Characterization of phenolic compound antioxidant activity in oat varieties using UHPLC–online ABTS and LC Q‐TOF

Abstract

Background and objectives: Phenolic compounds present in oats provide an opportunity for oats to increase its use in the form of functional food. In this study, eight varieties of Australian-grown whole-grain oat were investigated for their phenolic composition and antioxidant potential. Ultra-high-performance liquid chromatography-online 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), coupled with liquid chromatography quadrupole time-of-flight, was used to identify and quantify individual phenolic compounds and their respective antioxidant activity. Findings: Considerable variation in phenolic content (19.51 ± 1.20-52.49 ± 1.70 mg 100 g −1 GAE) and antioxidant activity was observed among the oat varieties. Several avenanthramides (AVNs) were detected with AVN A and AVN C being the most abundant. AVN C exhibited the highest antioxidant activity followed by caffeic acid, quercetin-3,4′-O-di-beta-glucopyranoside derivative, and 6-hydroxykaempferol 3,5,7,4′-tetramethyl ether 6-rhamnoside. Antioxidant activity in AVNs was observed to be the highest in AVN C followed by AVN B and AVN A. Conclusions: High levels of AVN C and the range of phenolic compounds present show promise of Australian-grown oats as an important source of antioxidant compounds. These antioxidant compounds may contribute to consumers' health benefits. Significance and novelty: This study contributes to the use of oats as potential functional food by characterizing its individual phenolic compounds and their antioxidant activity. K E Y W O R D S antioxidant, avenanthramide, LC Q-TOF, oats, UHPLC-online ABTS

Polyphenols and avenanthramides extracted from oat ( Avena sativa L.) grains and sprouts modulate genes involved in glucose and lipid metabolisms in 3T3 L1 adipocytes

“…Moreover, in this study we report for the first time the content of avenanthramide L (AV_4) in oat sprouts, which is an avenalumic acid substituted avenanthramide, and was increased by 1.9‐fold after oat germination. This avenanthramide has been previously identified in oat grain (Rao et al., 2019), but not in its sprout.…”

“…The phenolic acid profile includes several free phenolic acids previously reported in oat grains and oat sprouts, such as gallic acid, protocatechuic acid, p ‐hydroxybenzoic acid, syringic acid, cinnamic acid, sinapic acid, caffeic acid, p ‐coumaric acid, and ferulic acid (Aborus et al., 2018; Escobedo‐Flores et al., 2018; Multari et al., 2018; Rao et al., 2019; Varga et al., 2018). Interestingly, several phenolic acids were identified in this study for the first time in oat grain and oat sprouts, mainly hydroxycinnamic acids esterified with quinic acid such as sinapoylquinic, coumaroylquinic, and feruloylquinic acids, as well as other derivatives.…”

“…The major avenanthramide identified in both the OG and the OS was avenanthramide C (2c; AV_1), followed by avenanthramide B (2f; AV_7) and avenanthramide A (2p; AV_5), which are the major avenanthramides found in oat grains (Rao et al., 2019 and Jágr et al., 2020). Interestingly, the sprouting process significantly ( p < .05) increased their content by 9.0‐, 8.3‐, and 8.2‐fold, respectively.…”

Apoptosis Induction Pathway in Human Colorectal Cancer Cell Line SW480 Exposed to Cereal Phenolic Extracts

“…Extraction procedure followed methodology reported in previous publications [18,19]. Details of phenolic compound composition and antioxidant activity have been reported in References [18,19,40], for rice, oats and barley respectively. Sorghum chemical profile has been reported by Rao, et al [36] and variation with methanol extraction has been reported by Wu, et al [41].…”

Bioaccessibility and Bioactivity of Cereal Polyphenols: A Review

“…Some phenolic compounds are rare and highly specific to a few cereal grains. Some examples include the 3-deoxyanthocyanin found in sorghum and avenanthramides found in oats [ 23 ]. The biological effects of these phenolic extracts can be attributed to their structure–activity relationships.…”