An antioxidant exopolysaccharide devoid of pro-oxidant activity produced by the soil bacterium Bordetella sp. B4

► An exopolysaccharide was purified from Bordetella sp. B4. ► The exopolysaccharide has antioxidant but no pro-oxidant activity. ► The exopolysaccharide protected human umbilical vein endothelium cells from high glucose-mediated damage. ► The production of EPS reached to 10.2 g/L when cholesterol was added to the culture medium.