The inclusion complex formation of tanshinone IIA with hydroxypropyl-β-cyclodextrin was studied by using phase solubility method, and the formation constant for tanshinone IIA-hydroxypropyl-β-cyclodextrin was determined. The effect of temperature on the reaction was studied through thermodynamics, and the change of entropy, enthalpy and free energy of the reaction were calculated. The molecular modeling provided further evidence for the formation of the inclusion complexes. Stable inclusion complex in solid state was characterized by IR spectra.

Key words: hydroxypropyl-β-cyclodextrin, tanshinone IIA, phase solubility method, inclusion, thermodynamics, molecular modeling