The structure of the triacylglycerols, containing punicic acid, in the seed oil ofTrichosanthes kirilowii

Triacylglycerols of the seed oil ofTrichosanthes kirilowii have been resolved by high‐performance liquid chromatography (HPLC) in the silver‐ion and reverse‐phase modes. The fatty acids were identified by gas chromatography/mass spectrometry as the picolinyl esters. The main components arecis,cis‐C18:2n‐6 (38.2 mole%), C18:39c,11t,13c (punicic acid, 38.0 mole%), andcis‐C18:1n‐9 (11.8 mole%). Small amounts of C18:39c,11t,13t (α‐eleostearic acid) and C18:39t,11t,13c (catalpic acid) were detected. Silver‐ion HPLC exhibited excellent resolution in which fractions were resolved on the basis of the number and configuration of double‐bonds. In this instance, the strength of interaction of a conjugated trienoic double‐bond system with silver ions seemed to be between that of dienoic and monoenoic double bond systems. The triacylglycerols were also separated into 20 fractions by reverse‐phase HPLC, and the fractionation was achieved according to the partition number in which a conjugated trienoic double bond was not equivalent to three monoenoic double bonds in a molecule with a given chainlength. The principal triacylglycerol species are (C18:2n‐6) (C18:39c,11t,13c)2 (28.3 mol% of total), (C18:1n‐9)(C18:2n‐6) (C18: 39c,11t,13c) (19.0 mol%), and (C18:2n‐6)2(C18:39c,11t,13c) (16.2 mol%), while simple triacylglycerols such as (C18:39c11t,13c)3 and (C18:2n‐6)3 were present as minor components only (<1.0 mol%). Species esterified with conjugated trienoic acids comprise more than 96% of the total. Stereospecific analysis gave rise to insurmountable difficulties, but it is evident that there is some asymmetry in the distribution of fatty acids in the molecules.