title: Structural characterization of an intestinal immune system-modulating arabino-3,6-galactan-like polysaccharide from the above-ground part of Astragalus membranaceus (Bunge).
abstract: Arabino-3,6-galactan (AMA-1-b-PS2), an intestinal immunomodulatory compound, was purified from the above-ground portion of Astragalus membranaceus (Bunge). Its structure was characterized using sequential enzymatic digestion with exo-α-L-arabinofuranosidase (AFase) and exo-β-D-(1 → 3)-galactanase (GNase), producing small amounts of intermediate-sized and shorter oligosaccharide (AF-PS2-G2 and AF-PS2-G3) fractions, and a large GNase-resistant fraction (AF-PS2-G1). Simultaneous AFase and GNase digestion of the enzyme-resistant fraction produced two long fragments (AF3-PS2-G1-1-1 and AF3-PS2-G1-1-2). Products of GNase digestion of the upper fractions showed decreased intestinal immunomodulatory activity; the GNase-resistant fraction (AF-PS2-G1) retained significant activity. Sugar component, methylation, and FAB-MS analyses indicated that the oligosaccharides consisted of hexosyl tri- to hexa-decasaccharides and hexosyl di- to hepta-saccharides mainly comprising 6-linked Gal(f) and Gal(p); some were partially mono- or di-arabinosylated. These oligosaccharide fractions were attached to the non-reducing terminus of the β-D-(1 → 3)-galactan backbone as side chains at position 6. AMA-1-b-PS2 likely modulates both the systemic and gastric mucosal immune systems.
authors.affiliation: Department of Herbal Medicine Resource, Kangwon National University, Samcheok 245-905, Republic of Korea.
authors.forename: Jung Dae
authors.initials: JD
authors.lastname: Lim
authors.affiliation: Department of Applied Plant Sciences, Kangwon National University, 200-701, Republic of Korea.
authors.forename: Chang Yeon
authors.initials: CY
authors.lastname: Yu
authors.affiliation: Department of Applied Bioscience, Konkuk University, Seoul 143-701, Republic of Korea.
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Kim
authors.affiliation: Department of Applied Bioscience, Konkuk University, Seoul 143-701, Republic of Korea. Electronic address: imcim@konkuk.ac.kr.
authors.forename: Ill Min
authors.initials: IM
authors.lastname: Chung
mesh_terms: D000818:Animals; D027885:Astragalus propinquus / Q000737:chemistry*; D002240:Carbohydrate Sequence; D005260:Female; D005685:Galactans / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D006026:Glycoside Hydrolases / Q000378:metabolism; D007155:Immunologic Factors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D007422:Intestines / Q000187:drug effects* / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D010581:Peyer's Patches / Q000187:drug effects / Q000276:immunology; D035261:Plant Components, Aerial / Q000737:chemistry*
chemical_list: D005685:Galactans; D007155:Immunologic Factors; D006026:Glycoside Hydrolases; C063901:exo-beta-(1--3)-D-galactanase
keywords: Arabino-3,6-galactan; Astragalus membranaceus; Immunomodulatory activity; Peyer's patch; Polysaccharide