Antioxidant activity of broad bean seed extract and its phenolic composition

The crude acetonic extract of broad bean seeds was separated into fraction I (low-molecular-weight compounds) and fraction II (tannin fraction) using Sephadex LH-20 column chromatography with ethanol and acetone/water (1:1, v/v) as the mobile phases. Phenolics present in the crude extract and fractions thereof showed antioxidant and radical-scavenging properties determined using several methods (emulsion system, ABTS, DPPH, and reducing power assays). Fraction II exhibited higher antioxidant efficacy than those of the crude extract and fraction I. In the crude extract, 14 compounds, namely phenolic acids (p-coumaric, ferulic), catechins (epicatechin, epicatechin glucoside, epicatechin gallate), procyanidin gallate, prodelphidin dimer, gallate procyanidin dimer, and digallate procyanidin dimer, were identified by HPLC-DAD-MS. Catechin gallate, digallate procyanidin dimer, and gallate procyanidin dimer were the major phenolics present in the extract.