Raymond Andersen

The research interest of Dr. Andersen`s group involve the isolation and structure elucidation of novel organic metabolites produced by both terrestrial and marine organisms. Biosynthetic studies are carried out on the novel metabolites when it is feasible. As a rule, the molecules investigated have to meet one or more of the following criteria: i) they should be of theoretical interest due to the novelty of their biogenesis - for example terpenes with new carbon skeletons, ii) they should display in vitro biological activity which makes them potential leads for the development of pharmaceutical agents and/or iii) they should display biological activities that allow them to play a central role in the biology of the producing organism (i.e. chemical ecology). Some current projects are described below.

Marine organisms represent a vast reservoir of biologically active secondary metabolites that are potential leads for the development of new anti-cancer drugs. We continue to collect marine invertebrates and bacteria from tropical and cold temperate ocean habitats and to screen their extracts for in vitro and in vivo cytotoxicity against human cancer cell lines. Bioassay guided fractionation of promising extracts leads to the isolation of pure active constituents. The structures of the new metabolites are elucidated primarily by spectroscopic analysis. Multipulse 1D and 2D NMR experiments play a pivotal role in the structure elucidation.

Phytoplankton, acting as an energy source, form the base of most marine food webs. Secondary metabolites play a role in the competitive advantage or ecological impact of many phytoplankton species. The chemical structures of toxins and antifeedants produced by phytoplankton are currently under investigation.

Many terrestrial plants defend themselves chemically against herbivore predators. The chemical defenses of selected African and Arctic plants are under investigation.

Dorid nudibranchs are delicate, shell-less and often highly coloured molluscs that are apparently ill equipped to ward off predators. The defensive metabolites found in the skin extracts of nudibranchs are being studied.