Reversed phase High Performance Liquid Chromatography used for the physicochemical and thermodynamic characterization of piceatannol/β-cyclodextrin complex

Piceatannol is one of resveratrol derivatives having health promoting potential. However, its low water-solubility and bioavailability could limit its use in both food and pharmaceutical fields. The aim of this work is the study of piceatannol complexation by β-cyclodextrin (β-CD) in aqueous media. The complex formed could improve the bioavailability, the solubility and the stability of piceatannol. The method used was based on RP-HPLC in which, β-CD was added to methanol/water mixtures mobile phases. The apparent formation constant of piceatannol/β-cyclodextrin complex was determined. Within the concentration interval studied (0-4mM), whenever the concentration of β-CD increased, retention time of piceatannol decreased; indicating an enhancement of solubility due to the formation of the piceatannol/β-CD complex. The formation constants (K_F) of the piceatannol/β-CD complex varied significantly with both the methanol concentration in the water-methanol mixture and the temperature. Moreover, in all the physicochemical conditions tested, the stoichiometry of piceatannol/β-CD complex was 1:1. Finally, the thermodynamic parameters were determined: ΔG°=-13.123kJmol^-1, ΔH°=-33. 265kJmol^-1 and ΔS°=-67.559Jmol^-1K^-1.