Optimization of Degradation Conditions with PRG, a Polysaccharide from Phellinus ribis, by RSM and the Neuroprotective Activity in PC12 Cells Damaged by Aβ25-35

In the previous work, we found PRG, a polysaccharide from Phellinus ribis, exhibited neurotrophic activity. To obtain an active structural unit with lower molecular weight, PRG was degraded to prepare the degraded PRG (DPRG) using ascorbic acid and H2O2. The aim of the paper was to obtain DPRG by optimizing the degradation conditions using response surface methodology (RSM) and to study its protective effects of PC12 cells induced by A beta(25-35). The optimum conditions were as follows; the concentration of H2O2-Vc was 17 mM and degradation temperature was 50 degrees C; when degradation time was 1.6 h, the experimental response value of PC12 cell viability was 83.4 +/- 0.15%, which was in accordance with the predicted value (83.5%). We also studied the protective effects of DPRG against the A beta(25-35)-induced neurotoxicity and explored the underlying mechanism. The results showed that treatment with DPRG could attenuate PC12 cells death. The mechanism was relative to the inhibition of cell apoptosis by increasing the MMP level and decreasing the protein expression of cytochrome C (Cytc) in PC12 cells. In conclusion, DPRG with lower molecular weight was obtained successfully. It possessed neuroprotective properties and might be a candidate for neurodegenerative disease treatment.