Cereal Chem. 70:637-641   |  VIEW ARTICLE

Avenanthramides---A Group of Phenolic Antioxidants in Oats.

L. H. Dimberg, O. Theander, and H. Lingnert. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

Two avenanthramides belonging to a group of about 40 cinnamoylanthranilic acid derivatives in oat grains were isolated: N-(4'-hydroxy-3'-methoxy-(E)-cinnamoyl)-5-hydroxyantranilic acid (A1) and, not previously reported, N-(4'-hydroxy-3'-methoxy-(E)-cinnamoyl)-5-hydroxy-4-methoxyanthranilic acid (A2). The antioxidative capacities of the two avenanthramides, A1 and A2, were determined by measuring the oxygen consumption in a linoleic acid system. A1 had approximately 20% of the activity exerted by alpha- tocopherol and A2 had approximately 60%. Caffeic and ferulic acid, known to be antioxidative, had much lower activities: 6 and 4%, respectively. A1 was preferentially located in the outer part of the grain. It seems to be quite heat stable, at least when located within the oat tissue during steam treatment. A comparison of 10 different cultivars of oats revealed that the amount of A1 varied between 40 and 132 micrograms per gram of grain. The amount of A2 is at least 10 times lower.