Integrated analytical approaches towards toxic algal natural products discovery

Microalgae are known to produce toxins which affect the marine ecosystems. This include compounds active against competitors, grazers and in many cases also fish (1,2). Many strategies can be followed for discovery of novel bioactive secondary metabolites from marine sources. We have previously demonstrated that phenotypic based chemotaxonomy can be successfully used as the intial step in selection of talented strains for testing in various bioassays, using multivariate methods for clustering of whole profiles of metabolites. The second and very important step in the discovery process is dereplication, where we use explorative solid-phase extraction (E-SPE), and UHPLC-state-of-the-art high resolution mass spectrometry (<1 ppm mass accuracy and accurate isotope pattern) in combination with comprehensive compound databases in order to ensure not to waste time isolating and elucidating the structures of already known compounds (3). When likely unknown compounds have been identified, we use E-SPE results (4) to predict a fast and optimal purification strategy towards the pure novel compounds for NMR characterization. This presentation will highlight our integrated analytical approaches and present some of the initial results that we have gained looking into the chemistry of Alexandrium and Prymnesium in the new larger Danish strategic project: “Harmful algal blooms and fish kills”(5).