title: Isolation, characterization and structural determination of a unique type of arabinogalactan from an immunostimulatory extract of Chlorella pyrenoidosa.
abstract: An arabinogalactan was isolated from a hot water extract of freeze-dried cells of the green microalga, Chlorella pyrenoidosa. This hot water extract is a proprietary immunomodulator, with the trademark Respondintrade mark (ONC-107). The arabinogalactan was recovered from the ethanol-soluble fraction of the supernatant resulting from a process that involved controlled ethanol precipitation followed by size exclusion chromatography on Sephadex G-100, then Cetavlon precipitation. Sugar analyses, GC-MS data for (S)-2-octyl glycosides, and 1D and 2D NMR experiments established unambiguously that the repeating unit was -->2)-alpha-L-Araf-(1-->3)-[alpha-L-Araf-(1-->4)]-beta-D-Galp-(1-->. This structure does not fit into any of the known classes of arabinogalactans. SEC/MALS experiments gave a molecular mass for the arabinogalactan isolated as 47 +/- 4 kDa but the original structure was probably larger.
authors.affiliation: Department of Chemistry, Dalhousie University, Halifax, NS, Canada.
authors.forename: Erick Reyes
authors.initials: ER
authors.lastname: Suárez
authors.forename: Jaroslav A
authors.initials: JA
authors.lastname: Kralovec
authors.forename: Miguel D
authors.initials: MD
authors.lastname: Noseda
authors.forename: H Stephen
authors.initials: HS
authors.lastname: Ewart
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Barrow
authors.forename: Michael D
authors.initials: MD
authors.lastname: Lumsden
authors.forename: T Bruce
authors.initials: TB
authors.lastname: Grindley
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002457:Cell Extracts / Q000737:chemistry* / Q000276:immunology*; D002460:Cell Line; D002708:Chlorella / Q000737:chemistry* / Q000276:immunology*; D002850:Chromatography, Gel; D003911:Dextrans; D005685:Galactans / Q000737:chemistry* / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009569:Nitric Oxide / Q000378:metabolism
chemical_list: D002457:Cell Extracts; D003911:Dextrans; D005685:Galactans; D009569:Nitric Oxide; C025614:sephadex; C005653:arabinogalactan