An antioxidant acidic polysaccharide from Cuscuta chinensis

An acidic polysaccharide, H2, was isolated from the alkali_extract CHC of seeds of Cuscuta chinensis Lam. with the molecular weight more than 1.0×10 6. Chemical and spectroscopic studies led to the structure determination as follows: the backbone chain consists of 1,6_linked_β_ D Galp, 1,4_linked_β_ D Galp, 1,4_linked_β_ D GalA and 1,2_ or 1,4_linked_β_ L Rhap having branching points at position O_3 of some 1,6_linked_β_ D Galp residues (one among eight) and O_4 or O_2 of 1,2_ or 1,4_linked_β_ L Rhap residues to terminal β_D_galactopyranose. The side chains composed of terminal Galp, 1,6_linked_β_ D Galp, 1,4_linked β_ D Galp and 1,3,6_linked_β_ D Galp also linked at position O_3 of 1,6_linked_β_ D Galp residues in the backbone chain. β_ L _arabinofuranosyl and terminal β_ L _rhamnopyranosyl residues existed in the periphery of this polysaccharide linked to O_3 of 1,6_linked_β_ D Galp residues in the backbone chain and the side chains. The polysaccharide H2 increased significantly the survival rate of PC12 cells indicating that it had protective effects against H 2O 2 insult.