Odd-numbered very-long-chain polyunsaturated fatty acids from the dinoflagellate Amphidinium carterae identified by atmospheric pressure chemical ionization liquid chromatography–mass spectrometry

Abstract

A method is described for the enrichment of odd very-long-chain polyunsaturated fatty acids (VLCPUFAs) by means of RP-HPLC and argentation TLC from total fatty acids of the dinoflagellate A. carterae and their identification as picolinyl esters by means of microbore liquid chromatography-mass spectrometry with atmospheric pressure chemical ionization (LC–MS/APCI). The combination of argentation TLC and LC–MS/APCI was used to identify rare and unusual odd VLCPUFAs up to nonacosahexaenoic acid. Two acids, (all Z)-nonacosa-11,14,17,20,23-pentaenoic acid (29:5n-6) and (all Z)-nonacosa-11,14,17,20,23,26-hexaenoic acid (29:6n-3), were synthesized for the first time to unambiguously confirm their structure. Possible biosynthetic pathways for odd VLCPUFAs are also proposed.