Structure-antioxidant activity relationship of xylooligosaccharides obtained from carboxyl-reduced...

Xylooligosaccharides (XOs) have shown high potential as prebiotics with nutritional and health benefits. In this work, XOs were obtained from highly purified, carboxy-reduced glucuronoarabinoxylans by treatment with Driselase®. The mixtures were fractionated, and the structures were elucidated by methylation analysis and NMR spectroscopy. Antioxidant activity was determined by the methods of DPPH and β-carotene/linoleic acid. It was found that the most active oligosaccharides (P3 and G3) comprised 4 or 5 xylose units, plus two arabinoses and one 4-O-methylglucose as side chains, their sequence of units was determined. The optimal concentration for their use as antioxidants was 2 mg/mL. The synthetic antioxidant butylated hydroxytoluene (BHT, 0.2 mg/mL) showed a percentage of inhibition 15% higher than P3. Although its concentration was ∼10 times higher, P3 is non-toxic, and could have great advantages as food additive. These results show that pure XOs exert significant antioxidant activity, only due to their carbohydrate nature.