Quantum chemical investigation of the antiradical property of avenanthramides, oat phenolics

Abstract

Avenanthramides (AVs) are polyphenolic components found in oats. The present work is devoted to the exploration of structure-based radical scavenging activity of nine AVs; 2p, 2f, 2c, 1p, 1c, 1f, 1s, 2s, and 3f, using M06-2X functional level of density functional theory with basis set 6-31þG(d, p) both in gas and ethanol medium. The act of compounds towards the electron transfer mechanism was analyzed with the help of a Donor-acceptor map (DAM) and classified as antioxidants and anti-reductants. The main mechanism of radical action, HAT, SET-PT, and SPLET were examined and found to be the preference of HAT and SPLET respectively in the gas phase and ethanol medium. The computed quantum mechanical atom in molecule (QTAIM) parameters; the intramolecular H-bonding, Noncovalent interactions, aromaticity also acted as pillars to supports the activity of compounds. The activity was found to be increasing with the stabilizing group ortho to the reactive phenolic OH group.

Antioxidant Activity and Mechanism of Avenanthramides: Double H+/e– Processes and Role of the Catechol, Guaiacyl, and Carboxyl Groups

“…By contrast, a decrease of PAs with the increase of the solvent polarity makes them significantly smaller than the BDEs and IPs. This suggests that in the polar media, the investigated AVAs preferentially donate the first H + /e – to free radicals via the SPLET pathway, in line with a previous study on other AVAs …”

“…Although these previous studies have greatly enriched our knowledge about the antioxidant property of AVAs, understanding of the structure–activity relationship and the underlying mechanisms remain insufficient . Considering the success of the density functional theory (DFT) method in elucidating the antioxidant property of phenolic compounds, − we aimed to perform a systematic DFT study to clarify the relationship between the molecular/electronic structure and free radical scavenging activity and the possible mechanisms of AVAs.…”

Multiple Antioxidative and Bioactive Molecules of Oats (Avena sativa L.) in Human Health

“…The main polyphenolic compound found in oats includes protocatechuic, syringic, vanillic, p -hydroxybenzoic, gallic, p -coumaric, o -coumaric, and caffeic acids ( Figure 6 ) [ 91 , 92 , 93 ]. Among them, Avn biosynthesized from phenylalnine as an alkaloid ( Figure 7 ) [ 9 , 94 , 95 ] is a polyphenol with various physiological properties, including antioxidant, anti-inflammatory, anti-cancer, anti-thrombotic, anti-proliferative, and anti-itch activities [ 9 , 95 , 96 , 97 , 98 , 99 , 100 , 101 , 102 , 103 ]. Avn has 30 times higher antioxidant activity than other phenolic compounds [ 98 , 99 , 102 ].…”

“…There are various types of Avn found in oats. Depending on the residue of N-cinnamoyl anthranilic acid, Avn A combined with p -coumaric acid, Avn B combined with ferulic acid, and Avn C combined with caffeic acid are mainly found in oats [ 101 , 102 , 104 ]. The structure of Avn is similar to tranilast, a commercially available anti-allergic drug, and many studies assessed the anti-inflammatory and anti-atherogenic effects of Avn [ 105 , 106 , 107 , 108 ].…”

Effect of extract from common oat on the antioxidant activity and fatty acid composition of the muscular tissues of geese

“…And there are good reasons for this. Among the well-known phenolic compounds, avenanthramides, compounds with a broad range of biochemical action found exclusively in oats, have become especially significant in recent years (Aldubayan et al, 2019;De Bruijn et al, 2019;Sumayya et al, 2021). Avenanthramides are poly-functional compounds because of their molecules that contain not only the phenol hydroxyl group, but amino-and carboxyl-groups as well (Walsh et al, 2017;Pridal et al, 2018;Chen et al, 2018).…”