Characterization of polysaccharide from Astragalus radix as the macrophage stimulator

Astragalus polysaccharide (APS) was obtained by hot water extraction, alcohol precipitation, gel-permeation chromatography and ultrafiltration. Fluorescence material 2-aminoacridone (2-AMAC) labeled APS bind to macrophage in a time- dependent manner and the binding can be remarkably inhibited by APS. Furthermore, the effect of APS on RAW264.7 macrophage demonstrated APS increase the level of cytokines including TNF-α, GM-CSF and the production of NO. NF-κB protein levels are increased in response to APS. Blocking NF-κB with specific inhibitor resulted in decreased levels of NO and TNF-α. The results suggested that APS possess potent immunomodulatory activity by stimulating macrophage and could be used as an immunotherapeutic adjuvant.

► Polysaccharide from Astragalus radix (APS) is extracted and characterized with the MW 6.9 × 104 Da.
► APS bind to macrophage in time-dependent manner, and can be competitively blocked by itself.
► APS dose-dependent increase the level of TNF-α, GM-CSF and NO produced by macrophage.
► NF-κb dependent signaling pathway is involved in the activation of macrophage induced by APS.