title: Free radical generation in rosmarinic acid investigated by electron paramagnetic resonance spectroscopy.
abstract: 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.
authors.affiliation: Department of Environmental Research, Austrian Research Centers GmbH-ARC, Seibersdorf, Austria. katharina.pirker@arcs.ac.at
authors.forename: Katharina F
authors.initials: KF
authors.lastname: Pirker
authors.forename: Christopher W M
authors.initials: CW
authors.lastname: Kay
authors.forename: Klaus
authors.initials: K
authors.lastname: Stolze
authors.forename: Daniel
authors.initials: D
authors.lastname: Tunega
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Reichenauer
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Goodman
mesh_terms: 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
chemical_list: D000975:Antioxidants; D002934:Cinnamates; D053630:Depsides; D005609:Free Radicals; D016877:Oxidants; D000097123:Rosmarinic Acid