Isolation, structural characterization and neuroprotective activity of exopolysaccharide from Paecilomyces cicada TJJ1213

Two exopolysaccharide fractions (EPS1 and EPS2) were obtained from Paecilomyces cicadae TJJ 1213, and their structures were elucidated. The EPS1 and EPS2 were mainly composed of mannose and galactose with molar ratios of 3.2: 1.0 and 2.7: 1.0, respectively. They possessed average molecular weights of 1.69 × 10 6 and 8.06 × 10 5 Da, respectively. Structural characterization indicated that the backbone of EPS1 was consisted of →4)-α-D-Man p (1→, →3,4)-α-D-Man p (1 → and →2,6)-α-D-Man p (1→, →6)-α-D-Gal p (1→, →6)-β-D-Gal p (1→, and side chain was consisted of α-D-Man p residue. The backbone of EPS2 was composed of →6)-β-D-Gal p -(1→, →4)-α-D-Man p -(1→, →2,6)-α-D-Man p -(1 → and →6)-α-D-Gal p -(1→, and the branching point was also consisted of α-D-Man p residue. In addition, EPS1 and EPS2 had potential in protective effects of PC12 cells against hydrogen peroxide induced oxidative stress by inhibiting the production of ROS, reducing LDH leakage and alleviating mitochondrial damage. These results indicated that EPS1 and EPS2 might serve as therapeutic agents for neuronal disorders.