Structural characterization, antiproliferative and immunoregulatory activities of a polysaccharide from Boletus Leccinum rugosiceps.

A homogeneous water-soluble flaky polysaccharide named LRP-1 (18.82 kDa) was extracted and purified from the rare edible and medicinal fungi Leccinum rugosiceps. The structure characterization of LRP-1 was analyzed by GPC, GC, GC-MS, FT-IR, SEM, 1D/2D NMR, and its antitumor and immunoregulatory activities were determined. The results show that LRP-1 is a new polysaccharide with a backbone which is mainly composed of →1-α-D-Fucp-3→, →1-α-D-Rhap-3→, →1-β-D-Glcp-6→, →1-β-D-Glcp-3→, →1-α-D-Glcp-4→, →1-β-D-Galp-6 → and →1-α-D-Manp-6→. Results of MTT assay show that LRP-1 inhibit the growth of human hepatoma cells HepG-2 and human breast carcinoma MCF-7 cells in vitro. LRP-1 could also induce the secretion of NO and immune factors (IL-6 and TNF-α) of RAW264.7. This study suggests that LRP-1 has potential to be used as nutraceutical food with antitumor and immunoregulatory activities.