Antioxidant activity of gallates: an electrochemical study in aqueous media

Gunckel, S.; Santander, Paola; Cordano, G.; Ferreira, Jorge; Muñoz, Sergio; Núñez‐Vergara, Luis J.; Squella, J.A.

doi:10.1016/s0009-2797(98)00041-6

Cited by 118 publications

(96 citation statements)

References 12 publications

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“…Some authors have described the same dependence for oxidation of H 3 CAF, gallic acid and derivatives. 11,12 On the other hand, in 50/50 (v/v) water-methanol solvent, the anodic peak potential shifts to more positive values with an increase in pH. 5 In addition we observed that the separation between the peak potentials is also pH-dependent.…”

Section: Influence Of Phmentioning

confidence: 61%

Electrochemistry of Caffeic Acid Aqueous Solutions with pH 2.0 to 8.5

Giacomelli¹,

Ckless²,

Galato³

et al. 2002

J. Braz. Chem. Soc.

103

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O comportamento eletroquímico do ácido cafeico (H 3 CAF) em meio aquoso foi estudado na faixa de pH 2,0-8,5 aplicando-se as técnicas voltametria cíclica, eletrólise com potencial controlado e espectroscopia UV-vis. A eletro-oxidação envolve a transferência reversível de dois elétrons e de dois prótons em soluções de pH até 5,5, de acordo com o mecanismo uma etapa-dois elétrons. Em soluções de pH superiores a 5,5 a eletro-oxidação do H 3 CAF segue um mecanismo EC i . O principal produto desta oxidação é a o-quinona correspondente (o-HCAF), a qual decompõe-se rapidamente em soluções de pH superior a 7,4, obedecendo a uma cinética de primeira ordem. Na faixa de pH 2,0-8,5, o potencial formal (E 0' ) varia linearmente com o pH, gerando uma reta com coeficiente angular de -60,83 mV/pH. Em paralelo, a corrente de pico anódica (i pa ) diminui de modo não-linear. Os processos são controlados por difusão em toda a faixa de pH estudada.The electrochemical behavior of caffeic acid (H 3 CAF) in aqueous solutions with pH 2.0 to 8.5 was studied by cyclic voltammetry, controlled potential electrolysis and UV-vis spectroscopy. The electrooxidation of H 3 CAF involves a reversible transfer of two electrons and two protons in solutions of pH up to 5.5, in agreement with the one step-two electron mechanism. In solutions of pH higher than 5.5, the process of electro-oxidation of H 3 CAF follows an EC i mechanism. The main oxidation product is the corresponding o-quinone (o-HCAF), which is decomposed quickly at pH higher than 7.4 obeying a first order kinetics. In the pH range investigated, the formal potential (E 0' ) varies linearly with pH, generating a straight line with an angular coefficient of -60.83 mV/pH. In parallel, the anodic peak current (i pa ) decreases in a nonlinear mode. The processes are controlled by diffusion over the whole pH range studied.

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Section: Influence Of Phmentioning

confidence: 61%

Electrochemistry of Caffeic Acid Aqueous Solutions with pH 2.0 to 8.5

Giacomelli¹,

Ckless²,

Galato³

et al. 2002

J. Braz. Chem. Soc.

103

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“…1a and b shows the cyclic voltamograms of the standards ascorbic and gallic acids, respectively. Both compounds present typical irreversible oxidation processes, as observed in many antioxidant substances (Cosio et al, 2006;Gunckel et al, 1998;Kilmartin, Zou, & Waterhouse, 2001), with one anodic peak at E pa = 0.26 V for ascorbic and two anodic peaks at E(I) pa = 0.36 V, E(II) pa = 0.62 V for gallic acid. The same irreversible electrochemical behaviour was observed for all Agaricus sp.…”

Section: Evaluation Of Antioxidant Properties By Chemical and Biochemmentioning

confidence: 85%

Antioxidant activity of Agaricus sp. mushrooms by chemical, biochemical and electrochemical assays

et al. 2008

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a b s t r a c tThe antioxidant activity of five Agaricus sp. mushrooms was screened through chemical, biochemical and electrochemical techniques. The chemical assays allowed an evaluation of their reducing power and radical scavenging activity, while biochemical assays evaluated the lipid peroxidation inhibition capacity, using erythrocytes and brain cells as models; the electrochemical characterization of the mushrooms extracts were performed by cyclic voltammetry and differential pulse voltammetry. All the species proved to have antioxidant activity and particularly, by the electrochemical techniques, it has been shown that mushroom extracts revealed similar electrochemical responses, suggesting similar electroactive chemical composition, and oxidation potentials more positive than those of the standards (ascorbic and gallic acids). Agaricus silvaticus was the most efficient species presenting the lowest EC 50 values in the chemical and biochemical assays, and the highest ''antioxidant power" in the electrochemical assays.

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“…As gallic acid has been found to be a strong antioxidant, antimutagenic and anticarcinogenic agent (Gunckel et al, 1998), a high content in chestnut fruit is especially important. In fact, roasted chestnuts possessed significantly (p < 0.0001) higher gallic acid and total phenolics, and boiled chestnuts had higher gallic and ellagic acids, when compared to raw chestnuts (Table 1).…”

Section: Phenolicsmentioning

confidence: 99%