Electron paramagnetic resonance spectra of flavonoid anion-radicals

Abstract

Flavonoid anion-radicals, obtained in aqueous dimethyl sulphoxide by the aerial, alkaline oxidation of flavonoid compounds, have been studied by means of e.p.r. The spectra of these radicals indicate oxidation of the isolated or conjugated B-ring to give a para- or ortho-benzosemiquinone or a pyrogallol-type anion-radical. Solvent effects result in variations in hyperfine coupling constants and radical stability.