SYNTHESIS OF THE BENZYL b-GLYCOSIDE ANALOGUE OF THE CORE 2 TRISACCHARIDE OF MUCINS OF Trypanosoma cruzi

CORI, CARMEN R.; ALTALEFF, LAUTARO; DE LEDERKREMER, ROSA M.; GALLO -RODRIGUEZ, CAROLA

Florianopolis

Congreso; 30th International Carbohydrate Symposium; 2022

International Carbohydrate Organization

The mucin-like glycoproteins are major components in the surface of the protozoan T. cruzi, the etiological agent of Chagas disease. The oligosaccharides in the mucins are O-linked to the protein via a -GlcNAc which is further substituted with b-Galp and b-Galf residues depending on the strain. In the internal cuticle of the triatomine rectal ampoule of the insect vector, epimatigotes are attached leading to its differentiation into highly infective forms as metacyclic trypomastigotes. Ex vivo binding assays in the presence of chemically synthesized oligosaccharides as a-benzyl glycosides by our group allowed the identification of oligosaccharides containing the structure benzyl β-D-Galp(1→6)-[β-D-Galf(1→4)]-D-GlcNAcα (1) trisaccharide, as adhesion determinants[1]. We now present the synthesis of an analogue of trisaccharide 1, the a-benzyl glycoside 2 with the aim of studying the influence of the anomeric configuration of the GlcNAc unit on the adhesion to the inner lining of T. infestans rectal ampoule. Compound 1 was synthetized by introduction of the Galp unit on primary OH-6 followed by the Galf unit on OH-4 of a GlcNAc derivative [2]. However, this strategy was not useful for the β--analogue 3 giving poor yields of 2. An alternative strategy was performed by changing the order of the introduction of the glycosyl units. Thus, a TBDPS group was introduced to protect 6-OH in 3, and then a sequence of glycosylation of 4-OH of 4, deprotection of 6-position of 6 and further glycosylation of 6-OH was followed. The results of the strategies will be discussed.