Enantiomeric separation of triacylglycerols containing polyunsaturated fatty acids with 18 carbon atoms

•Triacylglycerols (TAGs) were analyzed by RP-HPLC/APCI-MS and chiral HPLC.•Chiral separation of TAGs containing C18 PUFA was performed.•Haptophyte alga shows enantioselective metabolism of TAGs dependent on salinity.•TAGs having stearidonic and octadecapentaenoic acids were found in Coccolithophora sp.

Regioisomers and enantiomers of triacylglycerols (TAGs) containing any combination of stearidonic (18:4n-3) and octadecapentaenoic (18:5n-3) acids were prepared by organic synthesis. Gradient polar organic liquid chromatography/high resolution atmospheric pressure chemical ionization-tandem mass spectrometry (NARP-LC/HRMS2-APCI) and chiral liquid chromatography were used for the separation and identification of molecular species of these TAGs. Further, NARP-LC and chiral LC were used to separate natural mixtures of TAGs obtained from the haptophyte alga Coccolithophora sp. cultivated in a salinity range from 7.5 to 60‰. The ratio of regioisomers and enantiomers was found to change with increasing salinity of the culture medium. This can be explained by variable activity of acyltransferases in cells exposed to salt stress.