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Title: Identification of minor acylglycerols less polar than triricinolein in castor oil by mass spectrometry

item Lin, Jiann
item Chen, Grace

Submitted to: American Chemistry Society Abstracts
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2012
Publication Date: 5/27/2012
Citation: Lin, J.T., Chen, G.Q. 2012. Identification of minor acylglycerols less polar than triricinolein in castor oil by mass spectrometry. American Chemistry Society Abstracts.

Interpretive Summary: Castor oil has been used in industry such as the manufacture of biodegradable plastics, nylon, plasticizers, lubricants, cosmetics and paints. We have identified various molecular species of acylglycerols containing various hydroxy fatty acids in castor oil. This characterization of castor oil will help the industrial uses of castor oil and to propose the biosynthetic pathway of castor oil enabling metabolic engineering. Castor bean contains the toxin, ricin, and potent allergens, which make it hazardous to grow, harvest and process. It would be desirable to produce castor oil substitute from a transgenic oilseed lacking these toxic components through metabolic engineering.

Technical Abstract: Triacylglycerols in castor oil less polar than triricinolein were identified by electrospray ionization – mass spectrometry using the lithium adducts of the acylglycerols from the HPLC fractions of castor oil. Thirty four new molecular species of acylglycerols containing hydroxy fatty acids in castor oil were identified by the MS. The chain lengths of fatty acid substituents were C16, C18, C20, C22 and C23. The numbers of double bonds of the fatty acids were from zero to three. The numbers of hydroxyl groups on the fatty acid chains were from zero to three as previously reported. The structure of fatty acid, OH18:2, was proposed as 12-hydroxy-9,13-octadecadienoic acid. An unusual odd-numbered long-chain fatty acid, 23:0 (tricosanoic acid), was identified. Some new estolides and tetraacylglycerols, were identified as (12-ricinoleoylricinoleoyl)-ricinoleoyl-lenoleoyl-glycerol (RRRL), (12-ricinoleoylricinoleoyl)-ricinoleoyl-oleoyl-glycerol (RRRO), (12-ricinoleoylricinoleoyl)-ricinoleoyl-palmitoyl-glycerol (RRRP), and (12-ricinoleoylricinoleoyl)-ricinoleoyl-stearoyl-glycerol (RRRS). The normal fatty acid (non-hydroxylated) of these tetraacylglycerols were directly attached to the glycerol backbone.