Structural Characterization and Immunobiological Activity of Polysaccharides from Astragalus Oyster Mushroom.

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Citation abstract

When added to mushroom growing substrates, edible and medicinal herbs affect the mushrooms' nutritional and medicinal value. In this study, polysaccharides (P 0 OP-I and P 15 OP-I) were extracted and purified from oyster mushrooms grown on substrates supplemented with 0% and 15% Astragalus roots (P 0 and P 15 ), respectively, and their chemical structure and immunobiological activities were compared. P 15 OP-I and P 0 OP-I were extracted using ultrasound-assisted hot water and deproteinized with the Sevage method, depigmented with 30% H 2 O 2, desalted with dialysis, and purified using DEAE-52 cellulose and Sephadex G-100 dextran column chromatography. The molecular weight of P 0 OP-I and P 15 OP-I was 21,706.96 and 20,172.65 Da, respectively. Both were composed of monosaccharides D -mannose, galacturonic acid, D -glucose, D -galactose, and L -arabinose but in different molar ratios, and both were connected by a pyranoside linkage. P 15 OP-I consisted of higher contents of mannose, glucose, galactose and arabinose and lower content of galacturonic acid as compared to P 0 OP-I. Both P 0 OP-I and P 15 OP-I induced NO and TNF-α production but did not show cytotoxic effect or induce ROS generation in RAW264.7 cells. P 15 OP-I showed a stronger ability to promote NO and TNF-α production relative to P 0 OP-I. In vitro experiments showed that the immunomodulatory activity of P 0 OP-I and P 15 OP-I in RAW264.7 macrophages were mediated by the JNK/MAPK, Erk/MAPK, and NF-κB signaling pathways. The results would be helpful for elucidation of the health promoting mechanism of Astragalus oyster mushrooms as a source of neutraceuticals.