| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1385663 | Carbohydrate Polymers | 2015 | 8 Pages |
•Xanthan was successfully C-6 carboxylated by TEMPO/NaOCl/NaBr media system.•A new family of polyglucuronic acid called xanthouronan was generated.•Xanthouronan was a high molecular weight polysaccharide with antioxidant properties.•Xanthouronan was very resistant to various enzymatic treatments.
A xanthouronic acid sodium salt called xanthouronan was produced from xanthan by regioselective oxidation with NaOCl/NaBr using 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO) as catalyst. The efficiency of the one pot TEMPO-mediated oxidation was confirmed by HPAEC-PAD, 13C NMR, and FT-IR. The oxidation degree was close to 98% and the mass yield of this new polyglucuronic acid was higher than 90% (w/w). The macromolecular characterization of xanthouronan using SEC-MALLS showed a molecular size reduced by a third due to the oxidation treatment and the degree of polymerization (DP) of the xanthouronan form was about 665. The evaluation of the enzymatic degradation of this C-6 carboxylated xanthan by various polysaccharide hydrolases and one polysaccharide lyase showed its high resistant to biodegradation. The antioxidant activity of xanthouronan was also tested by using the 2,2′-diphenyl-1-picrylhydrazyle (DPPH) and hydroxyl radical procedures. At 1 g/L, xanthouronan presented 75% of the ascorbic acid antioxidant activity.
