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Iminosugars are sugar analogues endowed with a high pharmacological potential. The wide range of biological activities exhibited by these glycomimetics associated with their excellent drug profile make them attractive therapeutic candidates for several medical interventions. The ability of iminosugars to act as inhibitors or enhancers of carbohydrate-processing enzymes suggests their potential use as therapeutics for the treatment of cystic fibrosis (CF). Herein we review the most relevant advances in the field, paying attention to both the chemical synthesis of the iminosugars and their biological evaluations, resulting from in vitro and in vivo assays. Starting from the example of the marketed drug NBDNJ (N-butyl deoxynojirimycin), a variety of iminosugars have exhibited the capacity to rescue the trafficking of F508del-CFTR (deletion of F508 residue in the CF transmembrane conductance regulator), either alone or in combination with other correctors. Interesting results have also been obtained when iminosugars were considered as anti-inflammatory agents in CF lung disease. The data herein reported demonstrate that iminosugars hold considerable potential to be applied for both therapeutic purposes.

Ten pairs of pyrrolidine analogues of pochonicine and its stereoisomers have been synthesized from four enantiomeric pairs of polyhydroxylated cyclic nitrones. Among the ten N-acetylamino pyrrolidine analogues, only compounds with 2,5-dideoxy-2,5-imino-d-mannitol (DMDP) and pochonicine (1) configurations showed potent inhibition of β-N-acetylhexosaminidases (β-HexNAcases); while 1-amino analogues lost almost all their inhibitions towards the tested enzymes. The assay results reveal the importance of the N-acetylamino group and the possible right configurations of pyrrolidine ring required for this type of inhibitors.

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.

The synthesis of a series of six‐membered 2‐acetamido l‐iminosugar C‐alkyl and C‐aryl glycosides is reported. A diastereoselective sugar‐ring enlargement/C‐alkylation (or arylation) /ring‐contraction sequence applied to d‐gluco‐ and d‐manno‐configured 2‐acetamido azidolactols provides new l‐iminosugar C‐glycosides. The 1,2‐trans stereocontrolled introduction of the pseudoanomeric substituent in these heterocycles strongly suggests a NHAc neighbouring‐group participation. In their deprotected form, the nine iminosugars exhibit moderate hexosaminidases and β‐glucuronidase inhibition. A Staudinger/azawittig/Grignard/ring‐contraction sequence applied to two d‐glycopyranose derivatives bearing an acetamido group at the C‐2 position and an azido group at the C‐6 position allows access to unprecedented six‐membered l‐iminosugars C‐glycosides as GlcNAc and ManNAc mimics. The high 1,2‐trans diastereoselectivity observed for the Grignard addition strongly suggests an anchimeric assistance by the NHAc group. [ABSTRACT FROM AUTHOR]

The synthesis of the peracetylated ketonitrone 4 is described in four steps from l-sorbose. This cyclic nitrone is crystalline and proved to preferentially adopt a 4H3 conformation with all acetate groups in pseudo-axial orientation. Nitrone 4 undergoes regioselective cycloadditions with alkynes, affording tetra-O-acetyl-isoxazolines with good yields and stereoselectivities (4 : 1 to 9 : 1 diastereomeric ratio). Nitrone 4 and the obtained isoxazolines were smoothly deacetylated to produce the polyhydroxylated nitrone 5 and novel iminosugars containing an isoxazoline motif. Evaluation of their glycosidase inhibitory activity demonstrated their rather weak, but selective affinity for a variety of enzymes. [ABSTRACT FROM AUTHOR]

Abstract Despite the availability of prophylactic vaccines the burden of human papillomavirus (HPV) associated malignancy remains high and there is a need to develop additional therapeutic strategies to complement vaccination. We have previously shown that the poorly characterised E5 oncoprotein forms a virus-coded ion channel or viroporin that was sensitive to the amantadine derivative rimantadine. We now demonstrate that alkylated imino sugars, which have antiviral activity against a number of viruses, inhibit E5 channel activity in vitro. Using molecular modelling we predict that imino sugars intercalate between E5 protomers to prevent channel oligomerisation. We explored the ability of these viroporin inhibitors to block E5-mediated activation of mitogenic signalling in keratinocytes. Treatment with either rimantadine or imino sugars prevented ERK-MAPK phosphorylation and reduced cyclin B1 expression in cells expressing E5 from a number of high-risk HPV types. Moreover, viroporin inhibitors also reduced ERK-MAPK activation and cyclin B1 expression in differentiating primary human keratinocytes containing high-risk HPV18. These observations provide evidence of a key role for E5 viroporin function during the HPV life cycle. Viroporin inhibitors could be utilised for stratified treatment of HPV associated tumours prior to virus integration, or as true antiviral therapies to eliminate virus prior to malignant transformation. Highlights • Imino sugars inhibit the viroporin activity of the E5 oncoprotein. • Imino sugars likely interact at E5 protomer interfaces within a channel to prevent oligomerisation. • Imino sugars and adamantanes block mitogenic signalling mediated by E5 from a range of high-risk HPV types. • Viroporin inhibitors reduce mitogenic signalling in differentiating primary keratinocytes containing high-risk HPV18. [ABSTRACT FROM AUTHOR]

Described here is the asymmetric synthesis of iminosugar 2b , a Lipid II analog, designed to mimic the transition state of transglycosylation catalyzed by the bacterial transglycosylase. The high density of functional groups, together with a rich stereochemistry, represents an extraordinary challenge for chemical synthesis. The key 2,6-anti- stereochemistry of the iminosugar ring was established through an iridium-catalyzed asymmetric allylic amination. The developed synthetic route is suitable for the synthesis of focused libraries to enable the structure–activity relationship study and late-stage modification of iminosugar scaffold with variable lipid, peptide and sugar substituents. Compound 2b showed 70% inhibition of transglycosylase from Acinetobacter baumannii , providing a basis for further improvement. [ABSTRACT FROM AUTHOR]

Synthetic analogues of the naturally occurring iminosugar homoDMDP, which feature a perfluoroalkyl group at the pseudo-anomeric position, have been synthesized from the corresponding sugar-derived cyclic aldonitrone. The new fluorinated iminosugars as well as homoDMDP and its 6-deoxy counterpart were evaluated for their inhibitory activity against a panel of glycosidases. While the replacement of the (1′,2′)-dihydroxyethyl substituent of homoDMDP with –C 4 F 9 proved detrimental for enzyme binding, introduction of a –C 3 F 7 moiety tuned the inhibitory activity spectrum selectively towards α-fucosidase and α-glucosidase from yeast. [ABSTRACT FROM AUTHOR]

Abstract: Multivalent design of glycosidase inhibitors is a promising strategy for the treatment of diseases involving enzymatic hydrolysis of glycosidic bonds in carbohydrates. An essential prerequisite for successful applications is the atomic‐level understanding of how outstanding binding enhancement occurs with multivalent inhibitors. Herein we report the first high‐resolution crystal structures of the Jack bean α‐mannosidase (JBα‐man) in apo and inhibited states. The three‐dimensional structure of JBα‐man in complex with the multimeric cyclopeptoid‐based inhibitor displaying the largest binding enhancements reported so far provides decisive insight into the molecular mechanisms underlying multivalent effects in glycosidase inhibition. [ABSTRACT FROM AUTHOR]

A rapid, sensitive, and validated method was developed for the simultaneous determination of four iminosugars, 1-deoxynojirimycin (DNJ), d -fagomine (FAG), 2- O - a - d -galactopyranosyl-DNJ (Gal-DNJ), and 4- O-β - d -glucopyranosyl-fagomine (Glu-FAG), in mulberry leaves. The method used hydrophilic interaction chromatography coupled with tandem mass spectrometry. Based on this method, the seasonal variations of iminosugars in the leaves of different mulberry species ( Morus alba , Morus multicaulis Perr , Morus atropurpurea Roxb. and Morus wittiorum Hand-Mazz. ) collected in Guangzhou, China, during 10 consecutive months in 2013 were investigated. The results indicated that the maximum content of DNJ in the leaves of all four species occurred in summer (June or July). The highest FAG level was found in spring (April or May). The highest levels of Gal-DNJ and Glu-FAG were recorded in autumn (September or October). [ABSTRACT FROM AUTHOR]

The convenient preparation of iminopentitol derivatives, based on a 1,4-dideoxy-1,4-imino- l -arabinitol scaffold carrying β-phosphono(difluoromethyl) or β-phosphonomethyl appendages, as Gal f -1P mimics, is reported. The compounds were tested for their ability to inhibit GlfT2, a vital galactofuranosyltransferase involved in the cell wall biosynthesis of mycobacteria. Interestingly, the Gal f -1P mimics lacking a fluorine atom ( 7 and 8 ) were very poor inhibitors, showing less than 20% inhibition of GlfT2, whereas compounds 2 and 3 , which contains a difluoromethylenephosphonate moiety were more potent inhibitors. Compound 3 that is fully deprotected was the most potent showing a significant IC 50 value (0.9 m m ), despite the absence of the diphosphate linkage present in the parent sugar nucleotide. This study paves the way to the synthesis of more complex β-phosphonomethyl-imino- l -arabinitol derivatives as simplified mimics of UDP-α- d -Gal f . [ABSTRACT FROM AUTHOR]

The synthesis of three libraries ( 1a-l , 1a’-l’ and 2a-l ) of dimeric iminosugars through CuAAC reaction between three different alkynyl pyrrolidines and a set of diazides was carried out. The resulting crude dimers were screened in situ against two α-fucosidases (libraries 1a-l and 1a’-l’ ) and one β-galactosidase ( 2a-l ). This method is pioneer in the search of divalent glycosidase inhibitors. It has allowed the rapid identification of dimer 1i as the best inhibitor of α-fucosidases from bovine kidney ( K i  = 0.15 nM) and Homo sapiens ( K i  = 60 nM), and dimer 2e as the best inhibitor of β-galactosidase from bovine liver ( K i  = 5.8 μM). In order to evaluate a possible divalent effect in the inhibition, the synthesis and biological analysis of the reference monomers were also performed. Divalent effect was only detected in the inhibition of bovine liver β-galactosidase by dimer 2e . [ABSTRACT FROM AUTHOR]

In the recent decades, the interest on glycosidases has dramatically increased, mainly because these enzymes play a vital role in many biological processes. Based on the biological potential associated to these enzymes, several glycosidase inhibitors have been developed. In this review, the most important inhibitors targeting these enzymes, including the disaccharides, iminosugars, monocyclic iminosugars, bicyclic iminosugars, thiosugars and carbasugars will be discussed and special attention will be given to the ones that are currently used clinically. This review summarizes and characterizes the current knowledge regarding the classes of glycosidase inhibitors that have therapeutic potential in a wide range of diseases. It highlights the patents, relevant research and patent applications filed in the past years in the field. Since the glycosidase inhibitors are involved in several chronic diseases and possibly pandemic, the pharmaceutical research towards developing new generations of these molecules is very important to public health. Most of the glycosidase inhibitors mimics the structures of monosaccharides or oligosaccharides and are well accepted by the organisms since they benefit from privileged drug-like properties. Disaccharides, iminosugars, carbasugars and thiosugars derivatives are the most popular inhibitors among the glycosidase inhibitors. [ABSTRACT FROM AUTHOR]

Lucerastat is a glucosylceramide synthase inhibitor aimed at reducing production of glycosphingolipids (GSLs), including those accumulating in Fabry disease. The safety, tolerability, pharmacodynamics, and pharmacokinetics of oral lucerastat were evaluated in an exploratory study in patients with Fabry disease. In this single‐center, open‐label, randomized study, 10 patients received lucerastat 1,000 mg b.i.d. for 12 weeks in addition to enzyme replacement therapy (ERT; the lucerastat group). Four patients with Fabry disease received ERT only. Eight patients reported 17 adverse events (AEs) in the lucerastat group. No clinically relevant safety abnormalities were observed. The mean (SD) levels of the plasma GSLs, glucosylceramide, lactosylceramide, and globotriaosylceramide, were significantly decreased from baseline in the lucerastat group (‐49.0% (16.5%), ‐32.7% (13.0%), and ‐55.0% (10.4%), respectively). Lucerastat 1,000 mg b.i.d. was well tolerated in patients with Fabry disease over 12 weeks. A marked decrease in plasma GSLs was observed, suggesting clinical potential for lucerastat in patients with Fabry disease. [ABSTRACT FROM AUTHOR]

The fluorinated piperidine iminosugars 2a-4a and their N -octyl and N -decyl derivatives 2b,c-4b,c were synthesized from d -mannose/ d -xylose using nucleophilic fluorination as the key step. The conformation of iminosugars 2 / 3 , either 2 C 5 or 5 C 2 , was assigned based on the 1 H NMR studies at different pH. Immunomodulatory activity of 2a,c-4a,c was examined using Mixed Lymphocyte Reaction (MLR) and B-cell assay. The N -alkylated fluorinated d - manno -iminosugars 3b/4b were found to be better immunosuppressive agents (IC 50  = 5–6  μ M) on T-cells. The fluorinated iminosugar 3a/4a act as potent and selective inhibitors of β -glucosidase (IC 50  = 4–8  μ M). The N -alkyl-iminosugars 4b-c were found to be moderate inhibitors of α -glucosidase (yeast) and α -galactosidase (coffee beans), respectively. [ABSTRACT FROM AUTHOR]

Abstract: The multivalent effect in glycosidase inhibition is a new topic in glycoscience that has emerged a few years ago, with the discovery of neoglycoclusters displaying strong binding enhancements over the corresponding monovalent inhibitor. Iminosugar–fullerene conjugates with high valencies have been prepared from iminosugar‐terminated dendrons and a clickable fullerene hexa‐adduct scaffold. The simultaneous grafting of twelve dendrons allows for a very fast dendritic growth thus limiting the number of synthetic steps required to prepare compounds with a high number of peripheral units. The grafting of first‐ and second‐generation dendrons provided fullerodendrimers surrounded by 36 and 108 peripheral iminosugars, respectively. Inhibition studies have been carried out with a panel of glycosidases. In the particular case of Jack bean α‐mannosidase, the 108‐valent nanoconstruct displays inhibition in the nanomolar range and an additional binding enhancement of one order of magnitude when compared to the 36‐valent analogues. [ABSTRACT FROM AUTHOR]

This work aims to synthesize new trehalase inhibitors selective towards the insect trehalase versus the porcine trehalase, in view of their application as potentially non-toxic insecticides and fungicides. The synthesis of a new pseudodisaccharide mimetic 8, by means of a stereoselective α-glucosylation of the key pyrrolizidine intermediate 13, was accomplished. The activity of compound 8 as trehalase inhibitor towards C. riparius trehalase was evaluated and the results showed that 8 was active in the μM range and showed a good selectivity towards the insect trehalase. To reduce the overall number of synthetic steps, simpler and more flexible disaccharide mimetics 9–11 bearing a pyrrolidine nucleus instead of the pyrrolizidine core were synthesized. The biological data showed the key role of the linker chain’s length in inducing inhibitory properties, since only compounds 9 (α,β-mixture), bearing a two-carbon atom linker chain, maintained activity as trehalase inhibitors. A proper change in the glucosyl donor-protecting groups allowed the stereoselective synthesis of the β-glucoside 9β, which was active in the low micromolar range (IC50 = 0.78 μM) and 12-fold more potent (and more selective) than 9α towards the insect trehalase. [ABSTRACT FROM AUTHOR]

Novel pentacyclic iminosugars 1 and 2 with the constrained butterfly-like conformation were first synthesized by the key intramolecular click reaction from the tricyclic iminosugars fused benzo[ e ][1,3]thiazin-4-one 3 and 4 . The pentacyclic iminosugar was constructed by fusing both benzo[ e ][1,3]thiazin-4-one and triazolo[5,1- c ][1,4]oxazepine scaffolds. Their structures were determined by their 1 H, 13 C NMR, and HRMS (ESI) spectra and X-ray. The pentacyclic iminosugars 1 ( a – c ), 2 ( a – b ) and their corresponding protected precursors 13 ( a – c ) and 14 ( a – b ) were examined for their HIV reverse transcriptase (RT) inhibitory activities. The result showed that all compounds could effectively inhibit RT activity. Among them, compound 13c was the best one with the IC 50 value of RT inhibitory activity of 0.69 μM. Structure-activity relationship analysis suggested that the improvement of the hydrophilicity of the pentacycles was of benefit to their anti-HIV RT activity. [ABSTRACT FROM AUTHOR]

Neuroinflammation is an early event during diabetic retinopathy (DR) that impacts the dynamics of microglia polarization. Gliosis is a hallmark of DR and we have reported the beneficial effects of 1R-DSO-ONJ, a member of the sp 2 -iminosugar glycolipid (sp 2 -IGL) family, in targeting microglia and reducing gliosis in diabetic db/db mice. Herein, we analyzed the effect of DSO 2 -ONJ, another family compound incorporating a sulfone group that better mimics the phosphate group of phosphatidylinositol ether lipid analogues (PIAs), in Bv.2 microglial cells treated with bacterial lipopolysaccaride (LPS) and in retinal explants from db/db mice. In addition to decreasing iNOS and inflammasome activation, the anti-inflammatory effect of DSO 2 -ONJ was mediated by direct p38α MAPK activation. Computational docking experiments demonstrated that DSO 2 -ONJ binds to p38α MAPK at the same site where PIAs and the alkyl phospholipid perifosine activators do, suggesting similar mechanism of action. Moreover, treatment of microglial cells with DSO 2 -ONJ increased both heme-oxygenase (HO)-1 and Il10 expression regardless the presence of LPS. In retinal explants from db/db mice, DSO 2 -ONJ also induced HO-1 and reduced gliosis. Since IL-10-mediated induction of HO-1 expression is mediated by p38α MAPK activation, our results suggest that this molecular mechanism is involved in the anti-inflammatory effects of DSO 2 -ONJ in microglia. [ABSTRACT FROM AUTHOR]

A stereoselective synthesis of 2-acetamido-1,2-dideoxyaltronojirimycin (8) and its manno epimer 9 is described. The synthetic approach is based on key bicyclic carbamate 7, which is easily accessible with high enantiomeric purity on a multigram scale by Sharpless asymmetric epoxidation of 1,4-pentadien-3-ol or 2,4-pentadien-1-ol. This procedure completes an efficient stereodivergent approach to five isomers of 2-acetamido-1,2-dideoxyiminosugars in high overall yields starting from the same key intermediate 7. The approach described in this paper is based on control of the stereoselectivity of the sulfite ring-opening reaction to give retention of configuration through anchimeric assistance from the endocyclic amine. [ABSTRACT FROM AUTHOR]

An efficient and practical strategy for the synthesis of unknown azetidine iminosugars (2 S ,3 R ,4 S )-2-(( R )-1,2-dihydroxyethyl)-3-hydroxy-4-(hydroxymethyl)azetidine 2 , (2 S ,3 r ,4 R )-3-hydroxy-2,4-bis(hydroxymethyl)azetidine 3 and (2 S ,3 R ,4 S )-3-hydroxy-4-(hydroxymethyl)- N -methylazetidine-2-carboxylic acid 4 , starting from the d -glucose has been reported. The methodology involves preparation of the 3-amino- N -benzyloxycarbonyl-3-deoxy-6- O - tert -butyldimethylsillyl-1,2- O -isopropylidene- α - d -glucofuranose 9 , which was converted to the C-5- OMs derivative 11 . Intramolecular nucleophilic displacement of the C-5- OMs group with in situ generated 3-amino functionality provided the required key azetidine ring skeletons 10 with additional hydroxymethyl group. Removal of 1,2-acetonide protection, followed by reduction and hydrogenolysis afforded azetidine iminosugar 2 . Alternatively, removal of 1,2-acetonide group and chopping of C1-anomeric carbon gave C2-aldehyde that on reduction or oxidation followed by hydrogenolysis gave 2,4-bis(hydroxymethyl) azetidine iminosugars 3 and N -methylazetidine-2-carboxylic acid 4 respectively. The glycosidase inhibitory activity of 2 – 4 iminosugars was screened against various glycosidase enzymes and compared with a standard miglitol. Amongst synthesized targets, the compound 2 was found to be more potent amyloglucosidase inhibitor than miglitol. These results were supported by molecular docking studies. [ABSTRACT FROM AUTHOR]

A novel three-component strategy has been developed for the synthesis of iminosugars in good to excellent yields. This is the first report on the Mannich type addition of cyclic 1,3-diketones to aza-acetal derived from hydroxy-γ-lactone and arylamine to produce a novel series of aza-sugars with high selectivity. [Display omitted] • Three component one-pot synthesis of aza-sugars. • First report on Mannich reaction of sugar hydroxy-γ-lactone. • Nucleophilic addition of 1,3-diketones to N -acyliminium Ions. • Use of readily available and low cost base. • High selectivity. [ABSTRACT FROM AUTHOR]

Cyclic N-propargyl α-peptoids of various sizes were prepared by way of macrocyclizations of linear N-substituted oligoglycines. These compounds were used as molecular platforms to synthesize a series of iminosugar clusters with different valency and alkyl spacer lengths by means of Cu(I)-catalysed azide–alkyne cycloadditions. Evaluation of these compounds as α-mannosidase inhibitors led to significant multivalent effects and further demonstrated the decisive influence of scaffold rigidity on binding affinity enhancements.

N-substituted iminosugar analogues are potent inhibitors of glucosidases and glycosyltransferases with broad therapeutic applications, such as treatment of diabetes and Gaucher disease, immunosuppressive activities, and antibacterial and antiviral effects against HIV, HPV, hepatitis C, bovine diarrhea (BVDV), Ebola (EBOV) and Marburg viruses (MARV), influenza, Zika, and dengue virus. Based on our previous work on functionalized isomeric 1,5-dideoxy-1,5-imino-D-gulitol (L-gulo-piperidines, with inverted configuration at C-2 and C-5 in respect to glucose or deoxynojirimycin (DNJ)) and 1,6-dideoxy-1,6-imino-D-mannitol (D-manno-azepane derivatives) cores N-linked to different sites of glucopyranose units, we continue our studies on these alternative iminosugars bearing simple N-alkyl chains instead of glucose to understand if these easily accessed scaffolds could preserve the inhibition profile of the corresponding glucose-based N-alkyl derivatives as DNJ cores found in miglustat and miglitol drugs. Thus, a small library of iminosugars (14 compounds) displaying different stereochemistry, ring size, and N-substitutions was successfully synthesized from a common precursor, D-mannitol, by utilizing an SN2 aminocyclization reaction via two isomeric bis-epoxides. The evaluation of the prospective inhibitors on glucosidases revealed that merely D-gluco-piperidine (miglitol, 41a) and L-ido-azepane (41b) DNJ-derivatives bearing the N-hydroxylethyl group showed inhibition towards α-glucosidase with IC50 41 µM and 138 µM, respectively, using DNJ as reference (IC50 134 µM). On the other hand, β-glucosidase inhibition was achieved for glucose-inverted configuration (C-2 and C-5) derivatives, as novel L-gulo-piperidine (27a) and D-manno-azepane (27b), preserving the N-butyl chain, with IC50 109 and 184 µM, respectively, comparable to miglustat with the same N-butyl substituent (40a, IC50 172 µM). Interestingly, the seven-membered ring L-ido-azepane (40b) displayed near twice the activity (IC50 80 µM) of the corresponding D-gluco-piperidine miglustat drug (40a). Furthermore, besides α-glucosidase inhibition, both miglitol (41a) and L-ido-azepane (41b) proved to be the strongest β-glucosidase inhibitors of the series with IC50 of 4 µM.

Here, the synthesis and glycosidase inhibition properties of the two first known 3-ethyloctahydro-1H-indole-4,5,6-triols are reported. This study shows the transformation of d-glucose into polyhydroxylated 1-(2-nitrocyclohexane) acetaldehydes, followed by a protocol involving the formation of the azacyclopentane ring. Results of inhibitory potency assays and docking calculations show that at least one of them could be a lead for optimization in the search for compounds that behave like folding chaperones in lysosomal storage diseases.

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 β-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.

Reagent stereocontrol in the proline-catalyzed aldol reaction of 2,2-dimethyl-1,3-dioxane-5-one 1 with chiral aldehydes has been investigated. Synthetically useful levels of diastereoselectivity could be achieved in reactions with acyclic chiral α-oxy and α-amino aldehydes in both matched and mismatched cases. By using this reaction as a key step, two medicinally relevant azasugars, 1-deoxy-galactonojirimycin (9) and 2,5-dideoxy-2,5-imino-D-altritol (10), were efficiently synthesized. [ABSTRACT FROM AUTHOR]

The convenient preparation of 1,4-dideoxy-1,4- imino-L-arabinitol derivatives bearing a propargyl group through the addition of a trimethylsilylpropargyl Grignard reagent to an N-sulfinylglycosylamine is reported. One of these compounds was coupled by a triazole tether to various aromatic and heteroaromatic groups to give structures that can be considered to be simplified mimics of UDP-Galf, the substrate of GlfT2, a galactofuranosyltransferase present in mycobacteria. The new compounds were evaluated as inhibitors of this enzyme and were found to have significant activity (IC50 values in the high µM to low mM range), despite the absence of the diphospho linkage present in the parent sugar nucleotide. [ABSTRACT FROM AUTHOR]

Niemann-Pick disease type C (NPC) is a rare, progressive autosomal recessive disease. It is caused by mutations in either the NPC1 or NPC2 genes, resulting in defective regulation of intracellular lipid trafficking. Miglustat, which reversibly inhibits glucosylceramide synthase, reportedly has beneficial effects on the progressive neurological symptoms of NPC and was approved in Japan in 2012. Some reports suggested that miglustat therapy delayed the onset or progression of NPC when treatment was initiated before the onset of neurological manifestation or at an early stage. We report here a patient with the early-infantile form of NPC who started on miglustat at 4 months of ages. To our knowledge, this patient is the youngest reported patient with NPC in which miglustat therapy was initiated. Our patient, who had hypotonia and developmental delay before treatment, remained stable and showed no new neurological symptoms. In addition, pulmonary involvement was improved during miglustat therapy. Our case and previous reports underscore the importance of early initiation of miglustat therapy for NPC. [ABSTRACT FROM AUTHOR]

We described herein a total synthesis of 1,4-dideoxy-1,4-imino-L-arabinitol [(2S,3S,4S)-2-(hydroxymethyl)pyrrolidine-3,4-diol, LAB-1], a polyhydroxylated pyrrolidine, which has been demonstrated to be a selective and potent a-glycosidase inhibitor. The main features of our approach are its shortness, efficiency, and simplicity. The total synthesis was accomplished in 6 steps with an overall yield of 12%, starting from a chiral optically active Morita-Baylis-Hillman (MBH) adduct prepared (without epimerization), from Garner's aldehyde. As far as we know, this is the first report describing the total synthesis of this biologically active pyrrolidine by exploring the synthetic versatility of a MBH adduct. [ABSTRACT FROM AUTHOR]

Novel pyrrolidine-based multivalent iminosugars, synthesized by a CuAAC approach, have shown remarkable multivalent effects towards jack bean α-mannosidase and a Golgi α-mannosidase from Drosophila melanogaster, as well as a good selectivity with respect to a lysosomal α-mannosidase, which is important for anticancer applications. STD NMR and molecular modeling studies supported a multivalent mechanism with specific interactions of the bioactive iminosugars with Jack bean α-mannosidase. TEM studies suggested a binding mode that involves the formation of aggregates, which result from the intermolecular cross-linked network of interactions between the multivalent inhibitors and two or more dimers of JBMan heterodimeric subunits. [ABSTRACT FROM AUTHOR]

Iminosugars are good starting points for the development of different kinds of drugs. Many are polyhydroxylated piperidines that behave as biomimetics of their corresponding pyranoses analogues. In the interaction with carbohydrate processing enzymes, selectivity is a crucial issue and the benefits of introducing a cyclopropane bridge in a piperidine structure is demonstrated. The synthesis of novel bicyclic piperidine-based iminosugars using a sulfur ylide cyclopropanation as the key synthetic step is described. [ABSTRACT FROM AUTHOR]

N-Alkyl pipecolamides were efficiently synthesized from D-glucurono-6,3-lactone via a key 5-azido N-alkylamide intermediate that can be used as a scaffold for the synthesis of 4-amino and N-sulfonated pipecolamide derivatives. [ABSTRACT FROM AUTHOR]

A straightforward synthesis of N-alkylated 1-deoxynojirimycin derivatives modified at the 6-O-position has been described. The key intermediate in the synthesis of target compounds was 2,3,4-tri-O-benzyl-1,5-dideoxy-1,5-imino-D-glucitol, which was prepared from 2,3,4,6-tetra-O-benzyl-1,5-dideoxy-1,5-imino-D-glucitol. Optimal conditions have been established for the synthesis of the key intermediate by varying reaction parameters. Reductive amination and subsequent alkylation of the 6-O-position followed by hydrogenolysis were the main reaction steps, which gave target compounds 6-O-ethyl-N-octyl-1,5-dideoxy-1,5-imino-D-glucitol and 6-O-butyl-N-octyl-1,5-dideoxy-1,5-imino-D-glucitol. This synthetic route is flexible and can be useful for the synthesis of other lipophilic iminosugar derivatives. [ABSTRACT FROM AUTHOR]

A simple strategy for the synthesis of α -geminal disubstituted pyrrolidine iminosugars 3a - c and their C -4 fluorinated derivatives 4a - c has been described from d -glucose. The methodology involves the Corey-Link and Jocic-Reeve reaction with 3-oxo- α - d -glucofuranose and nucleophilic displacement reaction to get the furanose fused pyrrolidine ring skeleton with requisite CH 2 OH/CO 2 H functionalities at C -3. The fluorine substituent in target molecules was introduced by nucleophilic displacement of - O Tf in 9a / 9c with CsF. Appropriate manipulation of the anomeric carbon in the furanose fused pyrrolidine ring skeleton afforded α -geminal disubstituted pyrrolidine iminosugars 3a – c and C -4 fluoro derivatives 4a – c . The pyrrolidine iminosugars 3a and 3c were found to be potent inhibitors of α -galactosidase while, the fluoro derivatives 4a and 4b showed strong inhibition of β -glucosidase and β -galactosidase, respectively. These results were substantiated by in silico molecular docking studies. [ABSTRACT FROM AUTHOR]

The preliminary screening of two libraries of epimeric (pyrrolidin-2-yl)triazoles ( 14a-s and 22a-s ), generated via click chemistry, allowed the rapid identification of four α-galactosidase (coffee beans) inhibitors ( 22b , k , p , r ) and two β-glucosidase (almond) inhibitors ( 14b , f ) in the low μM range. The additional biological analysis of 14b , f towards β-glucocerebrosidase (human lysosomal β-glucosidase), as target enzyme for Gaucher disease, showed a good correlation with the inhibition results obtained for the plant (almond) enzyme. Surprisingly, although these compounds showed inhibition towards β-glucocerebrosidase as acid hydrolase, they did not inhibit bovine liver β-glucosidase as neutral hydrolase. In contrast to what was observed for β-glucosidase inhibition, the coffee bean α-galactosidase inhibitors of the epimeric library ( 22b,k,p,r ) only showed weak inhibition towards human lysosomal α-galactosidase. [ABSTRACT FROM AUTHOR]

Rare C-7-substituted aziridinyl iminosugars can be synthesized through a short reaction sequence involving 1,3-cycloaddition of cyclic nitrones with alkynes and a Baldwin rearrangement of isoxazolines into bicyclic 2-acylaziridines. The method is efficient and completely diastereoselective, producing stable aziridinyl iminosugars in high yields. [ABSTRACT FROM AUTHOR]

Abstract: A combination of the Vasella‐reductive‐amination and carbamate annulation reactions was applied on a ketose starting material for the diastereoselective total synthesis of 2,5‐dideoxy‐2,5‐imino‐glycitols. The synthesis of 2,5‐dideoxy‐2,5‐imino‐ l‐iditol (4) was particularly expedient (6 steps and 18% overall yield) as the route minimises the use of protecting groups, thereby reducing the number of synthetic steps and increasing the overall yield. The Vasella reductive amination methodology could be readily applied to the amination of ketones, albeit with moderate diastereoselectivity. However, the I2‐mediated carbamate annulation strongly favours the formation of pyrrolidines with the 2,5‐trans and 4,5‐cis relationships. The highly diastereoselective carbamate annulation thus provided a general means by which to synthesise 2,5‐dideoxy‐2,5‐imino‐glycitols of defined stereochemistry. [ABSTRACT FROM AUTHOR]

The antiprotozoal effect of saponins is transitory, as when saponins are deglycosylated to sapogenins by rumen microorganisms they become inactive. We hypothesised that the combination of saponins with glycosidase-inhibiting iminosugars might potentially increase the effectiveness of saponins over time by preventing their deglycosylation in the rumen. Alternatively, modifying the structure of the saponins by substituting the sugar moiety with other small polar residues might maintain their activity as the sugar substitute would not be enzymatically cleaved. The aim of this in vitro study was to evaluate the acute antiprotozoal effect and the stability of this effect over a 24 h incubation period using ivy saponins, a stevia extract rich in iminosugars, ivy saponins with stevia extract, and a chemically modified ivy saponin, hederagenin bis-succinate (HBS). The effects on fermentation parameters and rumen bacterial communities were also studied. Ivy saponins with stevia and HBS had a greater antiprotozoal effect than ivy saponins, and this effect was maintained after 24 h of incubation (P<0.001). The combination of ivy and stevia extracts was more effective in shifting the fermentation pattern towards higher propionate (+39%) and lower butyrate (-32%) and lower ammonia concentration (-64%) than the extracts incubated separately. HBS caused a decrease in butyrate (-45%) and an increase in propionate (+43%) molar proportions. However, the decrease in ammonia concentration (-42%) observed in the presence of HBS was less than that caused by ivy saponins, either alone or with stevia. Whereas HBS and stevia impacted on bacterial population in terms of community structure, only HBS had an effect in terms of biodiversity (P<0.05). It was concluded that ivy saponins with stevia and the modified saponin HBS had a strong antiprotozoal effect, although they differed in their effects on fermentation parameters and bacteria communities. Ivy saponins combined with an iminosugar-rich stevia extract and/or HBS should be evaluated to determine their antiprotozoal effect in vivo. [ABSTRACT FROM AUTHOR]