Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/12/2014
Publication Date: 6/12/2014
Publication URL: http://dx.doi.org/10.1007/s11746-014-2486-2
Citation: Lin, J.T., Chen, G.Q. 2014. Quantification of TAG and DAG in lesquerella (Physaria fendleri) oil by HPLC and MS. Journal of the American Oil Chemists' Society. 91:1417-1424 DOI: 10.1007/s11746-014-2486-2.
Interpretive Summary: Ricinoleate, a hydroxy fatty acid, in castor oil has many industrial uses such as the manufacture of biodegradable plastics, plasticizers, lubricants, cosmetics, paints and surfactants. Castor is the only commercial source of ricinoleate. Lesquerolate, a hydroxy fatty acid in lesquerella oil, also can be used in industry similar to those of ricinoleate. Lesquerella is a new industrial oilseed crop in the southwestern region of the U. S. valued for its lesquerolate. Molecular species of triacylglycerols containing lesquerolate in lesquerella oil were quantified. This will help the industrial uses of lesquerella oil, and will help to propose the biosynthetic pathways of triacylglycerols in lesquerella for future plant modification.
Technical Abstract: Castor oil has many industrial uses because of its high content (90%) of the hydroxy fatty acid, ricinoleic acid (OH1218:19). Lesquerella oil containing lesquerolic acid (Ls, OH1420:111, 56.5%) is potentially useful in industry. Ten diacylglycerols (DAG) and 74 triacylglycerols (TAG) in the seed oil of Physaria fendleri were recently identified by HPLC and MS. These acylglycerols (AG) were quantified by HPLC with evaporative light scattering detector and electrospray ionization mass spectrometry of the lithium adducts of the AG in the HPLC fractions of lesquerella oil. The MS1 ion signal intensities of molecular ions [M + Li]+ were used to estimate the ratios of AG in HPLC fractions of a HPLC peak. The ratios of TAG with the same mass in HPLC fractions were estimated by the ratios of the sums of MS2 ion signal intensities from the neutral loss of the three fatty acids [M + Li - FA]+. The ratio of DAG with the same mass were estimated by the ratio of the sums of two MS2 ion signal intensities [M + Li - FA]+ and [FA + Li]+. We have estimated the contents of ten molecular species of DAG and 74 molecular species of TAG in Physaria fendleri oil. The content of ten DAG combined was about 1% and 74 TAG was about 98%. The contents of DAG in decreasing order were: LsLs (0.25%), LsLn (0.25%), LsO (0.24%), LsL (0.11%) and the contents of TAG in decreasing order were: LsLsO (31.2%), LsLsLn (24.8%), LsLsL (15.8%), LsL-OH20:2 (4.3%), LsO-OH20:2 (2.8%), and LsLn-OH20:2 (2.5%).