Unusual polymethylene-interrupted, Δ5 monounsaturated and omega-3 fatty acids in sea urchin (Arbacia punctulata) from the Gulf of Mexico identified by solvent mediated covalent adduct chemical ionization mass spectrometry

Sea urchin (class Echinoidea) gonads are a prized delicacy in Japan and many other world cultures. The complexity of its fatty acid (FA) profile, particularly minor FA, presents a formidable analytical challenge. We applied solvent mediated (SM) covalent adduct chemical ionization (CACI) tandem mass spectrometry to comprehensive de novo structural and quantitative characterization of the FA profile of Gulf of Mexico Atlantic sea urchin (Arbacia punctulata). >100 FA were detected including many with unusual double bond structure. Gulf sea urchin gonad lipids are rich in Delta 5 monounsaturated FA 20:1(5Z) at 2.7% and the polymethyleneinterrupted (PMI) diene 20:2(5Z,11Z) at 4.9%, as well as common omega-3 eicosapentaenoic acid (EPA; 5Z, 8Z, 11Z, 14Z, 17Z) at 9.8%+/- 3.1% and arachidonic acid (AA; 5Z, 8Z, 11Z, 14Z) at 6.1%+/- 2.1%. We propose plausible desaturation/elongation-based biochemical pathways for the endogenous production of unusual unsaturates. Unusual unsaturates may modify mammalian signaling and present novel bioactivities.

Automated summary

Sea urchin gonads are considered a delicacy in Japan and other cultures, with a complex fatty acid profile that poses analytical challenges. A comprehensive study using tandem mass spectrometry revealed over 100 fatty acids, including unique double bond structures. The presence of unusual unsaturates in sea urchin gonad lipids may have potential effects on mammalian signaling pathways and offer novel bioactivities.