Development of a Microwave-assisted Chemoselective Synthesis of Oxime-linked Sugar Linkers and Trivalent Glycoclusters

Synthesis and Nuclear Magnetic Resonance Structural Evaluation of Oxime-Linked Oligosialic Acid-Based Glycodendrimers

A series of four oxime-linked octavalent sialic acid and oligosialic acid poly(ether amidoamine) glycodendrimers were synthesized. In the attachment of the sialic acids to the dendrimer core, chemoselective oxime bonds were formed between the unprotected sugars (sialic acid or α-2,8-linked di- through tetra-sialic acids) and the aminooxy-terminated dendrimer core in a microwave-mediated reaction, resulting in good to excellent yields (58-100%) of the fully functionalized octavalent glycodendrimers. Next, using a combination of 1D and 2D nuclear magnetic resonance and working from the inside outward, we employed a systematic method to assign the proton and carbon signals starting with the smallest linkers and dendrimer cores and moving gradually up to the completed octavalent glycodendrimers. Through this approach, the assignment of the protons and carbons was possible, including the E- and Z-isomers related to the oxime dendrimer to sugar connections and relative quantities of each. These glycodendrimers were designed as broad-spectrum inhibitors of viral pathogens.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2019-2020

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2020. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. The review is basically divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of arrays. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other areas such as medicine, industrial processes and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. The reported work shows increasing use of incorporation of new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented nearly 40 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show little sign of diminishing.

Sulfoglycodendrimer Therapeutics for HIV-1 and SARS-CoV-2

Hexavalent sulfoglycodendrimers (SGDs) are synthesized as mimics of host cell heparan sulfate proteoglycans (HSPGs) to inhibit the early stages in viral binding/entry of HIV-1 and SARS-CoV-2. Using an HIV neutralization assay, the most promising of the seven candidates are found to have sub-micromolar anti-HIV activities. Molecular dynamics simulations are separately implemented to investigate how/where the SGDs interacted with both pathogens. The simulations revealed that the SGDs: 1) develop multivalent binding with polybasic regions within and outside of the V3 loop on glycoprotein 120 (gp120) for HIV-1, and consecutively bind with multiple gp120 subunits, and 2) interact with basic amino acids in both the angiotensin-converting enzyme 2 (ACE2) and HSPG binding regions of the Receptor Binding Domain (RBD) from SARS-CoV-2. These results illustrate the considerable potential of SGDs as inhibitors in viral binding/entry of both HIV-1 and SARS-CoV-2 pathogens, leading the way for further development of this class of molecules as broad-spectrum antiviral agents.

An Efficient Microwave-Mediated Synthesis of Hexavalent Sialic Acid Sulfoglycodendrimers as Potential Anti-HIV Agents

A series of four sialic acid-containing hexavalent sulfoglycodendrimers (SGDs) were synthesized in excellent yields using an efficient strategy involving multiple microwave-mediated reactions. Four sugars, sialic acid, and the dimer through tetramer of α-2→8-linked oligosialic acid were added to an aminooxy-terminated hexavalent dendrimer core using a chemoselective oxime-forming reaction. This method resulted in substantial improvements in reaction time and product yields over previous methods. These multivalent glycopolymers were designed as potential topical agents for preventing the sexual transmission of HIV-1. While inactive against HIV-1, the SGDs were also not cytotoxic, opening a pathway for the further development of anti-HIV SGDs.