Total synthesis of the O-antigen repeating unit of Providencia stuartii O49 serotype through linear and one-pot assemblies

• Tanmoy Halder and
• Somnath Yadav

Beilstein J. Org. Chem. 2021, 17, 2915–2921, doi:10.3762/bjoc.17.199

• , we herein report the total synthesis of a trisaccharide repeating unit of the O-antigen polysaccharide of the P. stuartii O49 serotype containing the →6)-β-ᴅ-Galp-(1→3)-β-ᴅ-GalpNAc(1→4)-α-ᴅ-Galp(1→ linkage. The synthesis of the trisaccharide repeating unit was carried out first by a linear strategy

• was then deprotected and N-acetylated to finally afford the desired trisaccharide repeating unit as its α-p-methoxyphenyl glycoside. Keywords: capsular polysaccharide; carbohydrate vaccines; O-antigen; oligosaccharide synthesis; one-pot synthesis; Introduction O-antigens or O-specific

• development [1][2][3][4][5][6][7][8]. This objective has been proposed to be achieved by the synthesis of chemically homogeneous glycoconjugates bearing the O-antigen oligosaccharide conjugated to peptides for eliciting the desired immune response through vaccines [9][10][11][12][13][14][15][16][17][18][19

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

• Jundi Xue,
• Ziyi Han,
• Gen Li,
• Khalisha A. Emmanuel,
• Cynthia L. McManus,
• Qiang Sui,
• Dongmian Ge,
• Qi Gao and
• Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

• -antigen [2]. While O-antigen and the core oligosaccharide are exposed to the external environment, lipid A, the hydrophobic domain of LPS, is embedded in the cell wall. The lipid A substructure is relatively conserved that consists of a β-1,6-linked diglucosamine with 1,4′-di-O-phosphorylation and 2,2′-N

• bacteria and the environment [1]. For example, lipopolysaccharide (LPS) comprises the Gram-negative bacterial cell wall and is crucial in bacterial pathogenicity [2]. LPS is a complex molecule that is composed of three structural regions: lipid A (endotoxin), a non-repeating core oligosaccharide, and O

Convenient synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigen of Escherichia albertii O4

• Tapasi Manna,
• Arin Gucchait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 106–110, doi:10.3762/bjoc.16.12

• corresponding to the cell wall O-antigen of the Escherichia albertii O4 strain in very good yield with the desired configuration at the glycosidic linkages using thioglycosides and trichloroacetimidate derivatives as glycosyl donors and perchloric acid supported over silica (HClO4/SiO2) as a solid supported

• protic acid glycosyl activator. The expected configuration at the glycosidic linkages was achieved using a reasonable selection of protecting groups in the manosaccharide intermediates. Keywords: Escherichia albertii O4; glycosylation; HClO4/SiO2; O-antigen; pentasaccharide; Introduction Diarrheal

• pentasaccharide repeating unit of the cell wall O-antigen of Escherichia albertii O4 in very good yield. Although the target compound can be achieved by block synthetic approach but a better yield of the product was obtained by a sequential approach. HClO4/SiO2 was used as a solid acid activator in the

Chemical synthesis of the pentasaccharide repeating unit of the O-specific polysaccharide from Escherichia coli O132 in the form of its 2-aminoethyl glycoside

• Debasish Pal and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2019, 15, 2563–2568, doi:10.3762/bjoc.15.249

• chemically synthesized oligosaccharides before [8][9][10]. The corresponding aminopropyl linker has also been used by others [11]. The chemically synthesized oligosaccharide structure will help to elucidate further biological implications of the O-antigen concerned and possible vaccine potential. Results and

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• micro-heterogeneous structure distinguished by three regions: the lipid A [5], the core oligosaccharide [6] and the O-antigen [7] (Figure 1B). The TLR4·MD-2 receptor complex senses picomolar amounts of LPS and initiates the biosynthesis of diverse mediators of inflammation (such as tumor necrosis factor

Elucidation of a masked repeating structure of the O-specific polysaccharide of the halotolerant soil bacteria Azospirillum halopraeferens Au4

• Elena N. Sigida,
• Yuliya P. Fedonenko,
• Alexander S. Shashkov,
• Nikolay P. Arbatsky,
• Evelina L. Zdorovenko,
• Svetlana A. Konnova,
• Vladimir V. Ignatov and
• Yuriy A. Knirel

Beilstein J. Org. Chem. 2016, 12, 636–642, doi:10.3762/bjoc.12.62

• chain (OPS) called O antigen and capsular polysaccharide (K antigen) of Azospirillum, which is an extracellular form of LPS [8][9], are important for the interaction between bacteria and host plants. The cell-surface polysaccharides of Azospirillum are involved in overcoming of unfavorable conditions

• , often non-stoichiometric, are not uncommon for Gram-negative bacteria. They occur independently of the polymerization mechanism [21][22] and often are associated with temperate bacteriophages that bear the corresponding transferases. Such alterations in certain O-antigen structures of emerging human

Synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O117:K98:H4

• Pintu Kumar Mandal

Beilstein J. Org. Chem. 2014, 10, 2724–2728, doi:10.3762/bjoc.10.287

• Pintu Kumar Mandal Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, BS-10/1, Sector 10, Jankipuram extension, Sitapur Road, Lucknow, 226 031, India 10.3762/bjoc.10.287 Abstract The pentasaccharide repeating unit of the O-antigen of E. coli O117:K98:H4 strain has

• coli; glycosylation; lipopolysaccharide; O-antigen; pentasaccharide; Introduction Escherichia coli becomes an important human pathogen in recent years owing to the emergence of new pathogenic strains [1]. Several diseases, such as meningitis and sepsis [2], diarrhoeal outbreaks [3] and urinary tract

• glycosylation strategy has been developed to synthesize a pentasaccharide 3-aminopropyl glycoside (1) corresponding to the O-antigen of E. coli O117:K98:H4 strain. The in situ removal of the PMB ether in one-pot following the glycosylation reaction reduced the overall number of steps. Structure of the

Efficient routes toward the synthesis of the D-rhamno-trisaccharide related to the A-band polysaccharide of Pseudomonas aeruginosa

• Aritra Chaudhury,
• Sajal K. Maity and
• Rina Ghosh

Beilstein J. Org. Chem. 2014, 10, 1488–1494, doi:10.3762/bjoc.10.153

• rendering O-antigen-based vaccines ineffective. But the conservation of the A-band polysaccharide even in the colonized form makes this repeating unit a viable candidate for A-band polysaccharide-based vaccines which can avoid the vulnerability applicable to their O-antigen-based counterparts [16]. Hence

Straightforward synthesis of a tetrasaccharide repeating unit corresponding to the O-antigen of Escherichia coli O16

• Manas Jana and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 1757–1762, doi:10.3762/bjoc.9.203

• Manas Jana Anup Kumar Misra Bose Institute, Division of Molecular Medicine, P-1/12, C.I.T. Scheme VII-M, Kolkata-700054, India, Fax: 91-33-2355 3886 10.3762/bjoc.9.203 Abstract A straightforward synthesis of the tetrasaccharide repeating unit of the O-antigen of Escherichia coli O16 has been

• stereoselective. Keywords: Escherichia coli; glycosylation; lipopolysaccharide; O-antigen; tetrasaccharide; Introduction Neonatal meningitis is a serious concern in developing countries [1]. The symptoms associated with this disease are unspecific and may ultimately lead to sepsis [2]. The common cause of the

• containing D-glucosamine, L-rhamnose, D-glucose and D-galactofuranose moieties in a 1:1:1:1 ratio (Figure 1). The emergence of multi drug resistant bacterial strains forces medicinal chemists to develop new approaches to combat bacterial infections. Since the structure of the O-antigen influences the

Convergent synthesis of the tetrasaccharide repeating unit of the cell wall lipopolysaccharide of Escherichia coli O40

• Abhijit Sau and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2012, 8, 2053–2059, doi:10.3762/bjoc.8.230

• yielding and stereoselective. Keywords: Escherichia coli; glycosylation; lipopolysaccharide; O-antigen; tetrasaccharide; Introduction Infantile diarrhoea is one of the major causes of morbidity and mortality in infancy in developing countries [1]. Among several factors, Escherichia coli (E. coli

The use of glycoinformatics in glycochemistry

• Thomas Lütteke

Beilstein J. Org. Chem. 2012, 8, 915–929, doi:10.3762/bjoc.8.104

• of nuclear magnetic resonance (NMR) experiments that had been performed to elucidate the structures. Other sources of NMR data are SugaBase [36], which similar to CarbBank is no longer maintained, GlycoBase (Lille), Escherichia coli O-antigen Database (ECODAB) [22], and Glycosciences.DB [31], the

Convergent synthesis of the tetrasaccharide repeating unit of the O-antigen of Shigella boydii type 9

• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2011, 7, 1182–1188, doi:10.3762/bjoc.7.137

• Abhishek Santra Anup Kumar Misra Bose Institute, Division of Molecular Medicine, P-1/12, C.I.T. Scheme VII-M, Kolkata-700054, India; Fax: 91-33-2355 3886 10.3762/bjoc.7.137 Abstract A convenient synthesis of the tetrasaccharide repeating unit of the O-antigen of Shigella boydii type 9 has been

• glycoside in high yield. Keywords: diarrhea; glycosylation; O-antigen; oligosaccharide; Shigella boydii; Introduction Diarrhoeal disease is a common cause of death in the tropical countries and it is the second mostly causing infant deaths worldwide. Shigella is one of the well-studied human pathogens

• the presence of acidic constituents (e.g., uronic acid, pseudaminic acid etc. or lactic acid, pyruvic acid etc.) in their structures [6][7]. Recently, L’vov et al. reported the structure of the O-antigen of Shigella boydii type 9, which is a tetrasaccharide repeating unit containing a D-glucuronic

Synthesis of 6-PEtN-α-D-GalpNAc-(1–>6)-β-D-Galp-(1–>4)-β-D-GlcpNAc-(1–>3)-β-D-Galp-(1–>4)-β-D-Glcp, a Haemophilus influenzae lipopolysacharide structure, and biotin and protein conjugates thereof

• Andreas Sundgren,
• Martina Lahmann and
• Stefan Oscarson

Beilstein J. Org. Chem. 2010, 6, 704–708, doi:10.3762/bjoc.6.80

• College Dublin, Belfield, Dublin 4, Ireland, Phone: +353 17162318 10.3762/bjoc.6.80 Abstract Background: In bacteria with truncated lipopolysaccharide structures, i.e., lacking the O-antigen polysaccharide part, core structures are exposed to the immune system upon infection and thus their use as