Identification and Total Synthesis of Novel Fatty Acids from the Siphonarid Limpet Siphonaria denticulata

Abstract

The novel fatty acids 17-methyl-6(Z)-octadecenoic acid and 17-methyl-7(Z)-octadecenoic acid were identified for the first time in nature in the mollusk Siphonaria denticulata from Queensland, Australia. The principal fatty acids in the limpet were hexadecanoic acid, octadecanoic acid, and (Z)-9-octadecenoic acid, while the most interesting series of monounsaturated fatty acids was a family of five nonadecenoic acids with double bonds at either Delta(7), Delta(9), Delta(11), Delta(12), or Delta(13). The novel compounds were characterized using a combination of GC-MS and chemical transformations, such as dimethyl disulfide derivatization. The first total syntheses for the two novel methyl-branched nonadecenoic acids are also described, and these were accomplished in four to five steps and in high yields.

First total synthesis and antiprotozoal activity of (Z)-17-methyl-13-octadecenoic acid, a new marine fatty acid from the sponge Polymastia penicillus

“…In addition, a strong M + -55 peak at m/z 255 (12%) as well as the typical McLafferty rearrangement at m/z 74 (48%) were also observed (Denis et al, 2009). However, the GC retention times (ECL values) for both methyl esters were just slightly different but within the range of where these iso methyl-branched nonadecenoic acid methyl esters normally elute (Carballeira et al, 2001). For example, the natural methyl ester of 1 was reported to have an ECL value of 18.21, while the synthetic methyl ester of 1 was determined to have an ECL value of 18.51.…”

“…One rather poorly studied class of fatty acids has been the iso methyl-branched nonadecenoic acids, from which only a handful number of compounds are known. Among these fatty acids it is worthwhile to mention here the ( Z )-17-methyl-6-octadecenoic acid and the ( Z )-17-methyl-7-octadecenoic acid, which were isolated from the mollusk Siphonaria denticulata and synthesized for the first time by our group (Carballeira et al, 2001). The isomeric ( Z )-17-methyl-11-octadecenoic acid was also identified in the Caribbean sponge Calyx podatypa (Carballeira et al, 1998), but it is probably arising from a marine bacterium since it was first identified in the sulfate-reducing bacteria Desulfobacter and Desulfobulbus (Taylor and Parkes, 1983).…”

Molluscan biological and chemical diversity: secondary metabolites and medicinal resources produced by marine molluscs

“…Chemical studies on the marine pulmonate gastropods have focused largely on the polyproprionates from the limpet‐like Siphonaria spp. (Darias, Cueto & Díaz‐Marrero, 2006), although some novel fatty acid derivatives have also been isolated from species in this genus (Carballeira et al , 2001). Polyproprionates have also been isolated from the intertidal systellommatophoran slug Onchidium sp.…”

Marine unsaturated fatty acids: structures, bioactivities, biosynthesis and benefits

“…The structures were conrmed by synthesis. 16 2.2.5 Microorganisms. An unidentied fungal strain (I96S215), which was obtained from a tissue sample of an unidentied marine sponge collected in Indonesia, produced seco-patulolide 13.…”