Abstract: As an extension of our previous work, where polysaccharides were extracted and purified from the rhizomes and roots of Gentiana scabra Bunge, this study was undertaken to investigate the structure and bioactivity of the polysaccharides. The type of glycosidic linkage was elucidated by methylation analysis. The backbones of the polysaccharides consisted of (→1) terminal and (1→5)-linked arabinofuranosyl, and (1→4)-linked galactopyranosyl residues with small amounts of other residues and branches. The uronic acid contained in the polysaccharides was composed of (1→4)-linked galacturonic acid residues, which played an important role in the bioactivity of the polysaccharides. The polysaccharides could enhance the proliferation of RAW264.7 cells to produce NO due to the increased mRNA expression of NO synthetase. The polysaccharides also could upregulate the mRNA expression of the cytokines COX-2 and TNF-α.

Key words: Gentiana scabra Bunge, polysaccharide, structure, immunomodulatory activity