THE INFLUENCE OF THE HOST-GUEST INTERACTION ON THE OXIDATION OF NATURAL FLAVONOID DYES

The influence of the molecular cavity protection on degradation processes of bioorganic compounds quercetin and luteolin used as the original dyes in old tapestries was studied. The degradation processes were studied by electrochemical methods in aqueous media. The products of the exhaustive electrolysis were separated and identified by GC-MS analysis. Cyclic voltammetry characteristics indicate that the inclusion complex is formed. The inclusion affects the redox potentials of both oxidation waves related to the different dissociation forms of the flavonoid molecule. It was shown that decomposition products formed by the oxidation of quercetin are stabilized in the cavity of beta-cyclodextrin, including the main oxidation product 2(3',4'-dihydroxybenzoyl)-2,4,6-trihydroxybenzofuran-3(2H)-one. The formation of the 1: 1 inclusion complex of luteolin with beta-cyclodextrin is supported by the enhancement of fluorescence intensity. In the case of quercetin, a decrease of fluorescence intensity occurs when 1: 1 inclusion complex with beta-cyclodextrin is formed.