Structural characterization of a pectic polysaccharide from Codonopsis pilosula and its immunomodulatory activities in vivo and in vitro.

A pectic polysaccharide (named as CPP1c) extracted from Codonopsis pilosula was evaluated for its structural features and potential of immune-modulating activities in an aging mouse model of senescence accelerated mouse prone 8 (SAMP8) in vitro and in vivo. The relative molecular weight and the absolute molecular weight of CPP1c were 1.26×105Da and 1.49×105Da, respectively. Investigation of structural features by a combination of chemical and instrumental analysis showed CPP1c was composed of →1)-α-l-Rhap-(2,4→, →1)-α-l-Araf-(5→, →1)-α-d-Galp-(6→ and →1)-α-d-GalpA-(4→ in a molar ratio of 3:1:2:33. CPP1c could promote lymphocyte proliferation, modulate the percentage of CD4+, CD8+, CD28+ and CD152+ T cells and enhance the production of IL-2, TNF-α and IFN-γ. Moreover, PCR assay revealed CPP1c augmented the expressions of CD28, PI3K and p38MAPK mRNA, and the increase of protein expressions of the same genes was also confirmed by western blot analyses. In addition, CPP1c had the potential of promoting the homing of lymphocytes. Taking all factors into consideration, we deduced CPP1c might exert its immunostimulating potency via promoting T cell activation by TCR/CD28 signaling pathways.