In vitro anti-oxidant activity of xylo-oligosaccharides derived from cereal and millet brans – A comparative study

Xylo-oligosaccharides (XO) were obtained from the respective WUP (water unextractable polysaccharides) of rice, ragi, wheat and maize brans by the xylanase action in 3.31%, 15.60%, 40.00% and 9.33% yields, respectively. Sugar composition of XO mixtures as analysed by GLC indicated arabinose:xylose in a relative ratio of 3.6:1; 1:2.43; 1:5.13 and 1:1.25 for rice, ragi, wheat and maize, respectively. The presence of phenolic acids in xylo-oligosaccharide mixtures was ascertained by high-performance liquid chromatography (HPLC) on C-18 column. Antioxidant activity of the xylo-oligosaccharide mixtures was carried out by three different methods that is (a) 1,1-di phenyl-2 picryl-hydrazyl (DPPH), (b) β-carotene emulsion and (c) ferric reducing anti-oxidant power (FRAP) assays. XO mixture of ragi exhibited relatively higher antioxidant activity compared to the XOs of rice, wheat and maize by DPPH and FRAP assays.