Characterization and antioxidant activities of intracellular polysaccharides from Agaricus bitorquis (QuéL.) Sacc. Chaidam ZJU-CDMA-12.

The antioxidant activities of polysaccharides from the fruiting body (PFB), extracellular polysaccharides (EPS) and intracellular polysaccharides (IPS) from Agaricus bitorquis (QuéL.) Sacc. Chaidam ZJU-CDMA-12 in vitro were compared. IPS showed stronger antioxidant activities than PFB and EPS in vitro. Further purification and structure analyses indicated that IPS mainly consisted of three fractions (IPS-I, IPS-II and IPS-III). FT-IR and NMR data indicated that IPS was mainly composed of (1 → 6)-linked α-d-glucose. There are significant differences of antioxidant activities among IPS-I, IPS-II and IPS-III fractions in vitro, and IPS-III showed stronger antioxidant activity than IPS-I and IPS-II. IPS-III also possesses a potent antioxidant ability inside HepG2 cells, and it could protect HepG2 cells from HO-induced cytotoxicity by scavenging overproduced cellular ROS and inhibiting SOD, CAT and GSH depletion to weaken lipid peroxidation. These findings suggested that IPS-III could be a novel antioxidant and that it could afford protection against HO-induced cytotoxicity and oxidative stress.