New unsaturated long-chain fatty acids in the phospholipids from the Axinellida sponges Trikentrion loeve and Pseudaxinella cf. lunaecharta.

In order to identify new structures and especially those involved as biosynthetic intermediates, the fatty acid composition of whole phospholipids from two Senegalese marine sponges from the order Axinellida, Trikentrion loeve and Pseudaxinella cf. lunaecharta, has been investigated by analytical gas chromatography and gas chromatography/mass spectrometry. Several new fatty acids were identified as methyl esters and N-acyl pyrrolidides, namely 16-eicosenoic, 11-tetracosenoic, 5-pentacosenoic, 11-hexacosenoic, 11-octacosenoic, 23-triacontenoic, 17,21-hexacosadienoic, 19,23-octacosadienoic, 9,23-triacontadienoic, 5,9,21-hexacosatrienoic, and 5,9,25-triacontatrienoic. Trikentrion loeve and P. cf. lunaecharta contain fifteen (25.7% of the total acid mixture) and thirteen (30.4%) delta 5,9 fatty acids, respectively. Based on gas chromatography/Fourier transform infrared experiments, the double bonds were assigned the (Z) configuration. Biosynthesis of dienoic and trienoic demospongic acids possessing an n-5 or an n-7 terminal double bond is discussed.