Contribution of carbohydrate chemistry to assessment of the biological role of natural α-glucosides

Significant progress was achieved in the field of the carbohydrate and oligosaccharide synthesis in the past decade. Complex fragments of natural glycopolymers with unusual stereochemistry and labile substituents have been successfully prepared by a large number of research groups and used for bioassays targeted for the investigation of molecular mechanisms of their biological activities. A part of these structures contains an α-glucose linkage that represents one of the main synthetic challenges. Surprisingly, despite tremendous success of synthetic oligosaccharide chemistry, enzymatic and chemical approaches proved to be of equal importance for the preparation of polysaccharides and glycoconjugates containing α-glucose units. Interest in enzymatic methods in this field is due to the practical demand of large amounts of synthetic probes that are not otherwise available through synthetic chemistry. This review surveys syntheses of glycopolymers related to reserve polysaccharides, molecules of recognition and immunogenic glycol-conjugates that possess one or more α-glucose residues. The special attention is paid to the contribution of these synthetic probes for exploring diverse biological mechanisms at the molecular level. The consideration of the most relevant and modern methods for the α-selectivity control is also included.