Phenolic amides (avenanthramides) in oats - a review

Abstract

Boz H. (2015): Phenolic amides (avenanthramides) in oats -a review. Czech J. Food Sci., 33: 399-404.Whole grain cereals such as oats are important sources of phenolic compounds. Oats contain phenolic amides, also named avenanthramides (AVAs), which have beneficial health properties because of their antioxidant, anti-inflammatory, and antiproliferative effects. The most common avenanthramides are esters of 5-hydroxyanthranilic acid with p-coumaric (AVA-A), ferulic (AVA-B), or caffeic (AVA-C) acids. The studies related to the stability of AVAs showed that AVA-B is sensitive to alkaline and neutral conditions and this sensitivity increases with higher temperatures. However, has been reported that AVA-A and AVA -C are more stable under the same conditions (alkaline and neutral conditions), and in addition that AVAs content of oats is increasing significantly with the germination process. AVAs help in preventing free radicals from damaging LDL cholesterol while AVAs-enriched extract of oats combined with vitamin C synergistically inhibited LDL oxidation in vitro. Both animal studies and human clinical trials confirmed that oats antioxidants have the potential of reducing cardiovascular risks by lowering serum cholesterol and inhibiting LDL oxidation and peroxidation. Therefore, the consumption of oats and products thereof is extremely important in reducing the risk of cardiovascular diseases.

Chemopreventive Effect of the Germinated Oat and Its Phenolic-AVA Extract in Azoxymethane/Dextran Sulfate Sodium (AOM/DSS) Model of Colon Carcinogenesis in Mice

“…In this regard, a more than four-fold increase in TPC was obtained after five days of germination in darkness at 25 • C/60% RH. Similar results have been previously reported [17,45,52]. This result could also reflect the better extractability of phenolic compounds from kernel structures after germination [17].…”

“…Studies regarding the chemopreventive effect of oat sprouts and whole oats are limited in comparison with those discussing the unique polyphenolic alkaloids-AVAs-exclusively extracted from oats, among other compounds such as steroidal saponins, β-glucan, and flavonoids [5,[9][10][11]13,15,44,45,52,[65][66][67][68], mainly through mechanisms related to their antioxidant, anti-inflammatory, immunomodulatory, antiproliferative, proapoptotic, cancer cell growth, and senescence control activities. These studies suggest that the notion of effective antitumor activity arising from whole oats may be due to the synergistic effects of multiple compounds rather than any one nutrient or compound alone.…”

Determination of selected phenolic acid and majoritarian avenanthramides in different varieties of naked oats (Avena sativa L.) grown in Slovakia

“…In the study by Xu et al (2009) was reported that gallic acid, vanillic acid, caffeic acid, ferulic acid, and p-coumaric acid are the main PAs in oats. The content of FA in oat bran was 33 mg/100g (Boz 2015). In the study by Chen et al (2018) was reported that FA was in range 1.32 -l8.98 μg/g.…”

“…AVNs are a group of unique soluble bioactive compounds that are absent in other food crops. Oats contain a unique group of approximately 40 different types of AVNs that consist of an anthranilic acid derivatives and hydroxycinnamic acid derivatives (Boz 2015). AVNs from oats exhibit (potent) antioxidant activity in vitro and in vivo (Thomas et al 2018).…”

Inhibitory Effects of Hydrolyzed Oat Bran Proteins on Human LDL Oxidation and Their Bile Acid Binding Capacity

“…They act as strong free radical scavengers and have showed lowering cholesterol abilities (Peterson & Qureshi, 1993). As in the case of OBG, despite the fact that AVAs have exhibited bioavailability ,antioxidant (Chen et al, 2007), and anti-inflammatory (Koenig et al, 2014) properties in humans, they also demonstrated poor stability during steaming, autoclaving, and flaking (Boz, 2015). Consequently processing steps need to be taken into account in order to establish effective relationship regarding their health promoting benefits.…”