title: Encapsulation of piceatannol, a naturally occurring hydroxylated analogue of resveratrol, by natural and modified cyclodextrins.
abstract: In this work, an in-depth study of the interaction between piceatannol (a type of stilbene with high biological activity) and different natural and modified cyclodextrins (CDs) is made, using steady state fluorescence. This bioactive molecule forms a 1 : 1 complex with all the natural (α-CD, β-CD and γ-CD) and modified (HP-β-CD, HE-β-CD and M-β-CD) CDs tested. Among natural CDs, the interaction of piceatannol with β-CD was the most efficient. However, the modified CDs showed higher encapsulation constants (KF) than β-CD, except M-β-CD; the highest KF being found for HP-β-CD (14 048 ± 702 M(-1)). The encapsulation of piceatannol in the internal cavity of CDs showed a strong dependence on pH and temperature. The interaction between HP-β-CD and piceatannol was less effective in the pH region where the stilbene begins to suffer the deprotonation of its hydroxyl group. Moreover, the values of KF decreased as the system temperature increased. To obtain information on the mechanism involved in the piceatannol affinity for CD, the thermodynamic parameters of the complexation (ΔH°, ΔS° and ΔG°) were studied, the results showed a negative entropy (-3.7 ± 0.2 J mol(-1) K(-1)), enthalpy (-24.6 ± 1.2 kJ mol(-1)) and Gibbs free energy change at 25 °C (-23.5 ± 1.2 J mol(-1)). Finally, molecular docking calculations provided further insights into how the different interactions influence the complexation constant. A high degree of correlation was observed between the computed scores and experimental values.
authors.affiliation: Department of Biochemistry and Molecular Biology-A, Faculty of Biology, University of Murcia, Campus de Espinardo, 30071, Murcia, Spain. josemln@um.es.
authors.forename: Adrián
authors.initials: A
authors.lastname: Matencio
authors.forename: Francisco
authors.initials: F
authors.lastname: García-Carmona
authors.forename: José Manuel
authors.initials: JM
authors.lastname: López-Nicolás
mesh_terms: D055598:Chemical Phenomena; D019295:Computational Biology; D003505:Cyclodextrins / Q000737:chemistry*; D019277:Entropy; D006863:Hydrogen-Ion Concentration; D062105:Molecular Docking Simulation; D000077185:Resveratrol; D013267:Stilbenes / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D003505:Cyclodextrins; D013267:Stilbenes; C041525:3,3',4,5'-tetrahydroxystilbene; D000077185:Resveratrol