Mechanism-based antitumor screening of Caribbean marine organisms: isolation and structure determination of novel diterpenoids from the gorgonian Eunicea tourneforti.

As part of a collaborative research effort between the University of the Virgin Islands and Virginia Polytechnic Institute and State University, we carried out the extraction and bioassay of 87 marine organisms in a mechanism-based assay involving genetically altered yeast strains. Of these, nineteen showed differential activity between the mutant and wild-type yeast strains indicating the presence of potential DNA interacting agents. We now report the isolation and characterization of five new diterpenoids, 2-6, together with the previously known diterpenoid 1, from the bioactive extracts of the gorgonian Eunicea tourneforti forma atra. The structures of the isolated compounds were determined by employing a variety of one- and two-dimensional nmr methods.