Antioxidant and lipoxygenase activities of polyphenol extracts from oat brans treated with polysaccharide degrading enzymes

This study used polysaccharide degrading enzymes and protein precipitation to extract polyphenols from oats and to determine their bioactivity. Duplicate oat brans were treated with viscozyme (Vis), cellulase (Cel) or no enzyme (control, CTL) then, proteins were removed in one set (Vis1, Cel1, CTL1) and not in the other (Vis2, Cel2, CTL2). HPLC analyses showed that for cellulase treated brans, precipitation of proteins increased phenolic acids and avenanthramides by 14%. Meanwhile, a decreased of 67% and 20% respectively was found for viscozyme and control brans. The effect of protein precipitation on soluble polyphenols is therefore dependent of the carbohydrase, as proteins with different compositions will interact differently with other molecules. Radical scavenging data showed that Cel1 and Vis1 had higher quenching effects on ROO(•) radicals with activities of 22.1 ± 0.8 and 23.5 ± 1.2 μM Trolox Equivalents/g defatted brans. Meanwhile, CTL2 had the highest HO(•) radicals inhibition (49.4 ± 2.8%) compared to 10.8–32.3% for others. Samples that highly inhibited lipoxygenase (LOX), an enzyme involved in lipid oxidation were Cel1 (23.4 ± 2.3%) and CTL1 (18 ± 0.4%).