Avenanthramide B

Ferulic Acid Derivatives and Avenanthramides Modulate Endothelial Function through Maintenance of Nitric Oxide Balance in HUVEC Cells.[Pubmed:34204635]

Nutrients. 2021 Jun 12;13(6):2026.

Wholegrain oats contain a variety of phenolic compounds thought to help maintain healthy vascular function, through the maintenance of local levels of the vasodilator nitric oxide (NO). Thus, the full molecular mechanisms involved are not yet clear. With this work we aim to understand the possible cellular mechanisms by which avenanthramides and ferulic acid derivatives, present in oats, may help maintain a healthy vascular function through the modulation of the NO pathway. Primary Human Umbilical Vein Endothelial Cells (HUVEC) were exposed to ferulic acid, isoferulic acid, hydroferulic acid, ferulic acid 4-O-glucuronide, isoferulic acid 3-O-sulfate, dihydroferulic acid 4-O-glucuronide, avenanthramide A, Avenanthramide B and avenanthramide C (1 muM) or vehicle (methanol) for 24 h. Apocynin and Nomega-Nitro-L-arginine (L-NNA) were additionally included as controls. NO and cyclic GMP (cGMP) levels, superoxide production and the activation of the Akt1/eNOS pathway were assessed. The statistical analysis was performed using one-way ANOVA followed by a Tukey post-hoc t-test. Apocynin and all phenolic compounds increased NO levels in HUVEC cells (increased DAF2-DA fluorescence and cGMP), and significantly reduced superoxide levels. Protein expression results highlighted an increase in the Akt1 activation state, and increased eNOS expression. Overall, our results indicated that the glucuronide metabolites do not enhance NO production through the Akt1/eNOS pathway, thus all compounds tested are able to reduce NO degradation through reduced superoxide formation.

Characterization and antioxidant activity of avenanthramides from selected oat lines developed by mutagenesis technique.[Pubmed:33158678]

Food Chem. 2021 May 1;343:128408.

From a mutagenized oat population, produced by ethyl methanesulfonate mutagenesis, hulled grains from 17 lines with elevated avenanthramide (AVN) content were selected and their AVN structures, concentrations and antioxidant potentials were determined by HPLC-MS(2) and HPLC equipped with an on-line ABTS(+) antioxidant detection system. The data obtained showed qualitative and quantitative differences in the synthesis of AVNs in the different lines, with a total AVN concentration up to 227.5 microg/g oat seed flour in the highest line, compared with 78.2 microg/g seed in the commercial line, SW Belinda. In total, 25 different AVNs were identified with Avenanthramide B structures being among the most abundant, and AVN C structures having the highest antioxidant activity. The findings indicate the potential of oat mutagenesis in combination with a high precision biochemical selection method for the generation of stable mutagenized lines with a high concentration of total and/or individual AVNs in the oat seed grain.

New dimeric compounds of avenanthramide phytoalexin in oats.[Pubmed:17432911]

J Org Chem. 2007 May 11;72(10):3830-9.

Avenanthramide B is an oat phytoalexin produced in response to pathogen attack and elicitation. We found the formation of new dimers (1-5) of Avenanthramide B in elicited oat leaves. The dimers were synthesized by a reaction of peroxidase and Avenanthramide B in the presence of hydrogen peroxide. The structures of 1-5 were determined by spectroscopic analyses, chemical derivatization, and 15N labeling. Compound 1 was a dehydrodimer of Avenanthramide B with a bisbutane lactam skeleton, while 2-4 were monohydrated dehydrodimers with butane lactam structures. Compound 5 was also a monohydrated dehydrodimer but with a tetrahydrofuran structure. All the compounds were classified into lignanamides that were formed by an 8'-8' coupling reaction between two Avenanthramide B units.

Metabolism of avenanthramide phytoalexins in oats.[Pubmed:15272874]

Plant J. 2004 Aug;39(4):560-72.

Oat leaves produce phytoalexins, avenanthramides, in response to infection by pathogens or treatment with elicitors. The metabolism of avenanthramides was investigated using low molecular weight, partially deacetylated chitin as an elicitor. When oat leaf segments are floated on the elicitor solution, avenanthramides accumulate in the solution. The transfer of elicited oat leaves to solutions containing stable-isotope-labeled avenanthramides resulted in a rapid decrease in the labeled avenanthramides, suggesting the metabolism of avenanthramides. The rate of decrease was enhanced by elicitor treatment, and was dependent on the species of avenanthramides, with Avenanthramide B decreasing most rapidly. The rates of biosynthesis and metabolism of avenanthramides A and B were measured using a model of isotope-labeling dynamics. Avenanthramide B was found to be more actively biosynthesized and metabolized than avenanthramide A. Radiolabeled Avenanthramide B was incorporated into the cell wall fraction and 99% of incorporated activity was released by alkaline treatment. Gel filtration indicated that high-molecular-weight compounds derived from Avenanthramide B were released by alkaline treatment. The decrease in stable-isotope-labeled avenanthramides was suppressed by catalase, salicylhydroxamic acid, and sodium ascorbate, suggesting the involvement of peroxidase in the metabolism. Consistent with this, peroxidase activity that accepts Avenanthramide B as a substrate was induced in apoplastic fractions by elicitor treatment. The appearance of multiple basic isoperoxidases was observed by activity staining with 3-amino-9-ethylcarbazole coupled with isoelectric focusing of proteins from elicitor-treated leaves. These findings suggest that accumulated avenanthramides are further metabolized in apoplasts in oat leaves by inducible isoperoxidases.

Occurrence of avenanthramides and hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyltransferase activity in oat seeds.[Pubmed:10739096]

Z Naturforsch C J Biosci. 2000 Jan-Feb;55(1-2):30-6.

Oat phytoalexins, avenanthramides, occur as constitutive components in seeds. The amounts of each avenanthramide were analyzed. The composition of avenanthramides in dry seeds was different from that in elicitor-treated leaves. In seeds, avenanthramide C was most abundant with an amount two times larger than that of avenanthramide A or B. On the other hand, avenanthramide A was the major component in elicitor-treated leaves. The total amount of avenanthramides in seeds increased 2.5 times during imbibition for 48 h although the composition did not change. The hydroxycinnamoyl-CoA:hydroxyanthranilate N-hydroxycinnamoyltransferase (HHT, EC 2.3.1.-) activity, which is responsible for the final condensation step in the Avenanthramide Biosynthesis, was detected in dry seeds. The activity was localized in endosperm and scutellum, and slightly increased during 48-h imbibition. The enzyme was partially purified by anion exchange chromatography from both dry seeds and elicitor-treated leaves The activity was separated into two peaks by chromatography, indicating that HHT consists of at least two isoforms. The substrate specificities of HHT isoforms from seeds were different from each other.