Novel Non-methylene-Interrupted Dienoic and Trienoic Fatty Acids with a Terminal Double Bond in Ovaries of the Limpet Cellana toreuma

In this study, to obtain further information on the structural diversity of non-methylene-interrupted (NMI) fatty acids (FA) in the gonads of the limpet Cellana toreuma, previously unreported minor NMI FA, fractionated by argentation thin-layer chromatography (TLC), in the ovaries were characterized by gas chromatography-mass spectrometry (GC-MS) analysis of their 3-pyridylcarbinol derivatives. As a result, five novel NMI FA were identified as 5,14-pentadecadienoic acid (15: 2Δ5,14), 5,9,18-nonadecatrienoic acid (19:3Δ5,9,18), 5,9,20-heneicosatrienoic acid (21:3Δ5,9,20), 7,13,20-heneicosatrienoic acid (21:3Δ7,13,20), and 5,9,22-tricosatrienoic acid (23:3Δ5,9,22). Possible biosynthetic pathways for these FA are also discussed in relation to structural variations of NMI FA regioisomers. This study clearly reinforces the findings of our previous works with structurally diverse NMI FA with a terminal double bond.

Identification and Total Synthesis of Two Previously Unreported Odd-Chain Bis-Methylene-Interrupted Fatty Acids with a Terminal Olefin that Activate Protein Phosphatase, Mg2+/Mn2+-Dependent 1A (PPM1A) in Ovaries of the Limpet Cellana toreuma

Diverse non-methylene-interrupted (NMI) fatty acids (FAs) with odd-chain lengths have been recognized in triacylglycerols and polar lipids from the ovaries of the limpet Cellana toreuma, however their biological properties remain unclear. In this study, two previously unreported odd-chain NMI FAs, (12Z)-12,16-heptadecadienoic (1) and (14Z)-14,18-nonadecadienoic (2) acids, from the ovary lipids of C. toreuma were identified by a combination of equivalent chain length (ECL) values of their methyl esters and capillary gas chromatography-mass spectrometry (GC-MS) of their 3-pyridylcarbinol derivatives. On the basis of the experimental results, both 1 and 2 were synthesized to prove their structural assignments and to test their biological activity. The ECL values and electron impact-mass (EI-MS) spectra of naturally occurring 1 and 2 were in agreement with those of the synthesized 1 and 2. In an in vitro assay, both 1 and 2 activated protein phosphatase, Mg²⁺/Mn²⁺-dependent 1A (PPM1A) up to 100 μM in a dose-dependent manner.