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United States Department of Agriculture

Agricultural Research Service

Research Project: Improvement and Utilization of Natural Rubber- and Castor Oil-producing Industrial Crops

Location: Bioproducts Research

Title: Identification and quantification of tetraacylglycerols in lesquerella oil by HPLC and MS

item Lin, Jiann-tsyh

Submitted to: Proceedings JOCS/AOCS World Congress
Publication Type: Abstract Only
Publication Acceptance Date: 1/8/2014
Publication Date: 5/4/2014
Citation: Lin, J.T. 2014. Identification and quantification of tetraacylglycerols in lesquerella oil by HPLC and MS. Proceedings JOCS/AOCS World Congress. ANA 3: Analysis of vegetable oil authentication and adulteration.

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. Tetraacylglycerols have different physical properties from those of triacylglycerols and can be used in industry for different physical properties such as viscosity and pour point improvers for lubricants. We have identified and quantified 13 tetraacylglycerols containing lesquerolate in lesquerella oil. The contents of these tetraacylglycerols can be increased in the future for industrial uses. The biosynthetic precursors of these tetraacylglycerols were proposed.

Technical Abstract: Tetraacylglycerol (an acylglycerol estolide) contains an acyl chain attached to the hydroxyl group of another acyl chain attached to the glycerol backbone. Lesquerolic acid (Ls) is the main fatty acid in lesquerella oil and may be used industrially for the manufacture of biodegradable industrial products. Electrospray ionization mass spectrometry of the lithium adducts of acylglycerols in the HPLC fractions of lesquerella oil was used to identify thirteen tetraacylglycerols. They were LsLsLsLn, LsLsLsL, LsLs-OH20:2-O, LsLsLsO, LsLsLnLn, LsLsLLn, LsLsOLn, LsLsLL, LsLsOL, LsLsOP, LsLsOO, LsLsLS and LsLsOS. For the four tetraacylglycerols containing one normal fatty acid (non-hydroxy fatty acid), LsLsLsLn, LsLsLsL, LsLs-OH20:2-O and LsLsLsO, the normal fatty acids were all directly attached to the glycerol backbone, not to the hydroxyl group of fatty acids. We propose that the biosynthetic precursors (triacylglycerol acyltransferase) of these four tetraacylglycerols were LsLsLn, LsLsL, LsLsO (Ls-OH20:2-O) and LsLsO individually. Quantitations of these tetraacylglycerols were by HPLC with evaporative light scattering detector and MS of HPLC fractions (comparing the ion signal intensities). The highest content of these tetraacylglycerols was LsLsLsO at about 0.3% in lesquerella oil.

Last Modified: 10/19/2017
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