Author(s): Uhrig ML, Couto AS, Colli W, de Lederkremer RM
In vivo labeling experiments with [3H]palmitic acid, [3H]inositol, and [3H]glucose allowed the identification of two main classes of inositolphospholipids (IPLs) from the trypomastigote stage of Trypanosoma cruzi. Purification of these compounds was achieved by ion-exchange chromatography, high performance liquid chromatography and thin layer chromatography. Specific phosphatidyl-inositol phospholipase C digestion, dephosphorylation and acid methanolysis showed a ceramide structure for the lower migrating IPL1. Palmitoyldihydrosphingosine and palmitoylsphingosine were detected by reverse-phase thin-layer chromatography. On the other hand, IPL2 showed to be a mixture of diacylglycero- and alkylacylglycero-phospholipids in a 1:1 ratio. After PI-PLC digestion, the lipids were separated by preparative TLC and individually analysed. The diacylglycerol contained mainly C18:0 fatty acid together with a low amount of C16:0. Hexadecylglycerol esterified with the C18:0 fatty acid was the only alkylacylglycerol detected. The C18:2 and C18:1 fatty acids, preponderant in the PI molecules of epimastigote forms, were not detected in trypomastigote forms. This is the first report on inositol phospholipids, putative precursors of lipid anchors in the infective stage of T. cruzi.