Phenolics content, antioxidant and antiproliferative activities of dehulled highland barley (Hordeum vulgare L.)

• Highland barley is an excellent source of phenolic compounds.
• Bound fraction makes a significant contribution to total.
• Free fraction exhibits a higher cellular availability than bound fraction.

Free and bound phenolic compounds were extracted from four varieties (BQ, Dulihuang; CHQK, Changheiqingke; ZQ25, Zangqing 25 and ZQ320, Zangqing 320) of dehulled highland barley. Phenolics composition, antioxidant and antiproliferative activities were analysed. Total phenolics ranged from 333.9 ± 17.1 to 460.8 ± 5.7 mg gallic acid equivalents (GAE)/100 g grain (dry weight, DW), total flavonoids are between 145.5 ± 10.0 and 247.4 ± 20.3 mg catechin equivalents (CE)/100 g grain (DW), and ferulic acid is the dominant phenolic compound. These extracts showed excellent antioxidant activities determined by oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity (CAA) assays, as well as potent antiproliferative activity towards HepG2 human liver cancer cells. Bound phenolics make a significant contribution to total phenolics content, antioxidant and anticancer activities. This study suggested that highland barley exhibits the unique phenolic compound profile with potential health benefits, and it may serve as ingredients for functional foods.