13C nuclear magnetic resonance spectroscopic analysis of the triacylglycerol composition ofBiota orientalis and carrot seed oil

Abstract

Abstract13C nuclear magnetic resonance (NMR) spectroscopic analysis of the whole oil (triacylglycerols) ofBiota orientalis seeds confirms the presence of oleate [18:1(9Z)], linoleate [18:2(9Z, 12Z)], linolenate [18:3((9Z, 12Z, 15Z)], 20:3 (5Z, 11Z, 14Z), 20:4(5Z, 11Z, 14Z, 17Z), and saturated fatty acids in the acyl groups by comparing the observed carbon shifts with previously established shift data for model triacylglycerols. This technique shows that the saturated, 20:3 and 20:4 fatty acids are distributed mainly in the α‐acyl positions, whereas oleate, linoleate, and linolenate are randomly acylated to the α‐ and β‐positions of the glycerol “backbone”. Stereospecific hydrolysis of theBiota oil with pancreatic lipase, followed by chromatographic analysis of fatty esters, reveals the presence of trace amounts of 16:0(0.7%), 18:0(0.5%), 20:3 (0.4%), and 20:4 (1.3%) in the β‐position of the glycerol “backbone”, which are undetectable by13C NMR technique on the whole oil. Semiquantitative assessment of the13C NMR signal intensities gives the relative percentages of the fatty acid distribution as: saturated 16:0, 18:0 (12.0% α‐acyl), oleate (7.7% α‐acyl 8.7% β‐acyl), total linoleate and linolenate (31.7% α‐acyl; 24.2% βacyl), total 20:3 and 20:4 (15.7% α‐acyl). The13C NMR spectroscopic analysis of carrot seed oil identifies the presence of saturated (18:0), 18:1(6Z), 18:1(9Z), and 18:2(9Z, 12Z). The saturated fatty acid is found in the α‐acyl positions. Semi‐quantitative assessment of the signal intensities gives the relative percentages of the fatty acids as: 18:0 (4.5% α‐acyl), 18:1(6Z) (49.6% α‐acyl; 19.7% β‐acyl), oleate (6.5% α‐acyl; 8.6% β‐acyl) and linoleate (5.2% α‐acyl; 6.9% β‐acyl).