Peter T. Murphy

The distribution of brominated long-chain fatty acids in sponge and symbiont cell types from the tropical marine sponge Amphimedon terpenensis

The tropical marine spongeAmphimedon terpenensis (family Niphatidae, order Haplosclerida) has previously been shown to possess unusual lipids, including unusual fatty acids. The biosynthetic origin of these fatty acids is of interest as the sponge supports a significant population of eubacterial and cyanobacterial symbionts. The total fatty acid composition of the sponge was analyzed by gas chromatography/mass spectrometry of the methyl esters. Among the most abundant of the fatty acids in intact tissue were 16∶0, 18∶0 and 3,7,11,15-tetramethylhexadecanoic (phytanic) acid. In addition, three brominated fatty acids, (5E,9Z)-6-bromo-5,9-tetracosadienoic acid (24∶2Br), (5E,9Z)-6-bromo-5,9-pentacosadienoic acid (25∶2Br) and (5E,9Z)-6-bromo-5,9-hexacosadienoic acid (26∶2Br) were also present. The three brominated fatty acids, together with phytanic acid, were isolated from both ectosomoal (superficial) and choanosomal (internal) regions of the sponge. Analysis of extracts prepared from sponge/symbiont cells, partitioned by density gradient centrifugation on Ficoll, indicated that phytanic acid and the three brominated fatty acids were associated with sponge cells only. Further, a fatty acid methyl ester sample from intact tissue ofA. terpenensis was partitioned according to phospholipid class, and the brominated fatty acids were shown to be associated with the phosphatidylserine and phosphatidylethanolamine fractions that are commonly present in marine sponge lipids. The phosphatidylcholine and phosphatidylglycerol fractions were rich in the relatively shorter chain fatty acids (16∶0 and 18∶0). The association of brominated long-chain fatty acids (LCFA) with sponge cells has been confirmed. The findings allow comment on the use of fatty acid profiles in chemotaxonomy and permit further interpretation of LCFA biosynthetic pathways in sponges. The assignment of the sponge studied, which is currently placed asA. terpenensis, is being supported to some extent, but the species is unusual in having C25 fatty acids as the major constituent in this group. Other factors, such as season or microenvironmental conditions, may influence observed fatty acid composition which tends to reduce the usefulness of fatty acid profiles as markers in sponge chemotaxonomy.

TERPENES IN SPONGE CELL-MEMBRANES - CELL-SEPARATION AND MEMBRANE FRACTIONATION STUDIES WITH THE TROPICAL MARINE SPONGE AMPHIMEDON-SP

The differing sponge and symbiotic microbial cell types in the tropical marine spongeAmphimedon sp. were fractionated according to density, investigated by electron microscopy, and analyzed by high-performance liquid chromatography and nuclear magnetic resonance for the presence of the terpene metabolite diisocyanoadociane (1) and Δ5,7-sterols (2–7). A sample of whole sponge was dissected into superficial ectosome and deeper choanosome. The superficial tissue was found to be enriched in sterol relative to choanosome; however, extracts from both tissues contained terpene. Dissociation of whole sponge followed by Ficoll density gradient fractionation showed that there are two chemically distinct types of sponge cells inAmphimedon sp.—small non-nucleolated cells of low density contain terpene 1 together with sterols, while larger nucleolated cells contain significant levels of terpene, but only traces of sterol. Membrane fractionation studies were undertaken to establish whether the terpene components were located specifically in the cell membranes of these two cell types. A membrane vesicle pellet spun down at 100,000×g from small sponge cells contained sterols, but only traces of terpene, whereas the membrane vesicle preparation from heavier cells contained both terpenes and sterols. Subsequently, the presence of terpenes together with sterols was demonstrated in a membrane vesicle preparation of purity >90% prepared from bacteria-free sponge cells. These results provide the first experimental evidence that terpenes are associated with sponge cell membranes, where they may function as structural components.

Octa- and nonaprenylhydroquinone sulfates, inhibitors of α1,3-fucosyltransferase VII, from an Australian marine sponge Sarcotragus sp

Alpha1,3-fucosyltransferase (Fuc TVII) is a key enzyme in the biosynthesis of selectin ligands. We have isolated two inhibitors of Fuc TVII from a marine sponge Sarcotragus sp. They were characterized as octa- and nonaprenylhydroquinone sulfates on the basis of spectral data. These compounds inhibited Fuc-TVII with IC50 values of 3.9 and 2.4 microg/mL, respectively.

Isolation of brominated long-chain fatty acids from the phospholipids of the tropical marine spongeAmphimedon terpenensis

Preliminary investigation of the phospholipid fatty acid composition of the tropical marine spongeAmphimedon terpenensis by gas chromatography/mass spectrometry revealed the presence of some novel brominated fatty acids. Two new brominated fatty acids, (5E, 9Z)-6-bromo-5,9-tetracosadienoic acid (2a) and (5E, 9Z)-6-bromo-5,9-pentacosadienoic acid (3a) were subsequently isolated from a chloroform/methanol (3∶1, vol/vol) extract of the sponge and characterized as their methyl esters 2b and 3b. The known brominated fatty acid (5E, 9Z)-6-bromo-5,9-hexacosadienoic acid (4a) was also isolated. The new fatty acid methyl esters were confirmed as brominated δ5,9 acid derivatives by chemical ionization mass spectrometry. The position of the bromine substituent was determined to be C-6 by nuclear magnetic resonance techniques while the stereochemistry of the two double bonds was deduced by nuclear Overhauser enhancement difference spectroscopy. The biosynthetic implications of the co-occurrence of the three brominated acids are discussed.

Synthesis of polycarpine, a cytotoxic sulfur-containing alkaloid from the ascidian Polycarpa aurata, and related compounds

Polycarpine 1, a highly cytotoxic marine natural product, has been synthesized in three steps from p-methoxyphenacyl bromide 4 in 57% overall yield. The key reaction for construction of the symmetrically substituted disulfide linkage of polycarpine is the treatment of 2-amino-4-(4-methoxyphenyl)-1-methylimidazole 17 with S2Cl2 in acetic acid. In a similar way ten related compounds, including three thiazole analogues, have been prepared. Most of them exhibit high cytotoxic activities against an array of human cancer cell lines.

Chemotaxonomic relationships within, and comparisons between, the orders Haplosclerida and Petrosida (Porifera: Demospongiae) using sterol complements

Abstract The sterol chemistry of 21 species of sponges from the orders Haplosclerida and Petrosida (Porifera: Demospongiae) was examined and compared, and the results analyzed using cluster analysis and ordination. Replicate samples within some species were examined statistically to determine if variability of sterol complements was constant within a species. The results of this study did not support separation of sponge species into the two orders, Haplosclerida and Petrosida, on the basis of sterol complements. While previous analyses of species within the Petrosida revealed the presence of unconventional sterol cyclopropenes and cyclopropanes, no such sterols were found in the petrosid sponges we examined. Species within the same families failed to group on the basis of sterol chemistry, suggesting either their taxonomic allocations at this level are incorrect, or sterol complement is not a useful feature at this taxonomic level. Some species within the same genus grouped together while others did not. Sterol complements of species remained constant irrespective of geographic locality or season collected. Sponge species have both a qualitative and quantitative sterol fingerprint. The data set provided evidence of a species complex within Xestospongia muta . Three specimens of this species contained significantly different sterol complements.

Echinoclasterol sulfate phenethylammonium salt, a unique steroid sulfate from the marine sponge, Echinoclathria subhispida

Abstract A phenethylammonium salt of a new steroid sulfate, echinoclasterol sulfate (1) has been isolated from the marine sponge, Echinoclathria subhispida. The structure was determined by interpretation of spectral data including 2D NMR and FABMS. It exhibited antifungal activity against Mortierella ramannianus, and cytotoxicity against PC-9 human lung cancer cells.

Dereplication and Profiling of Marine Bacteria by Fatty Acid Analysis of Crude Extracts Using Fourier Transform Mass Spectrometry

Methods for grouping of bacteria include analysis of fatty acids by pyrolysis mass spectrometry of free fatty acids (Sanglier et al., 1992), their methyl esters (Basile et al., 1995), phospholipids and glycolipids by fast atom bombardment mass spectrometry (Heller et al., 1987), measurement of fatty acid content by methylation and gas chromatographic analysis of methyl esters (Bertone et al., 1996), GCMS (Dzierzewicz et al., 1996), and mass spectral fingerprints generated by matrix assisted laser desorption of intact bacterial cells (Claydon et al., 1995). Methods developed for grouping terrestrial bacteria can be transferred to marine species (Basile et al., 1995). There has been considerable recent interest in methods for phylogenetic grouping and identification of marine bacteria, where traditional biochemical tests are not effective in grouping isolates.

L'océan pharmacien

Locean possede dimmenses ressources pharmacologiques. Mais leur extraction se heurte encore a de grosses difficultes.