Antioxidant, antitumor and immunostimulatory activities of the polypeptide from Pleurotus eryngii mycelium

The objective of this study was to investigate the antioxidant, antitumor and immunological activities of the polypeptide from Pleurotus eryngii mycelium (PEMP). The ability of the polypeptide to stimulate Ana-1 macrophages to englobe neutral red, secrete NO, H2O2, TNF-alpha, and IL-6, increase TLR2 and TLR4 expression levels and Ana-1 cell survival rate were investigated to study its immunocompetence. Its antitumor activities were studied by examining the survival of cervical, breast, and stomach cancer cells. The antioxidant activities of the polypeptide were studied by examining its reducing power and its ability to scavenge DPPH, O-2(-), and (OH-)-O-center dot radicals. The results showed that the PEMP was a good antioxidant with antitumor and immunostimulatory activities that was concentration dependent. At concentrations from 0.05 to 2 mg/mL, it inhibited the proliferation of cancer cells, but promoted the proliferation of macrophages, TNF-alpha and IL-6 secretion, TLR2 and TLR4 expression and increased macrophage phagocytic ability through NO and H2O2 release. From 0.2 to 1 mg/mL, the polypeptide had strong reducing power to clear free radical of DPPH, O-2(-), (OH-)-O-center dot, with a concentration-response relationship. Based on these results, PEMP has potential applications in functional foods as a natural anti-aging and anti-virus agent with antioxidant and immunostimulatory activities. (C) 2017 Elsevier B.V. All rights reserved.