Carbohydrate-derived bicyclic selenazolines as new dual inhibitors (cholinesterases/OGA) against Alzheimer’s disease

Opportunities for Therapeutic Modulation of O-GlcNAc

O-Linked β-N-acetylglucosamine (O-GlcNAc) is an essential, dynamic monosaccharide post-translational modification (PTM) found on serine and threonine residues of thousands of nucleocytoplasmic proteins. The installation and removal of O-GlcNAc is controlled by a single pair of enzymes, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), respectively. Since its discovery four decades ago, O-GlcNAc has been found on diverse classes of proteins, playing important functional roles in many cellular processes. Dysregulation of O-GlcNAc homeostasis has been implicated in the pathogenesis of disease, including neurodegeneration, X-linked intellectual disability (XLID), cancer, diabetes, and immunological disorders. These foundational studies of O-GlcNAc in disease biology have motivated efforts to target O-GlcNAc therapeutically, with multiple clinical candidates under evaluation. In this review, we describe the characterization and biochemistry of OGT and OGA, cellular O-GlcNAc regulation, development of OGT and OGA inhibitors, O-GlcNAc in pathophysiology, clinical progress of O-GlcNAc modulators, and emerging opportunities for targeting O-GlcNAc. This comprehensive resource should motivate further study into O-GlcNAc function and inspire strategies for therapeutic modulation of O-GlcNAc.

Phenylstyrylpyrimidine derivatives as potential multipotent therapeutics for Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial neurological disorder that affects millions of people worldwide. Despite extensive research efforts, there are currently no effective disease-modifying therapeutics available for the complete cure of AD. In the current study, we have designed and synthesized a series of phenyl-styryl-pyrimidine derivatives as potential multifunctional agents against different targets of AD. The compounds were evaluated for their ability to inhibit acetylcholinesterase (AChE), monoamine oxidase (MAO) and β amyloid aggregation which are associated with the initiation and progression of the disease. Several compounds in the series exhibited potent inhibitory activity against AChE and MAO-B, with IC50 values in the low micromolar range. In particular, two compounds, BV-12 and BV-14, were found to exhibit a multipotent profile and showed non-competitive inhibition against MAO-B with IC50 values of 4.93 ± 0.38 & 7.265 ± 0.82 μM, respectively and AChE inhibition with IC50 values of 7.265 and 9.291 μM, respectively. BV-12 and BV-14 also displayed β amyloid self-aggregation inhibition of 32.98% and 23.25%, respectively. Furthermore, molecular modelling studies revealed that BV-14 displayed a docking score of -11.20 kcal mol-1 with MAO-B & -6.767 kcal mol-1 with AChE, forming a stable complex with both proteins. It was concluded that phenyl-styryl-pyrimidine derivatives have the potential to be developed as multitarget directed ligands for the treatment of AD.

Practical Three-Component Regioselective Synthesis of Drug-Like 3-Aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnolines as Potential Non-Covalent Multi-Targeting Inhibitors To Combat Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are one of the prominent health challenges facing contemporary society, and many efforts have been made to overcome and (or) control it. In this research paper, we described a practical one-pot two-step three-component reaction between 3,4-dihydronaphthalen-1(2H)-one (1), aryl(or heteroaryl)glyoxal monohydrates (2a-h), and hydrazine monohydrate (NH2NH2•H2O) for the regioselective preparation of some 3-aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnoline derivatives (3a-h). After synthesis and characterization of the mentioned cinnolines (3a-h), the in silico multi-targeting inhibitory properties of these heterocyclic scaffolds have been investigated upon various Homo sapiens-type enzymes, including hMAO-A, hMAO-B, hAChE, hBChE, hBACE-1, hBACE-2, hNQO-1, hNQO-2, hnNOS, hiNOS, hPARP-1, hPARP-2, hLRRK-2(G2019S), hGSK-3β, hp38α MAPK, hJNK-3, hOGA, hNMDA receptor, hnSMase-2, hIDO-1, hCOMT, hLIMK-1, hLIMK-2, hRIPK-1, hUCH-L1, hPARK-7, and hDHODH, which have confirmed their functions and roles in the neurodegenerative diseases (NDs), based on molecular docking studies, and the obtained results were compared with a wide range of approved drugs and well-known (with IC50, EC50, etc.) compounds. In addition, in silico ADMET prediction analysis was performed to examine the prospective drug properties of the synthesized heterocyclic compounds (3a-h). The obtained results from the molecular docking studies and ADMET-related data demonstrated that these series of 3-aryl(or heteroaryl)-5,6-dihydrobenzo[h]cinnolines (3a-h), especially hit ones, can really be turned into the potent core of new drugs for the treatment of neurodegenerative diseases (NDs), and/or due to the having some reactionable locations, they are able to have further organic reactions (such as cross-coupling reactions), and expansion of these compounds (for example, with using other types of aryl(or heteroaryl)glyoxal monohydrates) makes a new avenue for designing novel and efficient drugs for this purpose.

Glycosidase-targeting small molecules for biological and therapeutic applications

Glycosidases are ubiquitous enzymes that catalyze the hydrolysis of glycosidic linkages in oligosaccharides and glycoconjugates. These enzymes play a vital role in a wide variety of biological events, such as digestion of nutritional carbohydrates, lysosomal catabolism of glycoconjugates, and posttranslational modifications of glycoproteins. Abnormal glycosidase activities are associated with a variety of diseases, particularly cancer and lysosomal storage disorders. Owing to the physiological and pathological significance of glycosidases, the development of small molecules that target these enzymes is an active area in glycoscience and medicinal chemistry. Research efforts carried out thus far have led to the discovery of numerous glycosidase-targeting small molecules that have been utilized to elucidate biological processes as well as to develop effective chemotherapeutic agents. In this review, we describe the results of research studies reported since 2018, giving particular emphasis to the use of fluorescent probes for detection and imaging of glycosidases, activity-based probes for covalent labelling of these enzymes, glycosidase inhibitors, and glycosidase-activatable prodrugs.

Recent advances in glycoside hydrolase family 20 and 84 inhibitors: Structures, inhibitory mechanisms and biological activities

Glycoside hydrolase family 20 (GH20) β-N-acetyl-d-hexosaminidase (Hex) catalyzes the cleavage of glycosidic linkages in glycans, glycolipids and glycoproteins, and is involved in glycoprotein modification, metabolism of glycoconjugate and the degradation of chitin in fungal cell walls and arthropod exoskeletons. GH84 O-β-N-acetyl-d-glucosaminidase (OGA), which is mechanistically similar related to GH20, participates in the O-GlcNAcylation modification, hydrolyzing the O-GlcNAc moiety from protein acceptors. Hex and OGA are of interest due to their potential for the treatment of disorder diseases and plant protection. Hex inhibitors act as molecular chaperones to treat lysosomal storage disease and as growth regulators to arrest insect molting. Inhibition of OGA is a promising therapeutic approach to treat tau pathology in neurodegenerative diseases such as Alzheimer's disease. However, since Hex and OGA exhibit similar active sites, there are challenges in designing highly selective inhibitors. The elucidation of the structural basis of the catalytic mechanism and substrate binding mode of Hex and OGA has provided core information for virtual screening and rational design of inhibitors. A large number of high-potency and selective inhibitors have been developed in the last five years. In this review, we focus on the recent advances in the structural modification, inhibitory activity, binding mechanisms and biological evaluation of Hex and OGA inhibitors, which will facilitate the development of new drugs and agrochemicals.

Biotinylated selenocyanates: Potent and selective cytostatic agents

Most of the currently available cytotoxic agents for tackling cancer are devoid of selectivity, thus causing severe side-effects. This situation stimulated us to develop new antiproliferative agents with enhanced affinity towards tumour cells. We focused our attention on novel chalcogen-containing compounds (thiosemicarbazones, disulfides, selenoureas, thio- and selenocyanates), and particularly on selenium derivatives, as it has been documented that this kind of compounds might act as prodrugs releasing selenium-based reactive species on tumour cells. Particularly interesting in terms of potency and selectivity was a pharmacophore comprised by a selenocyanato-alkyl fragment connected to a p-phenylenediamine residue, where the nature of the second amino moiety (free, Boc-protected, enamine-protected) provided a wide variety of antiproliferative activities, ranging from the low micromolar to the nanomolar values. The optimized structure was in turn conjugated through a peptide linkage with biotin (vitamin B₇), a cellular growth promoter, whose receptor is overexpressed in numerous cancer cells; the purpose was to develop a selective vector towards malignant cells. Such biotinylated derivative behaved as a very strong antiproliferative agent, achieving GI₅₀ values in the low nM range for most of the tested cancer cells; moreover, it was featured with an outstanding selectivity, with GI₅₀ > 100 µM against human fibroblasts. Mechanistic studies on the mode of inhibition of the biotinylated selenocyanate revealed (Annexin-V assay) a remarkable increase in the number of apoptotic cells compared to the control experiment; moreover, depolarization of the mitochondrial membrane was detected by flow cytometry analysis, and with fluorescent microscopy, what supports the apoptotic cell death. Prior to the apoptotic events, cytostatic effects were observed against SW1573 cells using label-free cell-living imaging; therefore, tumour cell division was prevented. Multidrug resistant cell lines exhibited a reduced sensitivity towards the biotinylated selenocyanate, probably due to its P-gp-mediated efflux. Remarkably, antiproliferative levels could be restored by co-administration with tariquidar, a P-gp inhibitor; this approach can, therefore, overcome multidrug resistance mediated by the P-gp efflux system.

Copper-catalyzed S-arylation of Furanose-Fused Oxazolidine-2-thiones

The 1,3-oxazolidine-2-thiones (OZTs) are important chiral molecules, especially in asymmetric synthesis. These compounds serve as important active units in biologically active compounds. Herein, carbohydrate anchored OZTs were explored to develop a copper-catalyzed C-S bond formation with aryl iodides. Chemoselective S-arylation was observed, with copper iodide and dimethylethylenediamine (DMEDA) as the best ligand in dioxane at 60–90 °C. The corresponding chiral oxazolines were obtained in reasonable to good yields under relatively mild reaction conditions. This approach is cheap, as using one of the cheapest transition metals, a simple protocol and various functional group tolerance make it a valuable strategy for getting S-substituted furanose-fused OZT. The structures of the novel carbohydrates were confirmed by NMR spectroscopy and an HRMS analysis.