Submitted to: Journal of Liquid Chromatography and Related Technologies
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/9/2002
Publication Date: 3/1/2003
Citation: Lin, J.T., Mckeon, T.A. 2003. Relative retention times of molecular species of acylglycerols, phosphatidylcholines, and phosphatidylethanolamines containing ricinoleate in reversed-phase hplc. Journal of Liquid Chromatography and Related Technologies. 2003. 26: 1051-1058 Interpretive Summary: Ricinoleate (a hydroxy fatty acid) has many industrial uses such as the manufacture of aviation lubricant, plastics, paints, coatings and cosmetics. Its only commercial source is castor bean. Since castor bean contains the toxin ricin as well as potent allergens, it is hazardous to grow, harvest and process. It would be desirable to produce ricinoleate instead in a transgenic oilseed lacking these toxic components. We have recently reported the biosynthetic pathway of castor oil and identified the key enzymatic steps, which drive ricinoleate into castor oil in castor bean. We have also identified and quantified molecular species of various lipid classes incorporated from various radiolabeled fatty acids. Here we report the relative retention times of the molecular species of various lipid classes containing ricinoleate in reversed-phase high-performance liquid chromatography. The results will help in the study of castor oil biosysthesis.
Technical Abstract: The relative retention times (RRT) of twenty one molecular species of diacylglycerols (DAG), forty two molecular species of triacylglycerols (TAG), thirty six molecular species of phosphatidylcholines (PC) and thirty six molecular species phosphatidylethanolamines (PE) in reversed-phase HPLC are reported. They were derived from incorporation of six [14C]-labeled fatty acids, ricinoleate, stearate, oleate, linoleate, linolenate and palmitate, in castor microsomal incubations. Most of these RRT were not reported earlier because the standards were not available including the molecular species containing ricinoleate. In general, DAG eluted earlier than TAG on a C18 HPLC used for the separation of the molecular species of AG. When only one acyl chain differed in the molecular species of both DAG and TAG, the elution order was: ricinoleate, linolenate, linoleate, palmitate, oleate, stearate. Two C8 HPLC systems were used for separation of the molecular species of PC and PE respectively, with a more polar eluent used to elute the less polar PE. The elution order for the molecular species of both PC and PE when one acyl chain was different were the same as that of AG. The pairs of positional isomers of the molecular species of AG, PC and PE elute closely. The RRT and elution characteristics reported are useful for the preliminary identification of molecular species of AG, PC and PE, the important lipid classes in oil biosynthesis and membrane formation.