Complexation of quercetin with three kinds of cyclodextrins: An antioxidant study

The slightly water-soluble flavonoid quercetin (QUE) and its inclusion with either beta-cyclodextrin (beta CD), hydroxypropyl-beta-cyclodextrin (HP-beta CD) or sulfobutyl ether-beta-cyclodextrin (SBE-beta CD) were investigated. The stoichiometric ratios and stability constants describing the extent of formation of the complexes have been determined by phase-solubility measurements; in all cases type-A(L) diagrams have been obtained (soluble 1:1 complexes). The results showed that the inclusion ability of beta CD and its derivatives was the order: SBE-beta CD > HP-beta CD >beta CD