Evaluation of antioxidant capacity of ulvan-like polymer obtained by regioselective oxidation of gellan exopolysaccharide

► Native gellan was subjected to oxidation at C6 with NaOCl in the presence of TEMPO. ► Four carboxylated polysaccharides with different uronics acid content were obtained. ► The antioxidant properties of gellan and its uronide derivatives were evaluated. ► The high uronic acids could promote the antioxidant activities.