Diverse Odd-Chain Monoenoic Fatty Acids and Novel Non-Methylene-Interrupted Heptadecadienoic Acids in Ovaries of the Limpet Cellana toreuma

Highly diverse dienoic fatty acids (FA), especially non-methylene-interrupted (NMI) FA, have been recognized in triacylglycerols (TAG) and polar lipids of ovaries of the limpet Cellana toreuma. To gain additional insights into the structural diversity of FA in ovaries, this study aimed to clarify previously undescribed minor monoenoic FA isomers and unidentified minor NMI FA by combined argentation thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) of their 3-pyridylcarbinol derivatives. A total 66 monoenoic FA from C14 to C22, including 12 branched-chain FA, were identified. A surprising finding was a series of 13 heptadecenoic acids with double bonds at either 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, or 16 positions. Besides previously identified NMI FA, 7,18-nonadecadienoic (19:27,18), 9,18-nonadecadienoic (19:29,18), 11,18-nonadecadienoic (19:211,18), 7,20-heneicosadienoic (21:27,20), and 11,20-heneicosadienoic (21:211,20) acids, two novel related NMI FA, 5,16-heptadecadienoic (17:25,16) and 7,16-heptadecadienoic (17:27,16) acids, were found in TAG. These findings could provide new insights into clarifying the biological characteristics of marine NMI FA.