Structural Characterization and Antifatigue Activity of a Novel Exopolysaccharide Isolated from Marasmius androsaceus

This study aimed at examining the structure-role modeling and antifatigue mechanism of polysaccharides, including M. androsaceus exopolysaccharide 3 (MEPS3), isolated from Marasmius androsaceus fermentation broth. The molecular weight of MEPS3 was 10.47 kDa. Furthermore, monosaccharide analysis showed the presence of mannose, glucose, and galactose in MEPS3 in a molar ratio of 0.08: 0.34 :1.46. Mannose, a-galactose, and a-d-glucose anomeric hydrogen signals were detected using nuclear magnetic resonance spectroscopy. MEPS3 was found to contain glyoxylic acid, forming rod-like chains that support high-purity polymerization. The weight-loaded swimming test results showed that MEPS3 treatment reduced lactic acid (LA) levels by 25.72% and increased the lactate dehydrogenase (LDH) activity by 5.67% in the plasma. Furthermore, it lowered malondialdehyde (MDA) levels by 47.09% and increased reactive oxygen species (ROS) and glutathione peroxidase (GSH-Px) levels by 52.42 and 97.03%, respectively, in the plasma. In addition, MEPS3 treatment reduced MDA and ROS levels in the liver by 28.85 and 18.64% while increasing superoxide dismutase (SOD) and GSH-Px levels by 17.41 and 38.13%, respectively. MEPS3 treatment increased the expression of nuclear factor-erythroid 2-related factor 2, glutamate-cysteine ligase, quinone oxidoreductase 1, and heme oxygenase 1 by 22.5, 24.8, 20.3, and 43.1%, respectively, in the liver. These findings demonstrate that MEPS3 efectively alleviates fatigue by removing harmful metabolites and indicate that the antifatigue mechanism is related to the Nrf-2 signaling pathway.