Demospongic acid

Lakes, rivers, swamps, and marshes - common in temperate areas - contribute little to the diversity of natural products. Abundant dull-green grass and dull-colored fish and moUusks characterize lakes and rivers, in contrasts with the vivid colors of tropical fish and seaweeds. Haplosclerid sponges are occasionally abundant in freshwater, but their secondary metabolism is limited to demospongic acids (Dembisky 1994), in contrast with the variety of metabolites from marine sponges in the same order. Where not for cyanobacteria (which are as rich of unusual metabolites as the marine strains), tropical amphibians, and aquatic fimgi, freshwater ecosystems would have passed unnoticed in this book. 

WiJEKOON, W.M.D., E. Ayanoglu, and C. Djerassi Phospholipid Studies of Marine Organisms 9. New Brominated Demospongic Acids from the Phospholipids of Two Petrosia Species. Tetrahedron Lett. 25, 3285 (1984). 

These acids are called demospongic acids because they have been found in most species of demosponges, but they are also present in marine invertebrates of other phyla. These acids are considered in more detail below. 

Phospholipids, which are basic constituents of cell membranes, are amphiphilic derivatives in which the hydrophilic part is a phosphoric ester and the hydrophobic part a fatty acid chain. Phospholipids of sponges differ pro-foimdly from those of other organisms by the presence of particular fatty adds called demospongic acids (Litchfield and Morales, 1976). These acids have very long chains (from 24 to 34 carbon atoms), with an unusual type of imsaturation, particularly dienic 5,9 and trienic 5,9, X systems, which are very frequent, as well as structural elements that are unknown or rare in other phyla, such as the presence of bromine in the vinylic position, methoxy and acetoxy groups, branches in the middle of the chain, triple bonds, cydopropanes and isoprenic stmctures. 

The existence of a continuous series acids with 24 to 32 carbon atoms and the existence of demospongic acids with up to 34 carbon atoms suggests that it is probably for technical reasons related to the stationary phase in gas chromatography that no acids with more than 34 carbon atoms seem to have been identified. For a recent review on very long-chain-fatty acids, see Rezanka and Sigler, 2009. 

The chromatographic profiles of the fatty acid compositions of sponge phospholipids are characteristic, because they show two zones corresponding respectively to short and normal acids, and demospongic acids. 

Intracellular Localization and Biological Activity of Demospongic Acids... 

Species of the family Spongillidae have been studied the most, and a comprehensive review of their lipids has been published (Dembitsky, 2003). Broadly speaking, there are no significant differences in membrane fatty acids between marine and freshwater sponges, which also contain many branched acids (iso, anteiso, prenylated chains acids) and long-chain demospongic acids with the 5,9 diunsaturation pattern (see above). 

Ando, Y, Kawabata, Y, Narukawa, K., and Ota, T. (1998) Demospongic acids of the marine sponge Halichondroia panicea from the coast of Hokkaido, Japan. Pish. Sci., 64,136-139. 

RaederstorlF, D., Shu, A.Y.L., Thompson, J.E., and Djerassi, C. (1987) Biosynthetic studies of marine lipids. 11. Synthesis, biosynthesis and absolute configuration of the internally branched demospongic acid, 22-methyl-5,9-octacosadienoic add. J. Org. Chem., 52, 2337-2346. 

Wijekoon, W,M Ayanoglu, E., and Djerassi, C, (1984) Phospholipid Studies of Marine Organisms 9. New brominated demospongic acids from the phospholipids of two Petrosia species. Tetrahedron Lett., 25, 3285-3288,... 

Fatty acids, Demospongic acids, and Related Compounds... 

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