Antioxidant properties of feruloylated oligosaccharides of different degrees of polymerization from wheat bran

In this study, four main components of feruloylated oligosaccharides (FOs),FOs-1, FOs-2, FOs-3 and FOs-4,were isolated from wheat bran by use of Amberlite XAD-2 and Sephadex LH-20. Structural characterization of FOs was determined by use of high performance liquid chromatography (HPLC), gas chromatography (GC) and fourier transform-infrared spectroscopy (FT-IR). Antioxidant properties were investigated in vitro. Average degrees of polymerization (DP) of the four components (FOs-1, FOs-2, FOs-3 and FOs-4) were approximately 10.6, 7.7, 6.1 and 3.4, respectively. In addition, DP were consistent with molar ratios of arabinose and xylose in 1:9.46, 1:5.30, 1:2.91 and 1:0.19, respectively. The presence of -glycosidic linkage was confirmed at 896cm-1 by use of FT-IR. In vitro antioxidant studies demonstrated that FOs-1, FOs-2, FOs-3 and FOs-4 possessed significant antioxidant activities in the dose-dependent manner. In addition, the degree of polymerization affected antioxidant capacity. These results have improved our understanding of the relationship between FOs with different structural types and their antioxidant activities.