Purification, characterization and biological activities of a polysaccharide from Lepidium meyenii leaves

The characteristics and biological activities of a novel polysaccharide from Lepidium meyenii leaves (LMLP) were investigated. LMLP was purified using DEAE-52 cellulose chromatography followed by SephadexG-100 chromatography. The average molecule weight of LMLP was 58.43kDa and it was composed of galactose, arabinose, rhamnose, glucose and mannose with a relative molar ratio of 5.51:4.05:1.15:0.77:0.01. Antioxidant activity results showed that LMLP presented an EC₅₀ of 3.72mg/mL in scavenging 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical, and it also had reducing power (OD700nm being 0.079 at 1mg/mL). Moreover, LMLP possessed the potential on stimulating immune response of RAW264.7 cells. It could promote proliferation, strengthen phagocytosis function, enhance the expression of CD80, and increase the secretion of nitric oxide (NO) in a dose-dependent manner. All of these results suggested that LMLP could be used as a natural ingredient for functional food.