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Multivalency represents an appealing option to modulate selectivity in enzyme inhibition and transform moderate glycosidase inhibitors into highly potent ones. The rational design of multivalent inhibitors is however challenging because global affinity enhancement relies on several interconnected local mechanistic events, whose relative impact is unknown. So far, the largest multivalent effects ever reported for a non‐polymeric glycosidase inhibitor have been obtained with cyclopeptoid‐based inhibitors of Jack bean α‐mannosidase (JBα‐man). Here, we report a structure‐activity relationship (SAR) study based on the top‐down deconstruction of best‐in‐class multivalent inhibitors. This approach provides a valuable tool to understand the complex interdependent mechanisms underpinning the inhibitory multivalent effect. Combining SAR experiments, binding stoichiometry assessments, thermodynamic modelling and atomistic simulations allowed us to establish the significant contribution of statistical rebinding mechanisms and the importance of several key parameters, including inhitope accessibility, topological restrictions, and electrostatic interactions. Our findings indicate that strong chelate‐binding, resulting from the formation of a cross‐linked complex between a multivalent inhibitor and two dimeric JBα‐man molecules, is not a sufficient condition to reach high levels of affinity enhancements. The deconstruction approach thus offers unique opportunities to better understand multivalent binding and provides important guidelines for the design of potent and selective multiheaded inhibitors. [ABSTRACT FROM AUTHOR]

Inhibition of glycoside hydrolases has widespread application in the treatment of diabetes. Based on our previous findings, a series of dihydrofuro[3,2-b]piperidine derivatives was designed and synthesized from D- and L-arabinose. Compounds 32 (IC50 = 0.07 μM) and 28 (IC50 = 0.5 μM) showed significantly stronger inhibitory potency against α-glucosidase than positive control acarbose. The study of the structure–activity relationship of these compounds provides a new clue for the development of new α-glucosidase inhibitors. [ABSTRACT FROM AUTHOR]

A synthesis of 1,4-imino-ᴅ-lyxitols and their N-arylalkyl derivatives altered at C-5 is reported. Their inhibitory activity and selectivity toward four GH38 α-mannosidases (two Golgi types: GMIIb from Drosophila melanogaster and AMAN-2 from Caenorhabditis elegans, and two lysosomal types: LManII from Drosophila melanogaster and JBMan from Canavalia ensiformis) were investigated. 6-Deoxy-DIM was found to be the most potent inhibitor of AMAN-2 (Ki = 0.19 μM), whose amino acid sequence and 3D structure of the active site are almost identical to the human α-mannosidase II (GMII). Although 6-deoxy-DIM was 3.5 times more potent toward AMAN-2 than DIM, their selectivity profiles were almost the same. N-Arylalkylation of 6-deoxy-DIM resulted only in a partial improvement as the selectivity was enhanced at the expense of potency. Structural and physicochemical properties of the corresponding inhibitor:enzyme complexes were analyzed by molecular modeling.

The late-onset form of Tay-Sachs disease displays when the activity levels of human β-hexosaminidase A (HexA) fall below 10% of normal, due to mutations that destabilise the native folded form of the enzyme and impair its trafficking to the lysosome. Competitive inhibitors of HexA can rescue disease-causative mutant HexA, bearing potential as pharmacological chaperones, but often also inhibit the enzyme O-glucosaminidase (GlcNAcase; OGA), a serious drawback for translation into the clinic. We have designed sp2-iminosugar glycomimetics related to GalNAc that feature a neutral piperidine-derived thiourea or a basic piperidine-thiazolidine bicyclic core and behave as selective nanomolar competitive inhibitors of human Hex A at pH 7 with a ten-fold lower inhibitory potency at pH 5, a good indication for pharmacological chaperoning. They increased the levels of lysosomal HexA activity in Tay-Sachs patient fibroblasts having the G269S mutation, the highest prevalent in late-onset Tay-Sachs disease.

Inhibition of glycoside hydrolases has widespread application in the treatment of diabetes. Based on our previous findings, a series of dihydrofuro[3,2-b]piperidine derivatives was designed and synthesized from D- and L-arabinose. Compounds 32 (IC50 = 0.07 μM) and 28 (IC50 = 0.5 μM) showed significantly stronger inhibitory potency against α-glucosidase than positive control acarbose. The study of the structure–activity relationship of these compounds provides a new clue for the development of new α-glucosidase inhibitors.

Substrate side chain conformation impacts reactivity during glycosylation and glycoside hydrolysis and is restricted by many glycosidases and glycosyltransferases during catalysis. We show that the side chains of gluco and manno iminosugars can be restricted to predominant conformations by strategic installation of a methyl group. Glycosidase inhibition studies reveal that iminosugars with the gauche,gauche side chain conformations are 6‐ to 10‐fold more potent than isosteric compounds with the gauche,trans conformation; a manno‐configured iminosugar with the gauche,gauche conformation is a 27‐fold better inhibitor than 1‐deoxymannojirimycin. The results are discussed in terms of the energetic benefits of preorganization, particularly when in synergy with favorable hydrophobic interactions. The demonstration that inhibitor side chain preorganization can favorably impact glycosidase inhibition paves the way for improved inhibitor design through conformational preorganization. [ABSTRACT FROM AUTHOR]

While most glycosidases that act on N‐linked glycans remove a single sugar residue at a time, endo‐α‐1,2‐mannosidases and endo‐α‐1,2‐mannanases of glycoside hydrolase family GH99 cut within a chain and remove two or more sugar residues. They are stereochemically retaining enzymes that use an enzymatic mechanism involving an epoxide intermediate. Human endo‐α‐1,2‐mannosidase (MANEA) trims glucosylated mannose residues; the endomannosidase pathway provides a glucosidase‐independent pathway for glycoprotein maturation. Cell‐active MANEA inhibitors alter N‐glycan processing and reduce infectivity of dengue virus, demonstrating that MANEA has potential as a host‐directed antiviral target. Sequence‐related enzymes from gut Bacteroides spp. exhibit endo‐α‐1,2‐mannosidase activity and are a fruitful test bed for structure‐guided inhibitor development. The genes encoding the Bacteroides spp. enzymes sit within polysaccharide utilization loci and are preferential endo‐α‐1,2‐mannanases. [ABSTRACT FROM AUTHOR]

Herein, we report a practical method for de novo preparation of imino‐d‐ribitol and C‐azanucleosides. The diastereopure Imino‐d‐ribitol was synthesized on a multigram scale by simple manipulation, and late‐stage anomeric derivatization by regio‐ and diastereoselective electrochemical C(sp3)−H activation enabled the efficient synthesis of the corresponding C‐azanucleosides with high β‐selectivity. [ABSTRACT FROM AUTHOR]

The late-onset form of Tay-Sachs disease displays when the activity levels of human β-hexosaminidase A (HexA) fall below 10% of normal, due to mutations that destabilise the native folded form of the enzyme and impair its trafficking to the lysosome. Competitive inhibitors of HexA can rescue disease-causative mutant HexA, bearing potential as pharmacological chaperones, but often also inhibit the enzyme O-glucosaminidase (GlcNAcase; OGA), a serious drawback for translation into the clinic. We have designed sp²-iminosugar glycomimetics related to GalNAc that feature a neutral piperidine-derived thiourea or a basic piperidine-thiazolidine bicyclic core and behave as selective nanomolar competitive inhibitors of human Hex A at pH 7 with a ten-fold lower inhibitory potency at pH 5, a good indication for pharmacological chaperoning. They increased the levels of lysosomal HexA activity in Tay-Sachs patient fibroblasts having the G269S mutation, the highest prevalent in late-onset Tay-Sachs disease. [ABSTRACT FROM AUTHOR]

The goal of this work is to explore if the changes induced by d-fagomine in the gut microbiota are compatible with its effect on body weight and inflammation markers in rats. Methods: Sprague Dawley rats were fed a standard diet supplemented with d-fagomine (or not, for comparison) for 6 months. The variables measured were body weight, plasma mediators of inflammation (hydroxyeicosatetraenoic acids, leukotriene B4, and IL-6), and the concentration of acetic acid in feces and plasma. The composition and diversities of microbiota in cecal content and feces were estimated using 16S rRNA metabarcoding and high-throughput sequencing. We found that after just 6 weeks of intake d-fagomine significantly reduced body weight gain, increased the plasma acetate concentration, and reduced the plasma concentration of the pro-inflammatory biomarkers' leukotriene B4, interleukin 6 and 12 hydroxyeicosatetraenoic acids. These changes were associated with a significantly increased prevalence of Bacteroides and Prevotella feces and increased Bacteroides, Prevotella, Clostridium, and Dysgonomonas while reducing Anaerofilum, Blautia, and Oribacterium in cecal content. In conclusion, d-fagomine induced changes in the composition and diversity of gut microbiota similar to those elicited by dietary fiber and compatible with its anti-inflammatory and body-weight-reducing effects. [ABSTRACT FROM AUTHOR]

Recently, the strategy of multivalency has been widely employed to design glycosidase inhibitors, as glycomimetic clusters often induce marked enzyme inhibition relative to monovalent analogs. Polyhydroxylated pyrrolidines, one of the most studied classes of iminosugars, are an attractive moiety due to their potent and specific inhibition of glycosidases and glycosyltransferases, which are associated with many crucial biological processes. The development of multivalent pyrrolidine derivatives as glycosidase inhibitors has resulted in several promising compounds that stand out. Herein, we comprehensively summarized the different synthetic approaches to the preparation of multivalent pyrrolidine clusters, from total synthesis of divalent iminosugars to complex architectures bearing twelve pyrrolidine motifs. Enzyme inhibitory properties and multivalent effects of these synthesized iminosugars were further discussed, especially for some less studied therapeutically relevant enzymes. We envision that this comprehensive review will help extend the applications of multivalent pyrrolidine iminosugars in future studies. [ABSTRACT FROM AUTHOR]

Six C-6 fluorinated d -swainsonine derivatives and their enantiomers have been designed based on initial docking calculations, and synthesized from enantiomeric ribose-derived aldehydes, respectively. Glycosidase inhibition assay of these derivatives with d -swainsonine (1) and l -swainsonine ( ent -1) as contrasts found that the C-6 fluorinated d -swainsonine derivatives with C-8 configurations as R (α) showed specific and potent inhibitions of jack bean α-mannosidase (model enzyme of Golgi α-mannosidase II); whereas their enantiomers with C-8 configurations as S (β) were powerful and selective α- l -rhamnosidase inhibitors. Molecular docking calculations found the C-6 fluorinated d -swainsonine derivatives 21 , 24 and 25 with highly coincident binding conformations with d -swainsonine (1) in their interactions with the active site of α-mannosidase (PDB ID: 1HWW). Reliability of the docking results were confirmed by Molecular Dynamics (MD) simulation. Additionally, solid interactions with residues Gln-392 and Tyr-393 in the active site of α- l -rhamnosidase (PDB ID: 3W5N) were proved to be vital for potent α- l -rhamnosidase inhibitions of the l -swainsonine derivatives. The role of C-6 fluorines in swainsonine derivatives well demonstrated the "mimic effect" of fluorine to hydrogen by minimal influence on the binding conformations and effective compensation for any possible lost interactions. This work contributes to a comprehensive understanding of the structure-activity relationship (SAR) of the fluorinated swainsonines and ever reported branched swainsonines, and has laid good foundation for development of more potent α-mannosidase and α- l -rhamnosidase inhibitors. [Display omitted] • Rational design of C-6 fluorinated d -swainsonines by docking calculations. • Convergent synthesis of enantiomeric C-6 fluorinated swainsonine derivatives. • Highly selective and potent α-mannosidase or α- l -rhamnosidase inhibitors. • Comprehensive structure-activity relationship study of d -swainsonine derivatives. • Docking calculations revealed typical "mimic effect" of fluorine to hydrogen. [ABSTRACT FROM AUTHOR]

A five-step synthesis of (S)-7-hydroxy-5-aza-8a- epi - d -swainsonine [(3 S ,4 S ,4a S ,5 S ,6 R)-octahydropyrrolo[1,2- b ]pyridazine-3,4,5,6-tetraol] was accessed in good overall yield from readily available d -erythrosyl benzylidene acetal buta-1,3-diene. The key step of the reaction sequence is a full stereoselective Diels–Alder cycloaddition between- the diene and dienophile: diethyl azodicarboxylate (DEAD) or di- tert -butyl azodicarboxylate (DBAD). The cycloadducts were further transformed into the title 5-aza-indolizidine. Optimized procedures were obtained for the synthesis of intermediates and products. [ABSTRACT FROM AUTHOR]

UV-4 (N-(9-methoxynonyl)-1-deoxynojirimycin) is a broad-spectrum antiviral drug candidate with demonstrated activity in vitro and in vivo against multiple, diverse viruses. Nonclinical safety pharmacology studies were conducted to support the filing of an Investigational New Drug (IND) application. Preliminary in vitro pharmacology testing evaluating potential for binding to "off-target" receptors and enzymes indicated no significant liability for advanced development of UV-4. The safety pharmacology of UV-4 was evaluated in the in vitro human ether-à-go-go-related gene (hERG) assay, in a central nervous system (CNS) study in the mouse (modified Irwin test), in a respiratory safety study in conscious mice using whole body plethysmography, and in a cardiovascular safety study in conscious, radiotelemetry-instrumented beagle dogs. There were no observed adverse treatment-related effects following administration of UV-4 as the hydrochloride salt in the hERG potassium channel assay, on respiratory function, in the CNS study, or in the cardiovascular assessment. Treatment-related cardiovascular effect of decreased arterial pulse pressure after 50 or 200 mg of UV-4/kg was the only change outside the normal range, and all hemodynamic parameters returned to control levels by the end of the telemetry recording period. These nonclinical safety pharmacology assessments support the evaluation of this host-targeted broad-spectrum antiviral drug candidate in clinical studies. [ABSTRACT FROM AUTHOR]

The antiviral activity of UV-4 was previously demonstrated against dengue virus serotype 2 (DENV2) in multiple mouse models. Herein, step-wise minimal effective dose and therapeutic window of efficacy studies of UV-4B (UV-4 hydrochloride salt) were conducted in an antibody-dependent enhancement (ADE) mouse model of severe DENV2 infection in AG129 mice lacking types I and II interferon receptors. Significant survival benefit was demonstrated with 10-20 mg/kg of UV-4B administered thrice daily (TID) for seven days with initiation of treatment up to 48 h after infection. UV-4B also reduced infectious virus production in in vitro antiviral activity assays against all four DENV serotypes, including clinical isolates. A set of purified enzyme, in vitro, and in vivo studies demonstrated that inhibition of endoplasmic reticulum (ER) α-glucosidases and not the glycosphingolipid pathway appears to be responsible for the antiviral activity of UV-4B against DENV. Along with a comprehensive safety package, these and previously published data provided support for an Investigational New Drug (IND) filing and Phases 1 and 2 clinical trials for UV-4B with an indication of acute dengue disease.

Short syntheses to high Fsp3 index natural-product analogues such as iminosugars are of paramount importance in the investigation of their biological activities and reducing the use of protecting groups is an advantageous synthetic strategy. An isopropylidene group was employed towards the synthesis of seven-membered ring iminosugars and the title compound, C9H15N3O5, was crystallized as an intermediate, in which the THF ring is twisted and the dioxolane ring adopts an envelope conformation: the dihedral angle between the rings is 67.50 (13)°. In the crystal, the hydroxyl groups participate in O—H...(O,O) and O—H...N hydrogen-bonding interactions, which generate chains of molecules propagating parallel to the a-axis direction. There is a notable non-classical C—H...O hydrogen bond, which cross-links the [100] chains into (001) sheets.

Sepsis is a life‐threatening condition involving a dysregulated immune response to infectious agents that cause injury to host tissues and organs. Current treatments are limited to early administration of antibiotics and supportive care. While appealing, the strategy of targeted inhibition of individual molecules in the inflammatory cascade has not proved beneficial. Non‐targeted, systemic immunosuppression with steroids has shown limited efficacy and raises concern for secondary infection. Iminosugars are a class of small molecule glycomimetics with distinct inhibition profiles for glycan processing enzymes based on stereochemistry. Inhibition of host endoplasmic reticulum resident glycoprotein processing enzymes has demonstrated efficacy as a broad‐spectrum antiviral strategy, but limited consideration has been given to the effects on host glycoprotein production and consequent disruption of signalling cascades. This work demonstrates that iminosugars inhibit dengue virus, bacterial lipopolysaccharide and fungal antigen‐stimulated cytokine responses in human macrophages. In spite of decreased inflammatory mediator production, viral replication is suppressed in the presence of iminosugar. Transcriptome analysis reveals the key interaction of pathogen‐induced endoplasmic reticulum stress, the resulting unfolded protein response and inflammation. Our work shows that iminosugars modulate these interactions. Based on these findings, we propose a new therapeutic role for iminosugars as treatment for sepsis‐related inflammatory disorders associated with excess cytokine secretion. [ABSTRACT FROM AUTHOR]

α-Amylase and α-glucosidase are central enzymes involved in the digestion of carbohydrates. α-Glucosidase includes maltase-glucoamylase and sucrase-isomaltase. We have previously performed the kinetic analysis of the inhibitory effects of powdered or roasted Morus australis leaf extract and its component iminosugars, such as 1-deoxynojirimycin (1-DNJ), fagomine, and 2- O -α- d -galactopyranosyl deoxynojirimycin (GAL-DNJ) on the activity of maltase. In this study, we analyzed the inhibitory effects of the aforementioned compounds against α-amylase, glucoamylase, sucrase, and isomaltase. At pH 6.0 and 37 °C, each leaf extract sample inhibited glucoamylase, sucrase, and isomaltase but not α-amylase. 1-DNJ and fagomine showed weak α-amylase inhibitory activity while GAL-DNJ exhibited none. 1-DNJ showed a strong glucoamylase, sucrase, and isomaltase inhibitory potential. The inhibitory potential against these three enzymes was 18–500 and 1500–3000-fold higher in the case of 1-DNJ than that observed in the case of fagomine and GAL-DNJ, respectively. We also observed that the indigestible dextrin could considerably inhibit α-amylase. When the powdered M. australis leaf extract was blended with indigestible dextrin, the mixture inhibited α-amylase, as well as maltase, glucoamylase, sucrase, and isomaltase. These results suggest that the ingestion of the leaf extract blended with indigestible dextrin might have the potential to efficiently suppress the postprandial blood glucose level increase. [ABSTRACT FROM AUTHOR]

Sinbaglustat (ACT‐519276), a brain‐penetrating inhibitor of glucosylceramide synthase and nonlysosomal glucosylceramidase, is developed as a new therapy for lysosomal storage disorders. In the first‐in‐human study, sinbaglustat was primarily excreted unchanged in urine. This study was conducted to evaluate the effect of mild, moderate, and severe renal function impairment on the safety, tolerability, and pharmacokinetics (PK) of sinbaglustat. In this single‐center, open‐label study, 32 subjects (8 per renal function group, assessed by the Cockcroft‐Gault formula, and 8 healthy subjects) received a single oral dose of 200 mg sinbaglustat. Plasma PK parameters of sinbaglustat were derived by noncompartmental analysis. Standard safety and tolerability evaluations were analyzed descriptively. When compared with healthy subjects, Cmax did not present clinically relevant differences in subjects with impaired renal function, but median tmax was slightly longer in subjects with moderate and severe renal function impairment. Overall, when compared with healthy subjects, exposure to sinbaglustat based on AUC0‐t (geometric mean and 90% confidence interval) increased in subjects with mild, moderate, and severe renal function impairment by 1.2‐fold (1.08‐ to 1.36‐fold), 1.8‐fold (1.47‐ to 2.17‐fold), and 2.6‐fold (2.23‐ to 3.00‐fold), respectively. There were no clinically relevant findings on electrocardiogram, vital signs, and clinical laboratory variables. Headache was reported by 2 of 24 subjects with renal function impairment and by 2 of 8 healthy subjects. In conclusion, 200 mg of sinbaglustat was well tolerated in all groups. In future studies, a 2‐ and 3‐fold dose reduction is needed for subjects with moderate and severe renal function impairment, respectively. [ABSTRACT FROM AUTHOR]

Recently, the strategy of multivalency has been widely employed to design glycosidase inhibitors, as glycomimetic clusters often induce marked enzyme inhibition relative to monovalent analogs. Polyhydroxylated pyrrolidines, one of the most studied classes of iminosugars, are an attractive moiety due to their potent and specific inhibition of glycosidases and glycosyltransferases, which are associated with many crucial biological processes. The development of multivalent pyrrolidine derivatives as glycosidase inhibitors has resulted in several promising compounds that stand out. Herein, we comprehensively summarized the different synthetic approaches to the preparation of multivalent pyrrolidine clusters, from total synthesis of divalent iminosugars to complex architectures bearing twelve pyrrolidine motifs. Enzyme inhibitory properties and multivalent effects of these synthesized iminosugars were further discussed, especially for some less studied therapeutically relevant enzymes. We envision that this comprehensive review will help extend the applications of multivalent pyrrolidine iminosugars in future studies.

Iminosugar compounds are monosaccharide mimetics with broad but generally weak antiviral activities related to inhibition of enzymes involved in glycobiology. Miglustat (N-butyl-1-deoxynojirimycin), which is approved for the treatment of lipid storage diseases in humans, and UV-4 [N-(9-methoxynonyl)-1-deoxynojirimycin] inhibit the replication of hepatitis A virus (HAV) in cell culture (50% inhibitory concentrations [IC50s] of 32.13mM and 8.05mM, respectively) by blocking the synthesis of gangliosides essential for HAV cell entry. We used a murine model of hepatitis A and targeted mass spectrometry to assess the capacity of these compounds to deplete hepatic gangliosides and modify the course of HAV infection in vivo. Miglustat, given by gavage to Ifnar12/2 mice (4,800mg/kg of body weight/day) depleted hepatic gangliosides by 69 to 75% but caused substantial gastrointestinal toxicity and failed to prevent viral infection. UV-4, similarly administered in high doses (400mg/kg/day), was well tolerated but depleted hepatic gangliosides by only 20% after 14 days. UV-4 depletion of gangliosides varied by class. Several GM2 species were paradoxically increased, likely due to inhibition of β-glucosidases that degrade gangliosides. Both compounds enhanced, rather than reduced, virus replication. Nonetheless, both iminosugars had surprising anti-inflammatory effects, blocking the accumulation of inflammatory cells within the liver. UV-4 treatment also resulted in a decrease in serum alanine aminotransferase (ALT) elevations associated with acute hepatitis A. These anti-inflammatory effects may result from iminosugar inhibition of cellular α-glucosidases, leading to impaired maturation of glycan moieties of chemokine and cytokine receptors, and point to the potential importance of paracrine signaling in the pathogenesis of acute hepatitis A. [ABSTRACT FROM AUTHOR]

Redox-induced regioselective C(sp³)-H C-glycosidation for unactivated prolinols was achieved by controlling the anomeric reactivity of electrochemically generated iminium cations. A mechanistic study revealed that the intermediate was pooled as covalent azaribose or iminium cation species in situ, and the electrophilicity of intermediates can be adjusted by changing coexisting acids. We found that the armed/disarmed analogy concept of traditional glycochemistry can be adapted to our Cglycosidation reaction. Finally, we invented a logical synthetic methodology, named "reactivity switching" concept, and synthesized a series of imino-C-nucleosides (C-azanucleosides) based on this methodology. [ABSTRACT FROM AUTHOR]

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic poses an unprecedented challenge for health care and the global economy. Repurposing drugs that have shown promise in inhibiting other viral infections could allow for more rapid dispensation of urgently needed therapeutics. The Spike protein of SARS-CoV-2 is extensively glycosylated with 22 occupied N glycan sites and is required for viral entry. In other glycosylated viral proteins, glycosylation is required for interaction with calnexin and chaperone-mediated folding in the endoplasmic reticulum, and prevention of this interaction leads to unfolded viral proteins and thus inhibits viral replication. As such, we investigated two iminosugars, celgosivir, a prodrug of castanospermine, and UV-4, or N-(9-methoxynonyl)-1-deoxynojirimycin, a deoxynojirimycin derivative. Iminosugars are known inhibitors of the α-glucosidase I and II enzymes and were effective at inhibiting authentic SARS-CoV-2 viral replication in a cell culture system. Celgosivir prevented SARS-CoV-2-induced cell death and reduced viral replication and Spike protein levels in a dose-dependent manner in culture with Vero E6 cells. Castanospermine, the active form of celgosivir, was also able to inhibit SARS-CoV-2, confirming the canonical castanospermine mechanism of action of celgosivir. The monocyclic UV-4 also prevented SARS-CoV-2-induced death and reduced viral replication after 24 h of treatment, although the reduction in viral copies was lost after 48 h. Our findings suggest that iminosugars should be urgently investigated as potential SARS-CoV-2 inhibitors. [ABSTRACT FROM AUTHOR]

All‐nitrogenated sugars (ANSs), in which all hydroxy groups in a carbohydrate are replaced with amino groups, are anticipated to be privileged structures with useful biological activities. However, ANS synthesis has been challenging due to the difficulty in the installation of multi‐amino groups. We report herein the development of a concise synthetic route to peracetylated ANSs in seven steps from commercially available monosaccharides. The key to success is the use of the sequential Overman rearrangement, which enables formal simultaneous substitution of four or five hydroxy groups in monosaccharides with amino groups. A variety of ANSs are available through the same reaction sequence starting from different initial monosaccharides by chirality transfer of secondary alcohols. Transformations of the resulting peracetylated ANSs such as glycosylation and deacetylation are also demonstrated. Biological studies reveal that ANS‐modified cholesterol show cytotoxicity against human cancer cell lines, whereas each ANS and cholesterol have no cytotoxicity. [ABSTRACT FROM AUTHOR]

Abstract— Dengue fever (DF), dengue hemorrhagic fever (DHF), and dengue shock syndrome (DSS) caused by the DENV virus are among the global problems regarding mosquito-borne viral infections. The DENV virus is transmitted through Aedes aegypti causing clinical manifestations that can cause critical illness for patients. The need for effective antiviral therapy is needed to treat DENV virus infections. 1-Deoxynojirimycin (DNJ), one of the many imino sugars found in mulberry leaves and several strains of bacteria, has potential as an antiviral against DENV virus infection. The antiviral activity of DNJ works as an inhibitor of the α-glucosidase enzyme which is important in virus secretion so that it affects the infection rate. DNJ also has the effect of boosting the immune system to initiate an immune response to a viral infection. Further research is needed to develop DNJ as an effective antiviral DENV in the future. Keywords: antiviral, dengue, iminosugar, therapy Abstrak— Dengue fever (DF), dengue hemorraghic fever (DHF), dan dengue shock syndrome (DSS) yang disebabkan oleh virus DENV merupakan salah satu permasalahan global mengenai infeksi virus. Virus DENV ditularkan melalui Aedes aegypti menyebabkan manifestasi klinis yang dapat menimbulkan kesakiatn kritis bagi pasien. kebutuhan terapi antiviral yang efektif diperlukan untuk mengobati infeksi virus DENV. 1-Deoxynojirimycin (DNJ), salah satu iminosugar yang banyak terdapat pada daun mulberry dan beberapa strain bakteri, memiliki potensi sebagai antiviral terhadap infeksi virus DENV. Aktivitas antiviral DNJ bekerja sebagai penghambat enzim α-glukosidase yang penting dalam sekresi virus sehingga mempengaruhi tingkat infeksi. DNJ juga memiliki efek meningkatkan sistem imun untuk menginisiasi respon imun terhadap infeksi virus. Penelitian lebih lanjut diperlukan untuk mengembangkan DNJ sebagai antiviral DENV yang efektif di masa depan. Kata kunci: antiviral, dengue, iminosugar, therapy

Zika virus (ZIKV), a vector-borne virus of the family Flaviviridae, continues to spread and remains a significant global public health threat. Currently, there are no approved vaccines or antivirals against ZIKV. We investigated the anti-ZIKV ability of three iminosugars with endoplasmic reticulum α-glucosidase inhibitor (ER-AGI) activity, namely deoxynojirimycin (DNJ), castanospermine, and celgosivir. None of the three iminosugars showed any significant cytotoxicity in Vero or human microglia CHME3 cells when applied for 72 h at concentrations up to 100 μM. Iminosugar treatment of Vero or CHME3 cells prior to ZIKV infection resulted in significant inhibition of ZIKV replication over 48 h. Reduction in ZIKV replication in iminosugar-treated cells was not associated with any significant change in the expression levels of key antiviral genes. Following infection with three different strains of ZIKV, iminosugar-treated Vero or CHME3 cells showed no cell death, whereas vehicle-treated control cells exhibited 50–60% cell death at 72 h post-infection (hpi). While there was no significant difference in apoptosis between iminosugar-treated and control cells, iminosugar-treated cells exhibited a substantial reduction of necrosis at 72 hpi following ZIKV infection. In summary, iminosugars with ER-AGI activity inhibit ZIKV replication and significantly reduce necrosis without altering the antiviral gene expression and apoptosis of infected human cells. The results of this study strongly suggest that iminosugars are promising anti-ZIKV antiviral agents and such warrant further in vivo studies.

The nitro-Mannich (aza-Henry) reaction, in which a nitroalkane and an imine react to form a β-nitroamine, is a versatile tool for target-oriented synthesis. Although the first stereoselective reaction was developed only 20 years ago, and enantioselective and diastereoselective versions for the synthesis of non-racemic compounds soon after, there are nowadays a variety of reliable methods which can be used for the synthesis of APIs and other biologically active substances. Hence many anticancer drugs, antivirals, antimicrobials, enzyme inhibitors and many more substances, containing C–N bonds, have been synthesized using this reaction. Several transition metal complexes and organocatalysts were shown to be compatible with the presence of a wide range of functional groups in these molecules, and very high levels of asymmetric induction have been achieved in some cases. The reaction has also been applied in cascade processes. The structural diversity of the products, ranging from simple heterocycles or azabicycles to complex alkaloids, iminosugars, amino acids or diamino acids and phosphonates, shows the versatility of the nitro-Mannich reaction and its potential for future developments.

Interfering with bacterial cell-to-cell communication is a promising strategy to combat antimicrobial resistance. The natural product hamamelitannin and several of its analogues have been identified as quorum sensing inhibitors. In this paper the synthesis of pyrrolidine-based analogues of a more lead-like hamamelitannin analogue is reported. A convergent synthetic route based on a key ring-closing metathesis reaction was developed and delivered the pyrrolidine analogue in 17 steps in high yield. Chemoselective derivatization of the pyrrolidine nitrogen atom resulted in 6 more compounds. The synthesized compounds were evaluated in a biofilm model, but were all inactive.

Diversity and balance of gut microorganisms is fundamental for health throughout life. The aim of this study is to explore the possible eubiotic effect of the buckwheat iminosugar d-fagomine (0.096% w/w in standard feed) in growing healthy Wistar Kyoto rats. Feed and energy intake, residual energy in feces, and body weight gain were independent of d-fagomine supplementation throughout the intervention (24 weeks). The populations of significant bacterial subgroups and species were determined in fecal and cecal DNA by quantitative real-time PCR. d-Fagomine increased the Bacteroidetes:Firmicutes ratio and partially counteracted the loss of Lactobacilliales and Bifidobacteriales over time. The supplementation reduced the levels of excreted short-chain fatty acids (SCFAs) as determined by gas chromatography. This paper provides preliminary evidence that d-fagomine has the capacity to promote microbial functional diversity by increasing the Bacteroidetes:Firmicutes ratio and to mitigate the age-related reduction in populations of the putatively beneficial Lactobacilliales and Bifidobacteriales.

Robert J Nash,1 Boris KG Azantsa,2 Hazel Sharp,1 Velmurugan Shanmugham31PhytoQuest Limited, Plas Gogerddan, Aberystwyth, Ceredigion, UK; 2Department of Biochemistry, University of Yaoundé I, Yaoundé, Cameroon; 3Samrat Research Institute, Bangalore, Karnataka, India Purpose: Osteoarthritis (OA) is an age-related disease caused by the wear and tear of the joints. Presently, there is no known cure for OA, but its management involves the use of high doses of pain killers and antiinflammatory agents with different side and dependency effects. Alternative management strategies involve the use of high doses of glucosamine-chondroitin (GC). This study was carried out to evaluate the efficacy of Q-Actin™, an aqueous extract of Cucumis sativus (cucumber; CSE) against GC in the management of moderate knee OA.Patients and methods: Overall, 122 patients (56 males and 66 females) aged between 40 and 75 years and diagnosed with moderate knee OA were included in this randomized double-blind, parallel-group clinical trial that took place in three different centers. The 180 day intervention involved two groups of 61 participants in each: the GC group, which received orally the generally prescribed dose of 1,350 mg of GC twice daily and the CSE group, which received orally10 mg twice daily of CSE. The Western Ontario McMaster Universities Osteoarthritis Index (WOMAC), Visual Analog scale, and Lequesne’s Functional Index were used to evaluate pain, stiffness, and physical function of knee OA in participants at baseline (Day 0) and on Days 30, 60, 90, 120, 150, and 180.Results: In the CSE group, the WOMAC score was decreased by 22.44% and 70.29% on Days 30 and 180, respectively, compared to a 14.80% and 32.81% decrease in the GC group. Similar trends were observed for all the other pain scores. No adverse effect was reported during the trial period.Conclusion: The use of 10 mg CSE, twice daily, was effective in reducing pain related to moderate knee OA and can be potentially used in the management of knee pain, stiffness, and physical functions related to OA.Keywords: Q-Actin™, cucumber, WOMAC, VAS, LFI, iminosugar

The effect of different leaving groups on the substitution versus elimination outcomes with C-5 d-glucose derivatives was investigated. The stereochemical configurations of 3-O-benzyl-1,2-O-isopropylidene-5-O-methanesulfonyl-6-O-triphenylmethyl-α-d-glucofuranose, C36H38O8S (3) [systematic name: 1-[(3aR,5R,6S,6aR)-6-benzyloxy-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxol-5-yl)-2-(trityloxy)ethyl methanesulfonate], a stable intermediate, and 5-azido-3-O-benzyl-5-deoxy-1,2-O-isopropylidene-6-O-triphenylmethyl-β-l-idofuranose, C35H35N3O5 (4) [systematic name: (3aR,5S,6S,6aR)-5-[1-azido-2-(trityloxy)ethyl]-6-benzyloxy-2,2-dimethyltetrahydrofuro[2,3-d][1,3]dioxole], a substitution product, were examined and the inversion of configuration for the azido group on C-5 in 4 was confirmed. The absolute structures of the molecules in the crystals of both compounds were confirmed by resonant scattering. In the crystal of 3, neighbouring molecules are linked by C—H...O hydrogen bonds, forming chains along the b-axis direction. The chains are linked by C—H...π interactions, forming layers parallel to the ab plane. In the crystal of 4, molecules are also linked by C—H...O hydrogen bonds, forming this time helices along the a-axis direction. The helices are linked by a number of C—H...π interactions, forming a supramolecular framework.

α‐l‐Arabinofuranosidases from glycoside hydrolase family 51 use a stereochemically retaining hydrolytic mechanism to liberate nonreducing terminal α‐l‐arabinofuranose residues from plant polysaccharides such as arabinoxylan and arabinan. To date, more than ten fungal GH51 α‐l‐arabinofuranosidases have been functionally characterized, yet no structure of a fungal GH51 enzyme has been solved. In contrast, seven bacterial GH51 enzyme structures, with low sequence similarity to the fungal GH51 enzymes, have been determined. Here, the crystallization and structural characterization of MgGH51, an industrially relevant GH51 α‐l‐arabinofuranosidase cloned from Meripilus giganteus, are reported. Three crystal forms were grown in different crystallization conditions. The unliganded structure was solved using sulfur SAD data collected from a single crystal using the I23 in vacuo diffraction beamline at Diamond Light Source. Crystal soaks with arabinose, 1,4‐dideoxy‐1,4‐imino‐l‐arabinitol and two cyclophellitol‐derived arabinose mimics reveal a conserved catalytic site and conformational itinerary between fungal and bacterial GH51 α‐l‐arabinofuranosidases. [ABSTRACT FROM AUTHOR]

The synthesis of fused bicyclic oxazolidin‐2‐one (OZO) iminosugars was achieved through a tandem Staudinger reduction/retro‐Michael/intramolecular Michael addition from the corresponding OZO azidosugars. Those precursors, based on both aldopentofuranoses and ketofuranohexoses backbones, were obtained following alkylation and oxidation of the related oxazolidine‐2‐thione (OZT) azidosugars. Eight OZO based iminosugars were isolated in good yields and evaluated for their potency as glycosidases inhibitors, thus extending the family of known 1‐Deoxynojirimycin (DNJ) bicyclic analogues. [ABSTRACT FROM AUTHOR]

Mulberry leaves contain iminosugars, such as 1-deoxynojirimycin (1-DNJ), fagomine, and 2-O-α-D-galactopyranosyl deoxynojirimycin (GAL-DNJ) that inhibit α-glucosidase. In this study, we quantified iminosugars in Morus australis leaves and made the kinetic analysis in the hydrolysis of maltose by α-glucosidase. By LC-MS/MS, the concentrations of 1-DNJ, fagomine, and GAL-DNJ in the powdered leaves were 4.0, 0.46, and 2.5 mg/g, respectively, and those in the roasted ones were 1.0, 0.24, and 0.73 mg/g, respectively, suggesting that the roasting process degraded iminosugars. Steady-state kinetic analysis revealed that the powdered and roasted leaves exhibited competitive inhibition. At pH 6.0 at 37ºC, the IC50 values of the extracts from the boiled powdered or roasted leaves were 0.36 and 1.1 mg/mL, respectively. At the same condition, the IC50 values of 1-DNJ, fagomine, and GAL-DNJ were 0.70 μg/mL, 0.18 mg/mL, and 2.9 mg/mL, respectively. These results suggested that in M. australis, 1-DNJ is a major inhibitor of α-glucosidase. 1-DNJ: 1-deoxynojirimycin; GAL-DNJ: 2-O-α-D-galactopyranosyl-DNJ 1-DNJ, fagomine, and GAL-DNJ are iminosugars contained in M. australis leaves. 1-DNJ inhibits α-glucosidase more strongly than fagomine or GAL-DNJ. [ABSTRACT FROM AUTHOR]

Short syntheses to high Fsp³ index natural-product analogues such as iminosugars are of paramount importance in the investigation of their biological activities and reducing the use of protecting groups is an advantageous synthetic strategy. An isopropylidene group was employed towards the synthesis of sevenmembered ring iminosugars and the title compound, C9H15N3O5, was crystallized as an intermediate, in which the THF ring is twisted and the dioxolane ring adopts an envelope conformation: the dihedral angle between the rings is 67.50 (13). In the crystal, the hydroxyl groups participate in O--H (O,O) and O--H N hydrogen-bonding interactions, which generate chains of molecules propagating parallel to the a-axis direction. There is a notable non-classical C--H O hydrogen bond, which cross-links the [100] chains into (001) sheets. [ABSTRACT FROM AUTHOR]

Some novel five-membered iminosugar analogues were efficiently synthesized via the MCRs of three components; amines, aldehydes and oxaloacetate to give 4-hydroxymethylpyrrolidines. Reduction of 3-hydroxy-4- carbomethoxy-3-pyrroliden-2-ones with Pd/C-catalyzed hydrogenation gave the corresponding cis-hydrogenated products at C3/C4 stereoselectively. Then following reductions of ester and amide functionalities with LiAlH4 afforded 4-(hydroxymethyl)pyrrolidin-3-ols. Among the synthesized compounds 4-hydrazineyl-3-hydroxymethyl-2- (4-methoxyphenyl)-N-methylpyrrolidine and 3-hydrazineyl-4-hydroxymethyl-1-methylpyrrolidine were found to be the most promising a-glucosidase inhibitor with IC50 values of 1.12 and 1.17 mM, respectively. [ABSTRACT FROM AUTHOR]

A number of bicyclic imino- and carba-sugars (examples are presented in the Scheme) can be obtained from simple monosaccharides (hexoses or pentoses) by various methods. [ABSTRACT FROM AUTHOR]

We achieved synthesis of seven stereoisomers of 1- C-n- butyl-L-iminofuranose derivatives using catalytic asymmetric alkylation and Negishi coupling as key reactions. The synthetic strategy based on these key reactions was quite useful, since both α- and β-iminofuranoses could be obtained by switching the chirality of the ligand employed for the AAA reaction. The common intermediates for α- and β-isomers were subjected to further manipulations to install a diol unit at C2 and C3 to give the desired stereoisomers of L-iminofuranose derivatives. We achieved the preparation of all stereoisomers of 1- C-n- butyl-L-iminofuranose derivatives, with the exception of β-lyxo type iminofuranose. It is noteworthy that a synthetic route for many stereoisomers of iminofuranose derivatives was developed. Unfortunately, none of the L-iminofuranoses obtained showed inhibitory activity against the α-glycosidases examined—e.g., maltase, sucrase, and isomaltase. Image 1 [ABSTRACT FROM AUTHOR]

Abstract Glycolipid mimetics consisting of a bicyclic polyhydroxypiperidine-cyclic carbamate core and a pseudoanomeric hydrophobic tail, termed sp2-iminosugar glycolipids (sp2-IGLs), target microglia during neuroinflammatory processes. Here we have synthesized and investigated new variants of sp2-IGLs for their ability to suppress the activation of human monocyte-derived dendritic cells (DCs) by lipopolysaccharide (LPS) signaling through Toll-like receptor 4. We report that the best lead was (1 R)-1-dodecylsulfonyl-5 N ,6 O -oxomethylidenenojirimycin (DSO 2 -ONJ), able to inhibit LPS-induced TNFα production and maturation of DCs. Immunovisualization experiments, using a mannoside glycolipid conjugate (MGC) that also suppress LPS-mediated DC activation as control, evidenced a distinct mode of action for the sp2-IGLs: unlike MGCs, DSO 2 -ONJ did not elicit internalization of the LPS co-receptor CD14 or induce its co-localization with the Toll-like receptor 4. In a mouse model of LPS-induced acute inflammation, DSO 2 -ONJ demonstrated anti-inflammatory activity by inhibiting the production of the pro-inflammatory interleukin-6. The ensemble of the data highlights sp2-IGLs as a promising new class of molecules against inflammation by interfering in Toll-like receptor intracellular signaling. Graphical abstract Image 1 Highlights • sp2-Iminosugar glycolipids (sp2-IGLs) with S-linked aglycones have been synthesized. • The configuration modulates the antiinflammatory response in LPS-activated human DCs. • sp2-IGLs interfere with TLR-4 intracellular signaling, likely by binding to p38α MAPK. • The best candidate proved efficacy in an in vivo model of LPS-mediated inflammation. [ABSTRACT FROM AUTHOR]