Physicochemical Analysis and Bioactivity Investigation of Polysaccharides Separated from Pleurotus eryngii by Ultrafiltration

Abstract:

Three different molecular weight fractions，i.e.，100 kD （PU100），10 kD-100 kD （PU10） and 1~10 kD （PU1），were separated from the extracts of Pleurotus eryngii leftover in hot water （100 ℃） by membrane ultrafiltration. The physicochemical characteristics of fractions in the extracts were characterized including the product yield，the content of total sugar and β-glucan，the distribution of molecular weight，the composition of monosaccharide and its effects on the NO release from macrophages. PU1 showed the highest yield of 14.6%，which was much higher than that of either PU10 or PU100. The β-glucan （over 50% of β-glucan） contents of PU10 and PU100 were 18.38% and 19.91%，respectively. The crude polysaccharide could be efficiently separated by ultrafiltration membrane within the range of molecular weight as HPSEC analysis suggested. There were several fractions in both PU100 and PU10. Around 73% of PU100 was the polysaccharides with molecular weight >100 kD，while the molecular weights of two components in PU10 were larger than 10 kD and the main component in PU1 was 1.11 kD. Monosaccharide composition analysis indicated 4 and 7 monosaccharides composed the polysaccharides in different fractions with significant differences in types and molar ratios of monosaccharide. The activity of stimulating RAW264.7 macrophages to release nitric oxide （NO） was observed for all of the ultrafiltration fractions，among which PU100 represented the highest activity at low concentration （50 μg/mL）.