title: Chemical and immunological modifications of an arabinogalactan present in tea preparations of Phyllanthus niruri after treatment with gastric fluid.
abstract: An arabinogalactan (AG) obtained from tea preparations of Phyllanthus niruri was previously investigated and presented immunological properties when tested with peritoneal mice macrophages. AG was now submitted to acidic and neutral gastric conditions using human gastric fluids and aq. HCl solution. Since the acidic procedures gave rise to the same free monosaccharidic composition, the acid hydrolyzate of AG at pH 2.00 was treated with ethanol to form insoluble (AG-P) and soluble fractions (AG-S). These were analyzed using (13)C NMR, HPSEC, and GC-MS for monosaccharide composition and methylation analyses. The results showed an intense partial degradation, including cleavages of the main chain. AG-S presented the monosaccharides released from the native polymer and some oligosaccharides as shown by methylation data. AG-P contained larger molecular fragments comprising the internal units from AG, which were not attacked by the hydrolysis condition. Both fractions were tested in peritoneal mice macrophages and remained active, promoting an increase of superoxide anion production of 2.0 and 2.3-fold, at 250 microg/mL, for AG-S and AG-P, respectively. When compared to AG, a slight diminished response was observed, revealing a structure-activity relation. The significance of the results is that most plant extracts are orally ingested and will reach the gastrointestinal tract before performing a biological function, so checking these changes is crucial to propose future clinical therapies based on the rational use of phytomedicine.
authors.affiliation: Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Paraná, Centro Politécnico 81531-980, Curitiba, PR, Brazil.
authors.forename: Caroline G
authors.initials: CG
authors.lastname: Mellinger
authors.forename: Thales R
authors.initials: TR
authors.lastname: Cipriani
authors.forename: Guilhermina R
authors.initials: GR
authors.lastname: Noleto
authors.forename: Elaine R
authors.initials: ER
authors.lastname: Carbonero
authors.forename: Maria Benigna M
authors.initials: MB
authors.lastname: Oliveira
authors.forename: Philip A J
authors.initials: PA
authors.lastname: Gorin
authors.forename: Marcello
authors.initials: M
authors.lastname: Iacomini
mesh_terms: D000818:Animals; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D000431:Ethanol; D005685:Galactans / Q000737:chemistry* / Q000276:immunology; D005744:Gastric Acid / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D029803:Phyllanthus / Q000737:chemistry*; D008517:Phytotherapy / Q000379:methods; D010936:Plant Extracts / Q000737:chemistry* / Q000276:immunology
chemical_list: D005685:Galactans; D010936:Plant Extracts; D000431:Ethanol; C005653:arabinogalactan