Study on the inclusion complexes of cryptotanshinone with beta-cyclodextrin and hydroxypropyl-beta-cyclodextrin.

The inclusion complexes of beta-cyclodextrin (beta-CD) and HP-beta-cyclodextrin (HP-beta-CD) with a kind of tanshinone, cryptotanshinone (CTan) were investigated by using spectrophotometry. Stable inclusion complexes were established in solution and in solid state and were characterized by UV, IR and 1H NMR spectra, respectively. The optimum pH for inclusion is about 7.5. Stoichiometry of the inclusion complex is 1:1. The stabilities of beta-CD and HP-beta-CD to CTan were in the order: beta-CD<HP-beta-CD. The effect of temperature on the inclusion interaction was examined and the thermodynamic parameters of inclusion process, DeltaG, DeltaH, DeltaS were determined. The experimental results indicated that the inclusion process was an exothermic and enthalpy-driven process. Special configuration of the inclusion complexes was proposed by 1D, 2D NMR.