Distribution of Delta 5-olefinic acids in the triacylglycerols from Pinus koraiensis and Pinus pinaster seed oils

Abstract

Purified triacylglycerols (TAG) from Pinus koraiensis and P. pinaster seed oils, which are interesting and commercially available sources of Delta 5-olefinic acids (i.e., cis-5,cis-9,cis-12 18:3 and cis-5,cis-11,cis-14 20:3 acids) were fractionated by reversed-phase high performance liquid chromatog- raphy, and each fraction was examined by capillary gas-liquid chromatography for its fatty acid composition. A structure could be assigned to more than 92% of TAG from both oils. In both instances, ca. 48% of the TAG were shown to contain at least one Delta 5-olefinic acid. In the great majority of TAG, our data showed that there is only one molecule of Delta 5-olefinic acid per molecule of TAG. This is compatible with theoretical calculations based on the proportion of total Delta 5-olefinic in the oils. The cis-5,cis-9,cis-12 18:3 acid (14.2 and 8.6% of total fatty acids in the seed oils of P. koraiensis and P. pinaster, respectively) and the cis-5,cis-11,cis-14 20:3 acid (1.1 and 8.1% of total fatty acids in the seed oils of P. koraiensis and P. pinaster, respectively) are preferentially associated with two molecules of linoleic acid, and to a lesser extent, to one molecule of linoleic acid and one molecule pi oleic acid, or two oleic acid molecules. However, several other combinations occur, each in low amounts. The distribution of Delta 5-olefinic acids in TAG is evidently not random. Combining these results with the known preferential esterification of Delta 5-olefinic acids to the 1,3-positions of TAG would suggest that most of these acids are present at only one of these positions at a time.