Identification of 2-Methoxyhexadecanoic Acid in Amphimedon compressa

Abstract

The phospholipid fatty acid composition of Amphimedoncompressa was reinvestigated and the 2-methoxyhexadecanoic acid was identified for the first time in nature. Structure characterization was accomplished by means of gas chromatography-mass spectrometry and total synthesis from commercially available 2-hydroxyhexadecanoic acid.

The first naturally occurring α‐methoxylated branched‐chain fatty acids from the phospholipids of Amphimedon complanata

“…Three of these acids, namely, 2-methoxy-5(Z)-hexadecenoic acid, 2-methoxy-6(Z)-hexadecenoic acid and 2- methoxyhexadecanoic acid, were previously reported by us from several Caribbean sponges (3,4). The finding in A. complanata that has never been observed before is that all three of these acids were present (at low levels) in the same sponge.…”

“…These values suggested methyl branching near the end of the chain, in particular when compared to a calculated ECL value of ca. 16.2 expected for a normal-chain methyl 2-methoxypentadecanoate and an ECL value of 17.2 reported for methyl 2-methoxyhexadecanoate (4). From the ECL values it was also clear that 1a and 1b had the same methyl substitution, while the methyl substitution in 2 was different.…”

“…This specimen of A. complanata contains a very complex phospholipid fatty acid profile typical of sponges belonging to the genus Amphimedon (4,5,7). Noteworthy is its ability to extend the n-7 and n-9 families of even-numbered chain monounsaturated fatty acids from 9-18:1 and 11-18:1 to 21-30:1 and 23-30:1, respectively.…”

“…All of these acids were reported to have the R configuration at the chiral center. Recent efforts have concentrated on the C 16 family of α-methoxylated fatty acids, such as the 2-methoxy-5(Z)-hexadecenoic acid, 2-methoxy-6(Z)-hexadecenoic acid, and the 2-methoxyhexadecanoic acid, which were identified in the phospholipids of several Caribbean sponges such as Amphimedon compressa (4). Both 2-methoxy-5(Z)-hexadecenoic acid and 2-methoxyhexadecanoic acid occur more often in the phospholipids of sponges than their ∆6 analogs (5).…”

Identification of Novel α‐Methoxylated Phospholipid Fatty Acids in the Caribbean Sponge Erylus goffrilleri

“…The a-methoxylated fatty acids have been mostly identified in the phospholipids of sponges, but there is a report of a terrestrial source [5]. Among the structural varieties of the a-methoxylated fatty acids identified so far we could mention those with iso/ anteiso methyl branching [6], monounsaturated a-methoxylated acids [6], very long-chain diunsaturated a-methoxylated acids [7], and saturated normal-chain a-methoxylated fatty acids [8]. There is only one a-methoxylated fatty acid known with the D5,9 diunsaturation, namely the acid (5Z,9Z)-2-methoxy-5,9-hexacosadienoic acid, which was identified in the sponge Topsentia roquensis [9].…”