The distribution of Δ5 polyene acids in some pine seed oils between the α- and β-chains by 13C-NMR spectroscopy

Abstract

Seven Pinus seed oils, previously examined by gas chromatography (Ref. [3]), have been re-examined by 13C-NMR spectroscopy. The spectra clearly indicate the presence of Δ5 acids (mainly a C 18 Δ5, 9, 12 isomer) and almost all the signals have been assigned on the basis of relevant data already in the literature for Δ5 esters. Using the intensities of appropriate signals it was possible to estimate the level of total Δ5 acids from signals associated with the C 1, C 2, and glycerol carbon atoms and the level of n-6 acids from the ω2 and ω3 signals. The results were in accord with those previously obtained by gas chromatography. The Δ5 acids were apparent only among the α-chains. Taxus baccata seed oil is shown to contain 5,9–18:2, but Δ5 acids in Chamaecyparis lawsoniana seed oil were too low to be identified by NMR spectroscopy.