Bioactive marine natural products from nudibranchs and other marine organisms from the bay of Naples – Marine natural product chemistry is a dynamic field of research with most of the compounds currently known having only been discovered since 1990 and with an ever increasing number of newly discovered compounds per year. Marine invertebrates including organisms that are vulnerable to predators are a particularly interesting source of bioactive natural products, which often constitute their most important means of defence.Apart from the sheer numbers still to be discovered, newly discovered marine natural products also encompass unexpected new carbon skeletons partially featuring new bioactivities based on formerly unknown modes of action. Equally interesting as the elucidation of the structure of marine natural products is the elucidation of their ecological role for the organisms producing them. These studies are made more complex because of emerging evidence that microbes associated with marine invertebrates may be the true producers of many of the natural products that were previously assumed to be produced by their invertebrate host. In the course of the proposed project, marine natural products from the Mediterranean and the Bay of Naples in particular, will be isolated and their structures elucidated by modern spectroscopic techniques. Pharmacological activities of these compounds will be tested in collaboration with other groups in fields of bioactivity which will be based on the structure of the isolated compounds and on some preliminary in-silico screenings. The focus of the investigations will be on nudibranchs but will also include other not yet studied marine organisms, in particular if ecological considerations make them interesting objects of study. In this respect, the focus will be on species which have been introduced or migrated to the Mediterranean only recently.