Abstract EN:

The goal of this work was to characterize an unknown phospholipid (PL) representing only 0. 7 % of cellular PL but acylated by more than 10 % of the cellular docosahexaenoic acid (DHA) and in comparating selectively DHA but not polyunsaturated fatty acids (PUFA) from the n-6 series. Fast Atom Bombardment Mass spectrometry (FAB-MS), allowed us to precise it structure. It was a bis(monoacylglycerol)phosphate (or BMP). BMP purified by thin layer chromatography was resolved into 3 peaks by HPLC. Mass spectrometry analysis by electrospray of BMP from control cell showed that the first two peaks contain the same molecular species (mainly 18:1 (n-9)/ 22:6 (n-3)) whereas the third peak contains mainly 18:1 (n-9)/18: 1 (n-9) molecular species. Stereo-configurational analysis of these three compounds showed an sn-l:sn-1’ configuration for compound 2 and 3, what was unique for a PL, whereas s the first compound was a mixture or n- l :sn-1' and sn-3: n-1 ' BMP. RMN analysis of the three peaks indicated that the two FA was esterified on the carbon wearing the primary alcohol of each glycerol, whereas the two FA of the compound 1 were esterified, one on the carbon wearing the primary alcohol and the other on the carbon wearing the secondary alcohol. We developed an original method for the quantification of BMP by HPLC, using the derivatization of free hydroxyls by a f1uorescent probe. This method allowed measuring the level of this PL in our cellular model (530 ± 40 ng/ 106 cells). This level was dramatically increasing when cells are cultivated in minima conditions which induced autophagy.