Carbamate as a potential anti-Alzheimer's pharmacophore: A review

Harnessing marine resources for Alzheimer's therapy: A review integrating bioactivity and molecular docking

Alzheimer's disease (AD) is a neurodegenerative condition resulting in cognitive impairment and the formation of neurofibrillary tangles and plaques in the brain. The drivers of AD's molecular progression and pathology include the accumulation of amyloid β protein (Aβ); thus, Aβ is an intervention target. However, the limitations in clinical trials of Aβ-targeted medicine and the failure to intervene in disease progression have raised concerns about the use of this drug and its veracious route. In particular, we comprehensively reviewed the potential effect of marine compounds and the mechanism of isolation and extraction from marine organisms resulting in the optimization of AD treatment. Furthermore, the hub compounds were docked with Beta-secretase receptors to strengthen the extrapolation of mechanistic interactions thus inhibiting the activity of an enzyme. An extensive review revealed that marine aquaculture and its byproducts are a promising source and isolated with green methods or less investment, ensuring their sustainability. MNPs harbor specific pharmacological features that enable them to exert neuroprotective effects by minimizing events such as Aβ peptide formation and reactive oxygen species (ROS) generation.

Computational Study on the Pd-Catalyzed Pathway for the Formation of (R)-Methyl-(2-Hydroxy-1-Phenylethyl)Carbamate

The formation of (R)-methyl-(2-hydroxy-1-phenylethyl)carbamate through Pd(PPh3)4-catalyzed synthesis was investigated using computational methods to elucidate the reaction pathway and energetic feasibility. Density functional theory (DFT) calculations confirmed that the direct reaction between (R)-(-)-2-phenylglycinol and methyl chloroformate is not spontaneous, requiring a catalyst to proceed efficiently. The study proposes a detailed mechanistic pathway involving ligand dissociation, intermediate formation, and hydrogenation. The role of Pd(PPh3)4 was examined, demonstrating its ability to stabilize reaction intermediates and facilitate key transformations, such as dehydrogenation and chlorine elimination. Two reaction pathways were identified, with Pathway 1 exhibiting a net energy of -84.7 kcal/mol and Pathway 2 showing an initial positive energy of 90.1 kcal/mol. However, the regeneration of key intermediates in Pathway 2 ultimately reduces the total reaction energy to -238.7 kcal/mol, confirming the feasibility of both routes. Computational results align with experimental NMR data, supporting the formation of the proposed intermediates. These findings provide valuable insights into catalyst optimization, suggesting that ligand modifications or alternative palladium-based catalysts could enhance efficiency. This study advances the understanding of Pd-catalyzed carbamate synthesis and offers a basis for future experimental and computational investigations.

Purine nucleosides as selective inhibitors of butyrylcholinesterase - a multidisciplinary study

The computational study of the most relevant interactions of the nanomolar purine nucleoside BuChE selective inhibitor has shown that the benzyl group at position 2 and the purine acetamido group are required for activity. In addition, the synthesis of a 6-iodinated radiolabelled analogue and the study of in vivo bioavailability have shown a low percentage of uptake by the brain after 1 hour. These results encouraged the synthesis of a small library of new compounds, focussing on deoxygenation at other positions aiming to access active and more bioavailable structures. Deoxygenation at positions 4 and 3,4 afforded new nucleosides that displayed low inhibition of both cholinesterases, while deoxygenation at position 6 and the lyxopyranosyl group afforded the two most active compounds (IC50 ranging from 3.7 to 7.8 μM); one of them was not cytotoxic at the bioactive concentration, while the other one showed a slight cytotoxicity. Interestingly, these structures exhibited the same anomeric stereochemistry and were purine N7-linked, similar to the lead compound 3 (IC50 = 50 nM), thus confirming the importance of the αDN7 purine nucleoside structure. Thus, optimization of the purine nucleoside synthetic procedure was carried out by changing the reaction temperature, the anomeric leaving group or the Lewis acid. The most satisfactory reaction yields and regioselectivity were obtained by using the original N-glycosylation conditions at 25 °C, which afforded the highest yield of 25% when compared to the 8% of the αDN7 purine nucleoside, and an increase in N7 regioselectivity, with the total N7 nucleoside yield increasing from 36% to 52%.

Natural phenol carbamates: Selective BuChE/FAAH dual inhibitors show neuroprotection in an Alzheimer's disease mouse model

FAAH inhibition can indirectly enhance endocannabinoid signaling to therapeutic levels, effectively preventing or slowing its progression of Alzheimer's disease (AD). Hence, the search for effective dual FAAH/cholinesterase inhibitors is considerable need for disease-modifying therapies. To this aim, we designed, synthesized, and tested three series of natural phenol carbamates. The majority of carbamates proved to be potent on a single target, amongst them, compound D12 containing paeonol motif was identified as an effective dual BuChE/FAAH inhibitor, with well-balanced nanomolar activity (IC50 = 81 and 400 nM for hBuChE and hFFAH, respectively). D12 possessed BBB penetrating ability, benign safety, neuroprotection and pseudo-irreversible BuChE inhibition (Kd = 2.11 μM, k2 = 2.27 min-1), showing good drug-like properties. D12 also modulated the BV2 microglial polarization to inhibit neuroinflammation. In vivo study verified that D12 improved Aβ1-41-induced learning impairments in AD mouse model for both short- and long-term memory responses. Thus, the dual activity of D12 could lead to a potentially more effective treatment for the counteraction of AD progression.

Deoxyvasicinone hybrids in the management of Alzheimer's disease: Recent advances on manmade derivatives, pharmacological activities, and structure-activity relationship

Alzheimer's disease (AD) is a prevalent neurological illness that affects over 80% of aged adults globally in cases of dementia. Although the exact pathophysiological causes of AD remain unclear, its pathogenesis is primarily driven by several distinct biochemical alterations: (i) the accumulation of toxic Aβ plaques, (ii) the hyperphosphorylation of tau proteins, (iii) oxidative stress resulting in cell death, and (iv) an imbalance between the two main neurotransmitters, glutamate and acetylcholine (ACh). Currently, there are very few medications available and no treatment. Presently marketed medications include memantine, an N-methyl-d-aspartate receptor (NMDA) antagonist, and acetylcholinesterase (AChE) inhibitors: rivastigmine, donepezil, and galantamine. Unfortunately, these medications are only useful in the initial stages of AD. The mentioned medications only provide symptomatic relief and do not slow down the disease progression in the advanced stages. Therefore, there is an urgent need to develop potential candidates to treat AD, symptomatically and therapeutically. Many research groups focus on natural products due to their diverse therapeutic profiles and easy availability. One such natural product is deoxyvasicinone, isolated from Adhatoda vasica. Given its broad pharmacological profile, various researchers have developed semisynthetic hybrids of deoxyvasicinone to address multifaceted diseases like AD. In this review article, we tried to summarize the semisynthetic hybrids of deoxyvasicinone developed over the past decade (2014-2024) for managing AD. We focus on their design, pharmacological activity, and structure-activity relationship (SAR) analysis. We hope this review enhances the reader's understanding of future exploratory options for deoxyvasicinone hybrids in AD management.

A Comprehensive Analysis on Galantamine Based Hybrids for the Management of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive chronic age-related neurodegenerative brain disorder characterized by the loss of memory and other cognitive functions. The exact etiology of AD is still under investigation, however several factors such as low level of neurotransmitter acetylcholine (ACh), aggregation of amyloid beta (Aβ) in the form of Aβ plaques, hyperphosphorylation of tau protein into neurofibrillary tangles (NFTs), oxidative stress, and metal ion imbalance are the major hallmarks of this disease. Of the multiple hypotheses for AD, the amyloid-β (Aβ) and cholinergic hypothesis are the main targeting hypotheses for AD. Some researchers hypothesized that the primary event associated with the cholinergic neurotransmitter (acetylcholine) is memory loss and cognitive impairment. Due to the disease's complicated pathogenesis, long-term therapy with a single target candidate is futile. As a result, multitargeted and multifunctional therapies have emerged. Various research teams are concentrating on addressing multiple disease factors through hybridization techniques. Consequently, this hybridization approach has been applied to all core scaffolds, including galantamine. In this article, we tried to provide a thorough overview of the most recent developments on galantamine, a prospective AChE inhibitor, and its hybrid analogs as possible therapeutic agents for treating AD. Furthermore, we also provided the design, synthesis, and SAR analysis of the galantamine-based compounds used in the last decades for the management of AD.

Recent Advances in Medicinal Chemistry of Memantine Against Alzheimer's Disease

Alzheimer's disease (AD) is a chronic progressive, age-related neurodegenerative brain disorder characterized by the irreversible decline of memory and other cognitive functions. It is one of the major health threat of the 21st century, which affects around 60% of the population over the age of 60 years. The problem of this disease is even more major because the existing pharmacotherapies only provide symptomatic relief without addressing the basic factors of the disease. It is characterized by the extracellular deposition of amyloid β (Aβ) to form senile plaques, and the intracellular hyperphosphorylation of tau to form neurofibrillary tangles (NFTs). Due to the complex pathophysiology of this disease, various hypotheses have been proposed, including the cholinergic, Aβ, tau, oxidative stress, and the metal-ion hypothesis. Among these, the cholinergic and Aβ hypotheses are the primary targets for addressing AD. Therefore, continuous advances have been made in developing potential cholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists to delay disease progression and restore cholinergic neurotransmission. In this review article, we tried to comprehensively summarize the recent advancement in NMDA receptor antagonist (memantine) and their hybrid analogs as potential disease-modifying agents for the treatment of AD. Furthermore, we also depicted the design, rationale, and SAR analysis of the memantine-based hybrids used in the last decade for the treatment of AD.

Lupeol-3-carbamate Derivatives: Synthesis and Biological Evaluation as Potential Antitumor Agents

In the following study, a series of new lupeol-3-carbamate derivatives were synthesized, and the structures of all the newly derived compounds were characterized. The new compounds were screened to determine their anti-proliferative activity against human lung cancer cell line A549, human liver cancer cell line HepG2, and human breast cancer cell line MCF-7. Most of the compounds were found to show better anti-proliferative activity in vitro than lupeol. Among them, obvious anti-proliferation activity (IC50 = 5.39~9.43 μM) was exhibited by compound 3i against all three tumor cell lines. In addition, a salt reaction was performed on compound 3k (IC50 = 13.98 μM) and it was observed that the anti-proliferative activity and water solubility of compound 3k·CH3I (IC50 = 3.13 μM), were significantly enhanced subsequent to the salt formation process. The preliminary mechanistic studies demonstrated that apoptosis in HepG2 cells was induced by compound 3k·CH3I through the inhibition of the PI3K/AKT/mTOR pathway. In conclusion, a series of new lupeol-3-carbamate derivatives were synthesized via the structural modification of the C-3 site of lupeol, thus laying a theoretical foundation for the design of this new anticancer drug.

Divergent synthesis of carbamates and N-methyl carbamates from dimethyl carbonate and nitroarenes with Mo(CO)6 as a multiple promoter

Dialkyl carbonates are green and versatile reagents that can be used in alkylation and alkoxycarbonylation reactions. Herein, we disclosed a reductive methoxycarbonylation of aromatic nitro compounds with dimethyl carbonate for the construction of diverse carbamates and N-methyl carbamates. Using Mo(CO)6 as a multiple promoter, different nitroarenes were smoothly transformed into the corresponding carbamates in yields between 27 and 94% using DMC as both solvent and reagent. It is worth noting that the choice of different bases allowed the desired products to be controlled: K3PO4 favoured the formation of carbamates as the primary product, whereas DBU facilitated the formation of N-methyl carbamates as the main product.

Trachyspermum ammi Bioactives Promote Neuroprotection by Inhibiting Acetylcholinesterase, Aβ-Oligomerization/Fibrilization, and Mitigating Oxidative Stress In Vitro

Neurodegenerative diseases (NDs) are a large category of progressive neurological disorders with diverse clinical and pathological characteristics. Among the NDs, Alzheimer's disease (AD) is the most widespread disease, which affects more than 400 million people globally. Oxidative stress is evident in the pathophysiology of nearly all NDs by affecting several pathways in neurodegeneration. No single drug can manage multi-faceted diseases like NDs. Therefore, an alternative therapeutic strategy is required, which can affect several pathophysiological pathways at a time. To achieve this aim, hexane and ethyl acetate extract from Trachyspermum ammi (Carom) were prepared, and GC/MS identified the bioactive compounds. For the cell-based assays, oxidative stress was induced in SH-SY5Y neuroblastoma cells using hydrogen peroxide to evaluate the neuroprotective potential of the Carom extracts/bioactives. The extracts/bioactives provided neuroprotection in the cells by modulating multiple pathways involved in neurodegeneration, such as alleviating oxidative stress and mitochondrial membrane potential. They were potent inhibitors of acetylcholine esterase enzymes and displayed competitive/mixed-type inhibition. Additionally, anti-Aβ1-42 fibrilization/oligomerization and anti-glycation activities were also analyzed. The multi-faceted neuroprotection shown via Carom/Carvacrol makes it a prospective contender in drug development for NDs.