Structural Elucidation and Immune-Enhancing Effects of Novel Polysaccharide from Grifola frondosa

Beta-glucan (β-glucan) is a macromolecule structure where glucose unit has bonded through β-glycosidic bond at 1 and 3 positions. It is well known as a natural immunomodulator without exhibiting any side effects via enhancing immunity. Mushroom contains a large amount of β-glucan and it has anticancerous and antioxidant efficacy. Structure and physical properties of β-glucan are highly influenced by the types of mushroom. In particular, Grifola frondosa has β-1, 3 and β-1, 6 bonds in their structure. It has been noted that β-glucan content also depends upon the size of mushroom particles. The exact content of β-glucan and their immunological activity by a particle size of G. frondosa have yet to be fully elucidated. Herein, β-glucan contents were analyzed according to the particle size of leaf mushroom followed by cell activation and immunoactivity analysis. The highest β-glucan content was observed at a particle size of 20-30 μm (27.65 ± 0.30 w/w). All samples showed ~ 103% cell activation compared to the control and greater cell activity was observed at higher concentration. The significant increase in cytokines secretion was observed in the presence of 20-30 μm particle size of G. frondosa compared to the control. This study suggested that 20-30 μm size is the suitable size of G. frondosa that can be used as a health supplement and food additive to act as an immune booster, hypotensive agent, and hypoglycemic agent.