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Multivalent Carbohydrate-Lectin Interactions: How Synthetic Chemistry Enables Insights into Nanometric Recognition. Molecules 2016; 21:molecules21050629. [PMID: 27187342 PMCID: PMC6274006 DOI: 10.3390/molecules21050629] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/02/2016] [Accepted: 05/10/2016] [Indexed: 12/15/2022] Open
Abstract
Glycan recognition by sugar receptors (lectins) is intimately involved in many aspects of cell physiology. However, the factors explaining the exquisite selectivity of their functional pairing are not yet fully understood. Studies toward this aim will also help appraise the potential for lectin-directed drug design. With the network of adhesion/growth-regulatory galectins as therapeutic targets, the strategy to recruit synthetic chemistry to systematically elucidate structure-activity relationships is outlined, from monovalent compounds to glyco-clusters and glycodendrimers to biomimetic surfaces. The versatility of the synthetic procedures enables to take examining structural and spatial parameters, alone and in combination, to its limits, for example with the aim to produce inhibitors for distinct galectin(s) that exhibit minimal reactivity to other members of this group. Shaping spatial architectures similar to glycoconjugate aggregates, microdomains or vesicles provides attractive tools to disclose the often still hidden significance of nanometric aspects of the different modes of lectin design (sequence divergence at the lectin site, differences of spatial type of lectin-site presentation). Of note, testing the effectors alone or in combination simulating (patho)physiological conditions, is sure to bring about new insights into the cooperation between lectins and the regulation of their activity.
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Abstract
Nitrogen-containing macrocyclic compounds (amines, amides, and N-heterocyclic derivatives) are important targets in supramolecular chemistry. This chapter discusses the importance of aza-macrocycles in general and, in particular, those receptors containing sugar unit(s). The combination of a carbohydrate scaffold bearing nitrogen-containing functional groups in macrocyclic molecules opens a convenient route to chiral receptors having potentially useful properties. The carbohydrate-based macrocycles discussed are classified into several general groups: (1) aza-crown ethers containing a carbohydrate subunit, (2) cyclic homooligomers from amino sugars, (3) sugar-based cryptands, (4) cyclic peptides containing amino sugar units (including C2- and C3-symmetrical macrocyclic glycopeptides), (5) nitrogen- containing glycophanes, and (6) 1,2,3-triazoles containing synthetic cyclodextrin analogues. The general strategies employed, as well as specific ones leading to such complex derivatives, are surveyed. Applications of such carbohydrate receptors, pointing to their importance as hosts in supramolecular chemistry, are discussed.
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Zhao J, Li W, Ma R, Chen S, Ren S, Jiang T. Design, synthesis and DNA interaction study of new potential DNA bis-intercalators based on glucuronic acid. Int J Mol Sci 2013; 14:16851-65. [PMID: 23955268 PMCID: PMC3759939 DOI: 10.3390/ijms140816851] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 06/30/2013] [Accepted: 07/07/2013] [Indexed: 11/18/2022] Open
Abstract
A series of novel potential DNA bis-intercalators were designed and synthesized, in which two glucuronic acids were linked by ethylenediamine, and the glucuronic acid was coupled with various chromophores, including quinoline, acridine, indole and purine, at the C-1 position. The preliminary binding properties of these compounds to calf thymus DNA (CT-DNA) have been investigated by UV-absorption and fluorescence spectroscopy. The results indicated that all the target compounds can interact with CT-DNA, and the acridine derivative, 3b, showed the highest key selection vector (KSV) value, which suggested that compound 3b binds most strongly to CT-DNA.
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Affiliation(s)
- Jiuyang Zhao
- Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Pharmacy, Ocean University of China, Qingdao 266003, China; E-Mails: (J.Z.); (W.L.); (R.M.); (S.C.); (S.R.)
| | - Wei Li
- Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Pharmacy, Ocean University of China, Qingdao 266003, China; E-Mails: (J.Z.); (W.L.); (R.M.); (S.C.); (S.R.)
- School of Pharmacy, Jining Medical University, Rizhao 276826, China
| | - Rui Ma
- Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Pharmacy, Ocean University of China, Qingdao 266003, China; E-Mails: (J.Z.); (W.L.); (R.M.); (S.C.); (S.R.)
| | - Shaopeng Chen
- Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Pharmacy, Ocean University of China, Qingdao 266003, China; E-Mails: (J.Z.); (W.L.); (R.M.); (S.C.); (S.R.)
| | - Sumei Ren
- Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Pharmacy, Ocean University of China, Qingdao 266003, China; E-Mails: (J.Z.); (W.L.); (R.M.); (S.C.); (S.R.)
| | - Tao Jiang
- Key Laboratory of Marine Drugs, The Ministry of Education of China, School of Pharmacy, Ocean University of China, Qingdao 266003, China; E-Mails: (J.Z.); (W.L.); (R.M.); (S.C.); (S.R.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +86-532-8203-2712; Fax: +86-532-8203-3054
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The third dimension of reading the sugar code by lectins: design of glycoclusters with cyclic scaffolds as tools with the aim to define correlations between spatial presentation and activity. Molecules 2013; 18:4026-53. [PMID: 23558543 PMCID: PMC6269965 DOI: 10.3390/molecules18044026] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 03/22/2013] [Accepted: 04/01/2013] [Indexed: 01/21/2023] Open
Abstract
Coding of biological information is not confined to nucleic acids and proteins. Endowed with the highest level of structural versatility among biomolecules, the glycan chains of cellular glycoconjugates are well-suited to generate molecular messages/signals in a minimum of space. The sequence and shape of oligosaccharides as well as spatial aspects of multivalent presentation are assumed to underlie the natural specificity/selectivity that cellular glycans have for endogenous lectins. In order to eventually unravel structure-activity profiles cyclic scaffolds have been used as platforms to produce glycoclusters and afford valuable tools. Using adhesion/growth-regulatory galectins and the pan-galectin ligand lactose as a model, emerging insights into the potential of cyclodextrins, cyclic peptides, calixarenes and glycophanes for this purpose are presented herein. The systematic testing of lectin panels with spatially defined ligand presentations can be considered as a biomimetic means to help clarify the mechanisms, which lead to the exquisite accuracy at which endogenous lectins select their physiological counterreceptors from the complexity of the cellular glycome.
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Wang GN, André S, Gabius HJ, Murphy PV. Bi- to tetravalent glycoclusters: synthesis, structure-activity profiles as lectin inhibitors and impact of combining both valency and headgroup tailoring on selectivity. Org Biomol Chem 2012; 10:6893-907. [PMID: 22842468 DOI: 10.1039/c2ob25870f] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The emerging functional versatility of cellular glycans makes research on the design of synthetic inhibitors a timely topic. In detail, the combination of ligand (or headgroup or contact site) structure with spatial parameters that depend on topological and geometrical factors underlies the physiological selectivity of glycan-protein (lectin) recognition. We herein tested a panel of bi-, tri- and tetravalent compounds against two plant agglutinins and adhesion/growth-regulatory lectins (galectins). In addition, we examined the impact of headgroup tailoring (converting lactose to 2'-fucosyllactose) in combination with valency increase in two assay types of increasing biorelevance (from solid-phase binding to cell binding). Compounds were prepared using copper-catalysed azide alkyne cycloaddition from peracetylated lactosyl or 2'-fucosyllactosyl azides. Significant inhibition was achieved for the plant toxin with a tetravalent compound. Different levels of sensitivity were noted for the three groups of the galectin family. The headgroup extension to 2'-fucosyllactose led to a selectivity gain, especially for the chimera-type galectin-3. Valency increase established discrimination against the homodimeric proteins, whereas the combination of valency with the headgroup extension led to discrimination against the tandem-repeat-type galectin-8 for chicken galectins but not human galectins-3 and -4. Thus, detailed structure-activity profiling of glycoclusters combined with suitably modifying the contact site for the targeted lectin will help minimize cross-reactivity among this class of closely related proteins.
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Affiliation(s)
- Guan-Nan Wang
- School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland
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Allam A, Dupont L, Behr JB, Plantier-Royon R. Convenient Synthesis of a Galacturonic Acid Based Macrocycle with Potential Copper-Complexation Ability. European J Org Chem 2011. [DOI: 10.1002/ejoc.201101406] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Chen S, Zhang X, Wang J, Wan S, Geng M, Jiang T. Design and synthesis of a series of novel bisquinazoline glycosides as epidermal growth factor receptor inhibitors. Chem Biol Drug Des 2011; 78:1006-13. [PMID: 21824331 DOI: 10.1111/j.1747-0285.2011.01209.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new series of potential epidermal growth factor receptor inhibitors possessing bisquinazoline and saccharide moieties were designed and synthesized. The biological results demonstrated that the synthetic derivatives significantly inhibited epidermal growth factor receptor enzymatic activity in vitro. Of them, compound 14b showed the highest inhibitory rate toward epidermal growth factor receptor protein tyrosine kinase (81.36%) at a concentration of 1 μM. Further molecular simulation predicted that 14b offered its saccharide moieties hydrogen bonding to ATP-binding pocket.
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Jarikote DV, Li W, Jiang T, Eriksson LA, Murphy PV. Towards echinomycin mimetics by grafting quinoxaline residues on glycophane scaffolds. Bioorg Med Chem 2010; 19:826-35. [PMID: 21195622 DOI: 10.1016/j.bmc.2010.12.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 11/23/2010] [Accepted: 12/03/2010] [Indexed: 11/25/2022]
Abstract
Echinomycin is a natural depsipeptide, which is a bisintercalator, inserting quinoxaline units preferentially adjacent to CG base pairs of DNA. Herein the design and synthesis of echinomycin mimetics based on grafting of two quinoxaline residues onto a macrocyclic scaffold (glycophane) is addressed. Binding of the compounds to calf-thymus DNA was studied using UV-vis and steady state fluorescence spectroscopy, as well as thermal denaturation. An interesting observation was enhancement of fluorescence emission for the peptidomimetics on binding to DNA, which contrasted with observations for echinomycin. Molecular dynamics simulations were exploited to explore in more detail if bis-intercalation to DNA was possible for one of the glycophanes. Bis-intercalating echinomycin complexes with DNA were found to be stable during 20ns simulations at 298K. However, the MD simulations of a glycophane complexed with a DNA octamer displayed very different behaviour to echinomycin and its quinoxaline units were found to rapidly migrate out from the intercalation site. Release of bis-intercalation strain occurred with only one of the quinoxaline chromophores remaining intercalated throughout the simulation. The distance between the quinoxaline residues in the glycophane at the end of the MD simulation was 7.3-7.5Å, whereas in echinomycin, the distance between the residues was ∼11Å, suggesting that longer glycophane scaffolds would be required to generate bis-intercalating echinomycin mimetics.
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Zhang Z, Ren S, Wan S, Li W, Jiang T. Synthesis of D-Glucosamine-Modified Benzo[d][1,2]selenazol-3-(2H)-one Derivatives. SYNTHETIC COMMUN 2010. [DOI: 10.1080/00397910903434562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Zhongwei Zhang
- a School of Medicine and Pharmacy, Key Laboratory of Marine Drugs, Ministry of Education, Ocean University of China , Qingdao, China
| | - Sumei Ren
- a School of Medicine and Pharmacy, Key Laboratory of Marine Drugs, Ministry of Education, Ocean University of China , Qingdao, China
| | - Shengbiao Wan
- a School of Medicine and Pharmacy, Key Laboratory of Marine Drugs, Ministry of Education, Ocean University of China , Qingdao, China
| | - Wei Li
- a School of Medicine and Pharmacy, Key Laboratory of Marine Drugs, Ministry of Education, Ocean University of China , Qingdao, China
| | - Tao Jiang
- a School of Medicine and Pharmacy, Key Laboratory of Marine Drugs, Ministry of Education, Ocean University of China , Qingdao, China
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Pilgrim W, Murphy PV. SnCl4- and TiCl4-Catalyzed Anomerization of Acylated O- and S-Glycosides: Analysis of Factors That Lead to Higher α:β Anomer Ratios and Reaction Rates. J Org Chem 2010; 75:6747-55. [DOI: 10.1021/jo101090f] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Wayne Pilgrim
- School of Chemistry, National University of Ireland, Galway, Ireland
- Centre for Synthesis and Chemical Biology, School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland
| | - Paul V. Murphy
- School of Chemistry, National University of Ireland, Galway, Ireland
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Affiliation(s)
| | - Paul V. Murphy
- School of Chemistry, National University of Ireland, Galway, Ireland, Fax: +353‐91‐525700
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Cirillo L, Silipo A, Bedini E, Parrilli M. A Urea-Linked Glucosamine Dimer as a Building Block for the Synthesis of Linear and Cyclic Neosaccharides. European J Org Chem 2010. [DOI: 10.1002/ejoc.201000292] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Fast synthesis of uronamides by non-catalyzed opening of glucopyranurono-6,1-lactone with amines, amino acids, and aminosugars. Tetrahedron Lett 2010. [DOI: 10.1016/j.tetlet.2010.03.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Li W, Zhang ZW, Wang SX, Ren SM, Jiang T. Synthesis and Analysis of Potential DNA Intercalators Containing Quinoline-Glucose Hybrids. Chem Biol Drug Des 2009; 74:80-6. [DOI: 10.1111/j.1747-0285.2009.00831.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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André S, Velasco-Torrijos T, Leyden R, Gouin S, Tosin M, Murphy PV, Gabius HJ. Phenylenediamine-based bivalent glycocyclophanes: synthesis and analysis of the influence of scaffold rigidity and ligand spacing on lectin binding in cell systems with different glycomic profiles. Org Biomol Chem 2009; 7:4715-25. [DOI: 10.1039/b913010a] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Doyle D, Murphy PV. Synthesis of novel glycophanes derived from glucuronic acid by ring closing alkene and alkyne metathesis. Carbohydr Res 2008; 343:2535-44. [DOI: 10.1016/j.carres.2008.06.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2008] [Revised: 05/30/2008] [Accepted: 06/07/2008] [Indexed: 11/17/2022]
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Efficient glycosydation and/or esterification of d-glucuronic acid and its 6,1-lactone under solvent-free microwave irradiation. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.09.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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D'Onofrio J, Coppola C, Di Fabio G, De Napoli L, Montesarchio D. Novel Cyclic Phosphate-Linked Oligosaccharides (CyPLOSs) Covalently Immobilized on Solid Supports for Potential Cation Scavenging. European J Org Chem 2007. [DOI: 10.1002/ejoc.200700203] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Di Fabio G, Randazzo A, D'Onofrio J, Ausín C, Pedroso E, Grandas A, De Napoli L, Montesarchio D. Cyclic Phosphate-Linked Oligosaccharides: Synthesis and Conformational Behavior of Novel Cyclic Oligosaccharide Analogues. J Org Chem 2006; 71:3395-408. [PMID: 16626119 DOI: 10.1021/jo0600757] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
CyPLOS (cyclic phosphate-linked oligosaccharides), that is, novel cyclic oligosaccharide surrogates, consisting of two, three, and four phenyl-beta-D-glucopyranoside units, 4,6-linked through stable phosphodiester bonds, were prepared by a straightforward and efficient solid-phase protocol. The assembly of the linear precursors was achieved by standard phosphoramidite chemistry on an automated DNA synthesizer, using a suitably protected 4-phosphoramidite derivative of D-glucose as the building block. For the crucial cyclization step a phosphotriester methodology was exploited, followed by a mild basic treatment releasing the desired cyclic molecules in solution in a highly pure form. The cyclic dimer and trimer were also independently prepared by classical solution synthesis, basically following the same approach. The solution structural preferences of the cyclic dimer and trimer, obtained by detailed NMR analysis, are also reported.
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Affiliation(s)
- Giovanni Di Fabio
- Dipartimento di Chimica Organica e Biochimica, Università degli Studi di Napoli Federico II, Complesso Universitario di Monte S. Angelo, via Cynthia, 4, I-80126 Napoli, Italy
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Murphy PV, Müller-Bunz H, Velasco-Torrijos T. The crystal structure of a cyclic glycolipid reveals a carbohydrate-carbohydrate interaction interface. Carbohydr Res 2005; 340:1437-40. [PMID: 15854619 DOI: 10.1016/j.carres.2005.02.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2005] [Revised: 02/23/2005] [Accepted: 02/23/2005] [Indexed: 10/25/2022]
Abstract
The crystal structure of an amphiphilic macrocycle [Velasco-Torrijos, T.; Murphy, P. V., Tetrahedron: Asymmetry2005, 16, 261-272] derived from saccharides shows extensive hydrogen-bonding networks, including participation of water, that may have relevance for the modelling of carbohydrate-carbohydrate recognition at cell-cell interfaces. The structure may provide a basis for understanding the binding of the macrocycle to hydrophobic probes.
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Affiliation(s)
- Paul V Murphy
- Centre for Synthesis and Chemical Biology, Department of Chemistry, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
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Ménand M, Blais JC, Hamon L, Valéry JM, Xie J. Synthesis of orthogonally protected cyclic homooligomers from sugar amino acids. J Org Chem 2005; 70:4423-30. [PMID: 15903321 DOI: 10.1021/jo0502899] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two new families of orthogonally protected cyclic homooligomers with two to four sugar units were synthesized from pyranoid sugar amino acids. Cyclic oligomers composed of amide-linked sugar amino acids (1-3) were prepared by cyclization of linear oligomers of the novel orthogonally protected pyranoid sugar amino acid 12 using a solution-phase coupling method. These orthogonally protected cyclic molecules can be selectively or fully deprotected, affording the macrocycles ready to further functionalization. The straightforward reduction of the amide bonds in the cyclic oligomers 1-3 gave the corresponding amine-linked macrocycles 4-6. This kind of amine-linked carbohydrate-based cyclic oligomer has never been reported before. These flexible molecular receptors could be studied as molecular hosts for molecular, cationic, and anionic recognition. Conformational analysis by molecular modeling (AM1) showed that all of the deprotected cyclic trimers and tetramers preferred a (4)C(1) chair conformation with oxygen atoms of the sugar ring located on the interior of the cavity and the secondary hydroxyl groups outward. In the amide-linked macrocycles, all of the amide bonds are in s-trans conformation. The estimated size of the internal cavity is about 4.5 A for the cyclic trimer and 6.9 A for the cyclic tetramer. The amine-linked macrocycles displayed similar conformational behavior with a slight decrease in internal cavity.
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Affiliation(s)
- Mickaël Ménand
- Synthèse, Structure et Fonction des Molécules Bioactives, CNRS UMR 7613, Université Pierre et Marie Curie, 4 Place Jussieu, F-75005 Paris, France
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Tosin M, Murphy PV. Synthesis of Structurally Defined Scaffolds for Bivalent Ligand Display Based on Glucuronic Acid Anilides. The Degree of Tertiary Amide Isomerism and Folding Depends on the Configuration of a Glycosyl Azide. J Org Chem 2005; 70:4107-17. [PMID: 15876103 DOI: 10.1021/jo050200z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[structures: see text] Syntheses and structural analyses of bivalent carbohydrates based on anilides of glucuronic acid are described. Secondary anilides predominantly adopted the Z-anti structure; there is also evidence for population of the Z-syn isomer. Bivalent tertiary anilides displayed two signal sets in their NMR spectra, consistent with the presence of (i) a major isomer where both amides have E configurations (EE) and (ii) a minor isomer where one amide is E and the other Z (EZ). Qualitative NOE/ROE spectroscopic studies in solution support the proposal that the anti conformation is preferred for E amides. The crystal structure of one bivalent tertiary anilide showed E-anti and E-syn structural isomers; intramolecular carbohydrate-carbohydrate stacking was observed and mediated by carbonyl-pyranose, azide-azide, and pyranose-aromatic interactions. The EE to EZ isomer ratio, or the degree of folding, for tertiary amides, was greatest for a bivalent compound containing two alpha-glycosyl azide groups; this was enhanced in water, suggesting that hydrophobic interactions are partially but not wholly responsible. Computational methods predicted azide-aromatic (N...H-C interaction) and azide-azide interactions for folded isomers. The close contact of the azide and aromatic protons (N...H-C interaction) was observed upon examination of the close packing in the crystal structure of a related monomer. It is proposed that the alpha-azide group is more optimally aligned, compared to the beta-azide, to facilitate interaction and minimize the surface area of the hydrophobic groups exposed to water, and this leads to the increased folding. The alkylation of bivalent secondary anilides induces a switch from Z to E amide that alters the scaffold orientation. The synthesis of a bivalent mannoside, based on a secondary anilide scaffold, for investigation of mannose-binding receptor cross-linking and lattice formation is described.
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Affiliation(s)
- Manuela Tosin
- Centre for Synthesis and Chemical Biology, Department of Chemistry, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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Tosin M, O'Brien C, Fitzpatrick GM, Müller-Bunz H, Glass WK, Murphy PV. Synthesis and Structural Analysis of the Anilides of Glucuronic Acid and Orientation of the Groups on the Carbohydrate Scaffolding. J Org Chem 2005; 70:4096-106. [PMID: 15876102 DOI: 10.1021/jo0501994] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[structures: see text] The synthesis of anilides derived from glucuronic acid is described. Secondary anilides had a Z configuration in the solid state and showed intramolecular and intermolecular hydrogen bonding. However, on the basis of NMR and IR studies, there was generally no evidence for the same hydrogen bonding in solution. Tertiary anilides showed a strong preference for the E configuration on the basis of NOE studies and molecular mechanics calculations. The alkylation of the secondary anilides induces a configurational switch that alters the orientation of the aromatic group with respect to the pyranose, which has relevance for presentation or orientation of pharmacophoric groups on carbohydrate scaffolds.
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Affiliation(s)
- Manuela Tosin
- Centre for Synthesis and Chemical Biology, Department of Chemistry, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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