Reducing activity of polyphenols with stable radicals of the TTM series. Electron transfer versus H-abstraction reactions in flavan-3-ols.
A new method to test the antioxidant activity of polyphenols by electron transfer reactions to a stable organic free radical, tris(2,4,6-trichloro-3,5-dinitrophenyl)methyl radical (HNTTM), is reported. Therefore, the activity of the natural flavanols, (-)-epicatechin, and two synthetic derivatives, 4beta-(S-cysteinyl)epicatechin and 4beta-(2-aminoethylthio)epicatechin, can be differentiated by their capacity to transfer hydrogen atoms to 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and to transfer electrons to HNTTM. [structure: see text]
Jiménez
Aurora
A
Departament de Química de Pèptids i Proteïnes and Departament de Química Orgànica Biologica, Institut d'Investigacions Químiques i Ambientals (IIQAB-CSIC), Jordi Girona 18-26, 08034 Barcelona, Spain.
Selga
Ariadna
A
Torres
Josep Lluís
JL
Julià
Lluís
L