NEW CHEMICAL TRENDS IN GANGLIOSIDE RESEARCH

A report is given of recent progress in the methodology for isolation of gangliosides from natural sources, for the preparation of molecular species of gangliosides homogeneous in both the oligosaccharide and ceramide portions of the molecule, for chemical manipulation and derivatization of gangliosides, and for the preparation of gangliosides radiolabelled in different parts of the molecule. Particular emphasis has been given to: (a) high performance liquid chromatographic procedures capable to separate gangliosides on the basis of their oligosaccharide or ceramide moieties and yielding completely homogeneous compounds, that is gangliosides with a single oligosaccharide, a single long chain base and a single fatty acid; (b) two-dimensional thin-layer chromatographic procedures, provided with a fully computerized quantification system, particularly suitable to identifying gangliosides containing alkali-labile linkages, including ganglioside lactones; (c) chemical procedures of high yield for reducing gangliosides at the double bond of long chain base, for selective removal of the fatty acyl moiety and replacement with a novel fatty acid, and for the synthesis of ganglioside lactones; (d) chemical procedures for inserting fluorescent, paramagnetic or photoreactive probes at the fatty acyl part of the ganglioside molecule; (e) procedures for chemical isotopic radiolabelling of gangliosides at the level of sialic acid acetyl group and at the fatty acid moiety. Examples are provided evidencing the significance and potential use of a variety of ganglioside derivatives in the study of ganglioside metabolism and functional implications.