Isolation and characterization of phenolic compound from Allium hookeri root for potential use as antioxidant in foods

This study was carried out to identify phenolic compounds with antioxidant activity from Allium hookeri root (AHR). A methanol extract of AHR was sequentially fractionated and separated based on solvent polarity (methylene chloride, ethyl acetate, and n-butanol) using column chromatography (Sephadex LH-20 and Kiesel gel 60). The antioxidant activity of AHR was investigated by assessing the 1,1-diphenyl-1-picrylhydrazyl radical scavenging activity (DPPH RSA), superoxide quenching activity (SQA), and superoxide radical scavenging activity (SRSA) of the isolated fractions. Based on the DPPH RSA results and yield of each fraction, the n-butanol fraction (8.4-85.2% and 3.9%) was selected for further analysis. There was no significant difference between the EC₅₀ value for SRSA of compound 1 purified from the n-butanol fraction and ascorbic acid. We identified compound 1 using mass spectrometry (MS) and nuclear magnetic resonance (NMR) as ferulic acid-4-O-β-Dglucopyranoside (FAG). Thus, this is the first report of a FAG isolated from AHR.