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

Publisher's version (útgefin grein)
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).
The authors thank Jani Sointusalo at University of Turku for assistance with the recycling system, Dr. Sigridur Jonsdottir at the Science Institute, University of Iceland, for the accurate mass measurements, Novozymes AS in Denmark for the lipase and Olav Thorstad of Pronova BioPharma ASA in Norway for pure DHA. The work was funded by the Academy of Finland (Decision Nos. 310982 and 315274 ), and the Finnish Cultural Foundation . Haraldur G. Gudmundsson acknowledges financial support for a temporary postdoctoral research at University of Turku and Jóhann D. Magnússon financial support from Lýsi hf. in Iceland .