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

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.