Towards the synthesis of sialic acid-based Salmonella typhimurium sialidase inhibitors

The synthesis of biotinylated carbohydrates as probes for carbohydrate-recognizing proteins

The intimate involvement of carbohydrate-protein interactions in a number of important biological processes has prompted several research efforts towards developing new methods of investigating these glycobiological interactions. Biotinylated oligosaccharides are emerging as a new and powerful tool in this area of research, primarily due to their high affinity towards streptavidin and their ease of immobilization on matrices. Here we describe a novel synthetic approach towards biotinylated saccharides which incorporate a UV absorbing group into the final compounds. The synthetic strategy described is applicable to a variety of saccharides, with examples of biotinylated mono-, di-, and trisaccharides being prepared with overall high efficiency.

The synthesis and evaluation of novel sialic acid analogues bound to matrices for the purification of sialic acid-recognising proteins

A novel N-acetylneuraminic acid analogue, 2-S-(5'-aminopentyl) 5-acetamido-3,5-dideoxy-2-thio-D-glycero-alpha-D-galacto-2- nonulopyranosidonic acid, as well as the thiosialoside 2-S-(2'-aminoethyl) 5-acetamido-3,5-dideoxy-2-thio-D-glycero-alpha-D-galacto-2- nonulopyranosidonic acid, have been synthesised and successfully coupled to CNBr-activated Sepharose 4B through the terminal amino group. The resultant affinity resins have proved efficient in purifying a number of sialic acid-recognising proteins such as Vibrio cholerae sialidase, sialidase-L from leech, trans-sialidase from Trypanosoma cruzi, and sialyltransferases from rat liver, all in high yield.

Investigation of the stability of thiosialosides toward hydrolysis by sialidases using NMR spectroscopy

[formula: see text] 1H NMR spectroscopy has been used to investigate whether the alpha(2-->6)-linked thiosialoside 3 and the alpha(2-->3)-linked thiosialoside 9 are hydrolyzed in the presence of Vibrio cholerae sialidase. Similarly, the hydrolysis of the O-ketosides Neu5Ac-2-O-alpha-(2-->3)-Gal beta Me (4) and the alpha-(2-->6)-sialyllactoside 7, representing natural alpha(2-->3)- and alpha(2-->6)-linked sialosides, respectively, was investigated. The results of the 1H NMR experiments clearly demonstrate that the thiosialosides are not hydrolyzed by Vibrio cholerae sialidase. As expected, the O-sialosides are hydrolyzed to give N-acetyl-alpha-D-neuraminic acid as the first product of substrate cleavage.

Synthesis and evaluation of N-acetylneuraminic acid-based affinity matrices for the purification of sialic acid-recognizing proteins

The synthesis of 2-S-(2-aminoethyl) 5-acetamido-3,5-dideoxy-2-thio-D-galacto-2-nonulopyranosidonic acid (1) has been successfully achieved from the precursors methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-2-S-acetyl-3,5-dideoxy-2-thio-D-glyce ro-alpha-D-galacto-2-nonulopyranosonate (2) and 2-bromo-N-(tert-butoxycarbonyl)-ethylamine (5). Compounds 1 and 2 were coupled, via amino and thioglycosidic linkages, respectively, to epoxy-activated Sepharose 6B. The resultant affinity adsorbents have proved efficient in purifying the sialic acid-recognizing enzyme Vibrio cholerae sialidase, in a one-step process with yields in the order of 60%.

Sialidases: structures, biological significance and therapeutic potential

The structure-based design of a potent inhibitor of the influenza-virus neuraminidase (sialidase) is one of the outstanding successes of rational drug design. Recent clinical trials of the drug have stimulated many companies to seek a share of the potentially huge flu market. Sialidases, however, are involved in the pathogenesis of a whole range of other diseases, so perhaps the knowledge and expertise gained from the influenza story can be used in the design of other drugs, given that they all share certain structural features.

Synthesis and biological evaluation of N-acetylneuraminic acid-based rotavirus inhibitors

Rotavirus can cause severe gastrointestinal disease, especially in infants and young children, and is particularly prevalent in Third-World countries. Therefore, the development of potential inhibitors of this virus is of great interest. The present study describes the synthesis and in vitro biological evaluation of a number of N-acetylneuraminic acid-based compounds as potential rotavirus inhibitors. Our data suggests that it is indeed possible to inhibit adhesion of the virus, and hence in vitro replication, with carbohydrate-based molecules, although this inhibition does appear to be strain dependent.