Syntheses of new peptidic glycoclusters derived from β-alanine: di- and trimerized glycoclusters and glycocluster–clusters

Clusters of ligands on dendrimer surfaces

The development of methodology that is designed to allow a significant increase in the patterning and in the functionalization of the dendrimer is the ultimate goal of the research described here. Glycoside clusters based on TRIS were formed using click chemistry and were attached to PAMAM dendrimers. A series of dendrimers bearing tris-mannoside and an ethoxyethanol group was synthesized, and the binding interactions of these dendrimers with Concanavalin A were evaluated using inhibition ELISAs. The results of the inhibition ELISAs suggest that tris-mannoside clusters can replace individual sugars on the dendrimer without loss of function. Since tris-mannoside clustering allows for a redistribution of the dendrimers' surface functionalities, from this chemistry one can envision patterned dendrimers that incorporate multiple groups to increase the function and utility of the dendrimer.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for the period 2005-2006

This review is the fourth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2006. The review covers fundamental studies, fragmentation of carbohydrate ions, method developments, and applications of the technique to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, glycated proteins, glycolipids from bacteria, glycosides, and various other natural products. There is a short section on the use of MALDI-TOF mass spectrometry for the study of enzymes involved in glycan processing, a section on industrial processes, particularly the development of biopharmaceuticals and a section on the use of MALDI-MS to monitor products of chemical synthesis of carbohydrates. Large carbohydrate-protein complexes and glycodendrimers are highlighted in this final section.

Design and creativity in synthesis of multivalent neoglycoconjugates

From the authors' opinion, this chapter constitutes a modest extension of the seminal and inspiring contribution of Stowell and Lee on neoglycoconjugates published in this series [C. P. Stowell and Y. C. Lee, Adv. Carbohydr. Chem. Biochem., 37 (1980) 225-281]. The outstanding progresses achieved since then in the field of the "glycoside cluster effect" has witnessed considerable creativity in the design and synthetic strategies toward a vast array of novel carbohydrate structures and reflects the dynamic activity in the field even since the recent chapter by the Nicotra group in this series [F. Nicotra, L. Cipolla, F. Peri, B. La Ferla, and C. Radaelli, Adv. Carbohydr. Chem. Biochem., 61 (2007) 353-398]. Beyond the more classical neoglycoproteins and glycopolymers (not covered in this work) a wide range of unprecedented and often artistically beautiful multivalent and monodisperse nanostructures, termed glycodendrimers for the first time in 1993, has been created. This chapter briefly surveys the concept of multivalency involved in carbohydrate-protein interactions. The topic is also discussed in regard to recent steps undertaken in glycobiology toward identification of lead candidates using microarrays and modern analytical tools. A systematic description of glycocluster and glycodendrimer synthesis follows, starting from the simplest architectures and ending in the most complex ones. Presentation of multivalent glycostructures of intermediate size and comprising, calix[n]arene, porphyrin, cyclodextrin, peptide, and carbohydrate scaffolds, has also been intercalated to better appreciate the growing synthetic complexity involved. A subsection describing novel all-carbon-based glycoconjugates such as fullerenes and carbon nanotubes is inserted, followed by a promising strategy involving dendrons self-assembling around metal chelates. The chapter then ends with those glycodendrimers that have been prepared using commercially available dendrimers possessing varied functionalities, or systematically synthesized using either divergent or convergent strategies.

Syntheses of glycoclusters containing a phosphocholine residue related to a glycosphingolipid from the earthworm Pheretima hilgendorfi

Three types of glycoclusters related to an amphoteric glycosphingolipid found in the earthworm Pheretima hilgendorfi were synthesized. The glycoclusters were prepared from a common precursor and a simple approach for the rational design of a glycocluster was developed.

Syntheses and Biological Activities of Glycoconjugates

This review describes the oligosaccharide syntheses and biological activities of glycosphingolipids, focusing especially on those found in invertebrates like millipedes, nematoda parasites, and cestoda parasites, and model compounds related to a major antigenic epitope against antibupleurum 2IIc/PG-1-IgG from antiulcer pectic polysaccharides. A novel and simple approach for the rational design of glycoclusters and glycodendrimers by coupling with a sugar unit and a cluster unit, was developed with beta-alanine derivatives used to construct the latter compounds.

Syntheses of New Model Compounds Related to an Antigenic Epitope from Bupleurum falcatum L. and Their Distributions in Various Ganglioside-Phospholipid Monolayers

6-N-[2-(Tetradecyl)hexadecanamido]hexyl beta-D-glucopyranosyluronic acid-(1-->6)-beta-D-galactopyranosyl-(1-->6)-beta-D-galactopyranoside (1) and its clustering compound (2) carrying a tetravalent sugar unit, which are new model compounds related to a major antigenic epitope from antiulcer pectic polysaccharide of Bupleurum falcatum L., were synthesized and the distributions of 1 and 2 in mixed ganglioside (GM1, GD1a or GT1b)/phospholipid (DPPC) monolayers were observed using atomic force microscopy (AFM). AFM images showed that 1 was distributed in the GM1, GD1a and GT1b region of the mixed monolayers, in which 1 was miscible with GD1a. Specific distribution of 1 was observed in the mixed GM1/DPPC monolayer. Compound 2 was miscible with GM1, while 2 formed associations with GD1a and GT1b in the mixed monolayers. The distribution mode of 1 and 2 was different among the mixed ganglioside/DPPC monolayers.