Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2008
Publication Date: 4/29/2008
Citation: Lin, J.T., Arcinas, A.J. 2008. Regiospecific Identification of 2-(12-Ricinoleoylricinoleoyl)-1,3-diricinoleoyl-glycerol in Castor (Ricinus communis L.)Oil by ESI-MS4. Journal of Agricultural and Food Chemistry. 56: 3616-3622. Interpretive Summary: Castor oil contains high levels of ricinoleate (hydroxyl fatty acid) for industrial uses. However castor also contains toxic substances. It is desirable to produce high levels of ricinoleate in transgenic oil seeds lacking these toxic substances. It is important to know the biosynthetic pathway of castor oil to develop transgenic oil seed plants that produce ricinoleate. We have recently identified a new oil component containing four ricinoleates (RRRR) in castor oil. This new oil component can be a new target to produce more ricinoleate in a transgenic oil seed plant because of the extra ricinoleate compared to triricinolein (RRR). The location of the fourth ricinoleate is identified in this report. This will help to understand the biosynthesis of RRRR and to develop a transgenic oil seed plant that produces RRRR.
Technical Abstract: (12-ricinoleoylricinoleoyl)diricinoleoylglycerol (RRRR), a tetraacylglycerol, was identified earlier in castor oil. Using ESI-MS4, 95% of the 12-ricinoleoylricinoleoyl chain was identified at the sn-2 position of the glycerol backbone of RRRR. Regiospecific location of the 12-ricinoleoylricinoleoyl chain of RRRR was identified and quantified by the ions from the losses of the acyl chains at the sn-2 position as unsaturated fatty acids from the lithium adduct of RRRR. By comparison to the mass spectrum of 1-O-palmityl-2,3-palmitoyl-rac-glycerol containing one ether bond, the 12-ricinoleoylricinoleoyl chain of RRRR is indeed the ester bond between the two ricinoleoyl chains, not the ether bond formed from the two hydroxyl groups of the two ricinoleoyl chains.