Abstract: The differences of physicochemical properties and macrophages-activation activity of crude polysaccharides extracted from Pleurotus eryngii leftover with different particle sizes were compared in this paper.The results revealed that average particle sizes of fine powder and ultrafine powder were 83.548 μm and 17.553 μm,respectively.Ultrafine powder showed well uniformity.Crude polysaccharide yields of fine powder and ultrafine powder of  P.eryngii leftover were 3.04 times and 4.14 times higher than that of fragments,respectively.Meanwhile,the contents of polysaccharides and β-glucan in crude polysaccharides also increased.The high performance size exclusion chromatography-multiple angle laser light scattering-viscostar-refractive index detector (HPSEC-MALLS-VS-RI) was adopted to determine the molecular weight and characteristics of these fractions.Analysis results indicated that all three crude polysaccharides mainly contained three fractions with different molecular weights.High molecular weight fractions (Fraction 1 and 2) with Mw higher than 1×10⁶ Da possessed higher proportion in grinding powder compared with that in the fragments.Furthermore,the molecular weight of all fractions in crude poloysaccharides extracted from fine powder and ultrafine powder was higher than that of the corresponding fractions from fragments.Monosaccharide composition analysis indicated that all crude polysaccharides consisted of 5 monosaccharides with varied molar ratios.The molar ratio of glucose increased along with the increasing of degree of grinding.All samples exhibited activities on stimulating RAW 264.7 macrophages to release NO.

Key words: Pleurotus eryngii leftover;ultrafine powder, β-glucan;monosaccharide composition analysis;molecular weight distribution;macrophages-activation activity