Characterisation and immunostimulatory activity of an α-(1→6)-d-glucan from the cultured Armillariella tabescens mycelia

IPS-B2, an intracellular polysaccharide with anti-tumor effect, was isolated from cultured Armillariella tabescens mycelia by hot water extraction, anion-exchange and gel chromatography. Based on the results of paper chromatography (PC), gas chromatography (GC), infra-red (IR) spectroscopy and 13C NMR, IPS-B2 was characterized as an α-(1→6)-d-glucan with a molecular weight of 49.5 kDa. The effects of IPS-B2 on murine peritoneal macrophages were further investigated. The results demonstrated that IPS-B2 induced nitric oxide (NO) and cytokines (TNF-α, IL-1β and IL-6) production in macrophages. The outcomes of real-time reverse transcription-polymerase chain reaction (RT-PCR) proved that the transcribing level of inducible NO synthase (iNOS), TNF-α, IL-1β and IL-6 mRNA in the peritoneal macrophages have been augmented by IPS-B2. These data suggest that the anti-tumor activity of the polysaccharide from A. tabescens may due to activation of macrophage.