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

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 x 10(3) Da. Additionally, FTIR, GC, NMR and methylation analysis further demonstrated that LMw-GFP was a homogeneous polysaccharide composed of alpha-T-Glcp (28.26%), alpha-1 -> 4-Glcp (50.24%) and alpha-1 -> 3,4-Glcp (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.