Abstract:

Objective: To investigate the physicochemical properties and immunomodulating activities of different edible
mushroom polysaccharides. Methods: Water extraction-ethanol precipitation method was employed to isolate mushroom
polysaccharides. Spectrophotometry, high performance gel permeation chromatography (HPGPC), gas chromatographymass
spectrometry (GC-MS), infrared spectrometry (IR) and enzyme-linked immunosorbent assay (ELISA) were using
to analyze the physicochemical properties and immunomodulatory activities of mushroom polysaccharides. Results:
Under the same conditions, the descending order of extraction rate of five mushroom polysaccharides was Pleurotus
ostreatus polysaccharides (POP), Agrocybe chaxingu polysaccharides (ACP), Flammulina velutipes polysaccharides
(FVP), Lentinus edodes polysaccharides (LEP) and Auriculari aauricular polysaccharides (AAP). These polysaccharides
from five different mushrooms had different molecular mass distributions. All the polysaccharides consisted of mannose
(Man), glucose (Glc) and galactose (Gal) with β-configuration although ACP also contained rhamnose (Rha) and arabinose
(Ara) and AAP contained a small quantity of xylose (Xyl). Methylation analysis indicated that different polysaccharides
had different glucosidic linkage types. The main glucosidic linkage types of POP and LEP consisted of →1,3-β-Glc
and →1,6-β-Glc whereas those of ACP consisted of →1,6-β-Glc and →1,6-β-Gal and those of AAP and FVP consisted
of→1,4-β-Glc. In vitro experiment results showed that the five mushroom polysaccharides had no cytotoxicity at the
concentration ranging from 25 to 400 μg/mL, could improve the phagocytic capacity of mouse peritoneal macrophages
and promote the secretion of NO, TNF-α and IL-1β from macrophages. Among all tested polysaccharides, LEP
containing →1,3-β-Glc and →1,6-β-Glc showed the strongest immunomodulating activity followed in a descending order by POP
containing →1,3-β-Glc and →1,6-β-Glc, ACP containing→1,6-β-Glc and→1,6-β-Gal, AAP and FVP containing→1,4-β-Glc.
Conclusions: These five mushroom polysaccharides had different physicochemical properties and immunomodulating
activities. Their immunomodulating activities depended on the existence of →1,3-β-Glc and →1,6-β-Glc.

Key words: edible mushroom, polysaccharides, physicochemical properties, macrophages, immunomodulation