New Castanospermine Glycoside Analogues Inhibit Breast Cancer Cell Proliferation and Induce Apoptosis without Affecting Normal Cells

sp2-Iminosugar-type castanospermine analogues have been shown to exhibit anti-tumor activity. However, their effects on cell proliferation and apoptosis and the molecular mechanism at play are not fully understood. Here, we investigated the effect of two representatives, namely the pseudo-S- and C-octyl glycoside 2-oxa-3-oxocastanospermine derivatives SO-OCS and CO-OCS, on MCF-7 and MDA-MB-231 breast cancer and MCF-10A mammary normal cell lines. We found that SO-OCS and CO-OCS inhibited breast cancer cell viability in a concentration- and time-dependent manner. This effect is specific to breast cancer cells as both molecules had no impact on normal MCF-10A cell proliferation. Both drugs induced a cell cycle arrest. CO-OCS arrested cell cycle at G1 and G2/M in MCF-7 and MDA-MB-231cells respectively. In MCF-7 cells, the G1 arrest is associated with a reduction of CDK4 (cyclin-dependent kinase 4), cyclin D1 and cyclin E expression, pRb phosphorylation, and an overexpression of p21Waf1/Cip1. In MDA-MB-231 cells, CO-OCS reduced CDK1 but not cyclin B1 expression. SO-OCS accumulated cells in G2/M in both cell lines and this blockade was accompanied by a decrease of CDK1, but not cyclin B1 expression. Furthermore, both drugs induced apoptosis as demonstrated by the increased percentage of annexin V positive cells and Bax/Bcl-2 ratio. Interestingly, in normal MCF-10A cells the two drugs failed to modify cell proliferation, cell cycle progression, cyclins, or CDKs expression. These results demonstrate that the effect of CO-OCS and SO-OCS is triggered by both cell cycle arrest and apoptosis, suggesting that these castanospermine analogues may constitute potential anti-cancer agents against breast cancer. © 2013 Allan et al.Peer Reviewe

Efficient stereoselective synthesis of 2-acetamido-1,2- dideoxyallonojirimycin (DAJNAc) and sp2-iminosugar conjugates: Novel hexosaminidase inhibitors with discrimination capabilities between the mature and precursor forms of the enzyme

Due to their capacity to inhibit hexosaminidases, 2-acetamido-1,2-dideoxy-iminosugars have been widely studied as potential therapeutic agents for various diseases. An efficient stereoselective synthesis of 2-acetamido-1,2-dideoxyallonojirimycin (DAJNAc), the most potent inhibitor of human placenta b-Nacetylglucosaminidase (b-hexosaminidase) among the epimeric series, is here described. This novel procedure can be easily scaled up, providing enough material for structural modifications and further biological tests. Thus, two series of sp2-iminosugar conjugates derived from DAJNAc have been prepared, namely monocyclic DAJNAc-thioureas and bicyclic 2-iminothiazolidines, and their glycosidase inhibitory activity evaluated. The data evidence the utmost importance of developing diversity-oriented synthetic strategies allowing optimization of electrostatic and hydrophobic interactions to achieve high inhibitory potencies and selectivities among isoenzymes. Notably, strong differences in the inhibition potency of the compounds towards b-hexosaminidase from human placenta (mature) or cultured fibroblasts (precursor form) were encountered. The ensemble of data suggests that the ratio between them, and not the inhibition potency towards the placenta enzyme, is a good indication of the chaperoning potential of TaySachs disease-associated mutant hexosaminidasePeer reviewe

Multivalency To Inhibit and Discriminate Hexosaminidases

A set of multivalent polyhydroxylated acetamidoazepanes based on ethylene glycol, glucoside, or cyclodextrin scaffolds was prepared. The compounds were assessed against plant, mammalian, and therapeutically relevant hexosaminidases. Multimerization was shown to improve the inhibitory potency with synergy, and to fine tune the selectivity profile between related hexosaminidases

Multivalent Tryptophan‐ and Tyrosine‐Containing [60]Fullerene Hexa‐Adducts as Dual HIV and Enterovirus A71 Entry Inhibitors

Unprecedented 3D hexa-adducts of [60]fullerene peripherally decorated with twelve tryptophan (Trp) or tyrosine (Tyr) residues have been synthesized. Studies on the antiviral activity of these novel compounds against HIV and EV71 reveal that they are much more potent against HIV and equally active against EV71 than the previously described dendrimer prototypes AL-385 and AL-463, which possess the same number of Trp/Tyr residues on the periphery but attached to a smaller and more flexible pentaerythritol core. These results demonstrate the relevance of the globular 3D presentation of the peripheral groups (Trp/Tyr) as well as the length of the spacer connecting them to the central core to interact with the viral envelopes, particularly in the case of HIV, and support the hypothesis that [60]fullerene can be an alternative and attractive biocompatible carbon-based scaffold for this type of highly symmetrical dendrimers. In addition, the functionalized fullerenes here described, which display twelve peripheral negatively charged indole moieties on their globular surface, define a new and versatile class of compounds with a promising potential in biomedical applications

Derivados Sp2 imnoazúcar como inhibidores de las a-glicosidasas

Derivados glicosilados de fórmula 1, donde los significados para los distintos sustituyentes son los indicados en la descripción. Estos compuestos son útiles como inhibidores de las a-glicosidasas.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Universidad de SevillaA1 Solicitud de patente con informe sobre el estado de la técnic

Fullerene-sp2-iminosugar balls as multimodal ligands for lectins and glycosidases: A mechanistic hypothesis for the inhibitory multivalent effect

Concerted functioning of lectins and carbohydrate-processing enzymes, mainly glycosidases, is essential in maintaining life. It was commonly assumed that the mechanisms by which each class of protein recognizes their cognate sugar partners are intrinsically different: multivalency is a characteristic feature of carbohydrate-lectin interactions, whereas glycosidases bind to their substrates or substrate-analogue inhibitors in monovalent form. Recent observations on the glycosidase inhibitory potential of multivalent glycomimetics have questioned this paradigm and led to postulate an inhibitory multivalent effect. Here the mechanisms at the origin of this phenomenon have been investigated. A D-gluco-configured sp2-iminosugar glycomimetic motif, namely 1-amino-5N,6O-oxomethylydenenojirimycin (1N-ONJ), behaving, simultaneously, as a ligand of peanut agglutinin (PNA) lectin and as an inhibitor of several glycosidases, has been identified. Both the 1N-ONJ-lectin- and 1N-ONJ-glycosidase-recognition processes have been found to be sensitive to multivalency, which has been exploited in the design of a lectin-glycosidase competitive assay to explore the implication of catalytic and non-glycone sites in enzyme binding. A set of isotropic dodecavalent C60-fullerene- sp2-iminosugar balls incorporating matching or mismatching motifs towards several glycosidases (inhitopes) was synthesized for that purpose, thereby preventing differences in binding modes arising from orientational preferences. The data supports that: 1) multivalency allows modulating the affinity and selectivity of a given inhitope towards glycosidases; 2) multivalent presentation can switch on the inhibitory capacity for some inhitope-glycosidase pairs, and 3) interactions of the multivalent inhibitors with non-glycone sites is critical for glycosidase recognition. The ensemble of results point to a shift in the binding mode on going from monovalent to multivalent systems: in the first case a typical >key-lock> model involving, essentially, the high-affinity active site can be assumed, whereas in the second, a lectin-like behavior implying low-affinity non-glycone sites probably operates. The differences in responsiveness to multivalency for different glycosidases can then be rationalized in terms of the structure and accessibility of the corresponding carbohydrate-binding regions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Peer Reviewe

Synthesis of N-, S-, and C-glycoside castanospermine analogues with selective neutral α-glucosidase inhibitory activity as antitumour agents

3 páginas, 2 figuras, 1 tabla, 1 esquemasp2-Iminosugar-type castanospermine analogues bearing an α-configured N-, S-, or C-linked pseudoanomeric group have been designed as selective inhibitors of the neutral α-glucosidases involved in N-glycoprotein processing; evaluation in breast cancer cell growth indicated a significant antiproliferative potential that was dependent on the nature of the pseudoanomeric group.This work was supported by the Spanish Ministerio de Educación y Ciencia (contract numbers CTQ2006-15515-C02-01/BQU, CTQ2009-14551-C02-01/BQU and TQ2007-61180/PPQ) and the Junta de Andalucía.Peer reviewe

Derivados sp2 imnoazúcar como inhibidores de las alf a-glicosidasas

[EN] The invention relates to glycosylated derivatives of fonnula 1, wherein the designations for the each substituent are indicated in the description. Said compounds can be used as a-glycosidase inhibitors.[ES] Derivados glicosilados de fónnula 1, donde los significados para los distintos sustituyentes son los indicados en la descripción. Estos compuestos son útiles como inhibidores de las a-glicosidasas.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Universidad de SevillaA1 Solicitud de patente con informe sobre el estado de la técnic

sp2-Iminosugar O-, S-, and N-glycosides as conformational mimics of α-linked disaccharides; implications for glycosidase inhibition

The synthesis of mimics of the a(1?6)- and a(1?4)-linked disaccharides isomaltose and maltose featuring a bicyclic sp(2)-iminosugar nonreducing moiety O-, S-, or N-linked to a glucopyranoside residue is reported. The strong generalized anomeric effect operating in sp(2)-iminosugars determines the a-stereochemical outcome of the glycosylation reactions, independent of the presence or not of participating protecting groups and of the nature of the heteroatom. It also imparts chemical stability to the resulting aminoacetal, aminothioacetal, or gem-diamine functionalities. All the three isomaltose mimics behave as potent and very selective inhibitors of isomaltase and maltase, two a-glucosidases that bind the parent disaccharides either as substrate or inhibitor. In contrast, large differences in the inhibitory properties were observed among the maltose mimics, with the O-linked derivative being a more potent inhibitor than the N-linked analogue; the S-linked pseudodisaccharide did not inhibit either of the two target enzymes. A comparative conformational analysis based on NMR and molecular modelling revealed remarkable differences in the flexibility about the glycosidic linkage as a function of the nature of the linking atom in this series. Thus, the N-pseudodisaccharide is more rigid than the O-linked derivative, which exhibits conformational properties very similar to those of the natural maltose. The analogous pseudothiomaltoside is much more flexible than the N- or O-linked derivatives, and can access a broader area of the conformational space, which probably implies a strong entropic penalty upon binding to the enzymes. Together, the present results illustrate the importance of taking conformational aspects into consideration in the design of functional oligosaccharide mimetics

Pharmacological Chaperones for the Treatment of α-Mannosidosis

α-Mannosidosis (AM) results from deficient lysosomal α-mannosidase (LAMAN) activity and subsequent substrate accumulation in the lysosome, leading to severe pathology. Many of the AM-causative mutations compromise enzyme folding and could be rescued with purpose-designed pharmacological chaperones (PCs). We found that PCs combining a LAMAN glycone-binding motif based on the 5N,6O-oxomethylidenemannojirimycin (OMJ) glycomimetic core and different aglycones, in either mono- or multivalent displays, elicit binding modes involving glycone and nonglycone enzyme regions that reinforce the protein folding and stabilization potential. Multivalent derivatives exhibited potent enzyme inhibition that generally prevailed over the chaperone effect. On the contrary, monovalent OMJ derivatives with LAMAN aglycone binding area-fitting substituents proved effective as activity enhancers for several mutant LAMAN forms in AM patient fibroblasts and/or transfected MAN2B1-KO cells. This translated into a significant improvement in endosomal/lysosomal function, reverting not only the primary LAMAN substrate accumulation but also the additional downstream consequences such as cholesterol accumulation