Stereoselective Conversion of Glucosides into Xylosides

The demand for safe and healthy food is generally increasing and with it the interest in the functional ingredients in the consumed products. Among these ingredients are dietary fibers, which have attracted increased attention in research over the last decades, since the human health benefits from the consumption of fibers were scientifically demonstrated.
Detailed studies of dietary fibers on a cellular level in plants benefits greatly from using the newest methods available in biotechnology such as specific monoclonal antibodies, which are a key-tool in protein-carbohydrate interactions, enzyme-linked immunosorbent assay (ELISA) and carbohydrate microarrays. To facilitate the development of monoclonal antibodies and characterization of their binding, it is necessary to obtain highly specific and pure oligosaccharides. However, methods for isolating acceptable quantities of required homogeneity from natural sources are difficult and time consuming, due to the heterogeneity and diversity of the plant cell wall polysaccharides. A alternative to isolation of oligosaccharides from the cell wall is chemical synthesis that makes it possible to obtain larger quantities of well-defined oligosaccharide structures in excellent purity.
This thesis describes the work on a new preparative synthesis method of D-xylose and D-xylobiose building blocks through carbohydrate interconversion of D-glucose and D-cellobiose. A range of methods for the transformation was investigated and the method of dehydrogenative decarbonylation was preferred because of its novelty and versatility. As proof of concept, the building blocks were applied to the synthesis of oligoxylans. Furthermore, the method proved to be an alternative route for selective equatorial deuterium labeling of D-xylose by stereo retention, whereas radical methods mainly afforded axial deuteration.
The work at University of Leeds during the external stay is described. It consisted of the utilization of monoclonal antibodies, ELISA and epitope detecting chromatography for the investigation of polysaccharides found in Arabidopsis thaliana root mucilage and mutants hereof.