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

Author
item CAI, SHENGBAO - China Agricultural University
item HUANG, CHEN - China Agricultural University
item JI, BAOPING - China Agricultural University
item Wise, Mitchell
item ZHANG, DI - China Agricultural University
item YANG, PEIYING - China Agricultural University

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/7/2010
Publication Date: 2/1/2011
Citation: Cai, S., Huang, C., Ji, B., Wise, M.L., Zhang, D., Yang, P. 2011. In vitro antioxidant activity and inhibitory effect, on oleic acid-induced hepatic steatosis, of fractions and subfractions from oat (Avena sativa L.) ethanol extract. Journal of Food Science. 124(3):900-905.

Interpretive Summary: Avenanthramides are phenolic antioxidants found, among food crops, exclusively in oats. These compounds are known to possess antioxidant properties and a growing body of evidence indicates that they can reduce inflammation based pathologies such as atherosclerotic plaque formation and skin irritation. Non-alcoholic steatohepatitis (NASH) is a growing concern in western populations where high caloric diets are causing an increased obesity rate, one of the predictors for NASH. The etiology for NASH appears to be diets high in carbohydrate and saturated fatty acid content resulting in excessive oxidative stress and inflammation in the liver. Current therapeutic options include dietary changes and treatment with antioxidants such as vitamin E. Using a tissue culture system, this investigation evaluated the effect of various extractions from oat on reducing the build up of fatty tissue in liver cells (steatosis). The oat fractions with the highest levels of avenanthramides proved to be most efficacious. Pure, synthetic avenanthramides showed the same effect, substantiating their role as the active component. The impact of these experiments is to expand the potential role of oat derived avenanthramides in reducing metabolic disorders.

Technical Abstract: 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 these extractions the ethyl acetate (EA) layer exhibited the highest total phenolic content (TPC), the strongest DPPH radical scavenging activity and the strongest inhibitory effect on oleic acid-induced (OA-induced) fatty liver model in vitro. Thus, the EA extract was further fractionated by a Sephadex LH-20 column into three sub-fractions (SF1-SF3). SF3 was the most active sub-fraction in all assays above, with the yield being 1.70% of the dry weight of EA fraction. The major components in SF3 were identified as avenanthramides Bc, Bp and Bf by HPLC analysis, with the contents being about 5.20%, 9.19% and 8.06% of the dry weight of SF3, respectively. All three avenanthramides showed significant inhibitory effect on oleic acid-induced (OA-induced) fatty liver.