Glycomimetics
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Galectin-3 plays a crucial role in cancerogenesis; its targeting is a prospective pathway in cancer diagnostics and therapy. Multivalent presentation of glycans was shown to strongly increase the affinity of glycoconjugates to galectin-3. Further strengthening of interaction with galectin-3 may be accomplished using artificial glycomimetics with apt aryl substitutions. We established a new, as yet undescribed chemoenzymatic method to produce selective C-3-substituted N,N'-diacetyllactosamine glycomimetics and coupled them to human serum albumin. From a library of enzymes, only β-N-acetylhexosaminidase from Talaromyces flavus was able to efficiently synthesize the C-3-propargylated disaccharide. Various aryl residues were attached to the functionalized N,N'-diacetyllactosamine via click chemistry to assess the impact of the aromatic substitution. In ELISA-type assays with galectin-3, free glycomimetics exhibited up to 43-fold stronger inhibitory potency to Gal-3 than the lactose standard. Coupling to human serum albumin afforded multivalent neo-glycoproteins with up to 4209-fold increased inhibitory potency per glycan compared to the monovalent lactose standard. Surface plasmon resonance brought further information on the kinetics of galectin-3 inhibition. The potential of prepared neo-glycoproteins to target galectin-3 was demonstrated on colorectal adenocarcinoma DLD-1 cells. We investigated the uptake of neo-glycoproteins into cells and observed limited non-specific transport into the cytoplasm. Therefore, neo-glycoproteins primarily act as efficient scavengers of exogenous galectin-3 of cancer cells, inhibiting its interaction with the cell surface, and protecting T-lymphocytes against galectin-3-induced apoptosis. The present neo-glycoproteins combine the advantage of a straightforward synthesis, selectivity, non-toxicity, and high efficiency for targeting exogenous galectin-3, with possible application in the immunomodulatory treatment of galectin-3-overexpressing cancers.
- MeSH
- biomimetické materiály chemická syntéza chemie farmakologie MeSH
- galektiny antagonisté a inhibitory genetika metabolismus MeSH
- glykoproteiny chemie metabolismus MeSH
- kinetika MeSH
- krevní proteiny antagonisté a inhibitory genetika metabolismus MeSH
- lidé MeSH
- molekulární struktura MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The C-type lectin DC-SIGN expressed on immature dendritic cells is a promising target for antiviral drug development. Previously, we have demonstrated that mono- and divalent C-glycosides based on d-manno and l-fuco configurations are promising DC-SIGN ligands. Here, we described the convergent synthesis of C-glycoside dendrimers decorated with 4, 6, 9, and 12 α-l-fucopyranosyl units and with 9 and 12 α-d-mannopyranosyl units. Their affinity against DC-SIGN was assessed by surface plasmon resonance (SPR) assays. For comparison, parent O-glycosidic dendrimers were synthesized and tested, as well. A clear increase of both affinity and multivalency effect was observed for C-glycomimetics of both types (mannose and fucose). However, when dodecavalent C-glycosidic dendrimers were compared, there was no difference in affinity regarding the sugar unit (l-fuco, IC50 17 μM; d-manno, IC50 12 μM). For the rest of glycodendrimers with l-fucose or d-mannose attached by the O- or C-glycosidic linkage, C-glycosidic dendrimers were significantly more active. These results show that in addition to the expected physiological stability, the biological activity of C-glycoside mimetics is higher in comparison to the corresponding O-glycosides and therefore these glycomimetic multivalent systems represent potentially promising candidates for targeting DC-SIGN.
- MeSH
- biomimetické materiály chemie farmakologie MeSH
- fukosa chemie MeSH
- inhibiční koncentrace 50 MeSH
- lektiny typu C antagonisté a inhibitory MeSH
- mannosa chemie MeSH
- molekuly buněčné adheze antagonisté a inhibitory MeSH
- receptory buněčného povrchu antagonisté a inhibitory MeSH
- Publikační typ
- časopisecké články MeSH
The binding of human galectins by glycomimetic inhibitors is a promising therapeutic approach. The structurally distinct group of tandem-repeat galectins has scarcely been studied so far, and there is hardly any knowledge on their ligand specificity or their inhibitory potential, particularly concerning non-natural carbohydrates. Here, we present the synthesis of a library of seven 3-O-disubstituted thiodigalactoside-derived glycomimetics and their affinity to two tandem-repeat galectins, Gal-8 and Gal-9. The straightforward synthesis of these glycomimetics involved dibutyltin oxide-catalyzed 3,3́-O-disubstitution of commercially available unprotected thiodigalactoside, and conjugation of various aryl substituents by copper-catalyzed Huisgen azide-alkyne cycloaddition (CuAAC). The inhibitory potential of the prepared glycomimetics for Gal-8 and Gal-9 was assessed, and compared with the established galectins Gal-1 and Gal-3. The introduction of C-3 substituents resulted in an over 40-fold increase in affinity compared with unmodified TDG. The structure-affinity relations within the studied series were discussed using molecular modeling. Furthermore, the prepared glycomimetics were shown to scavenge Gal-8 and Gal-9 from the surface of cancer cells. This pioneering study on the synthetic inhibitors especially of Gal-9 identified lead compounds that may be used in further biomedical research.
- MeSH
- galektiny * metabolismus MeSH
- lidé MeSH
- sacharidy chemie MeSH
- thiogalaktosidy * chemie MeSH
- vazba proteinů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Modification of the carbohydrate scaffold is an important theme in drug and vaccine discovery. Therefore, the preparation of novel types of glycomimetics is of interest in synthetic carbohydrate chemistry. In this manuscript, we present an early investigation of the synthesis, structure, and conformational behaviour of (1→1)-Si-disaccharides as a novel type of glycomimetics arising from the replacement of interglycosidic oxygen with a dimethyl-, methylpropyl-, or diisopropylsilyl linkage. We accomplished the preparation of this unusual group of umpoled compounds by the reaction of lithiated glycal or 2-oxyglycal units with dialkyldichlorosilanes. We demonstrated the good stability of the "Si-glycosidic" linkage under acidic conditions even at elevated temperatures. Next, we described the conformational landscape of these compounds by the combination of in silico modelling with spectroscopic and crystallographic methods. Finally, we explained the observed conformational flexibility of these compounds by the absence of gauche stabilizing effects that are typically at play in natural carbohydrates.
This work reveals new structural relationships in the complex process of the interaction between activation receptors of natural killer cells (rat NKR-P1, human CD69) and novel bivalent carbohydrate glycomimetics. The length, glycosylation pattern and linker structure of receptor ligands were examined with respect to their ability to precipitate the receptor protein from solution, which simulates the in vivo process of receptor aggregation during NK cell activation. It was found that di-LacdiNAc triazole compounds show optimal performance, reaching up to 100% precipitation of the present protein receptors, and achieving high immunostimulatory activities without any tendency to trigger activation-induced apoptosis. In the synthesis of the compounds tested, two enzymatic approaches were applied. Whereas a β-N-acetylhexosaminidase could only glycosylate one of the two acceptor sites available with yields below 10%, the Y284L mutant of human placental β1,4-galactosyltransferase-1 worked as a perfect synthetic tool, accomplishing even quantitative glycosylation at both acceptor sites and with absolute regioselectivity for the C-4 position. This work insinuates new directions for further ligand structure optimisation and demonstrates the strong synthetic potential of the mutant human placental β1,4-galactosyltransferase-1 in the synthesis of multivalent glycomimetics and glycomaterials.
- MeSH
- aktivace lymfocytů účinky léků imunologie MeSH
- beta-N-acetylhexosaminidasy metabolismus MeSH
- biomimetika metody MeSH
- buňky NK chemie účinky léků imunologie metabolismus MeSH
- CD antigeny imunologie metabolismus MeSH
- diferenciační antigeny T-lymfocytů imunologie metabolismus MeSH
- galaktosyltransferasy genetika metabolismus MeSH
- imunoprecipitace MeSH
- krysa rodu rattus MeSH
- lektiny typu C agonisté imunologie metabolismus MeSH
- lidé MeSH
- ligandy MeSH
- molekulární mimikry MeSH
- mutace MeSH
- placenta enzymologie MeSH
- polysacharidy chemická syntéza farmakologie MeSH
- receptory buněk NK agonisté imunologie metabolismus MeSH
- rekombinantní proteiny genetika metabolismus MeSH
- těhotenství MeSH
- vazba proteinů účinky léků imunologie MeSH
- vazebná místa účinky léků imunologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
DC-SIGN, a C-type lectin receptor expressed on immune cells, is considered a promising target for immunomodulatory and antiviral therapies. While mannose-based glycomimetics have been extensively studied as DC-SIGN ligands, fucose-based strategies remain underexplored. This study explores the fucosylation of linear alcohols and sugars using eight different fucosyl donors, aiming at designing strategies for the development of fucose-based glycomimetics targeting DC-SIGN. Four types of leaving groups and two different acyl-based protecting groups on the donors were tested. The glycosylation of 3-azidopropan-1-ol exclusively yielded the β-anomer, demonstrating high stereoselectivity. The azido group in the product is versatile, allowing for direct click chemistry reactions or reduction to an amine for further functionalization. Both types of reactions were demonstrated in a model reaction. In the glycosylation of a sugar, a disaccharide moiety of Lewis X antigen was selected as a target molecule. Only one of the eight tested fucosyl donors worked well in this reaction and provided the product in a reasonable yield. The disaccharide was also equipped with the 3-azidopropyl linker, facilitating future modifications. Finally, NMR studies confirmed compatibility of the linker with canonical Ca2+-dependent carbohydrate binding to DC-SIGN, suggesting potential for further development of fucose-based glycomimetics targeting this C-type lectin receptor.
- MeSH
- fukosa * chemie MeSH
- glykosidy * chemie chemická syntéza farmakologie metabolismus MeSH
- glykosylace MeSH
- lektiny typu C * metabolismus antagonisté a inhibitory MeSH
- lidé MeSH
- molekulární struktura MeSH
- molekuly buněčné adheze * metabolismus antagonisté a inhibitory MeSH
- receptory buněčného povrchu * metabolismus antagonisté a inhibitory MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
As a part of ongoing activities towards the design of ligands against pathogenic lectins, a synthesis of original α-C-galacto/α-C-manno/α-C-fucopyranosyl glycomimetics based on a calix[4]arene scaffold and their binding evaluation is described. The interactions of the glycomimetics with seven lectins of various origins were carried out using agglutination inhibition assays. The 1,3-alternate tetra-C-fucosylated ligand and its derivative having a tertBu group at the upper rim of the calix[4]arene scaffold were the most potent towards the AAL lectin family (RSL, AFL, AAL, AOL) and BC2L-C. As AFL and RSL originate from important human (Aspergillus fumigatus) and plant (Ralstonia solanacearum) pathogens, the inhibition potency of both leading structures was assessed by surface plasmon resonance. With AFL, both structures exhibited an approximately three orders of magnitude increase in affinity compared to the reference l-fucose. The role of tertBu groups as "aglycon-assisted" events was illustrated by NMR. Furthermore, both compounds showed significantly increased ability to inhibit BC2L-C (from human pathogen Burkholderia cenocepacia) cell agglutination and were able to cross-link whole B. cenocepacia cells. Although the ligands failed to significantly inhibit the agglutination activity of LecA and LecB from Pseudomonas aeruginosa, tetra-C-galactosylated calix[4]arene with tertBu groups at the upper rim of the 1,3-alternate conformation inhibited P. aeruginosa biofilm formation efficiently. This systematic and comprehensive study highlights the fact that hydrolytically stable polyvalent C-glycomimetics should be regarded as potent and selective ligands capable of acting as antiadhesive agents.
- MeSH
- aglutinace účinky léků MeSH
- biofilmy účinky léků MeSH
- biomimetické materiály chemie farmakologie MeSH
- kalixareny chemie farmakologie MeSH
- lektiny chemie MeSH
- lidé MeSH
- ligandy MeSH
- molekulární konformace MeSH
- molekulární modely MeSH
- Pseudomonas aeruginosa účinky léků fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Human placental beta1,4-galactosyltransferase-I (EC 2.4.1.38) transfers the galactosyl moiety from UDP-Gal to various GlcNAc or Glc acceptors in vivo. Here, we describe the construction of its Y284L mutant as a His(6)propeptide-catbeta4GalT1 construct, in which the Gal-transferase activity was totally abolished in favor of its GalNAc-transferase activity. We used this mutant in the synthesis of three mono- and bivalent LacdiNAc glycomimetics with good yields. These compounds proved to be powerful ligands of two activation receptors of natural killer cells, NKR-P1 and CD69. A synthetic bivalent tethered di-LacdiNAc is the best currently known precipitation agent for both of these receptors and has promising potential for the development of immunoactive glycodrugs.
- MeSH
- bakteriální proteiny metabolismus MeSH
- Campylobacter jejuni enzymologie MeSH
- CD antigeny metabolismus MeSH
- diferenciační antigeny T-lymfocytů metabolismus MeSH
- epimerázy sacharidů metabolismus MeSH
- galaktosyltransferasy genetika metabolismus MeSH
- glykokonjugáty biosyntéza chemická syntéza metabolismus MeSH
- laktosa analogy a deriváty biosyntéza chemická syntéza metabolismus MeSH
- lektinové receptory NK-buněk - podrodina B metabolismus MeSH
- lektiny typu C MeSH
- lidé MeSH
- mutace MeSH
- placenta enzymologie MeSH
- substrátová specifita MeSH
- těhotenství MeSH
- Check Tag
- lidé MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- Publikační typ
- odvolaná publikace MeSH
- práce podpořená grantem MeSH
Cellular communication events are mediated by interactions between cell-surface sugars and lectins, which are carbohydrate-binding proteins. Galectins are β-galactosyl-binding lectins that bridge molecules by their sugar moieties, forming a signaling and adhesion network. Severe changes in glycosylation and galectin expression accompany major processes in oncogenesis, cardiovascular disorders, and other pathologies, making galectins attractive therapeutic targets. Here we discuss advanced strategies of chemo-enzymatic carbohydrate synthesis for creating lead glycomimetics and (neo-)glycoconjugates for galectin-1 and -3 targeting in biomedicine and biotechnology. We will describe the challenges and bottlenecks on the route into biomedical and biotechnological practice and present the first clinical candidates. The coming era will see an exciting translation of selective well-defined high-affinity galectin ligands from bench to bedside.
The discovery of effective ligands for DC-SIGN receptor is one of the most challenging concepts of antiviral drug design due to the importance of this C-type lectin in infection processes. DC-SIGN recognizes mannosylated and fucosylated oligosaccharides but glycosidic linkages are accessible to both chemical and enzymatic degradations. To avoid this problem, the synthesis of stable glycoside mimetics has attracted increasing attention. In this work we establish for the first time mono- and divalent C-glycosides based on d-manno and l-fuco configurations as prospective DC-SIGN ligands. In particular, the l-fucose glycomimetics were more active than the respective d-mannose ones. The highest affinity was assessed for simple 1,4-bis(α-l-fucopyranosyl)butane (SPR: IC50 0.43 mM) that displayed about twice higher activity than natural ligand Le(x). Our results make C-glycosides attractive candidates for multivalent presentations.
- MeSH
- biomimetika MeSH
- fukosa chemie MeSH
- glykosidy chemická syntéza chemie MeSH
- lektiny typu C chemie metabolismus MeSH
- lidé MeSH
- mannosa chemie MeSH
- molekulární struktura MeSH
- molekuly buněčné adheze chemie metabolismus MeSH
- receptory buněčného povrchu chemie metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
