Novel Odd-Chain Fatty Acids with a Terminal Double Bond in Ovaries of the Limpet Cellana toreuma

Our previous study characterized highly diverse dienoic fatty acids (FA), in particular an uncommon non-methylene-interrupted (NMI) FA, in the ovaries of the Japanese limpet Cellana toreuma belonging to the archaeogastropods, but many minor chemically unidentified FA remain. In this study, among previously unidentified FA (less than 0.1% of total FA), four novel NMI FA with a terminal double bond [7,18-nonadecadienoic (19:2 Delta 7,18), 11,18-nonadecadienoic (19:2 Delta 11,18), 7,20-heneicosadienoic (21:2 Delta 7,20), and 11,20-heneicosadienoic (21:2 Delta 11,20) acids] were found, along with known 14-pentadecenoic (15:1 Delta 14), 16-heptadecenoic (17:1 Delta 16), and 9,18-nonadecadienoic (19:2 Delta 9,18) acids, based on capillary GC-MS of their methyl esters, 3-pyridylcarbinol derivatives, and argentation thin-layer chromatography. From our findings, possible biosynthetic pathways for the novel FA are discussed.