ARS | Publication request: REGIOSPECIFIC ANALYSIS OF DIRICINOLEOYL-OLEOYL-GLYCEROL IN CASTOR OIL USING ELECTROSPRAY IONIZATION-MASS SPECTROMETRY

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2006
Publication Date: September 10, 2006
Citation: Lin, J.T., Arcinas, A.J. 2006. Regiospecific analysis of diricinoleoyl-oleoyl-glycerol in castor oil using electrospray ionization-mass spectrometry. Meeting Abstract.

Interpretive Summary: Ricinoleate (R, a hydroxyl fatty acid) has many industrial uses such as the manufacture of aviation lubricant, plastics, paints and cosmetics. Ricinoleate and other fatty acids (FA) occur as acylglycerols(AG) in castor oil and castor oil is the only commercial source of ricinoleate. It is important to know the contents of castor oil for industrial applications and for the development of a transgenic plant that produce ricinoleate. The exact structure of diricinoleoyl-oleoyl-glycerol in castor oil is important to explain the biosynthetic pathway of caster oil. We have used mass spectrometry to show the locations of these three fatty acid chains.

Technical Abstract: Ricinoleate, an industrially useful hydroxy fatty acid occurs abundantly as triacylglycerols (TAG) in castor seed, in addition to the toxin, ricin. The stereospecific determination of diricinoleoyloleoylglycerol (RRO) in castor oil helps explain key enzymatic steps involved on the biosynthetic pathway of castor oil. The pathway can be used for the development of transgenic oilseed to produce castor oil substitute lacking this toxic component. Analysis of RRO in castor oil (~7%) was studied here. Using LC-ESI-MS3 with lithium acetate mobile phase modifier to promote adduct formation, the presence of key daughter ions indicate the vast majority of oleoyl chain to occupy at the sn-2 position of the glycerol backbone of RRO. The regiospecific determination of RRO indicates that phospholipase A2 in castor seed is specific to release ricinoleate from 2-ricinoleoyl-PC, blocking the release of oleate from 2-oleoyl-PC, the precursor of oleoyl-12-hydroxylase, thereby increasing the ricinoleate content in castor oil.