INHIBITION OF MALONALDEHYDE FORMATION FROM LIPIDS BY AN ISOFLAVONOID ISOLATED FROM YOUNG GREEN BARLEY LEAVES

The inhibitory effect of 2''-O-glycosylisovitexin (2''-O-GIV), isolated from young green barley leaves, on malonaldehyde (MA) formation from lipids was determined by gas chromatography. Two mumol of 2''-O-GIV inhibited MA formation from 0.2 mmol of squalene by almost 100% upon ultraviolet (UV) irradiation. Only 1 mumol of 2''-O-GIV inhibited 90% of MA formation from 0.2 mmol of ethyl linoleate upon UV irradiation. The effective quantities of 2''-O-GIV were much lower than those of either butylated hydroxy-toluene or alpha-tocopherol. When ethyl linoleate, ethyl linolenate and ethyl arachidonate were oxidized by Fenton's reagent in the presence of 2''-O-GIV or alpha-tocopherol, both compounds showed similar activity toward MA formation. Both compounds gave maximum inhibition at doses of 0.1-0.3 mumol for ethyl linoleate, 0.1-0.5 mumol for ethyl linolenate and 0.1-0.5 mumol for ethyl arachidonate.