14. Characterization of arabinogalactan-proteins from Viscum album L. berries and herb.Arabinogalactan-proteins (AGPs), ubiquitary found in plants, belong to the hydroxyprolin-rich glycoproteins. AGPs are involved in numerous physiological plant processes (Seifert and Roberts, 2007). For AGPs, especially from Echinacea, also different immunomodulating activities have been proven at least in vitro (Classen et al., 2006). Today mistletoe extracts play an important role in adjuvant cancer treatment because of their immunostimulating properties. Besides lectins, different polysaccharides from mistletoe are discussed to contribute to the in vivo activity (Stein et al., 1999). Therefore AGPs from mistletoe herb and berries were purified and characterized. AGPs were isolated from the high-molecular-weight fraction of an aqueous extract after protein removement, tangential flow filtration Tangential Flow Filtration (TFF) is a separation technique that uses membrane systems to purify proteins. It recirculates the retentate across the membrane surface, which minimises the fouling of the membrane. (MWCO 30.000 Da), dialysis and precipitation with [beta]-glucosyl-Yariv reagent. Methylation methylation, n a phase-II detoxification pathway in the liver; methyl groups combine with toxins to rid the body of various substances. methylation (meth´ analysis, partial acid hydrolysis and uronic acid reduction were performed to characterize the chemical structure of the carbohydrate moiety moiety: see clan. of the AGPs. Methylation analysis of AGP from herb revealed 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 arabinose Biochemistry A pentose that occurs in d and l configurations :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 monosaccharide: see carbohydrate. monosaccharide Any of the simple sugars that serve as building blocks for carbohydrates. They are classified based on their backbone of carbon (C) atoms: Trioses have three carbon atoms, tetroses four, pentoses (arabinose:galactose ratio of 1:0.7). Terminal GlcAp is the only uronic acid found in AGP from berries. Both AGPs were tested in a competitive ELISA ELISA (e-li´sah) Enzyme-Linked Immuno-Sorbent Assay; any enzyme immunoassay using an enzyme-labeled immunoreactant and an immunosorbent. ELISA n. for cross-reactivities with monoclonal antibodies raised against Echinacea purpurea AGP (Classen et al., 2004), to gain further information on structural details. AGP from berries and herb showed good reactivity, demonstrating the existence of comparable epitope regions on all three AGPs. Keywords: Viscum album; Arabinogalactan-protein; Structure elucidation; AGP-antibody References Classen, B., Csavas, M., Borbas, A., Dingermann, T., Zundorf, I., 2004. Monoclonal antibodies against an arabinogalactan-protein from pressed juice of Echinacea purpurea. Planta Med. 70, 861-865. Classen, B., Thude, S., Blaschek, W., Wack, M., Bodinet, C., 2006. Immunomodulatory effects of arabinogalactan-proteins from Baptisia and Echinacea. Phytomedicine 13, 688-694. Seifert, G.J., Roberts, K., 2007. The biology of arabinogalactan proteins. Annu. Rev. Plant Biol. 58, 137-161. Stein, G.M., Edmund, U., Pfuller, U., Bussing, A., Schietzel, M., 1999. Influence of polysaccharides from Viscum album L. on human lymphocytes, monocytes and granulocytes in vitro. Anticancer Res. 19, 3907-3914. B. Herbst*, B. Classen, W. Blaschek Pharmaceutical Institute, Christian-Albrechts-University of Kiel, Gutenbergstrasse 76, 24118 Kiel, Germany *Corresponding author. Tel.: +49 431 8801634; fax: +49 431 8801102. E-mail address: bherbst@pharmazie.uni-kiel.de (B. Herbst). |
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