Structure characterization of one polysaccharide from Lepidium meyenii Walp., and its antioxidant activity and protective effect against HO-induced injury RAW264.7 cells.

The structural characterization, antioxidant activity and protective effect against HO-induced injury RAW264.7 cells of a new polysaccharide (MP1) isolated from Lepidium meyenii Walp. were investigated. The molecular weight was estimated to be 4.67 × 10 Da by HPLC-ELSD analysis. Monosaccharide composition was determined to be arabinose and galactose in a molar ratio of 2:1 by GC-MS and PMP-HPLC-UV analysis. Methylation combined with 1D and 2D NMR spectrum analysis revealed that MP1 was an arabinogalactan. MP1 possessed a moderate antioxidant activity in vitro in DPPH, ABTS, superoxide and hydroxyl radicals scavenging, Fe chelating, lipid peroxidation inhibition and reducing power assays. MP1 could also effectively protect RAW264.7 cells from HO-induced injury by maintaining stable cell viability, decreasing ROS, MDA and LDH level and enhancing SOD, GSH-Px and CAT activity. These results suggested the potential utilization of MP1 as a natural antioxidant for food and pharmaceutical applications.