In vitro antioxidant activity and inhibitory effect, on oleic acid-induced hepatic steatosis, of fractions and subfractions from oat (Avena sativa L.) ethanol extract

Oats (Avena sativa L.) were extracted with 80% aqueous ethanol and the extract was successively isolated by liquid–liquid partition to yield n-hexane, ethyl acetate, n-butanol and water layers. Among them, the ethyl acetate (EA) layer exhibited the highest total phenolic content (TPC), the strongest DPPH radical-scavenging activity and an inhibitory effect on an oleic acid-induced (OA-induced) fatty liver model in vitro. Thus, it was further fractionated by a Sephadex LH-20 column into three subfractions (SF1–SF3). SF3 was the most active subfraction in all the assays above, the yield being 1.70% of the dry weight of the EA fraction. The major components in SF3 were identified as avenanthramides Bc, Bp and Bf by HPLC analysis, with contents of about 5.20%, 9.19% and 8.06% of the dry weight of SF3, respectively. Also, the avenanthramides Bc, Bp and Bf all had significant inhibitory effects on oleic acid-induced (OA-induced) fatty liver.