Avenanthramides Research Articles

Extraction and antioxidant activity of avenanthramides from oat bran

Extraction and antioxidant activity of avenanthramides from oat bran

Avenanthramides Are Bioavailable and Have Antioxidant Activity in Humans after Acute Consumption of an Enriched Mixture from Oats

The consumption of polyphenols is associated with a decreased risk of cardiovascular disease. Avenanthramides (AV), alkaloids occurring only in oats, may have anti-atherosclerotic activity, but there is no information concerning their bioavailability and bioactivity in humans. We characterized the pharmacokinetics and antioxidant action of avenanthramide A, B, and C in healthy older adults in a randomized, placebo-controlled, 3-way crossover trial with 1-wk washout periods. Six free-living subjects (3 mol/L, 3 F; 60.8 ± 3.6 y) consumed 360 mL skim milk alone (placebo) or containing 0.5 or 1 g avenanthramide-enriched mixture (AEM) extracted from oats. Plasma samples were collected over a 10-h period. Concentrations of AV-A, AV-B, and AV-C in the AEM were 154, 109, and 111 μmol/g, respectively. Maximum plasma concentrations of AV (free + conjugated) after consumption of 0.5 and 1 g AEM were 112.9 and 374.6 nmol/L for AV-A, 13.2 and 96.0 nmol/L for AV-B, and 41.4 and 89.0 nmol/L for AV-C, respectively. Times to reach the Cmax for both doses were 2.30, 1.75, and 2.15 h for AV-A, AV-B, and AV-C and half times for elimination were 1.75, 3.75, and 3.00 h, respectively. The elimination kinetics of plasma AV appeared to follow first-order kinetics. The bioavailability of AV-A was 4-fold larger than that of AV-B at the 0.5 g AEM dose. After consumption of 1 g AEM, plasma reduced glutathione was elevated by 21% at 15 min (P ≤ 0.005) and by 14% at 10 h (P ≤ 0.05). Thus, oat AV are bioavailable and increase antioxidant capacity in healthy older adults.

Phenolic Compounds in Oat Grains (Avena sativa L.) Grown in Conventional and Organic Systems

The concentrations of avenanthramides (AVAs), hydroxycinnamic acids (HCAs), a sucrose-linked truxinic acid (TASE), and certain agronomic parameters were analyzed in organically and conventionally grown oats. Three cultivars of oats (i.e. Freja, Sang, and Matilda) were grown according to standards for both conventional and organic farming in Sweden, from 1998 to 2000. Two levels of nitrogen (N) and three replicates were included. Overall, there were significant differences between years, cultivars, and N rate for AVA concentration in the grains, but there were no differences in concentration as a consequence of the conventional or organic cropping system used. The AVA content was higher in the samples grown in 2000, particularly in the cultivar Matilda, and was negatively affected by higher N rates. The HCAs showed cultivar and year differences, but were not influenced by N rates or the cropping system. The HCA content was highest in Matilda, and was significantly lower in samples grown in 1999. The concentration of TASE differed only between years, and was about 100% higher in samples from 1999, compared with samples from 1998 and 2000. The AVA and HCA concentrations were negatively correlated to the yield and specific weight of the grains and positively correlated to the protein content. Conversely, the concentration of TASE was positively correlated to the yield. The specific parameters responsible for the variation in the phenolic compounds are not known, but it seems that factors affecting the yield and/or the specific weight also affect the concentrations of AVAs, HCAs, and TASE in oat grains.

Effects of avenanthramides on oxidant generation and antioxidant enzyme activity in exercised rats

Avenanthramides (AVEN) are major phenolic acids in oat ( Avena sativa L.) that have potent antioxidant functions. Female Sprague-Dawley rats (n = 48, age 6-7 wk) were fed either an AIN-93 based control (C) diet or the same diet containing 0.1 g/kg AVEN-Bc [ N-(3′,4′-dihydroxycinnamoyl)-5-hydroxyanthranilic acid] for 50 days. Each group was further divided into rested (R) and exercised (E, treadmill running at 22.5 m/min, 10% grade for 1 hour) prior to killing. AVEN supplementation per se had no effect on reactive oxygen species (ROS) production in most tissues, except soleus muscle wherein ROS level was decreased. AVEN-fed rats had higher superoxide dismutase (SOD) activity in the deep portion of vastus lateralis muscle (DVL), liver and kidney and higher glutathione peroxidase (GPX) activity in the heart and DVL, compared to C-fed rats. E increased ROS production in the liver, DVL and soleus, and lipid peroxidation in the heart, liver and DVL. AVEN attenuated E-induced ROS in soleus and lipid peroxidation in the heart, but enhanced lipid peroxidation in DVL. We conclude that AVEN can serve as a potential dietary antioxidant supplement, but its tissue specific effects require further investigation.