Estelle Gallienne

Second-Generation Iminoxylitol-Based Pharmacological Chaperones for the Treatment of Gaucher Disease

A series of O‐alkyl iminoxylitol derivatives was synthesized and evaluated as β‐glucocerebrosidase (GCase) inhibitors. This structure–activity study shows a dramatic influence of the position of the alkyl chain (α‐C1, O2, O3, or O4) on human GCase inhibition. Remarkably, 1,2‐shift of the alkyl chain from C1 to O2 was found to maintain high inhibitory potency toward GCase as well as chaperone activity at sub‐inhibitory concentration (10 nM). Removal of the stereogenic center at the pseudo‐anomeric position led to shorter and more practical synthetic sequences. 2‐O‐Alkyl iminoxylitol derivatives constitute a new promising class of leads for the treatment of Gaucher disease by means of pharmacological chaperone therapy.

Synthesis of new β-1-C-alkylated imino-l-iditols: A comparative study of their activity as β-glucocerebrosidase inhibitors

A short synthesis of new beta-1-C-alkyl-1,5-dideoxy-1,5-imino-l-iditols by means of the diastereoselective addition of Grignard reagents onto a glucopyranosylamine is described. These compounds were evaluated as beta-glucocerebrosidase inhibitors and their activity was compared with that of related iminosugar derivatives in the d-gluco and d-xylo series. The results allowed us to conclude on the influence of the hydroxymethyl moiety and of the piperidine-ring conformation on the inhibitory activity.

Glucosylceramide Mimics: Highly Potent GCase Inhibitors and Selective Pharmacological Chaperones for Mutations Associated with Types 1 and 2 Gaucher Disease

A series of iminoxylitol derivatives carrying a C‐linked di‐O‐acyl or di‐O‐alkyl glyceryl substituent were prepared and characterized. All of these compounds, which were designed as glucosylceramide (GlcCer) mimics, were nanomolar inhibitors of lysosomal β‐glucosidase (glucocerebrosidase, GCase). Two of these pseudoglycolipids were further evaluated for their ability to enhance the activity of mutant GCase in human Gaucher cells. Although the di‐O‐hexyl ether was surprisingly devoid of chaperoning activity on both N370S and L444P GCases, the di‐O‐decanoyl ester was a potent chaperone of the L444P hydrolase, capable of increasing the residual activity of the enzyme by a factor of two at a very low concentration (50 nM); such a significant effect on the L444P mutation in human fibroblasts has not yet been observed. In heat‐stress studies, the diether was found to be much more effective in stabilizing the wild‐type enzyme than the diester. Four representative pseudoglycolipids were also assayed as inhibitors of GlcCer synthase, because such compounds could find use in the substrate reduction therapy approach to treat lysosomal storage diseases, but these compounds revealed only moderate activity. As efficient pharmacological chaperones, new structures such as the di‐C10‐ester constitute leads for the development of therapeutic agents for types 2 and 3 Gaucher disease, the most severe neuronopathic forms of this lysosomal disease.

Iminosugars as a new class of cholinesterase inhibitors

To 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.

Iminosugar-Based Galactoside Mimics as Inhibitors of Galactocerebrosidase: SAR Studies and Comparison with Other Lysosomal Galactosidases

Several families of iminosugar‐based galactoside mimics were designed, synthesized, and evaluated as galactocerebrosidase (GALC) inhibitors. They were also tested as inhibitors of lysosomal β‐ and α‐galactosidases in order to find new potent and selective pharmacological chaperones for treatment of the lysosomal storage disorder, Krabbe disease. Whereas 1‐C‐alkyl imino‐L‐arabinitols are totally inactive toward the three enzymes, 1‐C‐alkyl imino‐D‐galactitols were found to be active only toward α‐galactosidase A. Finally, 1‐N‐iminosugars provided the best results, as 4‐epi‐isofagomine was found to be a good inhibitor of both lysosomal β‐galactosidase and GALC. Further elaboration of this structure is required to achieve selectivity between these two galactosidases.

A Micromolar O-Sulfated Thiohydroximate Inhibitor Bound to Plant Myrosinase

The 1.6 A resolution structure of the micromolar competitive inhibitor S-(N,N-dimethylaminoethyl) phenylacetothiohydroximate-O-sulfate bound to Sinapis alba myrosinase, a plant thioglucosidase, is reported. Myrosinase and its substrates, the glucosinolates, are part of the plants defence system. The sulfate group and the phenyl group of the inhibitor bind to the aglycon-binding site of the enzyme, whereas the N,N-dimethyl group binds to the glucose-binding site and explains the large improvement in binding affinity compared with previous compounds. The structure suggests ways to increase the potency and specificity of the compound by improving the interactions with the hydrophobic pocket of the aglycon-binding site.

A reinvestigation of the synthesis and revision of spectral data of 1,2-O-isopropylidene-α-l-sorbofuranose, 1,2:4,6-di-O-isopropylidene-α-l-sorbofuranose and derivatives

Mono- and di-O-isopropylidene-l-sorbofuranose derivatives are important starting materials for the synthesis of modified sugars and useful chiral compounds. However, several inconsistencies in the spectral data of these compounds and erroneous structural assignments have been noted in the literature. The unambiguous synthesis of 1,2:4,6-di-O-isopropylidene-α-L-sorbofuranose and derivatives of 1,2- and 2,3-O-isopropylidene-α-L-sorbofuranoses has been achieved and definitive spectral data on these compounds are provided.

4-epi-Isofagomine derivatives as pharmacological chaperones for the treatment of lysosomal diseases linked to β-galactosidase mutations: Improved synthesis and biological investigations

(5aR)-5a-C-pentyl-4-epi-isofagomine 1 is a powerful inhibitor of lysosomal β-galactosidase and a remarkable chaperone for mutations associated with GM1-gangliosidosis and Morquio disease type B. We report herein an improved synthesis of this compound and analogs (5a-C-methyl, pentyl, nonyl and phenylethyl derivatives), and a crystal structure of a synthetic intermediate that confirms its configuration resulting from the addition of a Grignard reagent. These compounds were evaluated as glycosidase inhibitors and their potential as chaperones for mutant lysosomal galactosidases determined. Based on these results and on docking studies, the 5-C-pentyl derivative 1 was selected as the optimal structure for further investigations: this compound induces the maturation of mutated β-galactosidase in fibroblasts of a GM1-gangliosidosis patient and promote the decrease of keratan sulfate and oligosaccharide load in patient cells. Compound 1 is clearly capable of restoring β-galactosidase activity and of promoting maturation of the protein, which should result in significant clinical benefit. These properties strongly support the development of compound 1 for the treatment of GM1-gangliosidosis and Morquio disease type B patients harboring β-galactosidase mutations sensitive to pharmacological chaperoning.