IBBEA   24401
INSTITUTO DE BIODIVERSIDAD Y BIOLOGIA EXPERIMENTAL Y APLICADA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Synthesis of a tetrasaccharide and pentasaccharide constituents of Trypanosoma cruzi mucins
Autor/es:
CARMEN R. CORI CALIZAYA; CAROLA GALLO-RODRIGUEZ; ROSA M. DE LEDERKREMER; GUSTAVO A. KASHIWAGI
Lugar:
Lisboa
Reunión:
Simposio; 29th International Carbohydrate Symposium; 2018
Institución organizadora:
International Carbohydrate Organisation
Resumen:
Trypanosoma cruzi, the etiological agent of Chagas disease, is a protozoan parasite with a complex life cycle that alternates between hematophagous triatomine vectors and mammals, including humans. The surface of T. cruzi is covered by a dense glycocalix and its composition is characteristic of each differentiation stage. The mucin-like glycoproteins are major components in the protozoan surface. The oligosaccharides in the mucins are O-linked to the protein by alpha-D-GlcNAc unit. They are derived from two cores, Galp(b1-4)-GlcNAc or Galf(b1-4)-GlcNAc which are further branched by Galf or Galp. The terminal b-Galp residues are acceptors of sialic acid in the trans-sialidase reaction, which is involved in the invasion of the host cells. The presence of b-Galf in the oligosaccharide mucins is a remarkable feature restricted to certain parasite strains in the insect stage, the non-infective epimastigotes and the highly infective metacyclic trypomastigotes. We have been developing methods of synthesis of the Galf-containing oligosaccharide family with the aim to correlate their structure with the ability to act as substrates in the trans-sialidase reaction.Moreover, these synthetic oligosaccharides could be used as tools for elucidating their biological role and for biosynthetic studies.We now present the synthesis of pentasaccharide 1 and tetrasaccharide 2 as benzyl glycosides. The alditol of 1,  b-D-Galp(1-3)-b-D-Galp(1-6)-[b-D-Galf(1-2)-b-D-Galf(1-4)]-D-GlcNAc-ol was isolated from the Tulahuen strain by reductive beta-elimination. Previously, the synthesis of 1 was performed by a [3+2] convergent strategy with moderate yield.  In this case, a sequential strategy was followed by the use of trisaccharide 2 with an internal Galf as acceptor and thiogalactopyranoside 4 as donor to give the corresponding tetrasaccharide with excellent yield. Deprotection of the orthogonal Lev group gave 5. The differences of both strategies will be discussed.