ARS | Publication request: Identification of minor acylglycerols less polar than triricinolein in castor oil by mass spectrometry and the proposed biosynthetic pathway of castor oil

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 31, 2011
Publication Date: N/A

Technical Abstract: Ricinoleate (OH18:1), a monohydroxy fatty acid, has many industrial uses such as the manufacture of biodegradable plastics, nylon, plasticizers, lubricants, cosmetics and paints. Castor oil is the only commericial source of ricinoleate which occurs as triacylglycerols. Triacylglycerols in castor oil less polar than triricinolein were identified by electrospray ionization-mass spectrometry using the lithium adducts of the triacylglyceros from the HPLC fractions of castor oil. Forty six new molecular species of acylglycerols in castor oil were identifed 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 odd-numbered long-chain fatty acid, 23:0 (tricosanoic acid), was identified. Some estolides and tetraacylglycerols were identified as (12-ricinoleoylricinoleoyl)-ricinoleoyl-lenoleoyl-glycerol (RRL), (12-ricinoleoylricinoleoyl)-ricinoleoyl-oleoyl-glycerol (RRRO), (12-ricinoleoylricinoleoyl)-ricinoleiyl-palmitoyl-glycerol (RRRP), and (12 ricinoleoylricinoleoyl)-ricinoleoul-stearoul-glycerol (RRS). The normal fatty acid (non-hydroxylated) of these tetraacylglycerols were directly attached to the glycerol backbone. The biosynthetic pathway of castor oil including triacylglycerols containing polyhydroxy fatty acids is proposed.