Biosynthesic Studies of Marine Lipids. 11. Synthesis, Biosynthesis, and Absolute Configuration of the Internally Branched Demospongic Acid, 22-Methyl-5,9-octacosadienoic Acid

Article abstract of DOI:10.1021/jo00388a001

The 14C-labeled short-chain fatty acid 10-methylhexadecanoic acid (10-Me-16:0) as well as its hitherto undescribed 10R and 10S antipodes was incorporated into the marine sponge Aplysina fistularis and transformed in situ into 22-methyl-5,9-octacosadienoic acid (22-Me-Δ^5,9-28:2) by chain elongation.No qualitative specificity between the two enantiomers was observed. <3H> Methionine was also incorporated into the sponge to investigate the methylation process; a rapid incorporation into the short branched fatty acids occurred with subsequent chain elongation.Both enantiomers were synthesized starting from (+)-pulegone to determine the absolute configuration of the 22-methyl-5,9-octacosadienoic (22-Me-Δ^5,9-28:2) acid.The naturally occurring acid has the 22R configuration.