Sponges

Stevensine is a biologically active secondary metabolite produced by several marine sponges, including Teichaxinella morchella. Two in vitro methods were used to investigate the biosynthetic origin of stevensine in the sponge T. morchella. A cell-free enzyme extract was developed to test for the incorporation of the potential radiolabeled metabolic precursors histidine, arginine, ornithine, and proline. Secondly, cell cultures of T. morchella were used to determine the biosynthetic origin of stevensine from the radiolabeled amino acids histidine, arginine, ornithine, and proline. Histidine and ornithine/proline were converted to stevensine in the cell culture system. This represents the first study involving the use of cell cultures of a marine invertebrate to investigate the biosynthesis of a biologically active natural product. An understanding of the biosynthetic process leading to the production of this compound in the source organism could lead to the development of more efficient and environmentally safer production methods.

Chemical analysis of large number of specimens of the sponge Xestospongia muta have revealed the existence of three distinct sterol chemotypes. Since sponges are well known to contain a diverse array of all classes of lipids, the utility of fatty acid composition as a chemotaxonomic tool for Xestospongia muta has been addressed. Further the biosynthetic capabilities of the three chemotypes are being evaluated for possible taxonomic use. Further the utility of TLC and NMR as additional taxonomic tools has also been evaluated.

A-nor sterols have been isolated and characterized from the marine sponge Teichaxinella morchella using High Performance Liquid Chromatography, Nuclear Magnetic Resonance, and Mass Spectrometry. A cell free extract of T. morchella was used to determine the biosynthetic origin of the sterols. Incubation experiments with radiolabled Farnesyl Pyrophosphate and cholesterol showed that the sterols are coming from a dietary source. Subcellular localization studies showed that the sterols are part of the cell membrane.