Preparation, structural characterization and antioxidant activity of an extracellular polysaccharide produced by the fungus Oidiodendron truncatum GW

► Exopolysaccharide Os2-1 was prepared from Oidiodendron truncatum GW. ► Os2-1 is mainly composed of glucose with minor amounts of glucosamine. ► The backbone of Os2-1 mainly consists of (1→6)-linked glucopyranose residues. ► Os2-1 possessed a good antioxidant activity in vitro. ► Os2-1 was a novel exopolysaccharide and potential source of antioxidant.