Esther Marie Heise

Preliminary characterization and bioactivity of water-soluble polysaccharides from four Impatiens species—I. glandulifera Royle, I. parviflora DC., I. balsamina L., and I. noli-tangere L.—were investigated. The yields of polysaccharides range widely from 1.97% for I. parviflora roots to 18.63% for I. balsamina aerial parts. SEC (Size exclusion chromatography) chromatograms show that all samples contained a low molecular weight part that consisted of components of similar molecular weight. The aerial parts and roots of I. balsamina, and I. glandulifera aerial parts had considerable amounts of high molecular weight components up to 2.3 MDa. The sugar composition analysis revealed that Impatiens polysaccharides consisted primarily of galactose, arabinose, rhamnose, mannose, xylose, and glucose. All polysaccharide fractions, except for I. parviflora roots, also contain galacturonic acid. Moreover, in vitro bioactivity of obtained polysaccharides were evaluated. The antioxidant activity was evaluated on the basis of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-(3-ethyl-benzthia-6-sulfonic acid) (ABTS) radical scavenging assays. The highest antioxidant activity was obtained for I. balsamina aerial parts and I. parviflora roots. Among the tested fractions, only the polysaccharides from I. glandulifera aerial parts were able to significantly decrease the production of IL-8 by 32.7 ± 10.5%. The results suggest that Impatiens species can be considered as a new source of antioxidants.

Fertigarzneimittel aus dem Roten Sonnenhut werden als unspezifische Immunstimulanzien verwendet, wobei Hinweise bestehen, dass hochmolekulare AGPs an der Wirkung beteiligt sind. Strukturell gehören die AGPs aus Kraut und Wurzel von Echinacea purpurea zu den klassischen AGPs mit Typ-II-Arabinogalaktan-Einheiten. Eine neu entwickelte Methode der Immunfluoreszenz ermöglicht es, AGPs im pflanzlichen Gewebe zu detektieren. Sowohl in der Wurzel als auch in oberirdischen Teilen von Echinacea purpurea finden sich diese Glykoproteine v.a. in den Leitbündeln der Zentralzylinder und dort hauptsächlich im Bereich der Wasserleitbahnen (Xylem). Die höchsten Konzentrationen an AGPs zeigen sich in den Zellwänden der Tracheiden und Tracheen sowie im Bereich der Tüpfelkanäle, welche benachbarte Wasserleitbahnen miteinander verbinden. In der Pflanze scheinen AGPs an der Entwicklung der wasserleitenden Zellen beteiligt zu sein. Echinacea products are used as unspecific immunostimulants and contain high molecular weight arabinogalactan-proteins, which possibly are involved in the immunomodulating effects. These AGPs from root and aerial parts of Echinacea purpurea are classical arabinogalactan-proteins with type II arabinogalactans. For microscopic localization of different arabinogalactan-proteins in plant tissue, we developed a new method using immunofluorescence. Arabinogalactan-proteins were found in higher concentrations in the vascular bundles of the central cylinder of roots and aerial parts, especially in the area of the xylem. The most intense labelling was found in the cell walls of fully differentiated vessels and tracheids as well as in the cell wall area of the pit canals connecting adjacent vessels. In the plant, arabinogalactan proteins play a role in the development of the xylematic tissue.