Analysis of plasma lipids by NMR spectroscopy: application to modifications induced by malignant tumors

Lipid extracts of plasma were studied by 31P and 1H NMR spectroscopy at 9.4 T. Signals recorded on lipid mixtures were assigned to different lipid classes using a data base built with two-dimensional 1H COSY spectra of seven standard lipids. Signals unique to glycerophospholipids, sphingolipids, and triacylglycerols were identified. 31P and 1H NMR spectroscopy was used to study qualitative and quantitative modifications induced in plasma by malignant tumors. The results show a significant increase in triglyceride/phospholipid ratio and a concomitant decrease of total phospholipids in patients with cancer. In order to check for the possible presence of particular lipids such as glycolipids in these patients, 1H COSY spectra were recorded on the intact plasma and on extracts of plasma lipids in patients with cancer and in healthy subjects. Only in one case of ovarian cancer, a cross-peak at 1.35 and 4.15 ppm, corresponding to fucose residue in glycolipids, was detected.