Assignment of mono- and polyunsaturated fatty acids in lipids of tissues and body fluids

Abstract

Semi-selective 800 MHz 1H, 13C HSQC NMR spectra provide ultra-high resolution of the double bond region of lipid spectra and the possibility of assigning signals to individual unsaturated fatty acid side-chains such as 18:1, 18:2 or 20:4 even in complex mixtures such as biofluids. Additional HSQC-TOCSY spectra correlate the direct double bond signals with the adjacent allylic high-field proton signals of mono- and polyunsaturated fatty acids. These signals show characteristic chemical shifts to differentiate unsaturated fatty acids such as 18:1, 18:2 and 20:4 (or others). By this means, the amount of each type of unsaturated fatty acid can be quantified. Typical lipid spectra of body fluids (blood plasma and cerebrospinal fluid) and pig brain (grey and white matter) are presented and discussed with respect to the use of this technique for diagnostic purposes. © 1998 John Wiley & Sons, Ltd.