| Flavanoids is abundant in vegetables, fruits and other plants. Owing to its strong antioxidant properties, flavanoids can scavenge superfluous superoxide free radicals in human body, preventing DNA and cells from oxidative damage. It shows pharmacological effects in anti-tumour, anti-inflammation and anti-senility, etc. Rutin, one of flavonoids compounds, is a natural antioxidant, which has four hytroxyl groups which all present electro-activity. So far little attention has been paid to the complex electro-oxidation mechanism, which therefore remains unsolved. The present work studied the electrochemistry behaviors of quercetin on glassy carbon electrode(GCE) and graphite-wax electrode (GWE), respectively, in Britton-Robinson buffer solutions involving 0.5 mol·L-1 KC1 as supporting electrolyte, using cyclic voltammetry and differential pulse voltammetry and the in situ thin layer spectroelectrochemistry and high performance capillary electrophoresis (HPCE).The results indicate that there are great differences in both absorption and electrocatalysis activity among the two electrodes. The most distinct CV peaks are obtained on GWE, which indicates carbon nanotubes have very strong absorption and electrocatalysis activity to rutin. GWE shows good data stability. Differential pulse voltammetry indicates that there is a good linear relationship between the main oxidation peak current of quercetin on GWE and its concentration over the range 2.0×10-8 - 1.0×10-5mol·L-1, which indicates that GWE can be used in electroanalysis of rutin.Cyclic voltammetry and thin layer spectroelectrochemistry test results indicate that the adsorption and oxidation of rutin on a graphite-wax electrode in a longoptical-path thin-layer electrochemical cell. Three characteristic bands of rutin showed potential-dependent variations under controlled-potential oxidation. The dynamic absorbances during repetitive cyclic scans were recorded at three wavelengths respectively to follow the concentration fluctuations of rutin and its oxidation products. Five types of concentration fluctuations in the thin layer were firstly detected and distinguished by their whys. The oxidation of o-dihydroxy groups at B-ring occurred firstly in the lowest potentials and was a highly reversible reaction involving 2-electrons and 2-protons. The second oxidation in relatively positive potentials probably corresponded to the transformation between 7-OH group at A-ring and 7-position oxygen free radical, the lattercatalyzing a subsequent chemical O2-evolution reaction and the former regenerated simultaneously. The final oxidation in more positive potentials had the products with no structural characteristic of flavonoids entirely. Results suggest that the antioxidative activity of rutin originates fromB-ring o-dihydroxy groups, but both 7-OH and 5-OH have no oxygen radical-scavenging activity.The electro-oxidation mechanism of quercetin has been discussed detailedly in this paper.What's more,the electrochemical behavior of interaction of rutin with DNA was studied by cyclicvoltammetry.When DNA was added in the rutin solution,both reduction and oxidation peak currents of rutin decreased with no change in the peak potentials. The origin was discussed, we concluded that an electrochemical inactive supramolecular complex DNA-rutin was formed.
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