Structural characterization of a low molecular weight polysaccharide from Grifola frondosa and its antitumor activity in H22 tumor-bearing mice

Abstract

• A low molecular weight polysaccharide (LMw-GFP) was isolated from Grifola frondosa by ultrafiltration. • Structural characteristics of LMw-GFP were identified by HPGPC, MS, FT-IR, GC, NMR and methylation analysis. • LMw-GFP could inhibit the growth of solid tumor via activating anti-tumor immune responses in H22 tumor-bearing mice. • The apoptotic properties of H22 solid tumors in different groups were further investigated. A novel low molecular weight polysaccharide from Grifola frondosa (LMw-GFP) was prepared in this study, and its structural characteristics and antitumor mechanism in vivo were further investigated. The results showed that LMw-GFP contained 95.83% carbohydrate, 0.34% protein and 0.21% uronic acid, with the average molecular weight of approximately 1.79 × 10 3 Da. Additionally, FTIR, GC, NMR and methylation analysis further demonstrated that LMw-GFP was a homogeneous polysaccharide composed of α-T-Glc p (28.26%), α-1 → 4-Glc p (50.24%) and α-1 → 3,4-Glc p (21.50%). The in vivo antitumor experiments showed that LMw-GFP exhibited antitumor effects on H22 hepatoma cells with an inhibitory ratio of 40.1% via protecting immune organs and enhancing the activities of NK cells, macrophages and lymphocytes. Besides, the H&E staining, cell cycle analysis and fluorescent staining results showed that LMw-GFP could induce H22 solid tumor cells apoptosis in vivo via mitochondrial apoptotic pathway.