Identification of alpha-parinaric acid in the seed oil of Sebastiana brasiliensis Sprengel (Euphorbiaceae)

Abstract

Besides some usual fatty acids, the seed oil of Sabastiana brasiliensis (Euphorbiaceae) contains up to 39% (estimated by ultraviolet spectroscopy) of alpha-parinaric acid (cis, trans, trans,cis-9,11,13,15-octadecatetraenoic acid). The fatty acids were analyzed by gas chromatography and gas chromatography/mass spectrometry as their methyl esters. The structure of alpha-parinaric acid was proven by a combination of chemical and spectroscopic methods, conducted with the crude oil, the methyl ester mixture, and the isolated fatty acid methyl ester. Complete assignment of the H-1 and C-13 nuclear magnetic resonance (NMR) shifts of alpha-parinaric acid was carried out by two-dimensional NMR experiments.