| Summary: | 碩士 === 國立臺灣大學 === 農業化學研究所 === 103 === Xylaria nigripes (XN), also known as Wu Ling Shen, is a high value medicinal fungus belonging to the family Xylariaceae. In traditional Chinese medicine, it possesses the properties of diuretic, invigorating kidney, enhancing immune function, improving insomnia and post-surgery bleeding, and others. This study aimed to confirm the phylogenetic relationship of two cultivated XN that derived from different origins, namely TXN and CXN, as well as examining the physicochemical properties and immunomodulatory activities of polysaccharides prepared from their fruiting bodies. Based on the ITS phylogenetic analysis, TXN and CXN were confirmed to be XN and their ITS sequences have been registered in the NCBI Genbank with accession numbers KJ627786 and KJ627787, respectively. By hot water extraction and enzyme purification, the yields of purified water soluble polysaccharides of TXNP and CXNP were 8.3% and 7.8%, respectively. The FT-IR spectra of these two polysaccharides showed a relatively similar profile, which possessed the characteristic peaks of the hydroxyl group, pyranose ring and glycosidic bond. TXNP was white powders and identified to be a glucan, which had a molecular weight of 853.8 kDa coupled with triple helix conformation. While CXNP was dark brown powders and identified to be a hetropolysaccharide that had a molecular weight of 14.7 kD. The monosaccharide composition of CXNP contained xylose, mannose and glucose in a molar ratio of 41.5%, 41.4% and 17.1%, respectively. Results of these physicochemical properties suggested that TXNP and CXNP were two different kinds of polysaccharides. In the LPS-stimulated RAW 264.7 cell inflammation study, results showed that both TXNP and CXNP dose-dependently suppressed the production of IL-1, TNF-α, NO and PGE2, with the exception of IL-6. The expression of iNOS, COX-2 and NF-κB were also down-regulated by these XN polysaccharides. The MTT assay showed that TXNP and CXNP had no effect on RAW264.7 cells viability. Therefore, it implied that these inhibiting activities were actually mediated by TXNP and CXNP, not due to their cytotoxicity. In conclusion, this study indicated that hot water extracted polysaccharides from the fruiting bodies of the cultivated XN were effective in modulating the inflammation related factors, in which TXNP was more potent than CXNP; suggesting that the differences in the physicochemical properties of polysaccharides may affect their biological activities.
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