Structure elucidation and bioactivities of a new polysaccharide from Xiaojin Boletus speciosus Frost

A new water-soluble polysaccharide named BSF-X was extracted and purified from the fruiting bodies of Boletus speciosus Frost which had a molecular weight of 141,309 Da. The structure identification results showed that BSF-X was mainly composed of β-d-glucose and α-D-galactose. BSF-X had a backbone of 1, 4-linked β-d-glucose of which branches were mainly composed of two 1, 6-linked α-D-galactose residue and a 4-linked β-d-glucose at the end of the branches. Antitumor activities results showed that BSF-X could inhibit the proliferation of L929 cells in vitro and S180 tumor cells in vivo. Immunoregulatory activities results showed that BSF-X could promote the proliferation of T cells, B cells and macrophages by promoting the cells into S phase from G0/G1 phase. Polysaccharide BSF-X can also enhance the phagocytes is and cytokine secretion of macrophages. This study introduced the new polysaccharide BSF-X as a valuable source which exhibit unique antitumor and immunoregulatory properties.