Antioxidant and cytotoxicites of Pleurotus eryngii residue polysaccharides obtained by ultrafiltration

Response surface methodology was used to optimize the extraction of polysaccharides Pleurotus eryngii residue (CPPS). The yield of CPPS was 10.69 ± 0.31% under the modified condition (leaching temperature of 70 °C, leaching time of 140 min and ratio of water to raw material of 25 mL/g). Ultrafiltration technology was used for further purification of polysaccharides and two fractions of CPPS-1 and CPPS-2 with different molecular weight ranges were obtained. The antioxidant and cytotoxicities of CPPS-1, CPPS-2 and CPPS were determined in vitro. The results showed that CPPS-1 had the strongest activity. Western blotting results showed that the expression of tumor suppressor p53 and apoptosis activator Bax were up-regulated by CPPS-1 (PEPE-3) fraction while the expression of Bcl-2 was down-regulated. Our results suggested that the antitumor activity of PEPE-3 may be related to its capability in inducing apoptosis via activation of mitochondria apoptosis pathway.