Abstract: The immunomodulatory effect of soluble soybean polysaccharides (SSPS) from soybean dregs on RAW264.7 cells was studied in this work. It was clear that SSPS, soluble soybean acidic polysaccharide A1 (SSPS-A1) and a purified fraction c from SSPS-A1 (SSPS-A1-c) could activate RAW264.7 macrophages to release nitric oxide (NO). Furthermore, the immunomodulatory effect and mechanism of action of SSPS-A1-c were clarified. The results showed that SSPS-A1-c could promote RAW264.7 cells to release NO and reactive oxygen species (ROS), and stimulate the secretion of tumor necrosis factor α (TNF-α), interleukin (IL)-1β and IL-6 in a dose-dependent manner. In addition, SSPS-A1-c could promote the phosphorylation of the mitogen-activated protein kinase (MAPK)-related protein kinases c-Jun N-terminal kinase (JNK), extracellular regulated protein kinases (ERK) and phosphor-38 (p38), as well as the degradation of nuclear factor-kappa-B inhibitor alpha (IκB-α) in the nuclear factor kappa B (NF-κB) signaling pathway, suggesting that SSPS-A1-c played an immunomodulatory role through the MAPKs and NF-κB signaling pathway. These findings indicate that SSPS-A1-c has a good immunomodulatory effect on RAW264.7 cells. This study will provide a new idea for the comprehensive development and utilization of water-soluble polysaccharides from soybean dregs, and provide candidate molecules for functional food factors.

Key words: soluble acidic polysaccharides; macrophage; immunoregulation; mitogen-activated protein kinase; nuclear factor-κB