Synthesis and Evaluation of Chroman-4-One Linked to N-Benzyl Pyridinium Derivatives as New Acetylcholinesterase Inhibitors

Design, synthesis, and evaluation of dual-target inhibitors for the treatment of Alzheimer's disease

Aβ1-42 and acetylcholinesterase (AChE) are two key therapeutic targets for Alzheimer's disease (AD). The purpose of this study is to develop a dual-target inhibitor that inhibits both of these targets by fusing the chemical structure of baicalein and donepezil. Among them, we modified the structure of baicalein to arylcoumarin, synthesized three kinds of structural compounds, and evaluated their biological activities. The results showed that compound 3b had the strongest inhibitory effect on AChE (IC50 = 0.05 ± 0.02 µM), which was better than those of donepezil and baicalein. In addition, compound 3b has a strong ability to inhibit the aggregation of Aβ1-42 and protect nerve cells, and it can also penetrate the blood-brain barrier well. Using a zebrafish behavioral analyzer test, it was found that compound 3b can alleviate the behavioral effects of AlCl3-induced zebrafish larval movement retardation, which has a certain guiding significance for simulating the movement disorders of AD patients. In summary, compound 3b is expected to become a multifunctional agent for treating and alleviating the symptoms of AD patients.

Grid-Type Quaternary Metallosupramolecular Compounds Inhibit Human Cholinesterases through Dynamic Multivalent Interactions

We report the implementation of coordination complexes containing two types of cationic moieties, i. e. pyridinium and ammonium quaternary salt, as potential inhibitors of human cholinesterase enzymes. Utilization of ligands containing NNO-coordination site and binding zinc metal ion allowed mono- and tetra-nuclear complexes to be obtained with corner and grid structural type, respectively, thus affecting the overall charge of the compounds (from +1 to +8). We were able to examine for the first time the multivalency effect of metallosupramolecular species on their inhibitory abilities towards acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Importantly, resolution of the crystal structures of the obtained enzyme-substrate complexes provided a better understanding of the inhibition process at the molecular level.

Recent developments in the design and synthesis of benzylpyridinium salts: Mimicking donepezil hydrochloride in the treatment of Alzheimer's disease

Background: Alzheimer's disease (AD) is an advanced and irreversible degenerative disease of the brain, recognized as the key reason for dementia among elderly people. The disease is related to the reduced level of acetylcholine (ACh) in the brain that interferes with memory, learning, emotional, and behavior responses. Deficits in cholinergic neurotransmission are responsible for the creation and progression of numerous neurochemical and neurological illnesses such as AD. Aim: Herein, focusing on the fact that benzylpyridinium salts mimic the structure of donepezil hydrochlorideas a FDA-approved drug in the treatment of AD, their synthetic approaches and inhibitory activity against cholinesterases (ChEs) were discussed. Also, molecular docking results and structure-activity relationship (SAR) as the most significant concept in drug design and development were considered to introduce potential lead compounds. Key scientific concepts: AChE plays a chief role in the end of nerve impulse transmission at the cholinergic synapses. In this respect, the inhibition of AChE has been recognized as a key factor in the treatment of AD, Parkinson's disease, senile dementia, myasthenia gravis, and ataxia. A few drugs such as donepezil hydrochloride are prescribed for the improvement of cognitive dysfunction and memory loss caused by AD. Donepezil hydrochloride is a piperidine-containing compound, identified as a well-known member of the second generation of AChE inhibitors. It was established to treat AD when it was assumed that the disease is associated with a central cholinergic loss in the early 1980s. In this review, synthesis and anti-ChE activity of a library of benzylpyridinium salts were reported and discussed based on SAR studies looking for the most potent substituents and moieties, which are responsible for inducing the desired activity even more potent than donepezil. It was found that linking heterocyclic moieties to the benzylpyridinium salts leads to the potent ChE inhibitors. In this respect, this review focused on the recent reports on benzylpyridinium salts and addressed the structural features and SARs to get an in-depth understanding of the potential of this biologically improved scaffold in the drug discovery of AD.

Chalcone and its analogs: Therapeutic and diagnostic applications in Alzheimer's disease

Chalcone [(E)-1,3-diphenyl-2-propene-1-one], a small molecule with α, β unsaturated carbonyl group is a precursor or component of many natural flavonoids and isoflavonoids. It is one of the privileged structures in medicinal chemistry. It possesses a wide range of biological activities encouraging many medicinal chemists to study this scaffold for its usefulness to oncology, infectious diseases, virology and neurodegenerative diseases including Alzheimer's disease (AD). Small molecular size, convenient and cost-effective synthesis, and flexibility for modifications to modulate lipophilicity suitable for blood brain barrier (BBB) permeability make chalcones a preferred candidate for their therapeutic and diagnostic potential in AD. This review summarizes and highlights the importance of chalcone and its analogs as single target small therapeutic agents, multi-target directed ligands (MTDLs) as well as molecular imaging agents for AD. The information summarized here will guide many medicinal chemist and researchers involved in drug discovery to consider chalcone as a potential scaffold for the development of anti-AD agents including theranostics.

Anticholinesterase Activity of Cinnamic Acids Derivatives: In Vitro, In Vivo Biological Evaluation, and Docking Study

Background:

Acetylcholine deficiency in the hippocampus and cortex, aggregation of amyloid-beta, and beta-secretase overactivity have been introduced as the main reasons in the formation of Alzheimer’s disease.

Objective:

A new series of cinnamic derived acids linked to 1-benzyl-1,2,3-triazole moiety were designed, synthesized, and evaluated for their acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activities.

Methods:

Colorimetric Ellman’s method was used for the determination of IC50% of AchE and BuChE inhibitory activity. The kinetic studies, neuroprotective activity, BACE1 inhibitory activity, evaluation of inhibitory potency on Aβ1-42 self-aggregation induced by AchE, and docking study were performed for studying the mechanism of action.

Results:

Some of the synthesized compounds, compound 7b-4 ((E)-3-(3,4-dimethoxyphenyl)-N-((1- (4-fluorobenzyl)-1H-1,2,3-triazole-4-yl) methyl) acrylamide) depicted the most potent acetylcholinesterase inhibitory activities ( IC50 = 5.27 μM ) and compound 7a-1 (N- ( (1- benzyl- 1H- 1, 2, 3- triazole - 4-yl) methyl) cinnamamide) demonstrated the most potent butyrylcholinesterase inhibitory activities (IC50 = 1.75 μM). Compound 7b-4 showed neuroprotective and β-secretase (BACE1) inhibitory activitiy. In vivo studies of compound 7b-4 in Scopolamine-induced dysfunction confirmed memory improvement.

Conculusion:

It should be noted that molecular modeling (compounds 7b-4 and 7a-1) and kinetic studies (compounds 7a-1 and 7b-4) showed that these synthesis compounds interacted simultaneously with both the catalytic site (CS) and peripheral anionic site (PAS) of AChE and BuChE.

Design, Synthesis, In vitro Cytotoxic Activity Evaluation, and Study of Apoptosis Inducing Effect of New Styrylimidazo[1,2-a]Pyridines as Potent Anti-Breast Cancer Agents

BACKGROUND

This paper reports synthesis, cytotoxic activity, and apoptosis inducing effect of a novel series of styrylimidazo[1,2-a]pyridine derivatives.

OBJECTIVE

In this study, anti-cancer activity of novel styrylimidazo[1,2-a]pyridines was evaluated.

METHODS

Styrylimidazo[1,2-a]pyridine derivatives 4a-o were synthesized through a one-pot three-component reaction of 2-aminopyridines, cinnamaldehydes, and isocyanides in high yield. All synthesized compounds 4a-o were evaluated against breast cancer cell lines including MDA-MB-231, MCF-7, and T-47D using MTT assay. Apoptosis was evaluated by acridine orange/ethidium bromide staining, cell cycle analysis, and TUNEL assay as the mechanism of cell death.

RESULTS

Most of the synthesized compounds exhibited more potent cytotoxicity than standard drug, etoposide. Induction of apoptosis by the most cytotoxic compounds 4f, 4g, 4j, 4n, and 4m was confirmed through mentioned methods.

CONCLUSION

In conclusion, these results confirmed the potency of styrylimidazo[1,2-a]pyridines for further drug discovery developments in the field of anti-cancer agents.

Pyrano[3,2-c]quinoline Derivatives as New Class of α-glucosidase Inhibitors to Treat Type 2 Diabetes: Synthesis, in vitro Biological Evaluation and Kinetic Study

BACKGROUND

Pyrano[3,2-c]quinoline derivatives 6a-n were synthesized via simple two-step reactions and evaluated for their in vitro α-glucosidase inhibitory activity.

METHODS

Pyrano[3,2-c]quinoline derivatives 6a-n derivatives were prepared from a two-step reaction: cycloaddition reaction between 1-naphthyl amine 1 and malonic acid 2 to obtain benzo[h]quinoline-2(1H)-one 3 and reaction of 3 with aryl aldehydes 4 and Meldrum's acid 5. The anti- α-glucosidase activity and kinetic study of the synthesized compounds were evaluated using α-glucosidase from Saccharomyces cerevisiae and p-nitrophenyl-a-D-glucopyranoside as substrate. The α-glucosidase inhibitory activity of acarbose was evaluated as positive control.

RESULTS

All of the synthesized compounds, except compounds 6i and 6n, showed more inhibitory activity than the standard drug acarbose and were also found to be non-cytotoxic. Among the synthesized compounds, 1-(2-bromophenyl)-1H-benzo[h]pyrano[3,2-c]quinoline-3,12(2H,11H)-dione 6e displayed the highest α-glucosidase inhibitory activity (IC50 = 63.7 ± 0.5 µM). Kinetic study of enzyme inhibition indicated that the most potent compound, 6e, is a non-competitive inhibitor of α-glucosidase with a Ki value of 72 µM. Additionally, based on the Lipinski rule of 5, the synthesized compounds were found to be potential orally active drugs.

CONCLUSION

Our results suggest that the synthesized compounds are promising candidates for treating type 2 diabetes.

Novel cinnamic acid-tryptamine hybrids as potent butyrylcholinesterase inhibitors: Synthesis, biological evaluation, and docking study

A novel series of cinnamic acid-tryptamine hybrids was designed, synthesized, and evaluated as cholinesterase inhibitors. Anticholinesterase assays showed that all of the synthesized compounds displayed a clearly selective inhibition of butyrylcholinesterase (BChE), but only a moderate inhibitory effect toward acetylcholinesterase (AChE) was detected. Among these cinnamic acid-tryptamine hybrids, compound 7d was found to be the most potent inhibitor of BChE with an IC₅₀ value of 0.55 ± 0.04 μM. This compound showed a 14-fold higher inhibitory potency than the standard drug donepezil (IC₅₀  = 7.79 ± 0.81 μM) and inhibited BChE through a mixed-type inhibition mode. Moreover, a docking study revealed that compound 7d binds to both the catalytic anionic site (CAS) and the peripheral anionic site (PAS) of BChE. Also, compound 7d was evaluated against β-secretase, which exhibited low activity (inhibition percentage: 38%).

Design, Synthesis and In vitro Cytotoxicity of New 1,2,3-triazol- and Nitrostyrene Hybrids as Potent Anticancer Agents

Background:

A new series of 1,2,3-triazol-nitrostyrene derivatives was designed, synthesized, and evaluated for cytotoxic activity against Hep-2 and L929 cell lines. </P><P> Methods: The synthetic procedure started from the functionalization of 4-hydroxybenzaldehyde with propargyl bromide and a subsequent click reaction to give 1,2,3-triazole derivatives. Then, the reaction of the mentioned derivatives with nitromethane led to the formation of the title compounds in excellent yields.

Results:

Most of the compounds exhibited better cytotoxic activity with respect to the standard drug 5-fluorouracil. Among them, (E)-1-(3,4-dichlorobenzyl)-4-((4-(2-nitrovinyl)phenoxy)methyl)-1H- 1,2,3-triazole 6i (IC50 = 4.66 &#177; 1.3 &#181;M) against the Hep-2 cell line and (E)-1-(2,3-dichlorobenzoyl)- 4-((4-(2-nitrovinyl)phenoxy)methyl)-1H-1,2,3-triazole 6g (IC50 = 5.18 &#177; 0.8 &#181;M) against the L929 cell line exhibited the best cytotoxic effects.

Conclusion:

Moreover, the acridine orange/ethidium bromide double staining technique showed that the most potent compounds 6i and 6g could induce apoptosis in studied cancer cell lines.

Biology-Oriented Drug Synthesis (BIODS) Approach towards Synthesis of Ciprofloxacin-Dithiocarbamate Hybrids and Their Antibacterial Potential both in Vitro and in Silico

A novel series of ciprofloxacin-dithiocarbamate hybrids 7a - 7l were designed, synthesized, and evaluated against Gram-positive and Gram-negative bacteria. A significant part of the title compounds showed considerable antibacterial activity against Gram-positive species. The most potent compound against Gram-positive bacteria was 2-chloro derivative 7h and the most potent derivative against Gram-negative bacteria was 3-chloro compound 7i. In vitro antibacterial evaluation of compound 7h against clinically isolated bacteria methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) showed that this compound acted better than ciprofloxacin against the latter bacteria. Docking study of compound 7h in the active site of S. aureus DNA gyrase revealed that this ciprofloxacin-dithiocarbamate derivative interacted with the main components of the active site of the enzyme.

Novel tetrahydrocarbazole benzyl pyridine hybrids as potent and selective butryl cholinesterase inhibitors with neuroprotective and β-secretase inhibition activities

Butyrylcholinesterase (BuChE) inhibitors have become interesting target for treatment of Alzheimer's disease (AD). A series of dual binding site BuChE inhibitors were designed and synthesized based on 2,3,4,9-tetrahydro-1H-carbazole attached benzyl pyridine moieties. In-vitro assay revealed that all of the designed compounds were selective and potent BuChE inhibitors. The most potent BuChE inhibitor was compound 6i (IC₅₀ = 0.088 ± 0.0009 μM) with the mixed-type inhibition. Docking study revealed that 6i is a dual binding site BuChE inhibitor. Also, Pharmacokinetic properties for 6i were accurate to Lipinski's rule. In addition, compound 6i demonstrated neuroprotective and β-secretase (BACE1) inhibition activities. This compound could also inhibit AChE-induced and self-induced Aβ peptide aggregation at concentration of 100 μM and 10 μM respectively. Generally, the results are presented as new potent selective BuChE inhibitors with a therapeutic potential for the treatment of AD.

Design, synthesis, molecular modeling and anticholinesterase activity of benzylidene-benzofuran-3-ones containing cyclic amine side chain

Aim: A series of 2-benzylidene-benzofuran-3-ones were designed from the structures of Ebselen analogs and aurone derivatives and synthesized in good yields. Materials & methods: The target compounds were prepared by the condensation reaction between appropriate benzofuranones with amino alkoxy aldehydes and evaluated as cholinesterase inhibitors by Ellman’s method. Results: The in vitro anti-acetylcholinesterase (AChE)/butyrylcholinesterase activities of the synthesized compounds revealed that 7e (IC50 = 0.045 μM) is the most active compound against AChE. Furthermore, the docking study confirmed the results obtained through in vitro experiments and predicted the possible binding conformation. Conclusion: The anticholinesterase activities of benzylidene-benzofurane-3-ones as aurone analogs revealed that the compounds bearing piperidinylethoxy residue showed better activities against AChE, introducing these compounds for further drug discovery developments.

[Formula: see text]