The preparation of neoglycoconjugates containing inter-saccharide phosphodiester linkages as potential anti-Leishmania vaccines

The Leishmania express complex glycoconjugates containing phosphosaccharide repeat units at all stages of their life-cycle. One of these molecules, li pophosphoglycan (LPG) has been suggested to be a vaccine candidate. To asse ss the immunological properties of Leishmania phosphosaccharides, we have p repared neoglycoproteins and neoglycolipids containing synthetic Leishmania phosphosaccharide repeats. The coupling procedure uses the dec-9-enyl spac er of previously synthesised phosphosaccharides for linkage to protein and phospholipid. This alkene moiety is converted by ozonolysis to an aldehyde which is then attached to protein and phospholipid amino groups by reductiv e amination. The procedure produces neoglycoconjugates in good yield and wi thout compromising the labile phosphodiester linkages within the phosphosac charide chains.