A polysaccharide from Morchella esculenta mycelia: Structural characterization and protective effect on antioxidant stress on PC12 cells against H2O2-induced oxidative damage

Morchella esculenta (L.) Pers. is considered a precious edible and medicinal fungus due to its strict growth environment requirements, difficult to cultivate, resulted in expensive in the market. A polysaccharide (MMP-L) was isolated from the mycelia of Morchella esculenta, with molecular weight of 3.02 x 103 kDa. MMP-L was composed of galactose, glucose, and mannose in a molar ratio of 1.00: 12.89: 0.29. Structural characterization showed that MMP-L had a backbone mainly consisting of-*4)-alpha-D-Glcp-(1-*,-*6)-alpha-D-Glcp-(1-*,-*4,6)-alpha-DGlcp-(1-*,-*2)-alpha-D-Galp-(1-*,-*3)-alpha-D-Manp-(1-*, and-*4,6)-alpha-D-Manp-(1-*, and branched chains incorporating of alpha-D-Glcp(1-*. The antioxidant activity test results indicated that MMP-L has effective scavenging ability against 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2 ' 2-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS), and hydroxyl radicals. Within the range of concentration (0.05-3.20 mg/mL), MMP-L increased the enzyme activity of superoxide dismutase (SOD) and glutathione (GSH) in H2O2-induced PC12 cells in a dose-dependent manner, while inhibiting the content of lactate dehydrogenase (LDH) and malondialdehyde (MDA). Furthermore, the decrease in reactive oxygen species (ROS) and apoptosis in PC12 cells may be attributed to the activation of the PI3K/Akt signaling pathway and downstream mitochondrial apoptosis-related protein Bcl-2/BAX/Caspase-3 signaling pathways. In summary, MMP-L might serve as a potential functional components for the future prevention and treatment of neurodegenerative disorders caused by oxidative damage.