Free radical generation in rosmarinic acid investigated by electron paramagnetic resonance spectroscopy.
Free radical generation as a result of oxidation reactions of rosmarinic acid (RA), a caffeic acid ester with 3,4-dihydroxyphenyllactate, was investigated by electron paramagnetic resonance (EPR) spectroscopy using a variety of oxidation conditions. Limitations and possibilities of using the various methodologies to obtain information about the reaction chemistry of polyphenols are discussed. Three different spectra were detected dependent on the pH and oxidizing agent. Feasible structures for the observed radicals were tested by density functional theory (DFT) calculations and the results indicate that oxidation reactions can occur at both of the catechol groups.
Pirker
Katharina F
KF
Department of Environmental Research, Austrian Research Centers GmbH-ARC, Seibersdorf, Austria. katharina.pirker@arcs.ac.at
Kay
Christopher W M
CW
Stolze
Klaus
K
Tunega
Daniel
D
Reichenauer
Thomas G
TG
Goodman
Bernard A
BA
D000975:Antioxidants / Q000737:chemistry*; D002934:Cinnamates / Q000737:chemistry*; D053630:Depsides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000138:chemical synthesis*; D016877:Oxidants / Q000494:pharmacology; D010084:Oxidation-Reduction; D000097123:Rosmarinic Acid
D000975:Antioxidants; D002934:Cinnamates; D053630:Depsides; D005609:Free Radicals; D016877:Oxidants; D000097123:Rosmarinic Acid