Phospholpid studies of marine organisms: 2.¹ Phospholipids, phospholipid‐bound fatty acids and free sterols of the spongeAplysina fistularis (Pallas) formafulva (Pallas) (=Verongia thiona)². Isolation and structure elucidation of unprecedented branched fatty acids

Abstract

The free sterols and phospholipids of the demospongeAplysina fistularis were isolated and analyzed. The free sterols consisted mainly of the unusual 26-methylated sterols aplysterol (53%) and 24(28)-dehydroaplysterol (7%) together with 7 commonly occurring sterods. The major phospholipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylserine and diphosphatidylglycerol. The major fatty acyl components of the phospholipids consisted of 85% C14-C20 acids, including the unprecedented 2,6,10-trimethyl-5-tetradecenoic acid and 11-methyloctadecanoic acid. The remaining 15% were C27-C30 demospongic acids, including 2 novel acids tentatively assigned the structures 5,9,23-octacosatrienoic acid and 5,9,23-nonacosatrienoic acid, and 3 novel acids proven to be 5,9,21-octacosatrienoic acid, Z,Z-20-methyl-5,9-hexacosadienoic acid and Z,Z-22-methyl-5,9-octacosadienoic acid. The biosyntheses of the novel demospongic acids are proposed to occur by chain elongation of monoenoic or branched precursors followed by desaturation. The large quantities of typically bacterial phospholipids and fatty acids found implied the presence of bacteria in the sponge, in agreement with microscopic studies. Analysis of the phospholipid-bound fatty acids in a sponge cell-enriched fraction indicated that the demospongic acids, including the 2 branched structures, were the major acids of the sponge cells. The presence inA. fistularis of demospongic acids containing membrane disordering groups-methyl branches or double bonds-on the ω7 carbon is proposed to be due to the need by the sponge for membranes possessing fluidity near the middle of the phospholipid bilayer. It is also proposed that the C26 methyl group of aplysterol causes disordering of the phospholipid bilayer in the same region, and thus also evolved in response to this need.

Lipid composition of the spongeVerongia aerophoba from the Canary Islands

“…The sponges from family Verongiidae are unique in their diversity of FA with a generally high level of long-, unsaturated, branched, and odd-chains [6,29]. The sample investigated by us also contained significant amounts of branched and unsaturated FA.…”

“…Antibacterial and cytotoxic activities were proven for these compounds [1][2][3][4][5]. The sponges contain large quantities of C 14 -C 30 fatty acids with branched and odd-chains [6,7] and hydroxy-acids [8,9]. The biosynthesis of these fatty acids occurs by chain elongation of monoenoic or branched precursors followed by desaturation [10].…”

Acides gras inhabituels des organismes marins : une illustration de la biodiversité moléculaire marine

“…Cependant, de tels AG restent trop peu explorés du point de vue de leur intérêt éventuel comme agents thérapeutiques en dépit du fait que des AG iso-ramifiés similaires ont montré une importante activité inhibitrice de la topoisomérase-I et une activité cytotoxique (Lee et al, 1998 ;Reyes et Carballeira, 1996 ;Carballeira et al, 2007a). L'acide iso-9-heptadécènoïque a été identifié dans des éponges et est attribuable à une bactérie marine (Boon et al, 1977 ;Walkup et al, 1981). Le nouvel acide 7-méthyl-8-hexadécènoïque et son isomère 14-méthyl-8-hexadécènoïque ont été identifiés dans l'éponge Desmapsama anchorata (Carballeira et Maldonado, 1988).…”

“…En plus de l'acide 30:3 Δ5,9,23 (14,8 %), trois autres AG en C 30 y ont été découverts : 30:3 Δ5,9,25 (2.1%), 30:1 Δ23 et 30:2 Δ9,23 (< 1 %) (figure 7). L'existence de ces deux derniers AG avait été postulée comme intermé-diaires de biosynthèse du 30:3 Δ5,9,23 (Walkup et al, 1981). L'existence des acides 30:3 Δ5,9,25 et 26:3 Δ5,9,21 chez les éponges suggère une nouvelle voie de biosynthèse procédant à partir du 16:1 Δ11 par allongement en série monoènoïque n-5 (autre intermédiaire connu à l'état naturel, 24:1 Δ17) Barnathan et al, 1996).…”

The syntheses of the marine metabolites 3-bromoverongiaquinol and 5-monobromocavernicolin

“…1 These metabolites are part of the chemical arsenal employed by these organisms against predators or to mark their territory. 2 Verongida sponges attract the attention of chemists and biologists as natural sources of unusual fatty acids, 3 steroids, 4 carotenoids 5 and aminoacids. 6 For example, from Aplysina cavernicola several biologically active compounds such as 3-bromoverongiaquinol (1) 7 and 5-monobromocavernicolin (2) 8 have been isolated.…”