Bioactive surfactants and further new secondary metabolites from marine and terrestrial bacteria

Natural compounds are having a high structural diversity and often highly specific biological activities. As the largest source for drug discovery, natural compounds play still a major role in the research process. In recent years, during the development of the natural product chemistry more and more new compounds were exploited, which provided new ideas for drug development. Many synthesized or modified natural products are used as successful drugs in pharmaceutical applications. One of the new and promising fields in the development of new drugs is peptide research. In protein sub-units, peptide sequences are responsible for molecular recognition and biological activities. In the present work, structurally new and biologically active natural products such as surfactants (cyclic depsipeptides and glycolipids) were obtained from microorganisms, which were selected through chemical screenings (HPLC-MS/MS, colour reaction etc.) and biological tests (agar diffusion test, microwell cytotoxicity assay etc.). Sufficient amounts of the metabolites were obtained by fermentation, extraction, isolation and purification procedures. The structures of isolated compounds were elucidated using different spectroscopic methods (NMR, MS and UV). Finally, the purified compounds were tested for various biological activities, using a horizontal screening.