Effect of HP-β-cyclodextrins complexation on the antioxidant activity of flavonols

The beneficial effects from phenolic compounds have been attributed to their antioxidant activity. Differences in the chemical structure of flavonols and their degree of substitution will influence phenoxyl radical stability and, thereby, their antioxidant properties. Cyclodextrins (CDs) can be used as a flavonol complexation agent, since they act as a substrate reservoir in a dose-controlled manner. In the present paper, the effect of complexing flavonols, kaempferol, quercetin and myricetin with HP-beta-CDs on their antioxidant capacity is studied by means of the oxygen radical absorbance capacity-fluorescein (ORAC-FL) assay. This complexation phenomenon increased the antioxidant activity of the three flavonols, which reached a maximum level when each flavonol had been complexed in the hydrophobic cavity of CDs. The antioxidant activity increased because of the flavonol was protected against rapid oxidation by free radicals. (C) 2009 Elsevier Ltd. All rights reserved,