Antioxidant activity of flavonoids isolated from young green barley leaves toward biological lipid samples

Natural plant flavonoids, saponarin/lutonarin = 4.5/1, isolated from young green barley leaves were examined for their antioxidant activity using cod liver oil, omega-3 fatty acids, phospholipids, and blood plasma. The saponarin/lutonarin (S/L) mixture inhibited malonaldehyde (MA) formation from cod liver oil by 76.47 +/- 0.11% at a level of 1 mu mol and 85.88 +/- 0.12% at a level of 8 mu mol. The S/L mixture inhibited MA formation from the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) by 45.60 +/- 1.08 and 69.24 +/- 0.24%, respectively, at a level of 8 mu mol. The S/L mixture inhibited MA formation from the phospholipids lecithin I and II by 43.08 +/- 0.72 and 69.16 +/- 2.92%, respectively, at a level of 8 mu mol. It also inhibited MA formation from blood plasma by 62.20 +/- 0.11% at a level of 8 mu mol. The antioxidant activities obtained from the S/L mixture were comparable to those obtained from alpha-tocopherol and butylated hydroxy toluene (BHT) in all lipids tested.