Antioxidant activity of inclusion complexes of tea catechins with β-cyclodextrins by ORAC assays

Inclusion complexes of native and two derivatizated β-cyclodextrins with some tea catechins (TCs) like catechin (C), epigallocatechin gallate (EGCG) and gallocatechin gallate (GCG). The stoichiometry of TC complexes was determined and in all cases was 1:1. Stability constants were determined and their antioxidant capacity against reactive oxygen species (ROS) studied by means of the ORAC-fluorescein (ORAC-FL) and the ORAC-pyrogallol red (ORAC-PGR) assay. The antioxidant capacity of these TC in aqueous solution in the absence and presence of βCDs was studied using Multi-Detection Microplate Reader. The antioxidant reactivity mainly depends of the inclusion modes of the TC in the βCDs cavity. The difference between ORAC-PGR values for the same TC show that the inclusion structures should be different, maybe leading the same number of hydrogen atoms exposed (ORAC-FL values) outside or in the borders of βCDs cavity.