Physicochemical properties and bioactivities of Lentinula edodes polysaccharides at different development stages

Lentinula edodes polysaccharides from at four different development stages (referred to L1, L2, L3 and L4, respectively) were extracted by hot water method, and graded ethanol precipitation to final concentration of 20%, 50% and 70%, then12 crude polysaccharide fractions (referred to L1P20, L2P20, L3P20; L4P20, L1P50, L2P50, L3P50, L4P50 and L1P70, L2P70, L3P70, L4P70, respectively) were obtained. Physicochemical properties and exoteric bioactivities of the crude polysaccharide fractions were measured. The results of physicochemical properties revealed that extraction yields of P20 fractions were significantly higher than those of P50 and P70 fractions, and the contents of polysaccharide and β-glucan in L3P50 fractions were higher, and the viscosity-average molecular weight reached a maximum at L2, and high molecular weight polysaccharides could be obtained at a low alcohol concentration in P20 fractions, and the glycosidic bonds were found to exist in all crude polysaccharide fractions. These crude polysaccharide fractions showed different bioactivities, wherein the polysaccharides of higher molecular weight in P20 fractions had greater bioactivity. These results showed that immature stage of Lentinula edodes was the optimal harvest time for obtaining higher bioactivity of crude polysaccharides.