Antioxidant and Antiproliferative Potential of Pearled Barley (Hordeum vulgarae.)

Two barley varieties, Falcon and AC Metcalfe, were separated by pearling into seven fractions. Each fraction was subsequently extracted with 80% methanol. Total phenolic content of the extracts so obtained was determined by the Folin-Ciocalteu method and ranged from 0.51 to 6.26 and 0.17 to 4.16 mg ferulic acid equiv/g defatted material, respectively. In both barley varieties, the outermost fraction (F1) yielded the highest phenolic content. The extracts were evaluated for their efficacy in scavenging of peroxyl and hydroxyl radicals using electron paramagnetic resonance (EPR). IC50 value, an indicator of efficacy of a test extract in reducing radical concentration by 50%, ranged from 3.51 to 3.71 mg/mL and 0.27 to 0.51 mg/mL for peroxyl radical for Falcon and AC Metcalfe fraction extracts, respectively. The corresponding values for hydroxyl radical ranged from 0.51 to 3.30 mg/mL and 0.68 to 3.75 mg/mL. Metal chelation activity was determined using the 2,2′-bipyridyl competition assay. Effectiveness of phenolic extracts in inhibiting radical-induced supercoiled DNA breakage was also evaluated. Finally, the potential of phenolic extracts in inhibiting the growth of Caco-2 human adenocarcinoma cells was determined. Barley fractions showed a high level of antiproliferative activity toward inhibition of Caco-2 human colorectal adenocarcinoma cells. Percentage inhibition of cancer cells rendered by Falcon and AC Metcalfe barley fraction extracts ranged from 14% to 74% and 21% to 57%, respectively, at 0.5 mg/mL concentration. The results indicate that barley fractions tested possess significant antioxidant and antiproliferative activities.