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Electrochemical characterization of bioactive hydroxyxanthones by cyclic voltam...
Santos, Clementina M.M.; Garcia, Beatriz; Silva, Artur; Santus, René; Morlière, Patrice; Fernandes, EduardaThe present study reports the electrochemical behavior of several phenolic and catecholic-substituted 2,3-diarylxanthones on a glassy carbon electrode, challenged by cyclic voltammetry at different pH values (4.0, 7.4, and 11.0). Higher pH values required lower anodic and cathodic peak voltages. The oxidation of catecholic groups occurred at lower peak potentials in a reversible and pH dependent manner. Anodic ...
The dependence of alpha-tocopheroxyl radical reduction by hydroxy-2,3-diarylxan...
Morlière, Patrice; Patterson, Larry K.; Santos, Clementina M.M.; Silva, Artur; Marzière, Jean-Claude; Filipe, Paulo; Gomes, Ana; Fernandes, EduardaThe flavonoid quercetin is known to reduce the α-tocopheroxyl radical (˙TocO) and reconstitute α-tocopherol (TocOH). Structurally related polyphenolic compounds, hydroxy-2,3-diarylxanthones (XH), exhibit antioxidant activity which exceeds that of quercetin in biological systems. In the present study repair of ˙TocO by a series of these XH has been evaluated using pulse radiolysis. It has been shown that, among ...
Structure–activity relationships in hydroxy-2,3-diarylxanthone antioxidants. Fa...
Santos, Clementina M.M.; Silva, Artur; Filipe, Paulo; Santus, René; Patterson, Larry K.; Maziére, Jean-Claude; Cavaleiro, José; Morlière, PatriceA structure–activity relationship has been established for eight hydroxy-2,3-diarylxanthones (XH) bearing hydroxy groups on the two aryl rings. One-electron oxidation by superoxide radical-anions ( O2 -) and Trp radicals as well as reaction with CCl3O2 and CHCl2O2 radicals demonstrates that two OH groups are required for efficient antioxidant reactivity in cetyltrimethylammonium bromide micelles. Hydroxy gro...
Structure–activity relationships in hydroxy-2,3-diarylxanthone antioxidants. Fa...
Santos, Clementina M.M.; Silva, Artur; Filipe, Paulo; Santus, René; Patterson, Larry K.; Maziére, Jean-Claude; Cavaleiro, José; Morliere, PatriceA structure–activity relationship has been established for eight hydroxy-2,3-diarylxanthones (XH) bearing hydroxy groups on the two aryl rings. One-electron oxidation by superoxide radical-anions (ΣO2 -) and ΣTrp radicals as well as reaction with ΣCCl3O2 and ΣCHCl2O2 radicals demonstrates that two OH groups are required for efficient antioxidant reactivity in cetyltrimethylammonium bromide micelles. Hydroxy gro...
Polyhydroxy-2,3-diarylxanthones as antioxidants
Santos, Clementina M.M.; Morliere, Patrice; Silva, Artur; Maziére, Jean-Claude; Cavaleiro, José; Santús, RenéXanthones are a class of oxygenated heterocyclic compounds widely occurring in nature.[1] The biological properties of these compounds have been extensively reported in the literature and one of the most promising is their potential application as antioxidant agents.[2] This fact led us to start a programme on the synthesis of 2,3-diarylxanthones bearing hydroxyl groups in certain positions of their skeleton fo...
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