EXPERIMENTAL AND THEORETICAL CHARACTERIZATION OF THE DANOFLOXACIN-γ-CYCLODEXTRIN INCLUSION COMPLEXES

The interest on the drugs encapsulation in the cyclodextrin cavity is due to a series of benefits like the increase in the drug's solubility, bioavailability and the controlled release. In the followings, the interaction of danofloxacin, an antibiotic from the fluoroquinolone class, and gamma-cyclodextrin (gamma-CyD) will be studied by means of fluorescence, circular dichroism and molecular modeling. Both stoichiometry and association constants were obtained by fitting the dependences of the fluorescence intensity and ellipticity vs. gamma-CyD concentration to a non-linear regression model. The signs of the induced circular dichroism spectra were correlated, according to the Harata-Kodaka rules, with the orientation of the guest transition moments (obtained by TDDFT/B3LYP/631++G(d,p)) to the cavity axis. Starting with this information on the ligand orientation in the cavity, the structures of the inclusion complexes were optimized using molecular mechanics.