Planta Med 2011; 77 - SL24
DOI: 10.1055/s-0031-1282147

Arabinogalactan-proteins from Echinacea purpurea: Characterization, localization and immunomodulating properties

B Classen 1, C Gramann 1, E Goellner 1, W Blaschek 1
  • 1Pharmaceutical Institute, Department of Pharmaceutical Biology, Christian-Albrechts-University of Kiel, Gutenbergstr. 76, 24118 Kiel, Germany

Arabinogalactan-proteins (AGPs) are macromolecular glycoproteins belonging to the putative active compounds of Echinacea preparations [1]. (β-D-Glc)-Yariv phenylglycoside specifically binds to most plant AGPs and has been used to isolate AGPs from pressed juice of the aerial parts and from suspension cultures of Echinacea purpurea (L.) Moench (Asteraceae). These AGPs have been structurally characterized and compared concerning their protein- and polysaccharide moiety. The main components of the carbohydrate moiety of AGP from herbal material are 1,6-Galp, 1,3-Galp, 1,3,6-Galp and in the side chains 1,5-Araf, terminal Araf and terminal GlcAp. Side chains of AGP from cell cultures are structurally different with only traces of 1,5-Araf. The protein part of both AGPs mainly consists of Hyp, Asx, Glx, Ser, Thr and Ala. Interestingly, AGP from herbal material showed an amino acid sequence rather untypical for AGPs with predominantly contiguous arrangement of three to four Hyp residues in blocks [2].

For microscopic localization of AGPs in fresh plant tissue, a new method has been developed. Antibodies against Yariv's reagent have been generated in rabbits and used for immunofluorescent labeling of plant tissue. Xylem tracheary elements showed very strong labeling of the cell wall, especially at the inner side of the wall and in the area of pit canals.

Preparations of pressed juice from Echinacea purpurea are used as herbal medicinal products with immunomodulating properties. In vitro, AGP from the pressed juice of herbal material showed complement stimulating activities [3] as well as binding to human leucocytes [4].

Keywords: Echinacea purpurea, arabinogalactan-protein, structure elucidation, immunofluorescence, natural immune enhancer

Acknowledgement: The authors thank Rottapharm/Madaus GmbH, Köln, Germany, for financial support of this work.

References: 1. Classen B et al. (2006) Phytomedicine 13: 688–694.

2. Classen B et al. (2005) Planta Med 71: 59–66.

3. Alban S et al. (2002) Planta Med 68: 1118–1124.

4. Thude S et al. (2006) Phytomedicine 13: 425–427.