Structure-antioxidant activity relationship of xylooligosaccharides obtained from carboxyl-reduced glucuronoarabinoxylans from bamboo shoots

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 (R). 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 beta -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 similar to 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.