Antioxidative activities of natural compounds found in plants

The antioxidative activity of natural plant products-lacinilene A, naringin, galangin, and rutin-was examined using lipid peroxidation systems consisting of either ethyl linoleate, ethyl linolenate, or ethyl arachidonate plus Fenton's reagent. Inhibitory activity of plant products toward malonaldehyde (MA) formation from lipids was measured using gas chromatography. Lacinilene A, which showed the strongest antioxidative acitivity among the chemicals tested, inhibited MA formation from ethyl linolenate and ethyl arachidonate by 100% at the levels of 3.0 and 0.5 mu mol, respectively. Natural flavonoid compounds naringin, galangin, and rutin exhibited appreciable antioxidative activities at doses lower than 0.125 mu mol. Rutin, which exhibited the strongest activity among the three flavonoids, inhibited MA formation from ethyl arachidonate by 70% at the level of 0.125 mu mol. These flavonoids exhibited only slight inhibition of MA formation at levels higher than 0.5 mu mol from the ethyl esters of the three fatty acids.