Synthesis and enantiospecific analysis of enantiostructured triacylglycerols containing n-3 polyunsaturated fatty acids

• Published in: Chemistry and physics of lipids Vol. 231; p. 104937
• Main Authors: Kalpio, Marika, Magnússon, Jóhann D., Gudmundsson, Haraldur G., Linderborg, Kaisa M., Kallio, Heikki, Haraldsson, Gudmundur G., Yang, Baoru
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01-09-2020
• Subjects: Chemoenzymatic synthesis; Chromatography, High Pressure Liquid; Enantiospecific separation; Enantiostructured triacylglycerols; Fatty Acids, Omega-3 - chemistry; Molecular Structure; n-3 fatty acids; Recycling liquid chromatography; Stereoisomerism; Triglycerides - chemical synthesis; Triglycerides - chemistry; Recycling liquid chromatography; n-3 fatty acids; Chemoenzymatic synthesis; Enantiostructured triacylglycerols; Enantiospecific separation
• ISSN: 0009-3084; 1873-2941
• DOI: 10.1016/j.chemphyslip.2020.104937

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•Twelve enantiopure asymmetric TAGs containing ALA, EPA and DHA were synthesized.•Unique TAGs offer reference material e.g. for bioavailability studies of n-3 PUFAs.•Chiral separation of structured TAG enantiomers was performed by chiral R-HPLC.•New information about stereospecific resolution of TAGs was received.•R-HPLC was applied to study enantiopurity (>98 %).
The stereospecific structure of triacylglycerols (TAGs) affects the bioavailability of fatty acids. Lack of enantiopure reference compounds and effective enantiospecific methods have hindered the stereospecific analysis of individual TAGs. Twelve novel enantiostructured AAB-type TAGs were synthesized containing one of the three n-3 polyunsaturated fatty acid: α-linolenic acid (ALA), eicosapentaenoic acid (EPA), or docosahexaenoic acid (DHA) in sn-1 or sn-3 position. These compounds formed six enantiomer pairs, which were separated with recycling high-performance liquid chromatography using chiral columns and UV detection. The chromatographic retention behavior of the enantiomers and the stereospecific elution order were studied. The enantiomer with an n-3 PUFA in the sn-1 position eluted faster than the enantiomer with the n-3 PUFA in the sn-3 position, regardless of the carbon chain length and number of double bonds of the PUFA. TAG enantiomers containing DHA exhibited highly different retention on the chiral column and were separated after the first column, whereas recycling was needed to separate the enantiomer pairs containing ALA or EPA. The system using two identical columns and one mobile phase, without sample derivatization, proved to be very effective also for peak purity assessment, confirming the enantiopurity of the synthesized structured TAGs being higher than 98 % (96 % ee).