Arabino-3,6-galactan (AMA-1-b-PS2)-like polysaccharide was isolated from above-ground parts of Astragalus membranaceus (Bunge).
Structure of AMA-1-b-PS2 was characterized by sequential enzyme digestion with exo-α-l-arabinofuranosidase and exo-β-d-(1 → 3)-galactanase.
AMA-1-b-PS2 has β-d-(1 → 3)-galactan branched side-chains of β-d-(1 → 3,6)-galactan structures, comprised mainly of 6-linked galactose.
AMA-1-b-PS2 modulates the gastric mucosal and systemic immune system.