Structural characterization and immunomodulatory activity of a glucan from Radix Codonopsis

Abstract

• CPC was an α-glucan isolated from the roots of Codonopsis pilosula. • The structure of CPC exhibited the backbone of 1,4-linked α-D-glucose and the branched chains of 1,6-linked β-D-glucose. • CPC exhibited the potential of immunomodulatory activity on RAW264.7 cells. A glucan named as CPC was obtained from the roots of Codonopsis pilosula and its structure was determined by HPGPC, IR, GC–MS, and NMR. HPGPC showed that CPC was a homogeneous polysaccharide and exhibited a molecular weight (Mp) of 1698 Da according to the equation of standard molecular weight (lg Mp = −0.1869 t R + 9.7386). The results from NMR and GC–MS demonstrated that the main linkages in CPC were 1-linked β-D-glucose, 1,4-linked α-D-glucose, and 1,4,6-linked α-D-glucose in the molar ratio of 1.0:3.8:1.0, which indicated that the structure of CPC exhibited the backbone of 1,4-linked α-D-glucose and the branched chains of 1,6-linked β-D-glucose. The immunomodulatory activity indicated that CPC showed the significant induction on the productions of NO, ROS, iNOS, TNF-α, IL-6, IL-1β and IL-10 and the mRNA expressions of iNOS, TNF-α, IL-6, IL-1β and IL-10 in RAW 246.7 cells. These data suggested that CPC was potential to human health by regulating immunity.