The methanolic extract of the marine sponge Ircinia felix has yielded
nine novel fatty acid esters, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-
22-methyltricosadienoate, (7E, 12E, 18R, 20Z)-variabilin (5Z, 9Z)-tetr
acosadienoate, (7E, 12E, 18R, 20Z)-variabilin hexadecanoate, (7E, 12E,
18R, 20Z)-variabilin 10-methylhexadecanoate, (7E, 12E, 18R, 20Z)-vari
abilin 15-methylhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 14-methy
lhexadecanoate, (7E, 12E, 18R, 20Z)-variabilin 9-octadecenoate, (7E, 1
2E, 18R, 20Z)-variabilin octadecanoate, and (7E, 12E, 18R, 20Z)-variab
ilin 2,11-dimethyloctadecanoate, along with the recently described (7E
, 12E, 18R, 20Z)-variabilin 11-methyloctadecanoate. The characterizati
on of the new fatty acids (5Z, 9Z)-22-methyltricosadienoic and 2,11-di
methyloctadecanoic acids is also described. The chemical structures we
re determined by extensive spectroscopic, chromatographic, and chemica
l analyses.