The activation of RAW264.7 murine macrophage and natural killer cells by glucomannogalactan polysaccharides from Tornabea scutellifera

Abstract

A water-soluble polysaccharide was isolated from Tornabea scutellifera and fractionated using a DAEA Sepharose FF column to evaluate its capacity to stimulate natural killer (NK) cells and macrophages. Neutral sugars (71.8–93.5%) constituted the major part of crude polysaccharides and fractions (TSF1 and TSF2) with relatively lower levels of proteins (0.4–20.3%) and uronic acids (0.8–4.9%). The weight average molecular weights (Mw) of 152.7–537.3 × 103 g/mol were measured for isolated polysaccharides. The polysaccharides were composed of glucose (14.4–44.0%), galactose (23.2–43.2%), mannose (28.5–34.2%) and rhamnose (2.6–13.9%) units connected through (1→2)-Galp, (1→2,6)-Galp, (1→4)-Glcp, (1→6)-Glcp, (1→3)-Rhap, (1→2)-Rhap and (1→4)-Manp residues. TSF2 polysaccharide effectively induced RAW264.7 murine macrophages to release nitric oxide, TNF-α, IL-1β and IL-6, and activated NK cells to produce TNF-α, INF-γ, granzyme-B, perforin, NKG2D and FasL through NF-κB and MAPKs signaling pathways. Overall results suggested that polysaccharides from T. scutellifera could be potent immunostimulatory compounds inducing both macrophages and NK cells.