Characterization and Antitumor Effect of a Novel Polysaccharide from Grifola frondosa

Abstract

A novel polysaccharide, MZF, with a molecular mass of 23 kDa was isolated from Grifola frondosa. Results from methylation and ¹H NMR led to the conclusion that MZF is a heteropolysaccharide consisting of →6)-α-d-Galp-(1→ (36.2%), →3)-α-l-Fucp-(1→ (14.5%), →6)-α-d-Manp-(1→ (9.4%), →3)-β-d-Glcp-(1→ (10.1%), α-d-Manp-(1→ (23.2%), and →3,6)-β-d-Glcp-(1→ (6.5%). Although MZF did not affect the proliferation of colon-26 cells in vitro, it significantly inhibited tumor growth in BALB/cA mice inoculated with colon-26 cancer cells. Moreover, MZF significantly induced the proliferation of splenocytes and peritoneal macrophages. The mRNA expression of IL-12p40, IL-2 and IFN-γ were increased significantly in MZF-treated spleen. Furthermore, MZF augmented the percentage of IFN-γ-producing cells in both splenic CD4⁺ and CD8⁺ T cells and tumor infiltrating CD4⁺ and CD8⁺ T cells and enhanced the cytotoxic activity of NK cells and CTLs. These results indicate that MZF is a novel effective immunomodulator that has antitumor activity associated with induced cell-mediated immunity.