Polysaccharides from Moringa oleifera gum: structural elements, interaction with beta-lactoglobulin and antioxidative activity

A polysaccharide (F1) was isolated from Moringa oleifera gum using simple water extraction, graded precipitation with ethanol and anion-exchange chromatographic approaches. This polysaccharide, which had a molecular weight of 190 kDa, was primarily composed of Ara, Gal, Xyl, Rha and GlcA in a molar ratio of 64/25/4/3/4, respectively. The backbone of this polymer is made up of 1,6-, 1,3- & 1,3,6- linked beta-Galp units substituted with differently linked side chains. Additionally, information on the glycosidic linkage type, ring size and anomeric configuration, and the sequence of saccharide residues of several oligosaccharides generated from F1 were obtained. Remarkably, F1 exhibited dose dependent scavenging capacities against DPPH radicals in vitro and had a strong beta-lactoglobulin binding ability. Thus, M. oleifera gum provides an antioxidative arabinogalactan, which forms a stable water soluble complex with beta-lactoglobulin: this could be helpful in designing new value added, functional structures.