusion complex was synthesized by co-precipitation and analyzed by Thermogravimetric Analysis, showing a decrease in the number of water molecules of hydration in relation to the native beta-cyclodextrin. Differential Thermogravimetric Analysis indicated a peak corresponding to the evaporation of polygodial. With Differential Scanning Calorimetry, the melting peak to polygodial was not observed, however, there was an increase in the energy of vaporization of the water molecules in relation to native beta-cyclodextrin. Using a Scanning Electron Microscopy a clear difference in the morphology of crystals of the inclusion complex and native beta-cyclodextrin could be seen. The association constant between polygodial and beta-cyclodextrin, measured by UV spectroscopy was 1,006 M-1 at 37degreesC, pH 7.0 and ionic strength 0.2 M, following stoichiometry 1: 1.