Antioxidant activity of phosphorylated exopolysaccharide produced by Lactococcus lactis subsp. lactis.

Exopolysaccharide (EPS) of Lactococcus lactis subsp. lactis was isolated and purified from MRS culture broth. Phosphorylated exopolysaccharide (P-EPS) was synthesized by using the purified EPS and sodium hexametaphosphate (SHMP). The in vitro and in vivo antioxidant activity of EPS and P-EPS was analyzed. Both EPS and P-EPS displayed superoxide anion (O(2-•)), hydroxyl radical (OH•) and DPPH scavenging activity. Catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity increased in serum and the livers of mice treated with EPS and P-EPS, while malondialdehyde (MDA) levels decreased. P-EPS was shown to prevent the progression of D-galactose-induced oxidative stress in hepatocytes in vivo. P-EPS showed stronger in vitro and in vivo antioxidant activity than EPS.