Antioxidant and Immunomodulating Activities of Exo- and Endopolysaccharide Fractions from Submerged Mycelia Cultures of Culinary-Medicinal Mushrooms

A number of mushrooms are known to possess pharmacological activities. In this study, the phenolic and flavonoid contents of extracts of exo- and endopolysaccharide fractions obtained from submerged mycelia cultures of 7 edible or medicinal mushroom species, as well as their antioxidant and immunomodulatory properties, were evaluated. The exo- and endopolysaccharide yields were 0.576-1.950 and 0.438-0.933 g/L, respectively. The sugar and protein contents of these fractions were analyzed and contained predominantly sugars (52.3-87.6%). The exo- and endopolysaccharide fractions contained appreciable amounts of phenolics and flavonoids. The highest flavonoid contents were found in Cryptosporus volvatus (349.6 mg/g), followed by Cordyceps militaris (312.6 mg/g). The antioxidant activities were evaluated by 4 assays: biological assay using Saccharomyces cerevisiae, DPPH radical scavenging activity, chelating ability for ferrous ions and ferric reducing antioxidant power. The mycelia polysaccharide fractions had more ferric reducing antioxidant power than other antioxidant activities. Both exo- and endo polysaccharides of C. volvatus inhibited production of the T lymphocyte Th1 cytokines interferon (IFN)-gamma and interleukin (IL)-2, the Th2 cytokines IL-4 and IL-5, and macrophage enzyme activity. Although those from C. militaris had similar inhibitory effects on cytokine production, the exopolysaccharides stimulated macrophage enzyme activity. The other exopolysaccharides (Pleurotus citrinopileatus, P australis, and P pulmonarius) inhibited IFN-gamma and IL-5 production, but they had varying effects on IL-2 and IL-4 production. Only 3 exopolysaccharides (P pulmonarius, Tremella mesenterica, and Cordyceps sinensis) also stimulated macrophage enzyme activity to the same extent as lipopolysaccharides. All of them reduced IL-5 production, but those from T mesenterica also inhibited IFN-gamma, IL-2, and IL-4 production. Thus the polysaccharide fractions from the mushrooms studied have antioxidant activities and general immunomodulating effects in vitro.