Inhibition of the human O-linked β-N-acetylglucosaminidase (hOGA, GH84) enzyme is pharmacologically relevant in several diseases such as neurodegenerative and cardiovascular disorders, type 2 diabetes, and cancer. Human lysosomal hexosaminidases (hHexA and hHexB, GH20) are mechanistically related enzymes; therefore, selective inhibition of these enzymes is crucial in terms of potential applications. In order to extend the structure-activity relationships of OGA inhibitors, a series of 2-acetamido-2-deoxy-d-glucono-1,5-lactone sulfonylhydrazones was prepared from d-glucosamine. The synthetic sequence involved condensation of N-acetyl-3,4,6-tri-O-acetyl-d-glucosamine with arenesulfonylhydrazines, followed by MnO2 oxidation to the corresponding glucono-1,5-lactone sulfonylhydrazones. Removal of the O-acetyl protecting groups by NH3/MeOH furnished the test compounds. Evaluation of these compounds by enzyme kinetic methods against hOGA and hHexB revealed potent nanomolar competitive inhibition of both enzymes, with no significant selectivity towards either. The most efficient inhibitor of hOGA was 2-acetamido-2-deoxy-d-glucono-1,5-lactone 1-naphthalenesulfonylhydrazone (5f, Ki = 27 nM). This compound had a Ki of 6.8 nM towards hHexB. To assess the binding mode of these inhibitors to hOGA, computational studies (Prime protein-ligand refinement and QM/MM optimizations) were performed, which suggested the binding preference of the glucono-1,5-lactone sulfonylhydrazones in an s-cis conformation for all test compounds.

• Keywords
• Prime refinement, QM/MM optimization, glyconolactone sulfonylhydrazone, hHexB, hOGA, inhibitor,
• MeSH
• Antigens, Neoplasm chemistry   metabolism   MeSH
• beta-Hexosaminidase beta Chain chemistry   metabolism   MeSH
• Histone Acetyltransferases chemistry   metabolism   MeSH
• Hyaluronoglucosaminidase chemistry   metabolism   MeSH
• Hydrazones chemical synthesis   chemistry   pharmacology   MeSH
• Enzyme Inhibitors chemical synthesis   chemistry   pharmacology   MeSH
• Lactones chemistry   MeSH
• Humans MeSH
• Molecular Conformation MeSH
• Models, Molecular MeSH
• Oxides chemistry   MeSH
• Manganese Compounds chemistry   MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antigens, Neoplasm MeSH
• beta-Hexosaminidase beta Chain MeSH
• HEXB protein, human MeSH Browser
• Histone Acetyltransferases MeSH
• Hyaluronoglucosaminidase MeSH
• Hydrazones MeSH
• Enzyme Inhibitors MeSH
• Lactones MeSH
• manganese dioxide MeSH Browser
• OGA protein, human MeSH Browser
• Oxides MeSH
• Manganese Compounds MeSH

Two libraries of mono- and dimeric pyrrolidine iminosugars were synthesized by CuAAC and (thio)urea-bond-forming reactions from the respective azido/aminohexylpyrrolidine iminosugar precursors. The resulting monomeric and dimeric compounds were screened for inhibition of β-N-acetylglucosaminidase from Jack beans, the plant ortholog of human lysosomal hexosaminidases. A selection of the best inhibitors of these libraries was then evaluated against human lysosomal β-N-acetylhexosaminidase B (hHexB) and human nucleocytoplasmic β-N-acetylglucosaminidase (hOGA). This evaluation identified a potent (nM) and selective monomeric inhibitor of hOGA (compound 7A) that showed a 6770-fold higher affinity for this enzyme than for hHexB. The corresponding dimeric derivative (compound 9D) further remarkably improved the selectivity in the inhibition of hOGA (2.7 × 104 times more selective for hOGA over hHexB) and the inhibition potency (by one order of magnitude). Docking studies were performed to explain the selectivity of inhibition observed in compound 7A.

• Keywords
• Click reaction, Glycosidase inhibitors, Hexosaminidases, Iminosugars, In situ screening, Multivalency,
• MeSH
• Acetylglucosaminidase MeSH
• beta-N-Acetylhexosaminidases MeSH
• Imino Sugars * pharmacology   MeSH
• Enzyme Inhibitors pharmacology   MeSH
• Humans MeSH
• Pyrrolidines pharmacology   MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Acetylglucosaminidase MeSH
• beta-N-Acetylhexosaminidases MeSH
• Imino Sugars * MeSH
• Enzyme Inhibitors MeSH
• Pyrrolidines MeSH

Concerned by the urgent need to explore new approaches for the treatment of Alzheimer's disease, we herein describe the synthesis and evaluation of new multitarget molecules. In particular, we have focused our attention on modulating the activity of cholinesterases (AChE, BuChE) in order to restore the levels of the neurotransmitter acetylcholine, and of O-GlcNAcase (OGA), which is associated with hyperphosphorylation of tau protein, in turn related to the formation of neurofibrillary tangles in the brain. Specifically, we considered the possibility of using carbohydrate-fused 1,3-selenazolines, decorated with a 2-alkylamino or 2-alkoxy moieties. On the one hand, the presence of a selenium atom might be useful in modulating the intrinsic oxidative stress in AD. On the other hand, such bicyclic structure might behave as a transition state analogue of OGA hydrolysis. Moreover, upon protonation, it could mimic the ammonium cation of acetylcholine. The lead compound, bearing a propylamino moiety on C-2 position of the selenazoline motif, proved to be a good candidate against AD; it turned out to be a strong inhibitor of BuChE (IC50 = 0.46 µM), the most prevalent cholinesterase in advanced disease stages, with a roughly 4.8 selectivity index in connection to AChE (IC50 = 2.2 µM). This compound exhibited a roughly 12-fold increase in activity compared to galantamine, one of the currently marketed drugs against AD, and a selective AChE inhibitor, and virtually the same activity as rivastigmine, a selective BuChE inhibitor. Furthermore, it was also endowed with a strong inhibitory activity against human OGA, within the nanomolar range (IC50 = 0.053 µM for hOGA, >100 µM for hHexB), and, thus, with an outstanding selectivity (IC50(hHexB)/IC50(hOGA) > 1887). The title compounds also exhibited an excellent selectivity against a panel of glycosidases and a negligible cytotoxicity against tumor and non-tumor cell lines. Docking simulations performed on the three target enzymes (AChE, BuChE, and OGA) revealed the key interactions to rationalize the biological data.

• Keywords
• AChE, Alzheimer’s disease, BuChE, Docking simulations, OGA, Selenazolines,
• MeSH
• Acetylcholine MeSH
• Acetylcholinesterase metabolism   MeSH
• Alzheimer Disease * drug therapy   metabolism   MeSH
• beta-N-Acetylhexosaminidases * antagonists & inhibitors   MeSH
• Cholinesterase Inhibitors * chemistry   MeSH
• Cholinesterases * metabolism   MeSH
• Humans MeSH
• Nootropic Agents pharmacology   MeSH
• Carbohydrates MeSH
• Molecular Docking Simulation MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Acetylcholine MeSH
• Acetylcholinesterase MeSH
• beta-N-Acetylhexosaminidases * MeSH
• Cholinesterase Inhibitors * MeSH
• Cholinesterases * MeSH
• hexosaminidase C MeSH Browser
• Nootropic Agents MeSH
• Carbohydrates MeSH