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 μmol of 2″‐O‐GIV inhibited MA formation from 0.2 mmol of squalene by almost 100% upon ultraviolet (UV) irradiation. Only 1 μmol 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 hydroxytoluene or α‐tocopherol. When ethyl linoleate, ethyl linolenate and ethyl arachidonate were oxidized by Fenton’s reagent in the presence of 2″‐O‐GIV or α‐tocopherol, both compounds showed similar activity toward MA formation. Both compounds gave maximum inhibition at doses of 0.1–0.3 μmol for ethyl linoleate, 0.1–0.5 μmol for ethyl linolenate and 0.1–0.5 μmol for ethyl arachidonate.