Compounds from Other Marine Snails

Miscellaneous Compounds from Other Marine Snails 

Two novel tetraesters, kelletinin I (878) and II (879), which inhibited the growth of Bacillus subtilis and L1210 leukemia cells have been 

Marine pulmonates of the genus Siphonaria are air breathing molluscs that resemble limpets with which they co-occur in the intertidal zone. Nearly all specimens examined contained polypropionate metabolites that are believed to be employed in chemical defense against predators. Siphonaria diemenensis collected intertidally in southeastern Australia contained two antibiotics, diemenensin-A ( 2) and -B (883) 

The intertidal limpet Collisella limatula contains limatulone (914) which inhibits fish and crab predation (600b). Food pellets containing 914 at levels of 0.05% dry weight or more induced regurgitation in the intertidal fish Gibbonsia elegans, a known limped predator. The marine prosobranch mollusc, Lamellaria sp. furnished four aromatic metabolites, lamellarins A-D (915-918) (600 c). At concentrations of 19 pg/mL, 918 caused a 78% inhibition of cell division in the fertilized sea urchin egg assay while 917 caused 15% inhibition and 915 as well as 916 were inactive. 

Milkova et al. (325) investigated the sterol composition of Black sea organisms belonging to the phyla Coelenterata and Mollusca, in order to study food chains in this ocean and to shed light on the origin of sterols in marine organisms. 

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V.1.4. Miscellaneous Compounds from Other Marine Snails. . . . 275 V.2. Bivalvia.282... 

V,1.4. Miscellaneous Compounds from Other Marine Snails... 

Marine sponges contain a host of bioactive compounds, particularly small molecules, and also contain a range of peptides that are non-ribosomally synthesised, often containing non-native amino acids. However, there are examples of peptides of ribosomal origin, including, for example, asteropine A isolated from the sponge Asteropus simplex.133 This peptide comprises 36 residues and three disulphide bonds. It has potent sialidase inhibitory activity and thus has applications in the design of novel viral inhibitors. Structural analysis of asteropine A with NMR spectroscopy revealed a cystine-knot motif, similar to that already described for plant toxins. This observation emphasises the fact that the cystine-knot motif is extremely prevalent in disulphide-rich peptides.134 Asteropine A, discovered in 2006, was the first reported cystine-knot peptide isolated from marine invertebrates other than from cone snails, which are described in more detail below. 

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