Structural Characterization, Antioxidant Activity and Immunomodulatory Activity of the Polysaccharide LRLP3 from Leaves of Lycium ruthenicum Murra

A combination of chemical and instrumental analysis was performed to investigate the structural characterization and biological activity of a polysaccharide LRLP3 which was isolated from the Lycium ruthenicum leaves. The results demonstrated that LRLP3 was a highly branched polysaccharide with a backbone of (1 -> 3)-linked-beta Galp substituted at C-6 position by galactosyl. The branches were composed of (1 -> 6)-linked-beta Galp, (1 -> 4)-linked-beta Galp, (1 -> 3)-linked-alpha Araf and beta Arap, (1 -> 5)-linked-alpha Araf, and (1 -> 2, 4)-linked alpha Rhap, and the terminal residues were alpha Araf, beta Galp and beta Glcp. Additional, LRLP3 had strong reducing power, could significantly scavenge DPPH, hydroxyl and superoxide free radical, could effectually inhibit Cu2+/H2O2 induced protein damage and H2O2 induced cell damage in vitro. Meanwhile, immunological assay showed that LRLP3 could stimulate proliferation of spleen lymphocytes significantly with or without mitogens (ConA or LPS) in vitro. Therefore, LRLP3 was a natural arabinogalactan which had the potential function of antioxidant and immunoloregulation.