Planta Med 2014; 80 - PB10
DOI: 10.1055/s-0034-1382376

Shagenes A & B, tricyclic seqquiterpenes produced by an undescribed Antarctic octocoral

JL von Salm 1, NG Wilson 2, BA Vesely 3, DE Kyle 3, J Cuce 1, BJ Baker 1
  • 1Department of Chemistry and Center for Drug Discovery and Innovation, University of South Florida, Tampa, FL 33620, USA
  • 2Western Australia Museum, Perth, Western Australia, Australia
  • 3Department of Global Health, University of South Florida, Tampa, FL 33620, USA

Octocorals have been well investigated by natural products chemists and chemical ecologists around the world for their seemingly limitless production of unique terpene and terpenoid metabolites. Here we present the isolation and characterization of two new tricyclic sesquiterpenoids, shagenes A and B, with previously undescribed carbon skeletons and their respective biological activity. These compounds were produced by a cold-water soft coral collected at approximately 180 meters depth near Shag Rocks, South Georgia. Phylogenetic analyses using the octocorallian mitochondrial mismatch repair (mtMutS) gene places this organism outside of currently classified Octocorallia families. One- and two-dimensional NMR spectroscopy along with high-resolution mass spectrometry provided the data necessary to characterize the planar structures of shagenes A and B. Relative configuration and stereochemical assignments were possible via spatial ROESY correlations and 1D NOE experiments. Shagene A has shown moderate activity (54µM) in the axenic amastigote form of the visceral leishmaniasis causing parasite Leishmania donovani, however there is a tenfold increase in activity (5µM) in the infected macrophage stage of the parasite. Shagene A is not cytotoxic against J774.A1 mammalian cells at concentrations up to approximately 350µM. These promising results in conjunction with shagene B showing no cytotoxicity towards the parasites hints at the importance of functionalities present in shagene A.