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

The complexation of resveratrol with native α-, β- and γ-cyclodextrins (CDs) and modified CDs (hydroxypropyl-β-(HP-β-CDs), maltosyl-β-(G2-β-CDs), methyl-β-, carboxymethyl-β- and acetyl-β-cyclodextrins) was studied, and the complexation constants (Kc) were compared. The complexation constant between resveratrol and each type of CD was calculated using three different methods: enzymatic, solubility and fluorimetric. The Kc values obtained showed that HP-β-CDs with their very high Kc 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 Kc between resveratrol and all cyclodextrins, while the enzymatic and solubility methods were more precise for calculating the Kc between resveratrol and CDs, as demonstrated by the cyclodextrin-assay.