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Physicochemical Study of the Complexation of Pterostilbene by Natural and Modified Cyclodextrins
Ist Teil von
Journal of agricultural and food chemistry, 2009-06, Vol.57 (12), p.5294-5300
Ort / Verlag
Washington, DC: American Chemical Society
Erscheinungsjahr
2009
Link zum Volltext
Quelle
MEDLINE
Beschreibungen/Notizen
In this paper, the interaction between pterostilbene and cyclodextrins (CDs) is described for the first time using steady-state fluorescence. It was seen that pterostilbene forms a 1:1 complex with all of the natural (α-, β-, and γ-CDs) and modified (HP-β-CD, methyl-β-CD, and ethyl-β-CD) CDs tested. Among natural CDs, the interaction of pterostilbene with β-CD was the most efficient. However, all of the modified CDs showed higher complexation constants (K F) than β-CD. The highest K F was found for HP-β-CD (17520 ± 981 M−1), in which its value showed a strong dependence upon pH in the region where the pterostilbene begins the deprotonation of its hydroxyl group. Moreover, the values of K F decreased as the system temperature increased. To obtain information on the mechanism of pterostilbene affinity for CD, the thermodynamic parameters of the complexation (ΔH°, ΔS°, and ΔG°) were studied. Finally, a comparison of the K F values obtained for three types of stilbenes revealed that both the stoichiometry and the K F values of the complex are dependent upon the structure of the guest molecule. While the trans-resveratrol−HP-β-CD and pterostilbene−HP-β-CD complexes showed a 1:1 stoichiometry with a higher K F value for the trans-resveratrol−HP-β-CD complexes, trans-stilbene showed a 1:2 stoichiometry.