RAW264.7 Cell Activating Glucomannans Extracted from Rhizome of Polygonatum sibiricum

Water-soluble polysaccharides isolated from the rhizome of Polygonatum sibiricum and fractionated using ionexchange chromatography were investigated to determine their structure and immunostimulating activity. Crude and fractions ($F_1$ and $F_2$) consisted of carbohydrates (85.1~88.3%) with proteins (4.51~11.9%) and uronic acid (1.79~7.47%), and included different levels of mannose (62.3~76.3%), glucose (15.2~20.3%), galactose (4.35~15.3%), and arabinose (4.00~7.65%). The crude contained two peaks with molecular weights (Mw) of $151{\times}10^3$ and $31.8{\times}10^3$, but $F_1$ and $F_2$ exhibited one major peak with Mw of $103{\times}10^3$ and $628{\times}10^3$, respectively. Little immunostimulatory activity was observed by the crude; however, $F_1$ and $F_2$ significantly activated RAW264.7 cells to release nitric oxide and various cytokines, suggesting they were potent immunostimulators. The backbone of the most immunostimulating fraction ($F_1$) was ($1{\rightarrow}4$)-manno- and ($1{\rightarrow}4$)-gluco-pyranosyl residues with galactose and glucose attached to O-6 of manno-pyranoside.