Site-Specific Interaction between 2-Dibenzofuran Carboxylate and β- and γ-Cyclodextrins Determined by Intermolecular NOE and Molecular Modeling

Abstract

The topologies of the complexes between 2-dibenzofuran carboxylate (DBFC) and β- and γ-cyclodextrins (CDs) have been studied by NMR methods (1H NMR and 2D ROESY) and by molecular modeling strategies. The analysis of the spectra and the molar ratio plots reveal the formation of complexes of 1:1 stoichiometry with β-CD. The stability constants have been calculated by multivariable nonlinear least-squares regression from the changes in the chemical shifts of the protons of both host and guest molecules. For the β-CD complex, the interproton distances between the host and guest have been deduced from the NOE enhancements. Rigid docking calculations using the geometrical restraints given by the NMR experiments, together with molecular dynamics simulations assuming a continuum solvent model, indicate that DBFC is oriented with the carboxylate group at the narrow rim of the CD. The radial distribution functions obtained by considering explicit water molecules with periodic boundary conditions indicate that the s...