Structural characteristics of the molecular species of tetraacylglycerols in lesquerella (Physaria fendleri) oil elucidated by mass spectrometry

Tetraacylglycerols (triacylglycerol estolides) contain an acylacyl chain (one fatty acid attached to the hydroxyl group of another fatty acid attached to the glycerol backbone) and have different physical properties from those of triacylglycerols. Tetraacylglycerols can be used in industry such as the viscosity improver and pour point depressant of lubricants. The structures, contents and the ratios of the contents of regioisomers of the molecular species of tetraacylglycerols affect the physical properties of the mixture of tetraacylglycerols. They were elucidated by electrospray ionization mass spectrometry of the lithium adducts of tetraacylglycerols from the HPLC fractions of lesquerella oil. The ratios of the contents of acyl and acylacyl chains at the sn−2 position of the molecular species of tetraacylglycerols containing one normal FA (LsLsLsA type, Ls is lesquerolic acid. A is normal fatty acid and without hydroxyl group) in lesquerella oil were as: normal FA 58-98%), LsLs 0-35%), Ls 2-19%). For the molecular species of tetraacylglycerols containing two normal FA, 100% of the chains at the sn−2 position were normal FA, and the Ls, LsLs and LsA chains were all at the sn−1,3 positions. Acyl and acylacyl chains at the sn−2 position of the molecular species of tetraacylglycerols in lesquerella oil were predominately normal FA. Tetraacylglycerols are biodegradable and renewable, of low contents in seed oils, and can be produced through biotechnology focusing on triacylglycerol acyltransferase.