Cross reacting material (CRM197) as a carrier protein for carbohydrate conjugate vaccines targeted at bacterial and fungal pathogens.

This paper gives an overview of conjugate glycovaccines which contain recombinant diphtheria toxoid CRM197 as a carrier protein. A special focus is given to synthetic methods used for preparation of neoglycoconjugates of CRM197 with oligosaccharide epitopes of cell surface carbohydrates of pathogenic bacteria and fungi. Syntheses of commercial vaccines and laboratory specimen on the basis of CRM197 are outlined briefly.

Glycoconjugate Vaccines for Prevention of Haemophilus influenzae Type b Diseases.

This review summarizes the experience in laboratory- and industrial-scale syntheses of glycoconjugate vaccines used for prevention of infectious diseases caused by Haemophilus influenzae type b bacteria based on the linear capsular polysaccharide poly-3-ß-D-ribosyl-(1→1)-D-ribitol-5-phosphate (PRP) or related synthetic oligosaccharide ligands. The methods for preparation of related oligosaccharide derivatives and results of the studies evaluating effect of their length on immunogenic properties of the conjugates with protein carriers are overviewed.

[Synthesis, NMR and conformational studies of fucoidan fragments. VI. Fragments, content of alpha-(1--->2)-bound fucobioside unit]. / Sintez, IaMR i konformatsionnye issledovaniia fragmentov fukoidanov. VI. Fragmenty, soderzhanie alpha-(1--->2)-sviazannoe fukobiozidnoe zveno.

A series of selectively sulfated di- and trisaccharide derivatives corresponding to the potential fragments of fucoidans with a (1-->2)-alpha-bound fucobioside unit were synthesized and studied by 1H and 13C NMR spectroscopy. NOE experiments and molecular modeling were used for a conformational analysis of the compounds synthesized. In the case of disaccharides, the experimental NOE values were found to agree with those obtained using modeling with the use of density functional theory (DFT) and differ from those resulting from modeling by the molecular mechanics MM3 force field. Trisaccharide fragments partially or completely sulfated in position 4 turned out to be correctly described by both MM3 force field and DFT computation. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 2; see also http://www.maik.ru.

[Synthesis of aminoethylglycosides with oligosaccharide GM1 and asialo-GM1 ganglioside chains]. / Sintez aminoétilglikozidov oligosakharidnykh tsepei gangliozidov GM1 i asialo-GM1.

4'-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzyl-4-O-(2,3-di-O- benzyl-6-O-benzoyl-beta-D-galactopyranosyl)-beta-D-glucopyranoside with a disaccharide donor, 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-beta-D- galactopyranosyl)-1-thio-2-trichloroacetamido-beta-D-galactopyranoside, in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid resulted in a tetrasaccharide, 2-azidoethyl (2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-(1-->3)- (4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido-beta-D-galactopyranosyl)- (1-->4)-(2,3-di-O-benzyl-6-O-benzoyl-beta-D-galactopyranosyl)- (1-->4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside, in 69% yield. The complete removal of O-protecting groups in the tetrasaccharide, the replacement of N-trichloroacetyl by N-acetyl group, and the reduction of the aglycone azide group to amine led to the target aminoethyl glycoside of beta-D-Gal- (1-->3)-beta-D-GalNAc-(1-->4)-beta-D-Gal-(1-->4)-beta-D-Glc-OCH2CH2NH2 containing the oligosaccharide chain of asialo-GM1 ganglioside in 72% overall yield. Selective 3'-O-glycosylation of 2-azidoethyl 2,3,6-tri-O- benzyl-4-O-(2,6-di-O-benzyl-beta-D-galactopyranosyl)-beta-D-glucopyranoside with thioglycoside methyl (ethyl 5-acetamido-4,7,8,9-tetra-O- acetyl-3,5-dideoxy-2-thio-D-glycero-alpha-D-galacto-2-nonulopyranosyl)oate in acetonitrile in the presence of N-iodosuccinimide and trifluoroacetic acid afforded 2-azidoethyl [methyl (5-acetamido-4,7,8,9-tetra-O-acetyl- 3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosyl)oate in acetonitrile in the presence of N-iodosuccinimide and tri-fluoracetic acid afforded 2-azidoethyl[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl- 3,5-dideoxy-D-glycero-alpha-D-galacto-2-nonulopyranosyl) (2,6-di-O-benzyl-beta-D-galactopyranosyl)-(1-->4)-2,3,6-tri-O-benzyl-beta-D- glucopyranoside, the selectively protected derivative of the oligosaccharide chain of GM3 ganglioside, in 79% yield. Its 4'-O-glycosylation with a disaccharide glycosyl donor, (4-trichloroacetophenyl-4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O- acetyl-beta-D-galactopyranosyl) 1-thio-2-trichloroacetamido-beta-D-galactopyranoside in dichloromethane in the presence of N-iodosuccinimide and trifluoroacetic acid gave 2-azidoethyl (2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)- (1-->3)-(4,6-di-O-acetyl-2-deoxy-2-trichloroacetamido-beta-D- galactopyranosyl)-(1-->4)-[[methyl (5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D- galacto-2-nonulopyranosyl)onate]-(2-->3)]-(2,6-di-O-benzyl-beta-D- galactopyranosyl)-(1-->4)-2,3,6-tri-O-benzyl-beta-D-glucopyranoside in 85% yield. The resulting pentasaccharide was O-deprotected, its N-trichloroacetyl group was replaced by N-acetyl group, and the aglycone azide group was reduced to afford in 85% overall yield aminoethyl glycoside of beta-D-Gal-(1-->3)-beta-D-GalNAc-(1-->4)-[alpha-D-Neu5Ac-(2-->3)]- beta-D-Gal-(1-->4)-beta-D-Glc-OCH2CH2NH2 containing the oligosaccharide chain of GM1 ganglioside. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 1; see also http://www.maik.ru.

[Synthesis of aminoethyl glycosides of the carbohydrate chains of glycolipids Gb3, Gb4 i Gb5]. / Sintez aminoétilglikozidov oligosakharidnykh tsepei glikolipidov Gb3, Gb4 i Gb5.

4-O-Glycosylation of 2-azidoethyl 2,3,6-tri-O-benzoyl-4-O-(2,3,6-tri-O-benzoyl-beta-D-galactopyranosyl)-beta- D-glucopyranoside with ethyl 2,3,4,6-tetra-O-benzyl- and ethyl 3-O-acetyl-2,4,6-tri-O-benzyl-1-thio-alpha-D-galactopyranoside in the presence of methyl trifluoromethanesulfonate led to trisaccharide 2-azidoethyl (2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranosyl)-(1-->4)- (2,3,6-tri-O-benzoyl-beta-D-galactopyranosyl)-(1-->4)2,3,6-tri-O- benzoyl-beta-D-glucopyranoside and its 3"-O-acetylated analogue, 2-azidoethyl (3-O-acetyl-2,4,6-tri-O-benzyl- alpha-D-galactopyranosyl)-(1-->4)-(2,3,6-tri-O-benzoyl-beta-D- galactopyranosyl)-(1-->4)-2,3,6-tri-O-benzoyl-beta-D-glucopyranoside, in yields of 85 and 83%, respectively. Deacetylation of the latter compound and subsequent glycosylation with 4-trichloroacetamidophenyl 3,4,6-tri-O-acetyl-2-deoxy-1-thio-2-trichloroacetamido-beta-D- galactopyranoside and 4-trichloroacetamidophenyl 4,6-di-O-acetyl-2-deoxy-3-O-(2,3,4,6-tetra-O- acetyl-beta-D-galactopyranosyl)-1-thio-2-trichloroacetamido-beta-D- galactopyranoside in dichloromethane in the presence of N-iodosuccinimide and trifluoromethanesulfonic acid resulted in the corresponding selectively protected derivatives of tetrasaccharide GalNAc(beta 1-->3)Gal(alpha 1-->4)Gal(beta 1-->4)Glc beta-OCH2CH2N3 and pentasaccharide Gal(beta 1-->3)GalNAc(beta 1-->3)Gal(alpha 1-->4)Gal(beta 1-->4)Glc beta-OCH2CH2N3 in 88 and 73% yields, respectively. Removal of O-protecting groups, substitution of acetyl group for N-trichloroacetyl group, and reduction of the aglycone azide group resulted in the target 2-aminoethyl globo-tri-, -tetra-, and -pentasaccharide, respectively.

A study of fucoidan from the brown seaweed Chorda filum.

Fucoidan fractions from the brown seaweed Chorda filum were studied using solvolytic desulfation. Methylation analysis and NMR spectroscopy were applied for native and desulfated polysaccharides. Homofucan sulfate from C. filum was shown to contain poly-alpha-(1-->3)-fucopyranoside backbone with a high degree of branching, mainly of alpha-(1-->2)-linked single units. Some fucopyranose residues are sulfated at O-4 (mainly) and O-2 positions. Some alpha-(1-->3)-linked fucose residues were shown by NMR to be 2-O-acetylated. The 1H and 13C NMR spectra of desulfated, deacetylated fucan were completely assigned. The spectral data obtained correspond to a quasiregular polysaccharide structure with a branched hexasaccharide repeating unit. Other fucoidan fractions from C. filum have more complex carbohydrate composition and give rather complex methylation patterns. [formula: see text]

Synthesis and structural studies of branched 2-linked trisaccharides related to blood group determinants.

A series of trisaccharide glycosides, Fuc-(1 reversible 2)-beta-Gal-(1 reversible 3)-beta-X-OMe (X = GlcNAc, Glc, 2-deoxy-Glc) related to the blood group determinant Le(d) have been synthesised both as their alpha- and beta-Fuc anomers together with the component disaccharide starting compounds. The conformational properties of the six trisaccharides together with their parent disaccharides have been investigated by NMR spectroscopy (proton and carbon chemical shifts and proton NOEs) in combination with computer modeling using the Monte Carlo approach and the HSEA force field using the GEGOP programme. The interaction between the terminal fucose unit and the reducing unit was probed by substitution of bulky NAc group with hydroxyl and deoxy substituents, respectively. Compounds with severe steric interactions were identified by the non-additivity of their carbon chemical shifts. This was subsequently confirmed by the detailed conformational assessment by NOE spectroscopy and computer modeling. The most severe contacts arose in the alpha-L-Fuc derivatives, whereas the beta-linked L-Fuc derivatives only in one case exhibit severe steric interaction as probed by the NMR parameters.

[Synthesis and study of NMR spectra and conformations of branched oligosaccharides. 2,3-di-O-glycosylated methyl-alpha-L-rhamnopyranosides with one or two 2-acetamido-2-deoxy-beta-D-glucopyranosyl residues]. / Sintez i issledovanie spektrov IaMR i konformatsii razvetvlennykh oligosakharidov. 2,3-Di-O-glikozilirovannye metil-alpha-L-ramnopiranozidy s odnim ili dvumia 2-atsetamido-2-dezoksi-beta-D-gliukopiranozil'nymi ostatkami.

A series of methyl 2,3-di-O-glycosyl-alpha-L-rhamnopyranosides with 2-acetamido-2-deoxy-beta-D-glucopyranosyl substituents have been synthesized and the deviations from additivity (delta delta) in their 13C-NMR spectra determined. It is shown that the delta delta values for the trisaccharides with the GlcNAc substituent at O-2 of the diglycosylated Rha may markedly differ from the delta delta values in the spectra of the respective trisaccharides with the Glc substituent. These deviations are probably associated with the intramolecular spatial interactions with participation of the NHAc-group.