Phytochemical investigation of the Genus Leontodon

The phytochemical and pharmacological parts mainly include isolation and identification of new sesquiterpene lactones from a representative part of the about 50 Leontodon species described so far. The structures of these substances will be elucidated by modem NMR and MS techniques. Furthermore, the isolated natural compounds will be tested for antileukemic and cytotoxic activities in proliferation and clonogenic assays using cell lines like HL 60, K 562, U 937 and prostatic, ovarian, breast carcinoma cell lines. Resulting cell death may be due to apoptosis in vitro which will be measured by the DNA fragmentation assay, detergent method and the TUNEL test. The chemotaxonomic part of this project is focused on phenolic constituents of the investigated Leontodon species. Known phenolic compounds (i. e. flavonoids and phenolic acids) will be isolated and identified by comparison with reference substances, new natural compounds will be structurally elucidated by means of NMR and MS. An analytical system for identification (HPLC/MS) and quantification (HPLC/UV) of these substances in crude extracts will be established as well" The obtained analytical data of all available (ideally all existing) Leontodon species will be used for establishing a chemotaxonomically based system of the Leontodon genus. Comparison of this system with the already existing morphologically based systems of the group will hopefully answer the following main questions: Can closely related species and subspecies be differentiated by phytochemical methods and are the chemically related groups of species in correspondence with the sections and subgenera of the morphological system?