Identification of (12-ricinoleoylricinoleoyl) diricinoleoylglycerol, an acylglycerol containing four acyl chains, in castor (Ricinus communis L.) oil by LC-ESI-MS

acylglycerol (AG) containing four acyl chains, (12-ricinoleoylricinoleoyl)diricinoleoylglycerol (RRRR), positively identified for the first time in a natural source in castor oil using electrospray ionization mass spectrometry (ESI-MS/MS). HPLC-purified RRRR from castor oil was subjected to ion and high-resolution ESI-MS/MS. The precursor and fragment ions of [RRRR + Na](+) showed expected masses, and the sodiated fragment ions of both diacylglycerols and fatty acids were Because fragment ions of fatty acids from [AG + NH4](+) adducts cannot be detected by MS/MS, [AG + Na](+) adducts are more informative. Radiolabeled triricinolein (RRR) was into RRRR in castor microsomes, indicating that RRRR is biosynthesized in castor bean. newly identified and biosynthesized RRRR represents a new AG subclass of tetra-acylglycerols (or acylacyldiacylglycerol).