Polysaccharides fractionated from enzyme digests of Korean red ginseng water extracts enhance the immunostimulatory activity.

Polysaccharide with the enhanced immunostimulatory activities including intestinal immune system modulation was fractionated from Korean red ginseng (KRG) and its characteristics were investigated in the present experiment. When the water extracts were digested with α-amylase and amyloglucosidase and precipitated by ethanol to enhance immunostimulatory activity, enzyme digested-crude polysaccharides enhanced the macrophage and intestinal immune system via Peyer's patches compared to non-enzymatic crude polysaccharides. Starch-like polysaccharide also potently decreased in enzyme digested-crude polysaccharides. Especially, crude polysaccharide (RG-CW-EZ-CP) from the digest of cold water extracts showed significantly the most active immunostimulatory activities. By precipitation using ethanol concentrations (distilled water:ethanol = 1:4 and 1:8), two immunostimulatory polysaccharides (RG-CW-EZ-CP-4 and RG-CW-EZ-CP-8) were further fractionated from RG-CW-EZ-CP. In chemical analysis, RG-CW-EZ-CP-4 and RG-CW-EZ-CP-8 seems to be a pectic-like acidic polysaccharide and arabinose-rich polysaccharide, and heat treatment of polysaccharides (RG-CW-EZ-CP-4 and RG-CW-EZ-CP-8) did not significantly affect the intestinal immune system-modulating activity. RG-CW-EZ-CP-8 also significantly upregulated the phosphorylation of three major mitogen-activated protein kinases (MAPKs), including c-Jun N-terminal kinase, extracellular signal-regulated kinase, and p38. Thus, enzymatic digestion of KRG cold water extracts played a very important role in the isolation of the enhanced immunostimulatory polysaccharides from KRG.