Design, synthesis, and biological evaluation of carbamate derivatives of N-salicyloyl tryptamine as multifunctional agents for the treatment of Alzheimer's disease

New insights into butyrylcholinesterase: Pharmaceutical applications, selective inhibitors and multitarget-directed ligands

Butyrylcholinesterase (BChE), also known as pseudocholinesterase and serum cholinesterase, is an isoenzyme of acetylcholinesterase (AChE). It mediates the degradation of acetylcholine, especially under pathological conditions. Proverbial pharmacological applications of BChE, its mutants and modulators consist of combating Alzheimer's disease (AD), influencing multiple sclerosis (MS), addressing cocaine addiction, detoxifying organophosphorus poisoning and reflecting the progression or prognosis of some diseases. Of interest, recent reports have shed light on the relationship between BChE and lipid metabolism. It has also been proved that BChE is going to increase abnormally as a compensator for AChE in the middle and late stages of AD, and BChE inhibitors can alleviate cognitive disorders and positively influence some pathological features in AD model animals, foreboding favorable prospects and potential applications. Herein, the selective BChE inhibitors and BChE-related multitarget-directed ligands published in the last three years were briefly summarized, along with the currently known pharmacological applications of BChE, aiming to grasp the latest research directions. Thereinto, some emerging strategies for designing BChE inhibitors are intriguing, and the modulators based on target combination of histone deacetylase and BChE against AD is unprecedented. Furthermore, the involvement of BChE in the hydrolysis of ghrelin, the inhibition of low-density lipoprotein (LDL) uptake, and the down-regulation of LDL receptor (LDLR) expression suggests its potential to influence lipid metabolism disorders. This compelling prospect likely stimulates further exploration in this promising research direction.

Chromone-deferiprone hybrids as novel MAO-B inhibitors and iron chelators for the treatment of Alzheimer's disease

A series of chromone-deferiprone hybrids were designed, synthesized, and evaluated as inhibitors of human monoamine oxidase B (hMAO-B) with iron-chelating activity for the treatment of Alzheimer's disease (AD). The majority exhibited moderate inhibitory activity towards hMAO-B and potent iron-chelating properties. Particularly, compound 25c demonstrated remarkable selectivity against hMAO-B with an IC50 value of 1.58 μM and potent iron-chelating ability (pFe3+ = 18.79) comparable to that of deferiprone (pFe3+ = 17.90). Molecular modeling and kinetic studies showed that 25c functions as a non-competitive hMAO-B inhibitor. According to the predicted results, compound 25c can penetrate the blood-brain barrier (BBB). Additionally, it has been proved to display significant antioxidant activity and the ability to inhibit neuronal ferroptosis. More importantly, compound 25c reduced the cognitive impairment induced by scopolamine and showed significant non-toxicity in short-term toxicity assays. In summary, compound 25c was identified as a potential anti-AD agent with hMAO-B inhibitory, iron-chelating and anti-ferroptosis activities.

Indole-Based Compounds in the Development of Anti-Neurodegenerative Agents

Neurodegeneration is a gradual decay process leading to the depletion of neurons in both the central and peripheral nervous systems, ultimately resulting in cognitive dysfunctions and the deterioration of brain functions, alongside a decline in motor skills and behavioral capabilities. Neurodegenerative disorders (NDs) impose a substantial socio-economic strain on society, aggravated by the advancing age of the world population and the absence of effective remedies, predicting a negative future. In this context, the urgency of discovering viable therapies is critical and, despite significant efforts by medicinal chemists in developing potential drug candidates and exploring various small molecules as therapeutics, regrettably, a truly effective treatment is yet to be found. Nitrogen heterocyclic compounds, and particularly those containing the indole nucleus, which has emerged as privileged scaffold, have attracted particular attention for a variety of pharmacological applications. This review analyzes the rational design strategy adopted by different research groups for the development of anti-neurodegenerative indole-based compounds which have the potential to modulate various molecular targets involved in NDs, with reference to the most recent advances between 2018 and 2023.

Design, Synthesis, and Activity Evaluation of Fluorine-Containing Scopolamine Analogues as Potential Antidepressants

This study aimed to develop novel rapid-acting antidepressants with sustained efficacy and favorable safety profiles. We designed and synthesized a series of fluorine-containing scopolamine analogues and evaluated their antidepressant potential. In vitro cytotoxicity assays showed that most of these compounds exhibited minimal toxicity against neuronal and non-neuronal mammalian cell lines (IC50 > 100 μM). The antidepressant activities of the compounds were evaluated using the tail suspension test, and S-3a was identified as a lead compound with potent and sustained antidepressant effects. Behaviorally, S-3a alleviated depressive symptoms in mice and displayed a higher cognitive safety margin than scopolamine. Toxicological assessments confirmed S-3a's safety, while pharmacokinetics showed a rapid clearance (half-life: 16.6 min). Mechanistically, S-3a antagonized M1 receptors and elevated BDNF levels, suggesting its potential as an antidepressant for further exploration.

Design, synthesis, and biological evaluation of novel tryptanthrin derivatives as selective acetylcholinesterase inhibitors for the treatment of Alzheimer's disease

Two novel series of tryptanthrin (TRYP) derivatives were designed and synthesized as multifunctional agents for the treatment of Alzheimer's disease (AD). Inhibition assay against cholinesterase (ChE) indicated that these derivatives can act as acetylcholinesterase (AChE) inhibitors with selectivity over butyrylcholinesterase (BuChE). Among them, n1 exhibited the most excellent ChE inhibitory potency (AChE, IC50 = 12.17 ± 1.50 nM; BuChE, IC50 = 6.29 ± 0.48 μΜ; selectivity index = 517). Molecular docking studies indicated that compound n1 can interact with amino acid residues in the catalytic active site and peripheral anionic site of AChE and the molecular dynamics (MD) simulation studies demonstrated that the AChE-n1 complex had good stability. N1 also exhibited anti-amyloid-β (Aβ) aggregation (63.48 % ± 1.02 %, 100 μΜ) and anti-neuroinflammation activity (NO, IL-1β, TNF-α; IC50 = 2.13 ± 0.54 μΜ, 2.21 ± 0.37 μΜ, 2.47 ± 0.07 μΜ, respectively), and n1 had neuroprotective and metal-chelating properties. Further studies indicated n1 had proper blood-brain barrier permeability in the Parallel artificial membrane permeation assay. In vivo studies found that n1 effectively improved learning and memory impairment in scopolamine-induced AD mouse models. Nissl staining ofmice hippocampaltissue sections revealed that n1 restored neuronal cells in the hippocampus CA3 and CA1 regions. These findings suggested that n1 can be a promising compound for further development of multifunctional agents for AD treatment.

Design, synthesis, and biological evaluation of novel donepezil-tacrine hybrids as multi-functional agents with low neurotoxicity against Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory loss and deficits in cognitive domains. Low choline levels, oxidative stress, and neuroinflammation are the primary mechanisms implicated in AD progression. Simultaneous inhibition of acetylcholinesterase (AChE) and reactive oxygen species (ROS) production by a single molecule may provide a new breath of hope for AD treatment. Here, we describe donepezil-tacrine hybrids as inhibitors of AChE and ROS. Four series of derivatives with a β-amino alcohol linker were designed and synthesized. In this study, the target compounds were evaluated for their ability to inhibit AChE and butyrylcholinesterase (BuChE) in vitro, using tacrine (hAChE, IC50 = 305.78 nM; hBuChE, IC50 = 56.72 nM) and donepezil (hAChE, IC50 = 89.32 nM; hBuChE, IC50 = 9137.16 nM) as positive controls. Compound B19 exhibited an excellent and balanced inhibitory potency against AChE (IC50 = 30.68 nM) and BuChE (IC50 = 124.57 nM). The cytotoxicity assays demonstrated that the PC12 cell viability rates of compound B19 (84.37 %) were close to that of tacrine (87.73 %) and donepezil (79.71 %). Potential therapeutic effects in AD were evaluated using the neuroprotective effect of compounds against H2O2-induced toxicity, and compound B19 (68.77 %) exhibited substantially neuroprotective activity at the concentration of 25 μM, compared with the model group (30.34 %). Furthermore, compound B19 protected PC12 cells from H2O2-induced apoptosis and ROS production. These properties of compound B19 suggested that it was a multi-functional agent with AChE inhibition, anti-oxidative, anti-inflammatory activities, and low toxicity and that it deserves further investigation as a promising agent for AD treatment.

Multifunctional agents against Alzheimer's disease based on oxidative stress: Polysubstituted pyrazine derivatives synthesized by multicomponent reactions

As Alzheimer's disease (AD) is a neurodegenerative disease with a complex pathogenesis, the exploration of multi-target drugs may be an effective strategy for AD treatment. Multifunctional small molecular agents can be obtained by connecting two or more active drugs or privileged pharmacophores by multicomponent reactions (MCRs). In this paper, two series of polysubstituted pyrazine derivatives with multifunctional moieties were designed as anti-AD agents and synthesized by Passerini-3CR and Ugi-4CR. Since the oxidative stress plays an important role in the pathological process of AD, the antioxidant activities of the newly synthesized compounds were first evaluated. Subsequently, selected active compounds were further screened in a series of AD-related bioassays, including Aβ1-42 self-aggregation and deaggregation, BACE-1 inhibition, metal chelation, and protection of SH-SY5Y cells from H2O2-induced oxidative damage. Compound A3B3C1 represented the best one with multifunctional potencies. Mechanism study showed that A3B3C1 acted on Nrf2/ARE signaling pathway, thus increasing the expression of related antioxidant proteins NQO1 and HO-1 to normal cell level. Furthermore, A3B3C1 showed good in vitro human plasma and liver microsome stability, indicating a potential for further development as multifunctional anti-AD agent.

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

Alzheimer's disease (AD) is a progressive age-related neurodegenerative brain disorder, which leads to loss of memory and other cognitive dysfunction. The underlying mechanisms of AD pathogenesis are very complex and still not fully explored. Cholinergic neuronal loss, accumulation of amyloid plaque, metal ions dyshomeostasis, tau hyperphosphorylation, oxidative stress, neuroinflammation, and mitochondrial dysfunction are major hallmarks of AD. The current treatment options for AD are acetylcholinesterase inhibitors (donepezil, rivastigmine, and galantamine) and NMDA receptor antagonists (memantine). These FDA-approved drugs mainly provide symptomatic relief without addressing the pathological aspects of disease progression. So, there is an urgent need for novel drug development that not only addresses the basic mechanisms of the disease but also shows the neuroprotective property. Various research groups across the globe are working on the development of multifunctional agents for AD amelioration using different core scaffolds for their design, and carbamate is among them. Rivastigmine was the first carbamate drug investigated for AD management. The carbamate fragment, a core scaffold of rivastigmine, act as a potential inhibitor of acetylcholinesterase. In this review, we summarize the last 10 years of research conducted on the modification of carbamate with different substituents which primarily target ChE inhibition, reduce oxidative stress, and modulate Aβ aggregation.

Discovery of Novel Tryptanthrin Derivatives with Benzenesulfonamide Substituents as Multi-Target-Directed Ligands for the Treatment of Alzheimer's Disease

Based on the multi-target-directed ligands (MTDLs) approach, two series of tryptanthrin derivatives with benzenesulfonamide substituents were evaluated as multifunctional agents for the treatment of Alzheimer's disease (AD). In vitro biological assays indicated most of the derivatives had good cholinesterase inhibitory activity and neuroprotective properties. Among them, the target compound 4h was considered as a mixed reversible dual inhibitor of acetylcholinesterase (AChE, IC50 = 0.13 ± 0.04 μM) and butyrylcholinesterase (BuChE, IC50 = 6.11 ± 0.15 μM). And it could also potentially prevent the generation of amyloid plaques by inhibiting self-induced Aβ aggregation (63.16 ± 2.33%). Molecular docking studies were used to explore the interactions of AChE, BuChE, and Aβ. Furthermore, possessing significant anti-neuroinflammatory potency (NO, IL-1β, TNF-α; IC50 = 0.62 ± 0.07 μM, 1.78 ± 0.21 μM, 1.31 ± 0.28 μM, respectively) reduced ROS production, and chelated biometals were also found in compound 4h. Further studies showed that 4h had proper blood-brain barrier (BBB) permeability and suitable in vitro metabolic stability. In in vivo study, 4h effectively ameliorated the learning and memory impairment of the scopolamine-induced AD mice model. These findings suggested that 4h may be a promising compound for further development as a multifunctional agent for the treatment of AD.

Discovery of blood-brain barrier permeable and orally bioavailable caffeine-based amide derivatives as acetylcholinesterase inhibitors

Caffeine is one of the privileged natural products that shows numerous effects on the central nervous system. Herein, thirty-one caffeine-based amide derivatives were synthesized and evaluated in vitro for their anticholinesterase activity. The introduction of the amide group to the caffeine core augmented its anticholinesterase activity from an IC50 value of 128 to 1.32 µM (derivative, 6i). The SAR study revealed that N7 substitution on caffeine core is favorable over N1, and the presence of amide 'carbonyl' as a part of the linker contributes to the biological activity. The caffeine core of 6i exhibits interactions with the peripheral anionic site, whereas the N-benzyl ring fits nicely inside the catalytic anionic site. Analog 6i inhibits AChE in a mixed-type mode (Ki 4.58 µM) and crosses the BBB in an in-vitro PAMPA assay. Compound 6i has a descent metabolic stability in MLM (>70% remaining after 30 min) and favorable oral pharmacokinetics in Swiss albino mice.

Design and synthesis of salidroside analogs and their bioactivity against septic myocardial injury

Cardiac tissue suffers much from sepsis, and the incidence of myocardial injury is high in septic patients. The treatment of sepsis myocardial injury (SMI) has been the focus of clinical medicine. Salidroside shows myocardial cell protection, anti-oxidation and anti- inflammation effects, and it is thought as one of the potential compounds to treat sepsis myocardial injury. However, its anti-inflammatory activity is lower and its pharmacokinetic properties are not ideal, which is far from clinical application. Here, a series of salidroside analogs were synthesized, and their bioactivities were evaluated from several aspects, including their anti-oxidant and anti-inflammatory activities in vitro and anti-sepsis myocardial injury activities in vivo. Of all the compounds which synthesized, compounds 2 and 3 exhibited stronger anti-inflammatory activities than the others; after treating LPS-stimulated RAW264.7 or H9c2 cells with each of them, the levels of IL-1β, IL-6 and TNF-α were down-regulated in a dose-dependent manner. In the anti-oxidative stress injury test, compounds 2 and 3 not only markedly increased the survival rate of cells, and but also improved the cellular oxidative stress-related indicators MDA, SOD and cell damage marker LDH in a dose-dependent manner. In the LPS-induced septic rat myocardial injury models (in vivo), the two compounds also showed good bioactivities. They also reduced the expression of IL-1β, IL-6 and TNF-α, and blocked cell damage by suppressing overhauled oxidation in septic rats. In addition, the myocardial injury was significantly improved and the inflammatory infiltration was reduced after treatment with the two compounds. In conclusion, the salidroside analogs (2 and 3) showed promising therapeutical effect on septic myocardial injury in LPS-model rats, and they could be good candidates for clinical trials against inflammation and septic myocardial injury.

Synthesis and biological evaluation of substituted acetamide derivatives as potential butyrylcholinestrase inhibitors

Alzheimer's disease (AD) is the most common type of age-related dementia. Inhibition of butyrylcholinesterase (BChE) emerge as an effective therapeutic target for AD. A series of new substituted acetamide derivatives were designed, synthesized and evaluated for their ability to inhibit BChE. The bioassay results revealed that several compounds displayed attractive inhibition against BChE). Among them, compound 8c exhibited the highest BChE inhibition with IC₅₀ values of 3.94 μM. Lineweaver Burk plot indicated that 8c acted as a mixed-type BChE inhibitor. In addition, docking studies confirmed the results obtained through in vitro experiments, and showed that 8c bound to the catalytic anionic site (CAS) and peripheral anionic site (PAS) of BChE active site. Meanwhile, its ADME parameters were approximated using in silico method. Molecular dynamics simulation studies on the complex of 8c-BChE were performed, RMSD, RMSF, Rg, SASA, and the number of hydrogen bonds were calculated as well. These results implied that 8c could serve as appropriate lead molecule for the development of BChE inhibitor.

Current Pharmacotherapy and Multi-Target Approaches for Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by decreased synaptic transmission and cerebral atrophy with appearance of amyloid plaques and neurofibrillary tangles. Cognitive, functional, and behavioral alterations are commonly associated with the disease. Different pathophysiological pathways of AD have been proposed, some of which interact and influence one another. Current treatment for AD mainly involves the use of therapeutic agents to alleviate the symptoms in AD patients. The conventional single-target treatment approaches do not often cause the desired effect in the disease due to its multifactorial origin. Thus, multi-target strategies have since been undertaken, which aim to simultaneously target multiple targets involved in the development of AD. In this review, we provide an overview of the pathogenesis of AD and the current drug therapies for the disease. Additionally, rationales of the multi-target approaches and examples of multi-target drugs with pharmacological actions against AD are also discussed.

Discovery of pyrrole derivatives as acetylcholinesterase-sparing butyrylcholinesterase inhibitor

Inspired by the crucial roles of (hetero)aryl rings in cholinesterase inhibitors and the pyrrole ring in new drug discovery, we synthesized 19 pyrrole derivatives and investigated their cholinesterase inhibitory activity. As a result, compounds 3o, 3p, and 3s with a 1,3-diaryl-pyrrole skeleton showed high selectivity toward BChE over AChE with a best IC₅₀ value of 1.71 ± 0.087 µM, which were comparable to donepezil. The pharmaceutical potential of these structures was further predicted and compounds 3o and 3p were proved to meet well with the Lipinsky's five rules. In combination of the inhibition kinetic studies with the results of molecular docking, we concluded that compound 3p inhibited BChE in a mixed competitive mode. This research has proved the potential of the 1,3-diaryl-pyrrole skeleton as a kind of selective BChE inhibitor.

From tryptamine to the discovery of efficient multi-target directed ligands against cholinesterase-associated neurodegenerative disorders

A novel class of benzyl-free and benzyl-substituted carbamylated tryptamine derivatives (CDTs) was designed and synthesized to serve as effective building blocks for the development of novel multi-target directed ligands (MTDLs) for the treatment of neurological disorders linked to cholinesterase (ChE) activity. The majority of them endowed butyrylcholinesterase (BuChE) with more substantial inhibition potency than acetylcholinesterase (AChE), according to the full study of ChE inhibition. Particularly, hybrids with dibenzyl groups (2b-2f, 2j, 2o, and 2q) showed weak or no neuronal toxicity and hepatotoxicity and single-digit nanomolar inhibitory effects against BuChE. Through molecular docking and kinetic analyses, the potential mechanism of action on BuChE was first investigated. In vitro H2O2-induced HT-22 cells assay demonstrated the favorable neuroprotective potency of 2g, 2h, 2j, 2m, 2o, and 2p. Besides, 2g, 2h, 2j, 2m, 2o, and 2p endowed good antioxidant activities and COX-2 inhibitory effects. This study suggested that this series of hybrids can be applied to treat various ChE-associated neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD), as well as promising building blocks for further structure modification to develop efficient MTDLs.

Supramolecular Tools to Improve Wound Healing and Antioxidant Properties of Abietic Acid: Biocompatible Microemulsions and Emulgels

Abietic acid, a naturally occurring fir resin compound, that exhibits anti-inflammatory and wound-healing properties, was formulated into biocompatible emulgels based on stable microemulsions with the addition of a carbamate-containing surfactant and Carbopol^® 940 gel. Various microemulsion and emulgel formulations were tested for antioxidant and wound-healing properties. The chemiluminescence method has shown that all compositions containing abietic acid have a high antioxidant activity. Using Strat-M^® skin-modelling membrane, it was found out that emulgels significantly prolong the release of abietic acid. On Wistar rats, it was shown that microemulsions and emulgels containing 0.5% wt. of abietic acid promote the rapid healing of an incised wound and twofold tissue reinforcement compared to the untreated group, as documented by tensiometric wound suture-rupture assay. The high healing-efficiency is associated with a combination of antibacterial activity of the formulation components and the anti-inflammatory action of abietic acid.

Synthesis and hydrolysis of monocarbamate from allylic 1,4-dicarbamate: Bis-homodichloroinositol

The synthesis of novel bis-homodichloroinositol with a configuration similar to that of conduritol-D is reported for the first time. The photooxygenation of cis-dichloro-diene obtained using cyclooctatetraene as the starting molecule afforted the tricyclic endoperoxide. The reduction of the endoperoxide with thiourea gave the corresponding allylic cis-diol. Formation of the bis-carbamate groups with p-TsNCO of allylic cis-diol followed by the [(dba)₃Pd₂CHCl₃] in the presence of trimethylsilyl azide, gave a new monocarbamate as well as oxazolidinone derivative. Oxidation of the double bond in the monocarbamate with osmium tetraoxide followed by acetylation furnished the desired monocarbamate triacetate. Eventually, the desired halogenated bicyclo[4.2.0] inositol (bis-homodichloroinositol) were obtained in high yield by hydrolysis of the acetate groups and monocarbanate group by potassium carbonate in methanol. Characterization of all the synthesized compounds were performed by FT-IR, ¹H NMR, ¹³C NMR, COSY (2D-NMR), HRMS, and Elemental Analysis techniques.

Recent advance on pleiotropic cholinesterase inhibitors bearing amyloid modulation efficacy

Due to the hugely important roles of neurotransmitter acetylcholine (ACh) and amyloid-β (Aβ) in the pathogenesis of Alzheimer's disease (AD), the development of multi-target directed ligands (MTDLs) focused on cholinesterase (ChE) and Aβ becomes one of the most attractive strategies for combating AD. To date, numerous preclinical studies toward multifunctional conjugates bearing ChE inhibition and anti-Aβ aggregation have been reported. Noteworthily, most of the reported multifunctional cholinesterase inhibitors are carbamate-based compounds due to the initial properties of carbamate moiety. However, because their easy hydrolysis in vivo and the instability of the compound-enzyme conjugate, the mechanism of action of these compounds is rare. Thus, non-carbamate compounds are of great need for developing novel cholinesterase inhibitors. Besides, given that Aβ accumulation begins to occur 10-15 years before AD onset, modulating Aβ is ineffective only in inhibiting its aggregation but not eliminate the already accumulated Aβ if treatment is started when the patient has been diagnosed as AD. Considering the limitation of current Aβ accumulation modulators in ameliorating cognitive deficits and ineffectiveness of ChE inhibitors in blocking disease progression, the development of a practically valuable strategy with multiple pharmaceutical properties including ChE inhibition and Aβ modulation for treating AD is indispensable. In this review, we focus on summarizing the scaffold characteristics of reported non-carbamate cholinesterase inhibitors with Aβ modulation since 2020, and understanding the ingenious multifunctional drug design ideas to accelerate the pace of obtaining more efficient anti-AD drugs in the future.

A multi-target directed ligands strategy for the treatment of Alzheimer's disease: Dimethyl fumarate plus Tranilast modified Dithiocarbate as AChE inhibitor and Nrf2 activator

Alzheimer's disease (AD) possessed intricate pathogenesis. Currently, multi-targeted drugs were considered to have the potential to against AD by simultaneously triggering molecules in functionally complementary pathways. Hence, a series of molecules based on the pharmacophoric features of Dimethyl fumarate, Tranilast, and Dithiocarbate were designed and synthesized. These compounds showed significant AChE inhibitory activity in vitro. Among them, compound 4c₂ displayed the mighty inhibitory activity to hAChE (IC₅₀ = 0.053 μM) and held the ability to cross the BBB. Kinetic study and molecular docking pointed out that 4c₂ bound well into the active sites of hAChE, forming steady and sturdy interactions with key residues in hAChE. Additionally, 4c₂ as an Nrf2 activator could promote the nuclear translocation of Nrf2 protein and induce the expressions of Nrf2-dependent enzymes HO-1, NQO1, and GPX4. Moreover, 4c₂ rescued BV-2 cells from H₂O₂-induced injury and inhibited ROS accumulation. For the anti-neuroinflammatory potential of 4c₂, we observed that 4c₂ could lower the levels of pro-inflammatory cytokines (NO, IL-6 and TNF-α) and suppressed the expressions of iNOS and COX-2. In particular, 4c₂ was well tolerated in mice (2500 mg/kg, p.o.) and efficaciously recovered the memory impairment in a Scopolamine-induced mouse model. Overall, these results highlighted that 4c₂ was a promising multi-targeted agent for treating AD.

Recent advance on carbamate-based cholinesterase inhibitors as potential multifunctional agents against Alzheimer's disease

Alzheimer's disease (AD), as the fourth leading cause of death among the elderly worldwide, has brought enormous challenge to the society. Due to its extremely complex pathogeneses, the development of multi-target directed ligands (MTDLs) becomes the major strategy for combating AD. Carbamate moiety, as an essential building block in the development of MTDLs, exhibits structural similarity to neurotransmitter acetylcholine (ACh) and has piqued extensive attention in discovering multifunctional cholinesterase inhibitors. To date, numerous preclinical studies demonstrate that carbamate-based cholinesterase inhibitors can prominently increase the level of ACh and improve cognition impairments and behavioral deficits, providing a privileged strategy for the treatment of AD. Based on the recent research focus on the novel cholinesterase inhibitors with multiple biofunctions, this review aims at summarizing and discussing the most recent studies excavating the potential carbamate-based MTDLs with cholinesterase inhibition efficacy, to accelerate the pace of pleiotropic cholinesterase inhibitors for coping AD.

Discovery of carbamate-based N-salicyloyl tryptamine derivatives as novel pleiotropic agents for the treatment of Alzheimer's disease

In this work, based on the potential anti-AD molecule previously studied by our group, we continue to introduce different substituents at different positions to improve both drug-like properties and on target activities. 33 N-salicyloyl tryptamine-carbamate hybrids were designed, synthesized and evaluated as cholinesterase inhibitors. H327 was the most potent BChE inhibitor (eqBChE IC₅₀ = 0.057 ± 0.005 μM), and showed threefold improved inhibitory potency than the positive drug rivastigmine (eqBChE IC₅₀ = 0.19 ± 0.001 μM). In addition, H327 as a pseudo-irreversible BChE inhibitor was endowed with neuroprotective, antioxidative and anti-neuroinflammatory properties. Cytotoxicity and acute toxicity tests confirmed the safety of compound H327. The pharmacokinetics study showed that compound H327 had a longer T_1/2 time and higher bioavailability than the lead compound 1 g. Compound H327 was able to cross the blood-brain barrier (BBB) in vivo. Moreover, the behavioral tests showed that compound H327 could significantly improve scopolamine-induced cognitive impairment in vivo. Overall, these results demonstrated that compound H327 is a promising multi-target agent for the treatment of AD.