Immunostimulatory and anti-metastatic activity of polysaccharides isolated from byproducts of the corn starch industry

Corn steep liquor (CSL) is a major by-product of the corn steeping process that is utilized in the wet milling industry. To develop new physiologically active polysaccharides from CSL, polysaccharides were isolated and their innate immunostimulatory and anti-metastatic activities were investigated. Corn byproduct polysaccharides (CBP) were preferentially isolated from CSL and further separated into supernatant (CBP1S) and precipitate (CBP1P) fractions. The anti-complementary activity of CBP1S was more potent than CBP1P and CBP. In addition, CBP1S enhanced production of macrophage-stimulating cytokines (e.g., IL-6 and IL-12) and natural killer (NK) cell-activating substances (e.g., granzyme and interferon-γ). Further, CBP1S significantly inhibited lung metastasis at a dose of 1000 μg per mouse in an experimental lung metastasis model. These results suggest that CBP1S seems to promote the inhibition of lung metastasis through a mechanism leading to stimulation of the innate immune system, and CBP1S could be used as immunostimulating agents and for industrial applications.