Structure characterization of two functional polysaccharides from Polygonum multiflorum and its immunomodulatory

Two purified polysaccharides named WPMP-1 and WPMP-2 were obtained from Polygonum multiflorum with an average molecular weight of 2.04 kDa and 92.13 kDa, respectively. Structural characterization revealed that WPMP-1was supposed to be a glucan composed of 1,4-linked α-d-Glcp, 1,4,6-linked α-d-Glcp, and terminal α-d-Glcp. WPMP-2 contained a complex branched structre formed by 1,2-linked α-d-Rhap, 1,2,4-linked α-d-Rhap, 1,3,5-linked α-l-Ara, 1,5- linked α-l-Araf, terminal α-l-Araf, 1,4-linked β-d-Galp, 1,4-linked α-d-GalpA, and 4-linked α-d-GalpA. In vitro, WPMPs were of activation effect on splenocyte and macrophages, and could also protect immunocyte against 5-Fu induced immunosupression by restoring the proliferation rate, phagocytic index and cytokines secretion level. Moreover, the acid polysaccharide WPMP-2 exhibited better immunomodulatory activity than neutral polysaccharide WPMP-1, which indicated that the immunomodulatory activity of WPMPs were positively associated with higher content of uronic acid, percentage of rhamnose, arabinose and galactose, and branching degree. These findings could promote the polysaccharides from Polygonum multiflorum to be attractive functional food supplement and immunomodulatory adjuvant.