Antioxidant activities of an exopolysaccharide isolated and purified from marine Pseudomonas PF-6

An acidic exopolysaccharide (EPS) was isolated and purified from marine Pseudomonas PF-6. The test of physical properties indicated that the EPS was odorless, soluble in water, insoluble in organic solvents, and had a molecular weight of 8.83 × 105 Da. The test of chemical properties of the EPS showed that the EPS could be oxidized into uronic acid. Infrared spectrometry analysis exhibited absorption bands at 927.49 cm−1 and 811.76 cm−1, suggesting that the EPS belonged to a β-type heteropolysaccharide with a pyran group. Several in vitro assays were applied to evaluate the antioxidant potential of the EPS. Results showed that the acidic EPS had scavenging actions on DPPH·, ·OH and O2−· and the antioxidant activities increased with increases in its concentration. The scavenging action of the EPS on ·OH was stronger than that of Vc, and its activity on O2−· was almost the same as that of Vc.