Solid-Phase Synthesis of Polysaccharides from Unprotected Glucose Catalyzed by Hβ Zeolites

Abstract

Polysaccharide is a kind of biological macromolecule with a complex structure, which plays an irreplaceable role in the organism. Due to the complex purification process of natural polysaccharide, chemical synthesis is an important means to obtain it. In this work, a green and efficient solid-phase polymerization method was used to synthesize glucan polysaccharide from unprotected glucose in one step under mild solid-phase conditions, using Hβ zeolites as acidic catalyst. The final polysaccharide product was characterized by high-performance liquid chromatography (HPLC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) with a conversion of 35.0% and a maximum degree of polymerization of 26. More importantly, it was speculated that the glycosylation of unprotected glucose catalyzed by Hβ zeolites conforms to the Fischer glycosylation mechanism. In addition, the results of methylation analysis and one-dimensional, twodimensional nuclear magnetic resonance (1D, 2D NMR) showed that the resulting polysaccharides were mainly linear, containing 10 different glycosidic linkages, and (1,6-Glcp), (1-Glcp), and (1,4-Glcp) were the most abundant linkage types among them.

Structure-Tunable Glucan Oligomer Production from Glucose and Disaccharide Glycosylation in an Unacidified LiBr·3.2H2O Molten Salt Hydrate

“…Glucan oligomers can be produced by either a top–down approach from the hydrolysis of natural polysaccharides or a bottom–up approach from glucose or disaccharide glycosylation. , The glycosidic bond species can be readily controlled using the top–down method through substrate selection . For instance, β(1 → 4) and α(1 → 4)-linked glucan oligomers can be hydrolyzed from homopolymer cellulose and starch by the selective cleavage of partial glycosidic bonds, respectively. , Despite the uniform glycosidic bonds obtained in this way, the selectivity of the glucan oligomer is generally low due to the inevitable hydrolysis of polysaccharides to glucose .…”