Preparation and study on the inclusion complexes of two tanshinone compounds with β-cyclodextrin

Abstract

Solid inclusion complexes of two tanshinones (Tans): tanshinone IIA (Tan IIA), tanshinone I (Tan I) with β-cyclodextrin (β-CD) were synthesized by coprecipitation method. The solid inclusion complexes were characterized by using several analytical techniques: 1 H NMR spectra, IR spectra and thermal analysis. Stoichiometry of the inclusion complexes of Tans with β-CD or HP-β-CD is 1:1 which was investigated in solution. The formation constants of the complexes were determined by UV spectrophotometry. For same kind of CD, the stability was in the order: Tan IIA > Tan I; for same guest, the stability was in the order: HP-β-CD > β-CD. The effect of temperature on the inclusion interaction was examined and the thermodynamic parameters of inclusion process, Δ G, Δ H, Δ S were determined as well. The experimental results indicate that the inclusion process was an exothermic and enthalpy-driven process accompanied with a negative entropic contribution. The inclusion interaction between CD and Tans satisfied the law of enthalpy–entropy compensation.