Mushrooms have become popular sources of natural antitumor, antiviral, antibacterial, antioxidative, and immunomodulatory agents. Golden oyster mushroom, Pleurotus citrinopileatus , is a common mushroom in oriental countries for human consumption. We isolated a functional protein (PCP-3A) from the fresh fruiting body of this mushroom. The isolation procedure included ammonium sulfate fractionation, DEAE-Sepharose CL-6B ion exchange chromatography, and Sephacryl S-300 gel filtration. Electrophoresis demonstrated that PCP-3A is a glycoprotein composed of 10 subunits, each approximately 45.0 kDa in size. In vitro cell study showed that PCP-3A at a concentration about 12.5 microg/mL inhibits the proliferation of human tumor cell line U937, in a time- dependent manner (24, 48, and 72 h). It failed to agglutinate rabbit and human erythrocytes, excluding its possibility from being a lectin. Flow cytometry revealed that it is capable of inhibiting the growth of U937 cells by way of S phase arrest and apoptotic induction. We suggest that PCP-3A is worth further investigating for antitumor use.

A novel hemolysin was isolated from the edible mushroom Pleurotus nebrodensis by ion exchange and gel filtration chromatography on DEAE-Sepharose and Sephacryl S-100. The hemolysin from Pleurotus nebrodensis hemolysin (nebrodeolysin) is a monomeric protein with a molecular weight of approximately 27 kDa as determined by gel filtration and SDS-PAGE. Nebrodeolysin exhibited remarkable hemolytic activity towards rabbit erythrocytes and caused efflux of potassium ions from erythrocytes. Subsequently, this hemolysin showed strong cytotoxicity against Lu-04, Bre-04, HepG2, L929, and HeLa cells. It was also found that this hemolysin induced apoptosis in L929 and HeLa cells as evidenced by microscopic observations and DNA ladder, respectively. Moreover, this hemolysin was shown to possess anti-HIV-1 activity in CEM cell culture.