Leontopodium alpinum and related taxa.

Research project P 14389 Leontopodium alpinum and related taxa. Hermann STUPPNER 08.05.2000 Leontopodium alpinum Cass. (Asteraceae) commonly known as Edelweiß, is a very ornamental and protected species spread over the mountainous regions of Europe. In traditional medicine, extracts of this plant are used for the therapy of angina, bronchitis, cancer, diarrhea and dysentery. Preliminary pharmacological data obtained in the mouse ear edema assay showed that a crude extract of L. alvinum and subfractions obtained by column chromatography exhibited significant in vivo anti-inflammatory activity. Furthermore, these extracts show in vitro activities, such as inhibition of leukocyte migration, effect on the arachidonic acid metabolism and strong anti-bacterial activity against Bacillus subtifis, Pseudomonas aeruginosa and Staphylococcus aureus. Within the frame of this project constituents responsible for the anti-inflammatory activity will be isolated and identified by bioactivity-guided fractionation of the crude plant extract using the croton oil-induced mouse ear edema assay as in vivo model and appropriate in vitro assays like inhibition assays of chemotaxis of leukocytes, 5- lipoxygenase-, cyclooxygenase-1 and -2 activity, NO-release of macrophages, (Griess assay) and respiratory burst of leukocytes. Additionally, pure compounds with significant anti-inflammatory activities will be tested in the carrageenan-induced rat paw edema assay and for effects on the NF-KB binding activity. Bisabolane derivatives which we recently identified as constituents of L. alpinum will be of main interest, since they have to be considered as at least one active principle of L. alpinum. Isolation of anti-bacterial constituents of the Leontopodium extract will be monitored by a bioautographic assay on thin layer chromatography plates. The minimum inhibitory concentrations of the isolated compounds will be determined using a microbroth dilution method. The molecular structures of the isolated compounds will be established by mass spectrometry (MS) and I- and 2- dimensional NNM spectroscopy. Appropriate thin layer chromatography, high performance liquid chromatography (H:PLC), BPLC/1\4S and gas chromatography (GC)/1\4S methods should be developed for finger print analyses, standardisation and chemotaxonomic investigations of Leontopodium species. The distribution of biologically active compounds and main constituents in different plant organs (roots, leaves, flowers) as well as in different Leontopodium species (e.g. L. campestre, L. conglobatum, L. leontopoides and L. ochroleucum) will be determined. The chemotaxonomic part of this project is focused on phenolic constituents, bisabolane derivatives, essential oil components and polyacetylenes of a large number of L. alpinum populations in comparison with collections of other Leontopodium species. Non volatile constituents will be identified and quantified in crude extracts by means of BPLC/UV/MS, volatile ones by means of CTC/MS. Obtained quantitative data will be analysed statistically by multivariate methods like principal component analysis and hierarchical cluster analysis.

The European Edelweiss one of the most famous plants of the Alps was used in folk medicine for the treatment of gastro-intestinal diseases, dysentery, but also for the treatment of diseases of the respiratory tract. Mystification and the symbolism of Leontopodium alpinum probably caused by its rareness and the wild and rough growing habitat of this plant certainly influenced the traditional medicinal use. The aim of our project was on the one hand a scientific assessment of traditional use of Edelweiss and on the other hand a comparison of the European representative with the barely known ca. 40 Asian Edelweiss species. Preliminary results showed indeed that extracts of flowers, leaves and roots exhibited antibacterial and anti-inflammatory activity. Due to the complexity of Edelweiss-extracts - they consist of up to 150 secondary plant metabolites - the question came up, which one of these constituents might be responsible for the pharmacological effects of Edelweiss extracts. Accordingly, the crude extracts were separated into single, defined compounds. The development of suitable HPLC/DAD/MS methods for the analysis of different extracts and a GC method for the analysis of the essential oil of Edelweiss roots, together with other chromatographic methods, allowed the identification and assignment of 38 different compounds of diverse substance classes. Some of these constituents are unique and only occur in Edelweiss. Pharmacological investigation of the purified substances showed anti-inflammatory activity (in vitro and in vivo experiments) and antibacterial effects (e.g. against S. pneumoniae and S. aureus strains) but also extraordinary anti- oxidative and radical scavenging properties. Since Edelweiss is a protected plant, almost all of the investigations were carried out with plant material originating from cultures. Comparison of the constituents of the European Edelweiss with those of the 40 Asian species showed a close relationship between secondary metabolites pattern and morphology. This means a similar appearance of the species goes ahead with a similar secondary plant metabolite pattern. The project proofed that the European Edelweiss beside its symbolic importance is a unique source of medicinal relevant natural compounds.