Antioxidant and Neuroprotector Influence of Endo-Polyphenol Extract from Magnesium Acetate Multi-Stage Addition in the Oak Bracket Medicinal Mushroom, Phellinus baumii (Agaricomycetes)

The objective of this study was to explore the effect of magnesium acetate (MA) addition on the endo-polyphenol yield by Phellinus baumii and establish a feasible additive strategy. The optimal three-point MA addition strategy (0.05 g/L concentration of MA added at 0 h and 6 h, 0.9 g/L concentration of MA added at 12 h) was employed to obtain maximum endo-polyphenol yield. The maximum endo-polyphenol production was reached at 1.22 g/L, which was 1.39-fold higher than that of the control. Additionally, the endo-polyphenol showed stronger antioxidant activity in vitro compared with the control, including DPPH· scavenging capacity (78.76%) and Trolox equivalent antioxidant capacity (TEAC) (32.28 μmol Trolox/g sample). HPLC analysis showed that the endo-polyphenol production of the crude ethanol extracts was significantly higher than that of the control. Hispidin was isolated and identified from the ethanol extract of the culture mycelia from Ph. baumii with the three-point MA addition strategy. Hispidin showed a strong ability to scavenge DPPH free radicals and TEAC, equivalent to positive (vitamin C) value of 89.41% and 75.98%, respectively. Furthermore, hispidin protected H2O2-induced PC12 cells injured by decreased oxidative stress level. These results indicated that the MA multi-stage addition strategy was dependable, and could be used to develop new natural antioxidants for foods or medicines.