Punicalagin and Catechins Contain Polyphenolic Substructures That Influence Cell Viability and Can Be Monitored by Radical Chemosensors Sensitive to Electron Transfer

• DOI: 10.1021/jf204059x
• Publication Date: 2012-01-27T13:09:12Z
• Authors: Anna Carreras; María Luisa Mateo...; Amado Velázquez-P...; Enric Brillas; Marta Cascante; Luis Juliá; Josep Lluís Torres
• Keywords: Punicalagin; Cell viability; 0303 health sciences; Tea; Cell Survival; Polyphenols; Free Radical Scavengers; Pyrogallol; Antioxidants; Catechin; Hydrolyzable Tannins; TNPTM chemosensor; Catechins; Electron Transport; 03 medical and health sciences; Humans; HT29 Cells; Oxidation-Reduction

Plant polyphenols may be free radical scavengers or generators, depending on their nature and concentration. This dual effect, mediated by electron transfer reactions, may contribute to their influence on cell viability. This study used two stable radicals (tris(2,3,5,6-tetrachloro-4-nitrophenyl)methyl (TNPTM) and tris(2,4,6-trichloro-3,5-dinitrophenyl)methyl (HNTTM)) sensitive only to electron transfer reduction reactions to monitor the redox properties of polyphenols (punicalagin and catechins) that contain phenolic hydroxyls with different reducing capacities. The use of the two radicals reveals that punicalagin's substructures consisting of gallate esters linked together by carbon-carbon (C-C) bonds are more reactive than simple gallates and less reactive than the pyrogallol moiety of green tea catechins. The most reactive hydroxyls, detected by TNPTM, are present in the compounds that affect HT-29 cell viability the most. TNPTM reacts with C-C-linked gallates and pyrogallol and provides a convenient way to detect potentially beneficial polyphenols from natural sources.