Location: Cereal Crops ResearchTitle: In vitro total antioxidant capacity and anti-flammatory activity of three common avenanthramides) Author
|Chu, Yi Fong|
Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2014
Publication Date: 3/21/2014
Citation: Yang, J., Ou, B., Wise, M.L., Chu, Y. 2014. In vitro total antioxidant capacity and anti-flammatory activity of three common avenanthramides. Food Chemistry. 160:338-345. Interpretive Summary: This report describes the antioxidant activity of avenanthramides. Avenanthramides are natural antioxidants found, among food crops, uniquely in oats. These experiments compared the relative efficacy of three congeners of avenanthramides commonly found in oat grain (2c, 2f and 2p) in scavenging five specific forms of reactive oxygen species (ROS). Avenanthramide 2c proved to be the most effective antioxidant overall, but discernible differences were demonstrated between avenanthramide congeners for the individual ROS. Avenanthramides 2p and 2f, for example, were superior at scavenging metal ion generated hydroxyl radicals (a particular form of ROS). The relative activity of the three avenanthramides in inhibiting the activation of nuclear factor kappa beta (NF-kB, a key regulatory molecule in numerous inflammatory responses and other immune functions) was also determined in vitro. Avenanthramide 2c has previously been shown to inhibit NF-kB, the other two forms have never been tested. Interestingly, 2p, which shows significantly lower antioxidant capacity than 2c and approximately equal to 2f, but had the highest capacity for scavenging hydroxyl radicals, also proved to be the most efficacious inhibitor of NF-kB. The impact of this report will be to inform that additional avenanthramide congeners, beside 2c, are effective inhibitors of NF-kB and to suggest a possible chemical basis for this activity, namely inactivation of metal ions capable of generating hydroxyl radicals in vivo.
Technical Abstract: Oats possess numerous beneficial properties, including anti-inflammatory, antiatherogenic, antiproliferative, anticancer, and anti-itch effects. To better understand mechanisms underlying the health benefits of oats, we evaluated the free radical scavenging abilities of oat avenanthramides 2c, 2f, and 2p and assessed their ability to inhibit NF-kB activation. We evaluated the antioxidant capacities of 2c, 2f, and 2p against peroxyl radicals, hydroxyl radicals, superoxide anion, singlet oxygen, and peroxynitrite using ORAC, HORAC, SORAC, SOAC, and NORAC assays, respectively. We found that the total antioxidant capacity of 2c was approximately 1.5-fold those of 2f and 2p. Total antioxidant capacity was attributable primarily to SORAC and ORAC for 2c (>77%, p < 0.05), and was primarily attributable to ORAC (>26%) and SOAC (>25%) for 2f. ORAC accounted for approximately 32% of total antioxidant capacity in 2p. EC50 values for inhibiting TNF-alpha-induced NF-kB activation in C2C12 cells were 64.3 micromolar for 2c, 29.3 micromolar for 2f, and 9.10 micromolar for 2p. The total antioxidant capacities of the avenanthramides could be fully characterized by using all five assays. Differences in antioxidant capacities and ability to inhibit NF-kB among the avenanthramides could be attributed to structural variations.