Purification and Characterization of an Immuno-Stimulatory Compound from the Water Extract of Royoporus Badius (Pers.) A.B. De.

Five years ago, a novel immuno-stimulatory polysaccharide-protein complex (ISPP-Rb) was isolated from Royoporus badius sporocarps found in northern BC forests. The complex was purified using anion-exchange and size-exclusion chromatography and was found to significantly activate murine macrophage cells. The ISPP-Rb, with an average molecular weight of 400 kDa, is highly branched and its polysaccharide component has a backbone of (1 → 6)-Gal/Man and (1 → 2,6)-Glc. The protein component, which is essential for its immuno-stimulatory activity, is proposed to link to a mannose residue via O-linked glycosylation. ISPP-Rb was able to induce various proinflammatory cytokines including TNF-α, IP-10, MIP-2, G-CSF, GM-CSF, MIP-1α, and MIP-1β. This was the first immuno-stimulatory compound reported from R. badius, making ISPP-Rb novel.