Study Of Formation Constant, Thermodynamics And Beta-Ionone Release Characteristic Of Beta-Ionone-Hydroxypropyl-Beta-Cyclodextrin Inclusion Complex

beta-Ionone has a characteristic violet-like odor and is an important flavor and fragrance ingredient used in food and perfumery. Furthermore, it has the ability to selectively kill tumor cells and is a promising anticancer agent. In order to improve its solubility, stability and long-release characteristics, beta-ionone was encapsulated in hydroxypropyl-beta-cyclodextrin (HP-beta-CD) to form inclusion complex. The formation constants (K) and thermodynamics were explored by ultraviolet-visible (UV/V) absorption method. The values of K obtained at 35 degrees C, 45 degrees C and 55 degrees C were 29.6 x 10(3) l/mol, 8.4 x 10(3) l/mol and 4.9 x 10(3) l/mol, respectively. Gibbs free energy changes (Delta G) for the interactions of beta-ionone and HP-beta-CD at 35 degrees C, 45 degrees C and 55 degrees C were - 26.4 kJ/mol, - 23.9 kJ/mol and - 23.6 kJ/mol, respectively. Enthalpy change (Delta H) and entropy change (Delta S) were - 1.1 kJ/mol and - 2.3 J/(K mol), respectively. The solid beta-ionone-HP-beta-CD inclusion complex was characterized by FTIR and thermogravity analysis (TGA). The FTIR results confirmed that beta-ionone was successfully encapsulated in HP-beta-CD and that encapsulation of beta-ionone did not change the frame of HP-beta-CD. The TGA results showed that the release of most of the beta-ionone from beta-ionone-HP-beta-CD inclusion complex mainly occurred in the temperature range of 210-320 degrees C. A relative larger release rate appeared at 240 degrees C and the beginning stage of HP-beta-CD decomposition. It also revealed that the thermal stability of beta-ionone was improved by the encapsulation technology.