title: Punicalagin and catechins contain polyphenolic substructures that influence cell viability and can be monitored by radical chemosensors sensitive to electron transfer.
abstract: 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.
authors.affiliation: Department of Biological Chemistry and Molecular Modelling, Institute for Advanced Chemistry of Catalonia, IQAC-CSIC, Barcelona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Carreras
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Mateos-Martín
authors.forename: Amado
authors.initials: A
authors.lastname: Velázquez-Palenzuela
authors.forename: Enric
authors.initials: E
authors.lastname: Brillas
authors.forename: Susana
authors.initials: S
authors.lastname: Sánchez-Tena
authors.forename: Marta
authors.initials: M
authors.lastname: Cascante
authors.forename: Luis
authors.initials: L
authors.lastname: Juliá
authors.forename: Josep Lluís
authors.initials: JL
authors.lastname: Torres
mesh_terms: D000975:Antioxidants / Q000737:chemistry; D002392:Catechin / Q000737:chemistry*; D002470:Cell Survival / Q000187:drug effects*; D004579:Electron Transport; D016166:Free Radical Scavengers / Q000737:chemistry*; D019073:HT29 Cells; D006801:Humans; D047348:Hydrolyzable Tannins / Q000737:chemistry*; D010084:Oxidation-Reduction; D059808:Polyphenols / Q000737:chemistry*; D013662:Tea / Q000737:chemistry
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D047348:Hydrolyzable Tannins; D059808:Polyphenols; D013662:Tea; C115642:punicalagin; D002392:Catechin