Planta Med 2007; 73 - P_027
DOI: 10.1055/s-2007-986809

Structural and immunological comparison of arabinogalactan-proteins from Viscum album L. berries and herb

B Herbst 1, B Classen 1, A Ulmer 2, W Blaschek 1
  • 1Pharmaceutical Institute, Christian-Albrechts-University of Kiel, Gutenbergstraße 76, 24118 Kiel, Germany
  • 2Research Center Borstel, Parkallee 22, 23845 Borstel, Germany

Mistletoe (Viscum album L.) is used as a medicine since ancient times. Today mistletoe extracts play an important role in adjuvant cancer treatment [1] because of their immunostimulating properties. Besides lectins, different polysaccharides from mistletoe berries are discussed to contribute to the in vivo activity [2]. For arabinogalactan-proteins (AGPs), especially from Echinacea, different immunomodulating activities have been proven in vitro, e.g. enhanced production of cytokines [3]. Therefore AGPs from mistletoe herb and berries were purified, characterized and immunologically tested.

AGPs were isolated from the high molecular weight fraction of an aqueous extract after protein removement, tangential flow filtration (MWCO 30.000Da), dialysis and precipitation with ß-glucosyl-Yariv reagent. Methylation analysis, partial acid hydrolysis and uronic acid reduction were performed to characterize the chemical structure of the carbohydrate moiety of the AGPs. Methylation analysis of AGP from herb detected as main components 1,3,6-Galp and 1,3-Galp, in the side chains 1,5-Araf and terminal 1-Araf and a total arabinose: galactose ratio of 1: 1.8. Determination of uronic acids showed 1,4-GalAp and 1-GlcAp to be the acidic compounds in AGP from herb. The AGP from berries has a completely different structure rather untypical for AGPs with arabinose being the dominating monosaccharide.

Both AGPs were tested in a competitive ELISA for cross-reactivities with monoclonal antibodies raised against Echinacea purpurea AGP [4], to gain further information on structural similarities or differences.

First investigations on biological activities of mistletoe AGP from herbal drug preparations revealed interaction with human Toll-like receptor 2.

References: [1] Büssing, A. (2000) Mistletoe the genus Viscum. Harwood Academic Publishers. Amsterdam. [2] Stein, G.M. et al. (1999) Anticancer Res. 19: 3907–3914. [3] Classen, B. et al. (2006) Phytomed. 13: 688–694. [4] Classen, B. et al. (2004) Planta Med. 70: 861–865.