Antioxidant and Chelating Properties of Flavonoids

Korkina, Liudmila; Afanas’ev, Igor B.

doi:10.1016/s1054-3589(08)60983-7

Cited by 295 publications

(185 citation statements)

References 73 publications

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“…That mechanism, covalent double bonds reacting with 1 O2 through the charge transfer process, is often observed in other well known antioxidants, such as carotenoids (48)(49)(50) and flavonoids (51). In addition, the overall antioxidant and cell-protective capabilities of fullerenes are greater than those of vitamin E (52), and the O2…”

Section: Discussionmentioning

confidence: 80%

A Water-Soluble Fullerene Vesicle Alleviates Angiotensin II-Induced Oxidative Stress in Human Umbilical Venous Endothelial Cells

et al. 2008

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Section: Discussionmentioning

confidence: 80%

A Water-Soluble Fullerene Vesicle Alleviates Angiotensin II-Induced Oxidative Stress in Human Umbilical Venous Endothelial Cells

et al. 2008

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“…7 Interesting reports on the role of free radicals and antioxidants were given by Thomas 6 and Wolf et al 7 Quercetin (3,3',4',5,7-pentahydroxy-flavone, Figure 1), is a flavonoid of widespread occurrence in nature whose medicinal properties have been extensively demonstrated in the literature, especially the antioxidant capacity. [8][9][10][11] The antioxidant properties of these compounds (flavonoids) have been attributed to their capacity to scavenge free radicals generated in aqueous phase, increasing the resistance of lipids against peroxidation. 11 Despite this, the electrochemical behavior of quercetin has been almost always studied in organic solvents due to constrains imposed by its solubility characteristics.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical oxidation of quercetin in hydro-alcoholic solution

Timbola¹,

Souza²,

Giacomelli³

et al. 2006

J. Braz. Chem. Soc.

135

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O comportamento eletroquímico da quercetina em meio hidro-alcoólico foi estudado na faixa de pH 2,2-9,2 aplicando-se as técnicas voltametria cíclica, eletrólise com potencial controlado e espectroscopia UV-Vis. Voltamogramas cíclicos para a quercetina mostraram três picos de oxidação e um pico de redução dependente das condições experimentais. Um processo de oxidação envolvendo dois prótons e dois elétrons no primeiro pico conduziu à formação da orto-quinona correspondente, a qual é uma espécie eletroquimicamente ativa e instável, como evidenciado pela dependência do perfil dos voltamogramas cíclicos com a velocidade de variação de potencial, em concordância com um mecanismo do tipo eletroquímico-químico (EC). Eletrólises com potencial controlado geraram três produtos caracterizados por espectroscopia UV-Vis. Um esquema reacional envolvendo as etapas eletroquímica e química foi proposto para a eletro-oxidação da quercetina em solução hidro-alcoólica, com base em dados obtidos da literatura e em evidências experimentais.The electrochemistry of quercetin hydro-alcoholic solutions of pH 2.2 to 9.2 was studied by cyclic voltammetry, controlled-potential electrolysis and UV-Vis spectroscopy. Cyclic voltammograms for quercetin showed three oxidation peaks and one reduction peak depending on the experimental conditions. The two-electron two-proton oxidation process at the first peak led to the formation of the corresponding ortho-quinone, which is an electrochemically active and unstable species, as evidenced by the dependence of the cyclic voltammogram profile on the applied scan rate, in agreement with the EC mechanism. Controlled-potential electrolysis yielded three products as characterized by UV-Vis spectroscopy. A reaction scheme comprising electrochemical and chemical steps was proposed for the electro-oxidation of the quercetin in hydro-alcoholic solutions on basis of experimental evidences obtained in this work and elsewhere.

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“…Resolution is increased for a long column of small internal diameter when compared with a shorter column of larger internal diameter (with the same amount of stationary phase). 33 Choice of solvent systems can be efficiently performed by TLC34 or by analytical HPLC. Transposition to MPLC is straightforward and direct.…”

Section: Medium-pressure Liquid Chromatographymentioning

confidence: 99%