Antioxidant Activity of Oat Extracts added to Human LDL Particles and in Free Radical Trapping Assays

• Published in: Journal of cereal science 2002-09, Vol.36 (2), p.209-218
• Main Authors: Gray, David A., Clarke, Matthew J., Baux, Cathy, Bunting, John P., Salter, Andrew M.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Cereal and baking product industries; Chemical constitution; Economic plant physiology; Food industries; Fundamental and applied biological sciences. Psychology; oats, antioxidants, human LDL particles, free radical trapping assays
• ISSN: 0733-5210; 1095-9963
• DOI: 10.1006/jcrs.2001.0456

Commercial extracts of oats containing relatively hydrophilic phenolic compounds (including avenanthramides) were provided. They were generated using 50% ethanol as the extracting solvent, concentrated, and raised up in 50% aqueous butane diol (9G3, 9F1, 0C4). A more hydrophobic extract, fractionated into polar/amphiphilic lipids (including tocols), was generated using IPA (isopropanol) and designated the IPApolar extract. Two approaches were used to measure the antioxidant activity of oat extracts: the quenching of free radicals and the inhibition of human LDL (low density lipoprotein) oxidation. Results indicated that the order of antioxidant activity of the extracts was broadly similar for each of the methods used. Notably the order of decreasing antioxidant activity per unit mass of phenolics, as obtained from the DPPH (2,2-diphenyl-1-picrylhydrazyl) assays and LDL oxidation assays, was IPApolar > 0C4 > 9F1 > 9G3. FTCL (flow-through chemiluminescence) data were very similar, only showing a shift in the relative activity position of 0C4 from second to third. Interestingly, α-tocopherol and Trolox showed very similar activity per mole in the DPPH assay, but Trolox was more active in the FTCL and LDL oxidation assays.