Complexation of resveratrol by native and modified cyclodextrins:: Determination of complexation constant by enzymatic, solubility and fluorimetric assays

The complexation of resveratrol with native alpha-, beta- and gamma-cyclodextrins (CDs) and modified CDs (hydroxypropyl-beta-(HP-beta-CDs), maltosyl-beta-(G(2)-beta-CDs), methyl-beta-, carboxymethyl-beta- and acetyl-beta-cyclodextrins) was studied, and the complexation constants (K-c) were compared. The complexation constant between resveratrol and each type of CD was calculated using three different methods: enzymatic, solubility and fluorimetric. The K-c values obtained showed that HP-beta-CDs with their very high K-c of 18,048 +/- 625 M-1, were the most effective for complexing resveratrol. Moreover, comparison of the results obtained by the three methods revealed that the fluorimetric method undervalued the K-c between resveratrol and all cyclodextrins, while the enzymatic and solubility methods were more precise for calculating the K-c between resveratrol and CDs, as demonstrated by the cyclodextrin-assay. (C) 2008 Elsevier Ltd. All rights reserved.