Flavonoids, Coumarins, and Cinnamic Acids as Antioxidants in a Micellar System. Structure−Activity Relationship

The antioxidant activity of selected representatives of flavonoids, coumarins, and cinnamic acids was examined by measuring their protective action toward linoleic acid peroxidation in micelles of sodium dodecyl sulfate in buffer solution, pH 7.4. Results are expressed as relative antioxidant efficiency (RAE), defined as the ratio of the antioxidant efficiency (AE) of the tested compound to that of α-tocopherol. The best RAE values were observed for flavonoids, followed by coumarins and cinnamic acids. From the results, within each class of compounds a structure−activity relationship can be deduced. Keywords: Antioxidant; flavonoids; coumarins; cinnamic acids and esters; relative antioxidant efficiency (RAE); lipid peroxyl radicals; α-tocopherol