Synthesis, DFT Studies, Molecular Docking and Biological Activity Evaluation of Thiazole-Sulfonamide Derivatives as Potent Alzheimer's Inhibitors

Review of Pharmacotherapeutic Targets in Alzheimer's Disease and Its Management Using Traditional Medicinal Plants

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and impaired daily functioning. While there is currently no cure for AD, several pharmacotherapeutic targets and management strategies have been explored. Additionally, traditional medicinal plants have gained attention for their potential role in AD management. Pharmacotherapeutic targets in AD include amyloid-beta (Aβ) aggregation, tau protein hyperphosphorylation, neuroinflammation, oxidative stress, and cholinergic dysfunction. Traditional medicinal plants, such as Ginkgo biloba, Huperzia serrata, Curcuma longa (turmeric), and Panax ginseng, have demonstrated the ability to modulate these targets through their bioactive compounds. Ginkgo biloba, for instance, contains flavonoids and terpenoids that exhibit neuroprotective effects by reducing Aβ deposition and enhancing cerebral blood flow. Huperzia serrata, a natural source of huperzine A, has acetylcholinesterase-inhibiting properties, thus improving cholinergic function. Curcuma longa, enriched with curcumin, exhibits anti-inflammatory and antioxidant effects, potentially mitigating neuroinflammation and oxidative stress. Panax ginseng's ginsenosides have shown neuroprotective and anti-amyloidogenic properties. The investigation of traditional medicinal plants as a complementary approach to AD management offers several advantages, including a lower risk of adverse effects and potential multi-target interactions. Furthermore, the cultural knowledge and utilization of these plants provide a rich source of information for the development of new therapies. However, further research is necessary to elucidate the precise mechanisms of action, standardize preparations, and assess the safety and efficacy of these natural remedies. Integrating traditional medicinal-plant-based therapies with modern pharmacotherapies may hold the key to a more comprehensive and effective approach to AD treatment. This review aims to explore the pharmacotherapeutic targets in AD and assess the potential of traditional medicinal plants in its management.

Unveiling new thiazole-clubbed piperazine derivatives as multitarget anti-AD: Design, synthesis, and in silico studies

New thiazole-clubbed piperazine derivatives were designed, synthesized, evaluated for their inhibitory capabilities against human acetylcholinesterase and butyrylcholinesterase (hAChE and/or hBuChE) and β-amyloid (Aβ) aggregation, and investigated for their metal chelating potential as multitarget agents for the treatment of Alzheimer's disease. Compounds 10, 19-21, and 24 showed the highest hAChE inhibitory activity at submicromolar concentrations, of which compound 10 was the most potent with a half-maximal inhibitory concentration (IC50) value of 0.151 μM. Compounds 10 and 20 showed the best hBuChE inhibitory activities (IC50 values of 0.135 and 0.103 μM, respectively), in addition to remarkable Aβ1-42 aggregation inhibitory activities and metal chelating capabilities. Both compounds were further evaluated against human neuroblastoma SH-SY5Y and PC12 neuronal cells, where they proved noncytotoxic at their active concentrations against hAChE or hBuChE. They also offered a significant neuroprotective effect against Aβ25-35-induced cytotoxicity in human neuroblastoma SH-SY5Y cells. Compound 10 displayed acceptable physicochemical properties and could pass the blood-brain barrier. The molecular docking study revealed the good binding interactions of compound 10 with the key amino acids of both the catalytic active site and the peripheral anionic site of hAChE, explaining its significant potency.

Butterfly Effect in Cytarabine: Combined NMR-NQR Experiment, Solid-State Computational Modeling, Quantitative Structure-Property Relationships and Molecular Docking Study

Cytarabine (Ara-C) is a synthetic isomer of cytidine that differs from cytidine and deoxycytidine only in the sugar. The use of arabinose instead of deoxyribose hinders the formation of phosphodiester linkages between pentoses, preventing the DNA chain from elongation and interrupting the DNA synthesis. The minor structural alteration (the inversion of hydroxyl at the 2' positions of the sugar) leads to change of the biological activity from anti-depressant and DNA/RNA block builder to powerful anti-cancer. Our study aimed to determine the molecular nature of this phenomenon. Three 1H-14N NMR-NQR experimental techniques, followed by solid-state computational modelling (Quantum Theory of Atoms in Molecules, Reduced Density Gradient and 3D Hirshfeld surfaces), Quantitative Structure-Property Relationships, Spackman's Hirshfeld surfaces and Molecular Docking were used. Multifaceted analysis-combining experiments, computational modeling and molecular docking-provides deep insight into three-dimensional packing at the atomic and molecular levels, but is challenging. A spectrum with nine lines indicating the existence of three chemically inequivalent nitrogen sites in the Ara-C molecule was recorded, and the lines were assigned to them. The influence of the structural alteration on the NQR parameters was modeled in the solid (GGA/RPBE). For the comprehensive description of the nature of these interactions several factors were considered, including relative reactivity and the involvement of heavy atoms in various non-covalent interactions. The binding modes in the solid state and complex with dCK were investigated using the novel approaches: radial plots, heatmaps and root-mean-square deviation of the binding mode. We identified the intramolecular OH···O hydrogen bond as the key factor responsible for forcing the glycone conformation and strengthening NH···O bonds with Gln97, Asp133 and Ara128, and stacking with Phe137. The titular butterfly effect is associated with both the inversion and the presence of this intramolecular hydrogen bond. Our study elucidates the differences in the binding modes of Ara-C and cytidine, which should guide the design of more potent anti-cancer and anti-viral analogues.

Synthesis, In Vitro Biological Evaluation and Molecular Modeling of Benzimidazole-Based Pyrrole/Piperidine Hybrids Derivatives as Potential Anti-Alzheimer Agents

Benzimidazole-based pyrrole/piperidine analogs (1-26) were synthesized and then screened for their acetylcholinesterase and butyrylcholinesterase activities. All the analogs showed good to moderate cholinesterase activities. Synthesized compounds (1-13) were screened in cholinesterase enzyme inhibition assays and showed AChE activities in the range of IC50 = 19.44 ± 0.60 µM to 36.05 ± 0.4 µM against allanzanthane (IC50 = 16.11 ± 0.33 µM) and galantamine (IC50 = 19.34 ± 0.62 µM) and varied BuChE inhibitory activities, with IC50 values in the range of 21.57 ± 0.61 µM to 39.55 ± 0.03 µM as compared with standard allanzanthane (IC50 = 18.14 ± 0.05 µM) and galantamine (IC50 = 21.45 ± 0.21 µM). Similarly, synthesized compounds (14-26) were also subjected to tests to determine their in vitro AChE inhibitory activities, and the results obtained corroborated that all the compounds showed varied activities in the range of IC50 = 22.07 ± 0.13 to 42.01 ± 0.02 µM as compared to allanzanthane (IC50 = 20.01 ± 0.12 µM) and galantamine (IC50 = 18.05 ± 0.31 µM) and varied BuChE inhibitory activities, with IC50 values in the range of 26.32 ± 0.13 to 47.03 ± 0.15 µM as compared to standard allanzanthane (IC50 = 18.14 ± 0.05 µM) and galantamine (IC50 = 21.45 ± 0.21 µM). Binding interactions of the most potent analogs were confirmed through molecular docking studies. The active analogs 2, 4, 10 and 13 established numerous interactions with the active sites of targeted enzymes, with docking scores of -10.50, -9.3, -7.73 and -7.8 for AChE and -8.97, -8.2, -8.20 and -7.6 for BuChE, respectively.

Sulfonamide Derivatives: Recent Compounds with Potent Anti-alzheimer's Disease Activity

Facile synthetic procedures and broad spectrum of biological activities are special attributes of sulfonamides. Sulfonamide derivatives have demonstrated potential as a class of compounds for the treatment of Alzheimer's disease (AD). Recent sulfonamide derivatives have been reported as prospective anti-AD agents, with a focus on analogues that significantly inhibit the function of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes and exhibit remarkable antioxidant and anti-inflammatory properties, all of which are critical for the treatment of AD. Sulfonamide- mediated activation of nuclear factor erythroid 2-related factor 2 (NRF2), a key regulator of the endogenous antioxidant response, has also been suggested as a potential therapeutic approach in AD. Additionally, it has been discovered that a number of sulfonamide derivatives show selectivity for the β- and γ-secretase enzymes and a significant reduction of amyloid B (Aβ) aggregation, which have been implicated in AD. The comparative molecular docking of benzenesulfonamide and donepezil, an AD reference drug showed comparable anti-AD activities. These suggest that sulfonamide derivatives may represent a new class of drugs for the treatment of AD. Thus, the current review will focus on recent studies on the chemical synthesis and evaluation of the anti-AD properties, molecular docking, pharmacological profile, and structure-activity relationship (SAR) of sulfonamide derivatives, as well as their potential anti-AD mechanisms of action. This paper offers a thorough assessment of the state of the art in this field of study and emphasizes the potential of sulfonamide derivatives synthesized during the 2012-2023 period as a new class of compounds for the treatment of AD.

Recent Literature on the Synthesis of Thiazole Derivatives and their Biological Activities

The thiazole ring is naturally occurring and is primarily found in marine and microbial sources. It has been identified in various compounds such as peptides, vitamins (thiamine), alkaloids, epothilone, and chlorophyll. Thiazole-containing compounds are widely recognized for their antibacterial, antifungal, anti-inflammatory, antimalarial, antitubercular, antidiabetic, antioxidant, anticonvulsant, anticancer, and cardiovascular activities. The objective of this review is to present recent advancements in the discovery of biologically active thiazole derivatives, including their synthetic methods and biological effects. This review comprehensively discusses the synthesis methods of thiazole and its corresponding biological activities within a specific timeframe, from 2017 until the conclusion of 2022.

Novel xylenyl-spaced bis-thiazoles/thiazines: synthesis, biological profile as herpes simplex virus type 1 inhibitors and in silico simulations

Aims: Development of some potent bis-thiazole and bis-thiazine derivatives that could be used as antiviral prototypes. Materials & methods: Xylenyl-spaced bis-carbazone scaffold 3 was used as a versatile building block for bis-thiazole derivatives 6a-e and 9a-d and bis-thiazine derivatives 12a-f. These bis-heterocycles were screened as herpes simplex virus type 1 (HSV-1) inhibitors. Results: The new bis-heterocyclic compounds showed remarkable antiviral activity (e.g., compound 6d cytotoxicity concentration CC50 >500 μg/ml). The antiviral capacity of the synthesized bis-compounds was supported by a molecular docking study against the glycoprotein D receptor of HSV-1. Compounds 6b, 9b, and 12c displayed the best binding coefficients. Conclusion: A new series of xylenyl-spaced bis-carbazone scaffolds were used as a building scaffold to construct a host of bis-thiazole/thiazine derivatives that could be used as antiviral prototypes.

A Combined Experimental and Computational Study of Novel Benzotriazinone Carboxamides as Alpha-Glucosidase Inhibitors

Diabetes is a chronic metabolic disorder of the endocrine system characterized by persistent hyperglycemia appears due to the deficiency or ineffective use of insulin. The glucose level of diabetic patients increases after every meal and medically recommended drugs are used to control hyperglycemia. Alpha-glucosidase inhibitors are used as antidiabetic medicine to delay the hydrolysis of complex carbohydrates. Acarbose, miglitol, and voglibose are commercial drugs but patients suffer side effects of flatulence, bloating, diarrhea, and loss of hunger. To explore a new antidiabetic drug, a series of benzotriazinone carboxamides was synthesized and their alpha-glucosidase inhibition potentials were measured using in vitro experiments. The compounds 14k and 14l were found to be strong inhibitors compared to the standard drug acarbose with IC50 values of 27.13 ± 0.12 and 32.14 ± 0.11 μM, respectively. In silico study of 14k and 14l was carried out using molecular docking to identify the type of interactions developed between these compounds and enzyme sites. Both potent compounds 14k and 14l exhibited effective docking scores by making their interactions with selected amino acid residues. Chemical hardness and orbital energy gap values were investigated using DFT studies and results depicted affinity of 14k and 14l towards biological molecules. All computational findings were found to be in good agreement with in vitro results.

Scaffold Morphing and In Silico Design of Potential BACE-1 (β-Secretase) Inhibitors: A Hope for a Newer Dawn in Anti-Alzheimer Therapeutics

Alzheimer's disease (AD) is the prime cause of 65-80% of dementia cases and is caused by plaque and tangle deposition in the brain neurons leading to brain cell degeneration. β-secretase (BACE-1) is a key enzyme responsible for depositing extracellular plaques made of β-amyloid protein. Therefore, efforts are being applied to develop novel BACE-1 enzyme inhibitors to halt plaque build-up. In our study, we analyzed some Elenbecestat analogues (a BACE-1 inhibitor currently in clinical trials) using a structure-based drug design and scaffold morphing approach to achieve a superior therapeutic profile, followed by in silico studies, including molecular docking and pharmacokinetics methodologies. Among all the designed compounds, SB306 and SB12 showed good interactions with the catalytic dyad motifs (Asp228 and Asp32) of the BACE-1 enzyme with drug-likeliness properties and a high degree of thermodynamic stability confirmed by the molecular dynamic and stability of the simulated system indicating the inhibitory nature of the SB306 and SB12 on BACE 1.

A Comprehensive Investigation into the Crystallology, Molecule, and Quantum Chemistry Properties of Two New Hydrous Long-Chain Dibasic Ammonium Salts CnH2n+8N2O6 (n = 35 and 37)

Through the salification reaction of carboxylation, successful attachment of the long-chain alkanoic acid to the two ends of 1,3-propanediamine was realized, which enabled the doubling of the long-chain alkanoic acid carbon chain. Hydrous 1,3-propanediamine dihexadecanoate (abbreviated as 3C16) and 1,3-propanediamine diheptadecanoate (abbreviated as 3C17) were synthesized afterward, and their crystal structures were characterized by the X-ray single crystal diffraction technique. By analyzing their molecular and crystal structure, their composition, spatial structure, and coordination mode were determined. Two water molecules played important roles in stabilizing the framework of both compounds. Hirshfeld surface analysis revealed the intermolecular interactions between the two molecules. The 3D energy framework map presented the intermolecular interactions more intuitively and digitally, in which dispersion energy plays a dominant role. DFT calculations were performed to analyze the frontier molecular orbitals (HOMO–LUMO). The energy difference between the HOMO–LUMO is 0.2858 eV and 0.2855 eV for 3C16 and 3C17, respectively. DOS diagrams further confirmed the distribution of the frontier molecular orbitals of 3C16 and 3C17. The charge distributions in the compounds were visualized using a molecular electrostatic potential (ESP) surface. ESP maps indicated that the electrophilic sites are localized around the oxygen atom. The crystallographic data and parameters of quantum chemical calculation in this paper will provide data and theoretical support for the development and application of such materials.