Submitted to: Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/31/2002
Publication Date: 12/1/2002
Citation: PETERSON, D.M., HAHN, M.J., EMMONS, C.L. OAT AVENANTHRAMIDES EXHIBIT ANTIOXIDANT ACTIVITY IN VITRO. FOOD CHEMISTRY. 2002. 79:473-478. Interpretive Summary: Free radicals, which are damaging to cellular function, are produced in the course of normal metabolism. It is believed that these free radicals may accelerate ageing and lead to certain degenerative diseases. Foods are sources of antioxidants that can scavenge the free radicals and render them harmless. This study was planned to investigate the antioxidant activities of a group of compounds in oats called avenanthramides. The three most abundant avenanthramides, called Bc, Bf and Bp were synthesized and then tested for antioxidant activities in two assay systems. In both systems, Bc had very high activity, and Bf and Bp were also active. The impact of these results are that it is worthwhile to test these compounds in animal systems to determine if any protective effects against free radical damage can be detected and how much is required to reduce any damaging effects of the free radicals. If these animal tests are successful, plant breeders should breed new oat cultivars with higher levels of avenanthramides. The ultimate impact will be oats with greater nutritional value for the consumer.
Technical Abstract: Oat (Avena sativa L.) contains a group of alkaloids commonly known as avenanthramides, that consist of an anthranilic acid derivative linked to a hydroxycinnamic acid derivative with a pseudo peptide bond. Among this group, the three most abundant in grain tissues were synthesized and purified. These were tested for antioxidant activity using two in vitro systems: inhibition of beta-carotene bleaching and reaction with the free radical, 2,2-diphenyl-1-picrylhydrazyl (DPPH). In both systems, each avenanthramide displayed antioxidant activity. Avenanthramide Bc (N- (3',4'-dihydroxycinnamoyl)-5-hydroxyanthranilic acid) had greater activity than Bp (N-(4'-hydroxycinnamoyl)-5-hydroxy-2-aminobenzoic acid) and Bf (N- (4'-hydroxy-3'-methoxycinnamoyl)-5-hydroxyanthranilic acid). Bc was nearly as active as butylated hydroxytoluene (BHT) in the beta-carotene system and 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox) in the DPPH system. The relative activities of the avenanthramides correspond to the reported relative activities of the component hydroxycinnamic acid moieties in the DPPH system and in a lipophilic system.