Biological Properties of (1 → 3)-β-D-Glucan-Based Synthetic Oligosaccharides

Despite the fact that beta-glucans are well-established immunomodulators, the problems with batch-to-batch heterogeneity remains problematic. The aim of this study was to prepare and evaluate new type of synthetic oligosaccharides. A new family of oligo-(1 --> 3)-beta-D-glucans modified on the reducing end was synthesized using a controlled and specific inversion of configuration at C-2 starting from already formed oligo-(1 --> 3)-beta-D-glucans. The designed glycosides are characterized by the presence of four or five glucopyranose entities and a mannose residue at the reducing end. To study of the impact of well-defined structural modulations, we used murine and human models to evaluate their immunostimulating potential. These novel oligosaccharides showed strong and long-lasting stimulation of phagocytosis and significant potentiation of synthesis and/or secretion of interleukin (IL-2, IL-4, IL-5, IL-6), tumor necrosis factor-a, and vascular endothelial growth factor. In addition, the oligosaccharides tested showed significant effects on expression of several genes in human fibroblasts and breast cancer cells. From our results it is clear that these synthetic oligosaccharides represent a better alternative to natural beta-glucans.