Multi-targeted ChEI-copper chelating molecules as neuroprotective agents

Role of copper chelating agents: between old applications and new perspectives in neuroscience

The role of copper element has been an increasingly relevant topic in recent years in the fields of human and animal health, for both the study of new drugs and innovative food and feed supplements. This metal plays an important role in the central nervous system, where it is associated with glutamatergic signaling, and it is widely involved in inflammatory processes. Thus, diseases involving copper (II) dyshomeostasis often have neurological symptoms, as exemplified by Alzheimer's and other diseases (such as Parkinson's and Wilson's diseases). Moreover, imbalanced copper ion concentrations have also been associated with diabetes and certain types of cancer, including glioma. In this paper, we propose a comprehensive overview of recent results that show the importance of these metal ions in several pathologies, mainly Alzheimer's disease, through the lens of the development and use of copper chelators as research compounds and potential therapeutics if included in multi-target hybrid drugs. Seeing how copper homeostasis is important for the well-being of animals as well as humans, we shortly describe the state of the art regarding the effects of copper and its chelators in agriculture, livestock rearing, and aquaculture, as ingredients for the formulation of feed supplements as well as to prevent the effects of pollution on animal productions.

Copper and cuproptosis: new therapeutic approaches for Alzheimer's disease

Copper (Cu) plays a crucial role as a trace element in various physiological processes in humans. Nonetheless, free copper ions accumulate in the brain over time, resulting in a range of pathological changes. Compelling evidence indicates that excessive free copper deposition contributes to cognitive decline in individuals with Alzheimer's disease (AD). Free copper levels in the serum and brain of AD patients are notably elevated, leading to reduced antioxidant defenses and mitochondrial dysfunction. Moreover, free copper accumulation triggers a specific form of cell death, namely copper-dependent cell death (cuproptosis). This article aimed to review the correlation between copper dysregulation and the pathogenesis of AD, along with the primary pathways regulating copper homoeostasis and copper-induced death in AD. Additionally, the efficacy and safety of natural and synthetic agents, including copper chelators, lipid peroxidation inhibitors, and antioxidants, were examined. These treatments can restore copper equilibrium and prevent copper-induced cell death in AD cases. Another aim of this review was to highlight the significance of copper dysregulation and promote the development of pharmaceutical interventions to address it.

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.

New thiourea and benzamide derivatives of 2-aminothiazole as multi-target agents against Alzheimer's disease: Design, synthesis, and biological evaluation

In this study, two series of compounds were designed and synthesized, bearing thiourea and benzamide derivatives at position 2 of 4-subtituted-2-aminothiazole, respectively. Then, the inhibition potency of all final compounds for cholinesterase enzymes were evaluated. Among the thiourea derivatives, 3c (IC50 = 0.33 μM) was identified as the most potent and selective butyrylcholinesterase inhibitor. Additionally, benzamide derivative 10e (AChE IC50 = 1.47 and BChE IC50 = 11.40 μM) was found as a dual cholinesterase inhibitor. The type of inhibition for both compounds was determined by kinetic studies and the results showed that the compounds were mixed type inhibitors. Moreover, all title compounds were investigated in terms of their antioxidant (DPHH, ORAC) and metal chelator activities. In addition, the neuroprotective effects of selected compounds (3c, 3e, 6c, 6e and 10e) against H₂O₂-induced damage in the PC12 cell line were tested. The experimental findings demonstrated that thiourea-derived 6e (40.4 %) and benzamide-derived 10e (37.8 %) have a neuroprotective effect of about half as ferulic acid at 10 μM. Subsequently, the cytotoxicity of selected compounds was examined by the MTT assay, and the compounds were found not to have cytotoxic effect on the PC12 cell line in 24 h. Additionally, compounds 6e and 10e were also found to be more effective in inhibiting the release of IL-1β, IL-6, TNF-α and NO compared to other selected compounds in this study.

Non-Enzymatic Antioxidants against Alzheimer's Disease: Prevention, Diagnosis and Therapy

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive memory loss and cognitive decline. Although substantial research has been conducted to elucidate the complex pathophysiology of AD, the therapeutic approach still has limited efficacy in clinical practice. Oxidative stress (OS) has been established as an early driver of several age-related diseases, including neurodegeneration. In AD, increased levels of reactive oxygen species mediate neuronal lipid, protein, and nucleic acid peroxidation, mitochondrial dysfunction, synaptic damage, and inflammation. Thus, the identification of novel antioxidant molecules capable of detecting, preventing, and counteracting AD onset and progression is of the utmost importance. However, although several studies have been published, comprehensive and up-to-date overviews of the principal anti-AD agents harboring antioxidant properties remain scarce. In this narrative review, we summarize the role of vitamins, minerals, flavonoids, non-flavonoids, mitochondria-targeting molecules, organosulfur compounds, and carotenoids as non-enzymatic antioxidants with AD diagnostic, preventative, and therapeutic potential, thereby offering insights into the relationship between OS and neurodegeneration.

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.

Design, Synthesis, and In Vitro Evaluation of Novel 8-Amino-Quinoline Combined with Natural Antioxidant Acids

Overproduction of reactive oxygen species (ROS) and alterations in metallostasis are common and related hallmarks in several neurodegenerative diseases (NDDs). Nature-based derivatives always represent an attractive tool in MTDL drug design, especially against ROS in NDDs. On this notion, we designed a new series of 8-quinoline-N-substituted derivatives with a natural antioxidant portion (i.e., lipoic, caffeic, and ferulic acids). These compounds were shown to chelate copper, a metal involved in ROS-induced degeneration, and scavenger oxygen radicals in DPPH assay. Then, selected compounds 4 and 5 were evaluated in an in vitro model of oxidative stress and shown to possess cytoprotective effects in 661W photoreceptor-like cells. The obtained results may represent a starting point for the application of the proposed class of compounds in retinal neurodegenerative diseases such as retinitis pigmentosa (RP), comprising a group of hereditary rod–cone dystrophies that represent a major cause of blindness in patients of working age, where the progression of the disease is a multifactorial event, with oxidative stress contributing predominantly.

Advancements in the development of multi-target directed ligands for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial irreversible neurological disorder which results in cognitive impairment, loss of cholinergic neurons in synapses of the basal forebrain and neuronal death. Exact pathology of the disease is not yet known however, many hypotheses have been proposed for its treatment. The available treatments including monotherapies and combination therapies are not able to combat the disease effectively because of its complex pathological mechanism. A multipotent drug for AD has the potential to bind or inhibit multiple targets responsible for the progression of the disease like aggregated Aβ, hyperphosphorylated tau proteins, cholinergic and adrenergic receptors, MAO enzymes, overactivated N-methyl-d-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor etc. The traditional approach of one disease-one target-one drug has been rationalized to one drug-multi targets for the chronic diseases like AD and cancer. Thus, over the last decade research focus has been shifted towards the development of multi target directed ligands (MTDLs) which can simultaneously inhibit multiple targets and stop or slow the progression of the disease. The MTDLs can be more effective against AD and eliminate any possibility of drug-drug interactions. Many important active pharmacophore units have been fused, merged or incorporated into different scaffolds to synthesize new potent drugs. In the current article, we have described various hypothesis for AD and effectiveness of the MTDLs treatment strategy is discussed in detail. Different chemical scaffolds and their synthetic strategies have been described and important functionalities are identified in the chemical scaffold that have the potential to bind to the multiple targets. The important leads identified in this study with MTDL characteristics have the potential to be developed as drug candidates for the effective treatment of AD.

Synthesis of New 3-Arylcoumarins Bearing N-Benzyl Triazole Moiety: Dual Lipoxygenase and Butyrylcholinesterase Inhibitors With Anti-Amyloid Aggregation and Neuroprotective Properties Against Alzheimer’s Disease

A novel series of coumarin derivatives linked to the N-benzyl triazole group were synthesized and evaluated against 15-lipoxygenase (15-LOX), and acetyl- and butyrylcholinesterase (AChE and BuChE) to find the most potent derivative against Alzheimer’s disease (AD). Most of the compounds showed weak to moderate activity against ChEs. Among the most active BuChE and 15-LOX inhibitors, 8l and 8n exhibited an excellent neuroprotective effect, higher than the standard drug (quercetin) on the PC12 cell model injured by H2O2 and significantly reduced aggregation of amyloid Aβ1-42, with potencies of 1.44 and 1.79 times higher than donepezil, respectively. Compound 8l also showed more activity than butylated hydroxytoluene (BHT) as the reference antioxidant agent in reducing the levels of H2O2 activated by amyloid β in BV2 microglial cells. Kinetic and ligand–enzyme docking studies were also performed for better understanding of the mode of interaction between the best BuChE inhibitor and the enzyme. Considering the acceptable BuChE and 15-LOX inhibition activities as well as significant neuroprotection, and anti-amyloid aggregation activities, 8l and 8n could be considered as potential MTDLs for further modification and studies against AD.

A Novel Cu(II)-Binding Peptide Identified by Phage Display Inhibits Cu2+-Mediated Aβ Aggregation

Copper (Cu) has been implicated in the progression of Alzheimer’s disease (AD), and aggregation of Cu and amyloid β peptide (Aβ) are considered key pathological features of AD. Metal chelators are considered to be potential therapeutic agents for AD because of their capacity to reduce metal ion-induced Aβ aggregation through the regulation of metal ion distribution. Here, we used phage display technology to screen, synthesize, and evaluate a novel Cu(II)-binding peptide that specifically blocked Cu-triggered Aβ aggregation. The Cu(II)-binding peptide (S-A-Q-I-A-P-H, PCu) identified from the phage display heptapeptide library was used to explore the mechanism of PCu inhibition of Cu²⁺-mediated Aβ aggregation and Aβ production. In vitro experiments revealed that PCu directly inhibited Cu²⁺-mediated Aβ aggregation and regulated copper levels to reduce biological toxicity. Furthermore, PCu reduced the production of Aβ by inhibiting Cu²⁺-induced BACE1 expression and improving Cu(II)-mediated cell oxidative damage. Cell culture experiments further demonstrated that PCu had relatively low toxicity. This Cu(II)-binding peptide that we have identified using phage display technology provides a potential therapeutic approach to prevent or treat AD.

Discovery of a novel small molecule PT109 with multi-targeted effects against Alzheimer's disease in vitro and in vivo

Alzheimer's disease (AD), which is characterized by impairment of cognitive functions, is a chronic neurodegenerative disease that mainly affects the elderly. Currently available anti-AD drugs can only offer limited symptom-relieving effects. "One-compound-Multitargeted Strategy" have been recognized as the promising way to win the war against AD. Herein we report a potential anti-AD agent PT109 with multi-functions. First, an 81-kinase screening was carried out and results showed that PT109 potently inhibited c-Jun N-terminal kinases and Serum and glucocorticoid-inducible kinase 1, which are the important signaling molecules involved in neurogenesis, neuroprotection and neuroinflammation and mildly inhibit glycogen synthase kinase-3β as well as protein kinase C gamma, both are involved in AD pathological processes. In addition, invitro studies of immunofluorescent staining and Western blot showed that PT109 might promote the neurogenesis of C17.2 cells and induce synaptogenesis in primary cultured rat hippocampal neurons. We detected and confirmed the neuroprotective effect of PT109 in cultured HT22 cells by MTT assay, dehydrogenase assay, glutathione assay and reactive oxygen species assay. Furthermore, the results of Western blot, ELISA assay and immunofluorescent staining indicated that PT109 attenuated lipopolysaccharide-induced inflammation in BV2 cells and primary astrocytes. The results of Morris water maze and Step-through test indicated that PT109 improved the spatial learning ability in APP/PS1 mice. More importantly, the invivo pharmacokinetic parameters indicated that PT109 had better medicinal properties. Taken together, our findings suggest that PT109 may be a promising candidate for treating AD through multiple targets although further studies are ought to be conducted.

Development of novel N-(6-methanesulfonyl-benzothiazol-2-yl)-3-(4-substituted-piperazin-1-yl)-propionamides with cholinesterase inhibition, anti-β-amyloid aggregation, neuroprotection and cognition enhancing properties for the therapy of Alzheimer's disease

A novel series of benzothiazole–piperazine hybrids were rationally designed, synthesized, and evaluated as multifunctional ligands against Alzheimer's disease (AD). The synthesized hybrid molecules illustrated modest to strong inhibition of acetylcholinesterase (AChE) and Aβ_1-42 aggregation. Compound 12 emerged as the most potent hybrid molecule exhibiting balanced functions with effective, uncompetitive and selective inhibition against AChE (IC₅₀ = 2.31 μM), good copper chelation, Aβ_1-42 aggregation inhibition (53.30%) and disaggregation activities. Confocal laser scanning microscopy and TEM analysis also validate the Aβ fibril inhibition ability of this compound. Furthermore, this compound has also shown low toxicity and is capable of impeding loss of cell viability elicited by H₂O₂ neurotoxicity in SHSY-5Y cells. Notably, compound 12 significantly improved cognition and spatial memory against scopolamine-induced memory deficit in a mouse model. Hence, our results corroborate the multifunctional nature of novel hybrid molecule 12 against AD and it may be a suitable lead for further development as an effective therapeutic agent for therapy in the future.

A novel series of benzothiazole–piperazine hybrids were rationally designed, synthesized, and evaluated as multifunctional ligands against Alzheimer's disease (AD).

1-Benzylpyrrolidine-3-amine-based BuChE inhibitors with anti-aggregating, antioxidant and metal-chelating properties as multifunctional agents against Alzheimer's disease

Complex pathomechanism of Alzheimer's disease (AD) prompts researchers to develop multifunctional molecules in order to find effective therapy against AD. We designed and synthesized novel multifunctional ligands for which we assessed their activities towards butyrylcholinesterase, beta secretase, amyloid beta (Aβ) and tau protein aggregation as well as antioxidant and metal-chelating properties. All compounds showed dual anti-aggregating properties towards Aβ and tau protein in the in cellulo assay in Escherichia coli. Of particular interest are compounds 24b and 25b, which efficiently inhibit aggregation of Aβ and tau protein at 10 μM (24b: 45% for Aβ, 53% for tau; 25b: 49% for Aβ, 54% for tau). They display free radical scavenging capacity and antioxidant activity in ABTS and FRAP assays, respectively, and selectively chelate copper ions. Compounds 24b and 25b are also the most potent inhibitors of BuChE with IC₅₀ of 2.39 μM and 1.94 μM, respectively. Promising in vitro activities of the presented multifunctional ligands as well as their original scaffold are a very interesting starting point for further research towards effective anti-AD treatment.

Design and synthesis of H2S-donor hybrids: A new treatment for Alzheimer's disease?

Hydrogen sulphide (H₂S) is an endogenous gasotransmitter, largely known as a pleiotropic mediator endowed with antioxidant, anti-inflammatory, pro-autophagic, and neuroprotective properties. Moreover, a strong relationship between H₂S and aging has been recently identified and consistently, a significant decline of H₂S levels has been observed in patients affected by Alzheimer's disease (AD). On this basis, the use of H₂S-donors could represent an exciting and intriguing strategy to be pursued for the treatment of neurodegenerative diseases (NDDs). In this work, we designed a small series of multitarget molecules combining the rivastigmine-scaffold, a well-established drug already approved for AD, with sulforaphane (SFN) and erucin (ERN), two natural products deriving from the enzymatic hydrolysis of glucosinolates contained in broccoli and rocket, respectively, endowed both with antioxidant and neuroprotective effects. Notably, all new synthetized hybrids exhibit a H₂S-donor profile in vitro and elicit protective effects in a model of LPS-induced microglia inflammation. Moreover, a decrease in NO production has been observed in LPS-stimulated cells pre-treated with the compounds. Finally, the compounds showed neuroprotective and antioxidant activities in human neuronal cells. The most interesting compounds have been further investigated to elucidate the possible mechanism of action.