Rapid, simple and sensitive determination of the apparent formation constants of trans-resveratrol complexes with natural cyclodextrins in aqueous medium using HPLC.

The study of the complexation of trans-resveratrol with natural cyclodextrins (CDs) in aqueous medium under different physico-chemical conditions of pH or temperature is essential if this antioxidant compound is to be used successfully in the food industry as ingredient of functional foods, due its poor stability, bioavailability and solubility. In this paper, a rapid, simple and sensitive determination of the apparent formation constant of trans-resveratrol/CD complexes by HPLC in aqueous medium has been investigated for first time. It can be observed that trans-resveratrol forms a 1:1 complex with α-, β- and γ-CD. The highest value of the apparent formation constant (KF=1922±89M(-1)) was found for β-CD and a strong dependence of KF on pH can be seen in the region where the trans-resveratrol begins the deprotonation of their hydroxyl groups. Moreover, an increase in the system's temperature produced a decrease in the values of KF. Finally, to gain information on the mechanism of the trans-resveratrol affinity for CD, the thermodynamic parameters of the complexation were obtained.