Understanding multivalent effects in glycosidase inhibition using C-glycoside click clusters as molecular probes

The synthesis of the first examples of multivalent C-glycosides based on C60-fullerene or β-cyclodextrin cores by way of Cu(I)-catalyzed azide–alkyne cycloadditions is reported. These compounds were designed as molecular probes to understand the mechanisms underlying the outstanding multivalent effects observed in glycosidase inhibition. The inhibition results obtained support a multivalent-binding model based on two scenarios both involving nonspecific interactions and varying by the presence or the absence of active site specific interactions. The magnitude of the multivalent effect obtained depends on the identity of the glycosidase involved and more specifically on the accessibility of its catalytic active site. Large inhibitory multivalent effects can be obtained when both glycosidase active sites and non-catalytic sites at the protein surface are involved in binding events. On the other hand, nonspecific interactions alone are not sufficient to achieve relative affinity enhancements exceeding a simple statistical effect (i.e., a relative inhibition potency not better than one on a valence-corrected basis).Ministerio de Economía y Competitividad de España (MINECO) y Fondos Europeos de Desarrollo Regional (FEDER y FSE). SAF2013-44021-

Conception et synthèse d’iminosucres di- à tétravalents comme sondes mécanistiques et agents thérapeutiques potentiels

Because multivalent iminosugars represent, as potent glycosidase inhibitors, privileged structures for the design of novel drugs, we took a particular interest in this class of compounds for the treatment of two rare genetic diseases. The first research topic was dedicated to the synthesis of di- to tetravalent iminosugars in the 1-deoxymannojirimycin series in order to inhibit the endoplasmic reticulum α1,2-mannosidase I involved in the destruction of delF508-CFTR, the mutant protein responsible of cystic fibrosis. A strong multivalent effect for restoring its activity in cells was reported with a trivalent analogue based on pentaerythritol. This submicromolar corrector was found to be 140-fold more potent than the corresponding monovalent model. The second research topic focused on the identification of novel pharmacological chaperones of the β-glucocerebrosidase, the lysosomal enzyme involved in Gaucher’s disease. For this purpose, we developed a series of heterodivalent iminosugars designed to both bind to the active site and a secondary site of the enzyme. This goal could not be reached yet, nevertheless we identified monovalent chaperones which were able to fourfold increase β-glucocerebrosidase activity in G202R cell lines. Next to these main research topics, a mechanistic probe based on a multivalent C-glycoside was also developed to investigate the multivalent effect of iminosugar clusters in glycosidase inhibition.Dans un contexte où les iminosucres multivalents représentent, en tant qu’inhibiteurs puissants de glycosidases, des structures privilégiées pour le développement de nouveaux agents thérapeutiques, nous nous sommes intéressés à ce type de composés pour le traitement de deux maladies génétiques rares. Le premier axe de recherche a consisté à synthétiser des iminosucres di- à tétravalents en série 1-désoxymannojirimycine dans le but d’inhiber l’α1,2-mannosidase I du réticulum endoplasmique qui est impliquée dans la destruction de la protéine delF508-CFTR chez les malades atteints de la mucoviscidose. Un effet multivalent fort sur la correction de cette protéine mutée a alors été mis en évidence avec un composé trivalent basé sur le pentaérythritol. Efficace à des concentrations submicromolaires, ce dernier s’est montré 140 fois plus efficace que le modèle monovalent correspondant. Le second axe de recherche a consisté à identifier de nouveaux chaperons pharmacologiques de la β-glucocérébrosidase, l’enzyme lysosomale impliquée dans la maladie de Gaucher. Pour cela, nous avons préparé une série d’iminosucres hétérodivalents conçus pour cibler simultanément le site actif et un site secondaire de cette enzyme. Même si cet objectif n’a pas encore été atteint, nous avons malgré tout mis en évidence des chaperons monovalents capables de quasiment quadrupler l’activité de la β-glucocérébrosidase portant la mutation G202R. En marge de ces deux axes principaux, une sonde mécanistique basée sur un C-glycoside multivalent a également été développée dans le but de préciser les mécanismes à l’origine des effets multivalents puissants observés pour l’inhibition des glycosidases

Design and synthesis of di- or tetravalent iminosugars as mechanistic probes and potential therapeutic agents

Dans un contexte où les iminosucres multivalents représentent, en tant qu’inhibiteurs puissants de glycosidases, des structures privilégiées pour le développement de nouveaux agents thérapeutiques, nous nous sommes intéressés à ce type de composés pour le traitement de deux maladies génétiques rares. Le premier axe de recherche a consisté à synthétiser des iminosucres di- à tétravalents en série 1-désoxymannojirimycine dans le but d’inhiber l’α1,2-mannosidase I du réticulum endoplasmique qui est impliquée dans la destruction de la protéine delF508-CFTR chez les malades atteints de la mucoviscidose. Un effet multivalent fort sur la correction de cette protéine mutée a alors été mis en évidence avec un composé trivalent basé sur le pentaérythritol. Efficace à des concentrations submicromolaires, ce dernier s’est montré 140 fois plus efficace que le modèle monovalent correspondant. Le second axe de recherche a consisté à identifier de nouveaux chaperons pharmacologiques de la β-glucocérébrosidase, l’enzyme lysosomale impliquée dans la maladie de Gaucher. Pour cela, nous avons préparé une série d’iminosucres hétérodivalents conçus pour cibler simultanément le site actif et un site secondaire de cette enzyme. Même si cet objectif n’a pas encore été atteint, nous avons malgré tout mis en évidence des chaperons monovalents capables de quasiment quadrupler l’activité de la β-glucocérébrosidase portant la mutation G202R. En marge de ces deux axes principaux, une sonde mécanistique basée sur un C-glycoside multivalent a également été développée dans le but de préciser les mécanismes à l’origine des effets multivalents puissants observés pour l’inhibition des glycosidases.Because multivalent iminosugars represent, as potent glycosidase inhibitors, privileged structures for the design of novel drugs, we took a particular interest in this class of compounds for the treatment of two rare genetic diseases. The first research topic was dedicated to the synthesis of di- to tetravalent iminosugars in the 1-deoxymannojirimycin series in order to inhibit the endoplasmic reticulum α1,2-mannosidase I involved in the destruction of delF508-CFTR, the mutant protein responsible of cystic fibrosis. A strong multivalent effect for restoring its activity in cells was reported with a trivalent analogue based on pentaerythritol. This submicromolar corrector was found to be 140-fold more potent than the corresponding monovalent model. The second research topic focused on the identification of novel pharmacological chaperones of the β-glucocerebrosidase, the lysosomal enzyme involved in Gaucher’s disease. For this purpose, we developed a series of heterodivalent iminosugars designed to both bind to the active site and a secondary site of the enzyme. This goal could not be reached yet, nevertheless we identified monovalent chaperones which were able to fourfold increase β-glucocerebrosidase activity in G202R cell lines. Next to these main research topics, a mechanistic probe based on a multivalent C-glycoside was also developed to investigate the multivalent effect of iminosugar clusters in glycosidase inhibition

Design and synthesis of di- or tetravalent iminosugars as mechanistic probes and potential therapeutic agents

Dans un contexte où les iminosucres multivalents représentent, en tant qu’inhibiteurs puissants de glycosidases, des structures privilégiées pour le développement de nouveaux agents thérapeutiques, nous nous sommes intéressés à ce type de composés pour le traitement de deux maladies génétiques rares. Le premier axe de recherche a consisté à synthétiser des iminosucres di- à tétravalents en série 1-désoxymannojirimycine dans le but d’inhiber l’α1,2-mannosidase I du réticulum endoplasmique qui est impliquée dans la destruction de la protéine delF508-CFTR chez les malades atteints de la mucoviscidose. Un effet multivalent fort sur la correction de cette protéine mutée a alors été mis en évidence avec un composé trivalent basé sur le pentaérythritol. Efficace à des concentrations submicromolaires, ce dernier s’est montré 140 fois plus efficace que le modèle monovalent correspondant. Le second axe de recherche a consisté à identifier de nouveaux chaperons pharmacologiques de la β-glucocérébrosidase, l’enzyme lysosomale impliquée dans la maladie de Gaucher. Pour cela, nous avons préparé une série d’iminosucres hétérodivalents conçus pour cibler simultanément le site actif et un site secondaire de cette enzyme. Même si cet objectif n’a pas encore été atteint, nous avons malgré tout mis en évidence des chaperons monovalents capables de quasiment quadrupler l’activité de la β-glucocérébrosidase portant la mutation G202R. En marge de ces deux axes principaux, une sonde mécanistique basée sur un C-glycoside multivalent a également été développée dans le but de préciser les mécanismes à l’origine des effets multivalents puissants observés pour l’inhibition des glycosidases.Because multivalent iminosugars represent, as potent glycosidase inhibitors, privileged structures for the design of novel drugs, we took a particular interest in this class of compounds for the treatment of two rare genetic diseases. The first research topic was dedicated to the synthesis of di- to tetravalent iminosugars in the 1-deoxymannojirimycin series in order to inhibit the endoplasmic reticulum α1,2-mannosidase I involved in the destruction of delF508-CFTR, the mutant protein responsible of cystic fibrosis. A strong multivalent effect for restoring its activity in cells was reported with a trivalent analogue based on pentaerythritol. This submicromolar corrector was found to be 140-fold more potent than the corresponding monovalent model. The second research topic focused on the identification of novel pharmacological chaperones of the β-glucocerebrosidase, the lysosomal enzyme involved in Gaucher’s disease. For this purpose, we developed a series of heterodivalent iminosugars designed to both bind to the active site and a secondary site of the enzyme. This goal could not be reached yet, nevertheless we identified monovalent chaperones which were able to fourfold increase β-glucocerebrosidase activity in G202R cell lines. Next to these main research topics, a mechanistic probe based on a multivalent C-glycoside was also developed to investigate the multivalent effect of iminosugar clusters in glycosidase inhibition

Tight-binding inhibition of jack bean α-mannosidase by glycoimidazole clusters

The best multivalent effects observed in glycosidase inhibition have been achieved so far with jack bean α-mannosidase (JBα-man) using iminosugar clusters based on weakly binding mismatching active-site-directed inhibiting epitopes (inhitopes) in the d-gluco series. Here, we synthesize and evaluate as JBα-man inhibitors a series of mono- to 14-valent glycoimidazoles with inhitopes displaying inhibition values up to the range of hundreds of nMs to study the impact of inhitope affinity on the multivalent effect. The most potent inhibitor of the series, a 14-valent mannoimidazole derivative, inhibits JBα-man with a nanomolar Ki value (2 ± 0.5 nM) and binding enhancements observed are, at best, relatively small (up to 25-fold on a valency-corrected basis). The results of this study support the fact that JBα-man-inhitope affinity and the strength of the inhibitory multivalent effect evolve in the opposite direction. The major impact of the glycoimidazole-based inhitope is found on the binding scenario; most of the synthesized mannoimidazole clusters as well as a 14-valent glucoimidazole derivative prove to be tight binding inhibitors of JBα-man.</p

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

The synthesis and photophysical properties of the first examples of iminosugar clusters based on a BODIPY or a pyrene core are reported. The tri- and tetravalent systems designed as molecular probes and synthesized by way of Cu(I)-catalysed azide–alkyne cycloadditions are fluorescent analogues of potent pharmacological chaperones/correctors recently reported in the field of Gaucher disease and cystic fibrosis, two rare genetic diseases caused by protein misfolding

A convenient, gram-scale synthesis of 1-deoxymannojirimycin

A novel gram-scale synthesis of 1-deoxymannojirimycin from tetra-O-benzyl-d-glucopyranose in 9 steps and 28% overall yield with a limited number of purification steps is reported. The synthetic strategy is based on the regioselective deprotection and subsequent inversion of configuration of the OH group at C-2 in tetra-O-benzyl-d-glucono-δ-lactam, also an advanced intermediate toward the synthesis of 1-deoxynojirimycin derivatives.</p

Iminosugar-based ceramide mimicry for the design of new CERT START domain ligands

International audienc

Iminosugars as a new class of cholinesterase inhibitors.

International audienceTo further extend the scope of iminosugar biological activity, a systematic structure-activity relationship investigation has been performed by synthesizing and evaluating as cholinesterase inhibitors a library of twenty-three iminoalditols with different substitutions and stereochemistry patterns. These compounds have been evaluated in vitro for the inhibition of cholinesterases (different sources of acetylcholinesterase and butyrylcholinesterase). Some compounds have IC50 values in the micromolar range and display significant inhibition selectivity for butyrylcholinesterase over acetylcholinesterase. These are the first examples of iminosugar-based inhibitors of cholinesterases

Selective Targeting of the Interconversion between Glucosylceramide and Ceramide by Scaffold Tailoring of Iminosugar Inhibitors

A series of simple C-alkyl pyrrolidines already known as cytotoxic inhibitors of ceramide glucosylation in melanoma cells can be converted into their corresponding 6-membered analogues by means of a simple ring expansion. This study illustrated how an isomerisation from iminosugar pyrrolidine toward piperidine could invert their targeting from glucosylceramide (GlcCer) formation toward GlcCer hydrolysis. Thus, we found that the 5-membered ring derivatives did not inhibit the hydrolysis reaction of GlcCer catalysed by lysosomal &beta;-glucocerebrosidase (GBA). On the other hand, the ring-expanded C-alkyl piperidine isomers, non-cytotoxic and inactive regarding ceramide glucosylation, revealed to be potent inhibitors of GBA. A molecular docking study showed that the positions of the piperidine ring of the compound 6b and its analogous 2-O-heptyl DIX 8 were similar to that of isofagomine. Furthermore, compound 6b promoted mutant GBA enhancements over 3-fold equivalent to that of the related O-Hept DIX 8 belonging to one of the most potent iminosugar-based pharmacological chaperone series reported to date