Cluster sialoside inhibitors for influenza virus: synthesis, NMR, and biological studies

• Published in: Journal of the American Chemical Society Vol. 114; no. 22; pp. 8363 - 8375
• Main Authors: Sabesan, Subramaniam, Duus, Jens O, Neira, Susana, Domaille, Peter, Kelm, Soerge, Paulson, James C, Bock, Klaus
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01-10-1992
• Subjects: Biological and medical sciences; Fundamental and applied biological sciences. Psychology; influenza virus; Microbiology; Replicative cycle, interference, host-virus relations, pathogenicity, miscellaneous strains; Virology; Virus; Hemagglutinin; Oligosaccharide; Orthomyxoviridae; Antiviral; Glycoproteins; Influenzavirus; Host virus relation; Cell surface; Induced conformation; Biological receptor
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00048a004

Two alpha DNeuAc(2 arrow right 6) beta DGal(1 arrow right 4) beta DGlcNAc units which are the receptor determinants for the influenza virus hemagglutinin have been anchored on a galactose in order to design structures capable of bimodal viral binding. To determine the optimum alpha DNeuAc distance for the best intramolecular binding to the hemagglutinin trimer, the attachment sites of the two alpha DNeuAc(2 arrow right 6) beta DGal(1 arrow right 4) beta DGlcNAc units have been systematically varied by proper choice of the galactose glycosylation sites. Thus, we have chemoenzymatically prepared five heptasaccharides of the general formula alpha DNeuAc(2 arrow right 6) beta DGal(1 arrow right 4) beta DGlcNAc(1 arrow right x)[ alpha DNeuAc(2 arrow right 6) beta DGal(1 arrow right 4) beta DGlcNA c(1 arrow right y)] beta DGalOR, where x and y are 2 and 3, 2 and 4, 2 and 6, 3 and 6, and 4 and 6, respectively. The structural identity and the complete proton and carbon chemical shift assignments of the tri-, penta-, and heptasaccharides have been established by a combination of 1D TOCSY, 1D and 2D NOESY, and super(1)H- super(13)C correlation techniques. One-dimensional and two-dimensional NOESY experiments have been used to assess the conformational properties of these molecules. These, together with Monte Carlo simulations, suggested that the end C-2 to C-2 atoms of the sialic acid residues in these bivalent receptor structures are separated by similar to 19 angstrom in 2,4-heptasaccharides to similar to 9 angstrom in 3,6- and 4,6-heptasaccharides, with the others falling between these two distances. The five heptasaccharides, when evaluated as inhibitors of the influenza virus adsorption to resialylated human erythrocytes, showed that relative to the methyl alpha -sialoside the 3,6- and 4,6-disialosides with a 9-angstrom end distance exhibited 10- and 8.4-fold better inhibitory activity, respectively, whereas the 2,4-disialoside with a similar to 19-angstrom sialic acid end distance had no increased inhibitory activity. Conjugation of the 3,6-heptasaccharide to bovine serum albumin increased the inhibitory potency even more, suggesting the therapeutic potential of a macromolecule containing the 3,6-heptasaccharides for influenza viral inhibition.