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Patricia Valentao - One of the best experts on this subject based on the ideXlab platform.
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studies on the antioxidant activity of lippia citriodora infusion scavenging effect on superoxide radical hydroxyl radical and hypochlorous Acid
Biological & Pharmaceutical Bulletin, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Maria De Lourdes BastosAbstract:Lippia citriodora is an herbal species which contains several flavonoids and phenolic Acids. In view of the pharmacological interest in natural phenolic compounds as antioxidants, this study examined the superoxide radical, hydroxyl radical and hypochlorous Acid scavenging activities of L. citriodora infusion. Superoxide radical was generated either in an enzymatic or in a chemical system, and scavenging ability was assessed by the inhibition of nitroblue tetrazolium reduction. Hydroxyl radical was generated by the reaction of an iron-EDTA complex with H 2 O 2 in the presence of ascorbic Acid, and was assayed by evaluating deoxyribose degradation. Hypochlorous Acid scavenging activity was tested by measuring the inhibition of 5-thio-2-Nitrobenzoic Acid oxidation. The results demonstrate that this infusion has a potent superoxide radical scavenging activity and a moderate scavenging activity of hydroxyl radical and hypochlorous Acid. The chemical composition of the lyophilized infusion was also determined in an attempt to establish its relationship with the antioxidant activity found in the present study.
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antioxidant activity of hypericum androsaemum infusion scavenging activity against superoxide radical hydroxyl radical and hypochlorous Acid
Biological & Pharmaceutical Bulletin, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Maria De Lourdes BastosAbstract:Hypericum androsaemum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic Acids. Since polyphenolic compounds have high antioxidant potential, the ability of H. androsaemum infusion to act as a scavenger of reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous Acid) was investigated. Superoxide radical was generated by the xanthine/xanthine oxidase and phenazine methosulphate/NADH systems. The infusion-mediated prevention of nitroblue tetrazolium reduction by the superoxide radical was used as the measured endpoint. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and assayed by evaluating deoxyribose degradation using the thiobarbituric Acid method. Hypochlorous Acid scavenging activity was tested by measuring the inhibition of hypochlorous Acid-induced 5-thio-2-Nitrobenzoic Acid oxidation to 5,5′-dithiobis(2-Nitrobenzoic Acid). The tested infusion mainly exhibited a potent scavenging effect on superoxide radicals (although a noncompetitive inhibitory effect on xanthine oxidase was also observed). The infusion also acted as a moderate scavenger of hydroxyl radicals and hypochlorous Acid. A phytochemical study of the infusion was also undertaken, and nine phenolic compounds were identified.
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antioxidative properties of cardoon cynara cardunculus l infusion against superoxide radical hydroxyl radical and hypochlorous Acid
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Lourdes M BastosAbstract:Polyphenols are able to act as antioxidants by virtue of their hydrogen-donating and metal-chelating capacities. Cardoon (Cynara cardunculus L.) is a species containing considerable amounts of polyphenolic compounds, namely flavonoids and phenolic Acids. This study examined the antioxidant activity of cardoon lyophilized infusion against superoxide radical, hydroxyl radical, and hypochlorous Acid. Superoxide radical was generated either in an enzymatic system or nonenzymatically, and the scavenging ability was assessed by the inhibition of superoxide radical-induced reduction of nitroblue tetrazolium. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and scavenging capacity was estimated by evaluating the inhibition of hydroxyl radical-induced deoxyribose degradation into thiobarbituric Acid-reactive substances. Inhibition of hypochlorous Acid-induced 5-thio-2-Nitrobenzoic Acid oxidation to 5,5‘-dithiobis(2-Nitrobenzoic Acid) was used in order to test the hypochlorous Acid scavengin...
Lourdes M Bastos - One of the best experts on this subject based on the ideXlab platform.
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antioxidative properties of cardoon cynara cardunculus l infusion against superoxide radical hydroxyl radical and hypochlorous Acid
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Lourdes M BastosAbstract:Polyphenols are able to act as antioxidants by virtue of their hydrogen-donating and metal-chelating capacities. Cardoon (Cynara cardunculus L.) is a species containing considerable amounts of polyphenolic compounds, namely flavonoids and phenolic Acids. This study examined the antioxidant activity of cardoon lyophilized infusion against superoxide radical, hydroxyl radical, and hypochlorous Acid. Superoxide radical was generated either in an enzymatic system or nonenzymatically, and the scavenging ability was assessed by the inhibition of superoxide radical-induced reduction of nitroblue tetrazolium. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and scavenging capacity was estimated by evaluating the inhibition of hydroxyl radical-induced deoxyribose degradation into thiobarbituric Acid-reactive substances. Inhibition of hypochlorous Acid-induced 5-thio-2-Nitrobenzoic Acid oxidation to 5,5‘-dithiobis(2-Nitrobenzoic Acid) was used in order to test the hypochlorous Acid scavengin...
Richard G Compton - One of the best experts on this subject based on the ideXlab platform.
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electrochemically initiated catalytic oxidation of 5 thio 2 nitrobenzoic Acid tnba in the presence of thiols at a boron doped diamond electrode implications for total thiol detection
Electroanalysis, 2003Co-Authors: Olga Nekrassova, Nathan S Lawrence, Richard G ComptonAbstract:The electrochemical response of 5,5-dithiobis(2-Nitrobenzoic Acid) (DTNB) to increasing additions of thiol species has been examined at a boron doped diamond electrode. A reaction has been shown to occur with a range of biologically relevant thiols and proceeds via a CECC' process. A total thiol detection methodology has been developed showing that the sensitivities of the standard addition plots are independent of the individual thiol species added to the solution. The analytical utility of the reaction process has been assessed using chronoamperometry with the corresponding data producing detection limits of 5.7 μM, 4.4 μM and 5.8 μM for the detection of cysteine, homocysteine and glutathione respectively.
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the electrochemical oxidation of 5 thio 2 nitrobenzoic Acid tnba at a boron doped diamond electrode demonstration of a cec reaction
Electroanalysis, 2003Co-Authors: Olga Nekrassova, Nathan S Lawrence, Richard G ComptonAbstract:The oxidation of 5-thio-2-Nitrobenzoic Acid (TNBA) over a wide pH range has been investigated using cyclic voltammetry at a boron doped diamond electrode. The reaction has been shown to proceed via a CEC reaction process in which at lower pH the thiol moiety of the TNBA species has to undergo deprotonation before oxidation. DIGISIM modelling of the voltammetric profiles deduced a value of 5.2 for the pKa of the thiol moiety which is in good agreement with that obtained from spectrophotometric data. Also reported are the rate constants for all the heterogeneous and homogeneous processes.
Paula B Andrade - One of the best experts on this subject based on the ideXlab platform.
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studies on the antioxidant activity of lippia citriodora infusion scavenging effect on superoxide radical hydroxyl radical and hypochlorous Acid
Biological & Pharmaceutical Bulletin, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Maria De Lourdes BastosAbstract:Lippia citriodora is an herbal species which contains several flavonoids and phenolic Acids. In view of the pharmacological interest in natural phenolic compounds as antioxidants, this study examined the superoxide radical, hydroxyl radical and hypochlorous Acid scavenging activities of L. citriodora infusion. Superoxide radical was generated either in an enzymatic or in a chemical system, and scavenging ability was assessed by the inhibition of nitroblue tetrazolium reduction. Hydroxyl radical was generated by the reaction of an iron-EDTA complex with H 2 O 2 in the presence of ascorbic Acid, and was assayed by evaluating deoxyribose degradation. Hypochlorous Acid scavenging activity was tested by measuring the inhibition of 5-thio-2-Nitrobenzoic Acid oxidation. The results demonstrate that this infusion has a potent superoxide radical scavenging activity and a moderate scavenging activity of hydroxyl radical and hypochlorous Acid. The chemical composition of the lyophilized infusion was also determined in an attempt to establish its relationship with the antioxidant activity found in the present study.
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antioxidant activity of hypericum androsaemum infusion scavenging activity against superoxide radical hydroxyl radical and hypochlorous Acid
Biological & Pharmaceutical Bulletin, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Maria De Lourdes BastosAbstract:Hypericum androsaemum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic Acids. Since polyphenolic compounds have high antioxidant potential, the ability of H. androsaemum infusion to act as a scavenger of reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous Acid) was investigated. Superoxide radical was generated by the xanthine/xanthine oxidase and phenazine methosulphate/NADH systems. The infusion-mediated prevention of nitroblue tetrazolium reduction by the superoxide radical was used as the measured endpoint. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and assayed by evaluating deoxyribose degradation using the thiobarbituric Acid method. Hypochlorous Acid scavenging activity was tested by measuring the inhibition of hypochlorous Acid-induced 5-thio-2-Nitrobenzoic Acid oxidation to 5,5′-dithiobis(2-Nitrobenzoic Acid). The tested infusion mainly exhibited a potent scavenging effect on superoxide radicals (although a noncompetitive inhibitory effect on xanthine oxidase was also observed). The infusion also acted as a moderate scavenger of hydroxyl radicals and hypochlorous Acid. A phytochemical study of the infusion was also undertaken, and nine phenolic compounds were identified.
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antioxidative properties of cardoon cynara cardunculus l infusion against superoxide radical hydroxyl radical and hypochlorous Acid
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Lourdes M BastosAbstract:Polyphenols are able to act as antioxidants by virtue of their hydrogen-donating and metal-chelating capacities. Cardoon (Cynara cardunculus L.) is a species containing considerable amounts of polyphenolic compounds, namely flavonoids and phenolic Acids. This study examined the antioxidant activity of cardoon lyophilized infusion against superoxide radical, hydroxyl radical, and hypochlorous Acid. Superoxide radical was generated either in an enzymatic system or nonenzymatically, and the scavenging ability was assessed by the inhibition of superoxide radical-induced reduction of nitroblue tetrazolium. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and scavenging capacity was estimated by evaluating the inhibition of hydroxyl radical-induced deoxyribose degradation into thiobarbituric Acid-reactive substances. Inhibition of hypochlorous Acid-induced 5-thio-2-Nitrobenzoic Acid oxidation to 5,5‘-dithiobis(2-Nitrobenzoic Acid) was used in order to test the hypochlorous Acid scavengin...
Félix Carvalho - One of the best experts on this subject based on the ideXlab platform.
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studies on the antioxidant activity of lippia citriodora infusion scavenging effect on superoxide radical hydroxyl radical and hypochlorous Acid
Biological & Pharmaceutical Bulletin, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Maria De Lourdes BastosAbstract:Lippia citriodora is an herbal species which contains several flavonoids and phenolic Acids. In view of the pharmacological interest in natural phenolic compounds as antioxidants, this study examined the superoxide radical, hydroxyl radical and hypochlorous Acid scavenging activities of L. citriodora infusion. Superoxide radical was generated either in an enzymatic or in a chemical system, and scavenging ability was assessed by the inhibition of nitroblue tetrazolium reduction. Hydroxyl radical was generated by the reaction of an iron-EDTA complex with H 2 O 2 in the presence of ascorbic Acid, and was assayed by evaluating deoxyribose degradation. Hypochlorous Acid scavenging activity was tested by measuring the inhibition of 5-thio-2-Nitrobenzoic Acid oxidation. The results demonstrate that this infusion has a potent superoxide radical scavenging activity and a moderate scavenging activity of hydroxyl radical and hypochlorous Acid. The chemical composition of the lyophilized infusion was also determined in an attempt to establish its relationship with the antioxidant activity found in the present study.
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antioxidant activity of hypericum androsaemum infusion scavenging activity against superoxide radical hydroxyl radical and hypochlorous Acid
Biological & Pharmaceutical Bulletin, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Maria De Lourdes BastosAbstract:Hypericum androsaemum is a medicinal plant species containing many polyphenolic compounds, namely flavonoids and phenolic Acids. Since polyphenolic compounds have high antioxidant potential, the ability of H. androsaemum infusion to act as a scavenger of reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous Acid) was investigated. Superoxide radical was generated by the xanthine/xanthine oxidase and phenazine methosulphate/NADH systems. The infusion-mediated prevention of nitroblue tetrazolium reduction by the superoxide radical was used as the measured endpoint. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and assayed by evaluating deoxyribose degradation using the thiobarbituric Acid method. Hypochlorous Acid scavenging activity was tested by measuring the inhibition of hypochlorous Acid-induced 5-thio-2-Nitrobenzoic Acid oxidation to 5,5′-dithiobis(2-Nitrobenzoic Acid). The tested infusion mainly exhibited a potent scavenging effect on superoxide radicals (although a noncompetitive inhibitory effect on xanthine oxidase was also observed). The infusion also acted as a moderate scavenger of hydroxyl radicals and hypochlorous Acid. A phytochemical study of the infusion was also undertaken, and nine phenolic compounds were identified.
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antioxidative properties of cardoon cynara cardunculus l infusion against superoxide radical hydroxyl radical and hypochlorous Acid
Journal of Agricultural and Food Chemistry, 2002Co-Authors: Patricia Valentao, Félix Carvalho, Eduarda Fernandes, Rosa M Seabra, Paula B Andrade, Lourdes M BastosAbstract:Polyphenols are able to act as antioxidants by virtue of their hydrogen-donating and metal-chelating capacities. Cardoon (Cynara cardunculus L.) is a species containing considerable amounts of polyphenolic compounds, namely flavonoids and phenolic Acids. This study examined the antioxidant activity of cardoon lyophilized infusion against superoxide radical, hydroxyl radical, and hypochlorous Acid. Superoxide radical was generated either in an enzymatic system or nonenzymatically, and the scavenging ability was assessed by the inhibition of superoxide radical-induced reduction of nitroblue tetrazolium. Hydroxyl radical was generated by the Fe3+-EDTA/ascorbate Fenton system, and scavenging capacity was estimated by evaluating the inhibition of hydroxyl radical-induced deoxyribose degradation into thiobarbituric Acid-reactive substances. Inhibition of hypochlorous Acid-induced 5-thio-2-Nitrobenzoic Acid oxidation to 5,5‘-dithiobis(2-Nitrobenzoic Acid) was used in order to test the hypochlorous Acid scavengin...