Carbohydrate PEGylation, an approach to improve pharmacological potency

• M. Eugenia Giorgi,
• Rosalía Agusti and
• Rosa M. de Lederkremer

Beilstein J. Org. Chem. 2014, 10, 1433–1444, doi:10.3762/bjoc.10.147

• yielding a more defined product. Thus, glycoPEGylation was successfully applied to the introduction of a PEGylated sialic acid to a preexisting or enzymatically linked glycan in a protein. Carbohydrates are now recognized as playing an important role in host–pathogen interactions in protozoal, bacterial

• steric effects [31]. The strategy is based on the finding that certain PEGylated nucleotide-sugars are effectively transferred to a glycan acceptor by the corresponding glycosyltransferase. A modified sialic acid PEGylated at the 5’-amino position in the CMP nucleotide (CMP-SA-5-NHCOCH2NHPEG) can be

• transferred to a glycan acceptor in a glycoprotein by a sialyltransferase [32][33]. A chemoenzymatic method for its preparation is shown in Scheme 1. It is based on the coupling of Fmoc-glycyl-mannosamine with pyruvate catalized by SA-aldolase to afford the N-protected sialic acid. After reaction with CTP

Biantennary oligoglycines and glyco-oligoglycines self-associating in aqueous medium

• Svetlana V. Tsygankova,
• Alexander A. Chinarev,
• Alexander B. Tuzikov,
• Nikolai Severin,
• Alexey A. Kalachev,
• Juergen P. Rabe,
• Alexandra S. Gambaryan and
• Nicolai V. Bovin

Beilstein J. Org. Chem. 2014, 10, 1372–1382, doi:10.3762/bjoc.10.140

• with similar tri- and tetraantennary analogs. Here, we synthesized oligoglycines of the general formula R-Glyn-Х-Glyn-R (X = -HN-(СН2)m-NH-, m = 2, 4, 10; n = 1–7) without pendant ligands (R = H) and with two pendant sialoligands (R = sialic acid or sialooligosaccharide). Biantennary oligoglycines

A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors

• El Sayed H. El Ashry,
• El Sayed H. El Tamany,
• Mohy El Din Abdel Fattah,
• Mohamed R. E. Aly,
• Ahmed T. A. Boraei and
• Axel Duerkop

Beilstein J. Org. Chem. 2013, 9, 135–146, doi:10.3762/bjoc.9.16

• precursors for the synthesis of the herbicidal and fungicidal agents thiazolidine-4-ones [11]. Thiosemicarbazide (TSC) and related amines were used to prepare modified amylase and amylopectin for biological studies [12]. Moreover, glycosylthiosemicarbazides are formed in vivo to modify cell-surface sialic

• acid. This is known as a metabolic cell-surface-engineering technique for cell-surface interactions and consequently shows the potential of these compounds for the development of anticancer agents [13][14][15][16]. Antituberculosis effects of glycosylthiosemicarbazides were also reviewed [17

Automated synthesis of sialylated oligosaccharides

• Davide Esposito,
• Mattan Hurevich,
• Bastien Castagner,
• Cheng-Chung Wang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 1601–1609, doi:10.3762/bjoc.8.183

• Berlin, Germany Institute of Pharmaceutical Sciences, Swiss Federal Institute of Technology (ETH) Zurich, 8093 Zurich, Switzerland Institute of Chemistry, Academia Sinica, Taipei, 11529, Taiwan 10.3762/bjoc.8.183 Abstract Sialic acid-containing glycans play a major role in cell-surface interactions with

• sialyl α-(2→3) and α-(2→6) galactosyl imidates, which, used in combination with the automated platform, provided rapid access to a small library of conjugation-ready sialosides of biological relevance. Keywords: automated synthesis; disaccharide building blocks; solid-phase synthesis; sialic acid

• ; sialosides; Introduction Sialic acid (Sia) belongs to a family of nonulosonic acids, i.e., monosaccharides equipped with a carboxylic moiety and a nine-carbon backbone, which play a unique role in glycobiology. Sia-containing glycans mediate pathogen invasion [1] and are involved in signalling cascades

Synthetic glycopeptides and glycoproteins with applications in biological research

• Ulrika Westerlind

Beilstein J. Org. Chem. 2012, 8, 804–818, doi:10.3762/bjoc.8.90

• β-subunit of human follicle-stimulating hormone (hFSH) glycoprotein was prepared, containing two complex type N-glycans, modified with core fucose and terminal sialic acid glycan residues [57]. The FSH β-subunit was prepared by sequential native chemical ligation. Initially, a larger C-terminal

Facile synthesis of nitrophenyl 2-acetamido-2-deoxy-α-D-mannopyranosides from ManNAc-oxazoline

• Karel Křenek,
• Petr Šimon,
• Lenka Weignerová,
• Barbora Fliedrová,
• Marek Kuzma and
• Vladimír Křen

Beilstein J. Org. Chem. 2012, 8, 428–432, doi:10.3762/bjoc.8.48

• ManNAc. This carbohydrate is a precursor of sialic acid(s). The pathogenicity of some bacterial strains occurring in their R-forms (R stands for rough: virulent, containing ManNAc in the capsular structures) and S-forms (S stands for smooth: nonvirulent, lower level of ManNAc in the capsules) is related

Preparation of aminoethyl glycosides for glycoconjugation

• Robert Šardzík,
• Gavin T. Noble,
• Martin J. Weissenborn,
• Andrew Martin,
• Simon J. Webb and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2010, 6, 699–703, doi:10.3762/bjoc.6.81

• more successful and produced mainly the beta anomer 17. Maltoside 18 was generated by the same microwave-mediated glycosylation as developed for lactoside 16 (Method B) and in reasonable yield. N-Acetyl neuraminic acid (sialic acid) is an important component of cell surfaces and chemical glycosylation

• procedures involving sialic acid are generally challenging. In our hands activation as the chloride (prepared from Neu5Ac in 3 steps) using silver carbonate (Method F) gave reasonable yields of 19. Deprotection reactions The general deprotection for compounds 10–18 is shown in Scheme 2. Acetates were cleaved

Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid

• Arne Homann,
• Riaz-ul Qamar,
• Sevnur Serim,
• Petra Dersch and
• Jürgen Seibel

Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24

• at the termini of mammalian cell-surface glycostructures, which participate in essential interaction processes including adhesion of pathogens prior to infection and immunogenicity. Here we present the synthesis and bioorthogonal metabolic incorporation of the sialic acid analogue N-(1-oxohex-5-ynyl

• )neuraminic acid (Neu5Hex) into the cell-surface glycocalyx of a human larynx carcinoma cell line (HEp-2) and its fluorescence labelling by click chemistry. Keywords: bioorthogonal metabolic glycoengineering; click chemistry; sialic acid; Introduction The surface of eukaryotic cells is heavily covered with

• inactive, small amounts of Neu5Gc 2 are also found in the human metabolism presumably dietary derived from carbohydrate salvage pathways [5][6]. The efficient uptake and incorporation of sialic acid modified in positions C-5 and C-9 into human B-lymphoma cells (BJA-B), Jurkat and others including primary

Acid- mediated reactions under microfluidic conditions: A new strategy for practical synthesis of biofunctional natural products

• Katsunori Tanaka and
• Koichi Fukase

Beilstein J. Org. Chem. 2009, 5, No. 40, doi:10.3762/bjoc.5.40

• of mammalian N-glycans of the diverse structures, have motivated us to establish a practical and library-directed synthesis of the complex-type N-glycans on solid-support [32]; the initial target of our strategy is a sialic acid-containing N-glycan with asymmetric branching chains (Figure 1), which

• , β-mannosylation, as well as reductive opening of sugar 4,6-O-benzylidene acetals, significantly facilitated the large scale preparation of the N-glycan fragments b–d. A stock of these key synthetic intermediates eventually led to the first solid-supported synthesis of the sialic acid-containing