Characterization of an arabinogalactan-protein isolated from pressed juice of Echinacea purpurea by precipitation with the β-glucosyl Yariv reagent

• Published in: Carbohydrate research 2000-08, Vol.327 (4), p.497-504
• Main Authors: Classen, Birgit, Witthohn, Klaus, Blaschek, Wolfgang
• Format: Article
• Language: English
• Subjects: Arabinogalactan-proteins; Carbohydrate Conformation; Chemical Precipitation; Chromatography, Gel; Echinacea - chemistry; Echinacea purpurea; Galactans - analysis; Galactans - chemistry; Galactans - isolation & purification; Glucosides; Glycoproteins - analysis; Glycoproteins - chemistry; Glycoproteins - isolation & purification; Indicators and Reagents; Magnetic Resonance Spectroscopy; Molecular Weight; Phloroglucinol - analogs & derivatives; Plant Extracts - chemistry; Plants, Medicinal; Structural analysis; β-Glucosyl Yariv reagent
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/S0008-6215(00)00074-4

An arabinogalactan-protein (AGP) from pressed juice of Echinacea purpurea herb was isolated from a high molecular weight fraction by precipitation with the β-glucosyl Yariv reagent, followed by gel-permeation chromatography. It revealed characteristic features of other AGPs: i.e., a high amount of polysaccharide (83%) with a ratio of galactose to arabinose of 1.8:1, some uronic acids (4–5%), and a low protein content (7%) with high levels of serine, alanine and hydroxyproline. The molecular weight was estimated to be 1.2×10 6 Da. Linkage and 13C NMR analyses showed that the AGP is composed of a highly branched core polysaccharide of 3-, 6-, and 3,6-linked Gal p residues with terminal Ara f, GlcA p and terminal units of Ara f-(1→5)-Ara f-(1→. Partial acid hydrolysis resulted in loss of Ara f residues at the periphery of the molecule. Complete loss of reactivity toward the β-glucosyl Yariv antigen was then noticed.