New methoxylated fatty acids from the Caribbean sponge Callyspongia fallax

The saturated 2-methoxylated fatty acids 2-methoxytetradecanoic acid (1), 2 -methoxypcntadecanoic acid (2), and 2-methoxyoctadecanoic acid (3) as well as the Delta (6) monoenoic methoxylated fatty acids (6Z)-2-methoxy-6-tetrad ecenoic acid (4), (6Z)-2-methoxy-6-pentadecenoic acid (5), and (6Z)-2-metho xy-13-methyl-6-tetradecenoic acid (7) were identified for the first time in nature in the phospholipids from the Caribbean sponge Callyspongia fallax. These findings expand the occurrence of 2-methoxylated fatty acids to C-14 -C-15 chain lengths and establish new fatty acid biosynthetic possibilities for marine organisms. The novel methoxylated fatty acids could have origin ated from the phospholipids of a bacterium in symbiosis with the sponge.