Characterization of the inclusion interaction between prednisolone and di-O-methyl-β-cyclodextrin: Spectroscopic methods and molecular modeling

Prednisolone (PN) is one kind of cortiadrenal hormone having poor aqueous solubility. The inclusion interactions of PN with di-O-methyl-beta-cyclodextrin (DM beta CD) have been investigated by ultraviolet spectroscopy (UV), circular dichroism (CD), Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (H-1 NMR), 2D-ROESY spectrum and molecular modeling. The results obtained from spectroscopic experiments and molecular modeling revealed that the inclusion complex of DM beta CD with PN was formed by non-bond interaction. The stoichiometry and inclusion constant (K) of PN-DM beta CD complex are 1:1 and (1.63 +/- 0.07) x 103 M-1 at 298 K, respectively. In the structure of PN-DM beta CD complex, the A-ring and B-ring moieties of PN molecule were embedded into the cavity of DMpCD from the wider rim of DM beta CD. However, the inclusion process of PN with DM beta CD is enthalpy-driven process, and the primary driving forces responsible for the inclusion interaction are the hydrogen bonding force and Van der Waals force. (c) 2014 Elsevier B.V. All rights reserved.