title: Determination of stoichiometric coefficients and apparent formation constants for beta-cyclodextrin complexes of trans-resveratrol using reversed-phase liquid chromatography.
abstract: The complexation of trans-resveratrol with beta-cyclodextrin (beta-CD) was investigated using reversed-phase liquid chromatography and mobile phases to which beta-CD was added. The decrease in the retention times with increasing concentrations of beta-CD (0-2.5 mM) showed that trans-resveratrol forms a 1:1 complex with beta-CD, while the apparent formation constants (K(F)) were strongly dependent of the water-methanol proportion of the mobile phase employed. A slight decrease in K(F) was observed at 50-55% water in the mobile phase but a large increase from 55 to 70% water. The values of K(F) for the trans-resveratrol-beta-CD interaction decreased when the temperature was raised from 20 to 37 degrees C. In order to gain information about the mechanism aspect of the trans-resveratrol affinity for beta-CD, the thermodynamic parameters of the complexation were obtained. Complex formation of trans-resveratrol with beta-CD (DeltaG degrees =-17.01 kJ/mol) is largely driven by enthalpy (DeltaH degrees = -30.62 kJ/mol) and slightly entropy changes (DeltaS degrees = -45.68 J/mol K).
authors.affiliation: Department of Biochemistry and Molecular Biology-A, Faculty of Biology, University of Murcia, Campus de Espinardo, 30071 Murcia, Spain. josemln@ya.com
authors.forename: José Manuel
authors.initials: JM
authors.lastname: López-Nicolás
authors.forename: Estrella
authors.initials: E
authors.lastname: Núñez-Delicado
authors.forename: Antonio J
authors.initials: AJ
authors.lastname: Pérez-López
authors.forename: Angel Carbonell
authors.initials: AC
authors.lastname: Barrachina
authors.forename: Paula
authors.initials: P
authors.lastname: Cuadra-Crespo
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D000432:Methanol; D000077185:Resveratrol; D013056:Spectrophotometry, Ultraviolet; D013267:Stilbenes / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D013267:Stilbenes; D047392:beta-Cyclodextrins; D014867:Water; C031215:betadex; D000077185:Resveratrol; D000432:Methanol