Cholinesterase Inhibitors Research Articles

Anticholinergic co-prescribing in nursing home residents using cholinesterase inhibitors: Potential deprescribing cascade.

Polypharmacy may result from inappropriate prescribing of medications to treat adverse drug reactions (ADRs), i.e., "prescribing cascade." A potentially harmful prescribing cascade affecting those with severe dementia can result when anticholinergics are prescribed to manage side effects of cholinesterase inhibitors (ChEIs). We investigated 1) factors associated with co-prescribing of anticholinergics and ChEIs and 2) whether discontinuation of ChEIs was associated with subsequent discontinuation of anticholinergics-a potentially beneficial reversal or "deprescribing cascade." We conducted a retrospective analysis of linked Medicare Part A/B/D claims, Master Beneficiary Summary File, Minimum Data Set, Area Health Resource File, and Nursing Home Compare from 2015 to 2016. Subjects were Medicare beneficiaries residing in nursing homes, ≥65 years old with severe dementia admitted for non-skilled stays, who were prescribed ChEIs. Cross-sectional analysis evaluated factors associated with co-prescribing of anticholinergics with ChEIs. Longitudinal Cox proportional hazards regression examined whether discontinuation of ChEIs was associated with subsequent discontinuation of anticholinergics over a 1-year period. We found 15% of our sample experienced co-prescribing of anticholinergics and ChEIs. Several resident and facility-level factors were associated with co-prescribing anticholinergics. Advancing age, minority race or ethnicity, end-stage renal disease, heart failure, and poor appetite were associated with a decreased likelihood of co-prescribing. Female sex, polypharmacy, and non-geriatric prescriber-type were associated with a higher likelihood of co-prescribing. In longitudinal analyses, we observed that discontinuation of ChEIs was associated with a reduced likelihood (HR 0.58 [95% CI, 0.47-0.71]) of discontinuing any medications with anticholinergic properties, except for bladder antimuscarinics (HR 1.32 [95% CI, 0.83-2.09]). Younger, healthier older adults with dementia were more likely to experience co-prescribing anticholinergics and ChEIs. Discontinuation of anticholinergics was infrequent. Further research is needed to understand prescribers' ability to recognize and reverse potential prescribing cascades through deprescribing.

Monitoring the Activity and Inhibition of Cholinesterase Enzymes using Single-Walled Carbon Nanotube Fluorescent Sensors.

Cholinesterase enzymes are involved in a wide range of bodily functions, and their disruption is linked to pathologies such as neurodegenerative diseases and cancer. While cholinesterase inhibitors are used as drug treatments for diseases such as Alzheimer and dementia at therapeutic doses, acute exposure to high doses, found in pesticides and nerve agents, can be lethal. Therefore, measuring cholinesterase activity is important for numerous applications ranging from the search for novel treatments for neurodegenerative disorders to the on-site detection of potential health hazards. Here, we present the development of a near-infrared (near-IR) fluorescent single-walled carbon nanotube (SWCNT) optical sensor for cholinesterase activity and demonstrate the detection of both acetylcholinesterase and butyrylcholinesterase, as well as their inhibition. We show sub U L–1 sensitivity, demonstrate the optical response at the level of individual nanosensors, and showcase an optical signal output in the 900–1400 nm range, which overlaps with the biological transparency window. To the best of our knowledge, this is the longest wavelength cholinesterase activity sensor reported to date. Our near-IR fluorescence-based approach opens new avenues for spatiotemporal-resolved detection of cholinesterase activity, with numerous applications such as advancing the research of the cholinergic system, detecting on-site potential health hazards, and measuring biomarkers in real-time.

Anti-cholinergic drug burden in patients with dementia increases after hospital admission: a multicentre cross-sectional study

BackgroundAnticholinergic medications are drugs that block cholinergic transmission, either as their primary therapeutic action or as a secondary effect. Patients with dementia may be particularly sensitive to the central effects of anticholinergic drugs. Anticholinergics also antagonise the effects of the main dementia treatment, cholinesterase inhibitors. Our study aimed to investigate anticholinergic prescribing for dementia patients in UK acute hospitals before and after admission.MethodsWe included 352 patients with dementia from 17 UK hospital sites in 2019. They were all inpatients on surgical, medical or Care of the Elderly wards. Information about each patient’s medications were collected using a standardised form, and the anticholinergic drug burden of each patient was calculated with an evidence-based online calculator. Wilcoxon’s rank test was used to look at the correlation between two subgroups upon admission and discharge.ResultsOn admission to hospital, 37.8% of patients had an anticholinergic burden score ≥ 1 and 5.68% ≥3. On discharge, 43.2% of patients with an anticholinergic burden score ≥ 1 and 9.1% ≥3. The increase in scores was statistically significant (p = 0.001). Psychotropics were the most common group of anticholinergic medications prescribed at discharge. Of those patients taking cholinesterase inhibitors, 44.9% were also prescribed anticholinergic medications.ConclusionsOur cross-sectional, multicentre study found that people with dementia are commonly prescribed anticholinergic medications, even if concurrently taking cholinesterase inhibitors, and are significantly more likely to be discharged from hospital with a higher anticholinergic burden than on admission.

Synthesis and Characterization of Copper-Nanoflowers with the Utilization of Medicinal Plant Extracts for Enhanced Various Enzyme Inhibitory Activities.

In this study, organic-inorganic hybrid nanoflowers were synthesized using methanolic extracts of the medicinal plants Ajuga chamaepitys subsp. chia var. chia, Achillea wilhelmsii, Bongardia chrysogonum, Malva sylvestris, Phlomis grandiflora var. grandiflora, Verbascum sp. together with copper ions (Cu2+ ). The synthesized plant extract based-inorganic hybrid nanoflowers (PE-ihNFs) of A. chamaepitys subsp. chia var. chia (Ac-ihNFs), A. wilhelmsii (Aw-ihNfs), B. chrysogonum (Bc-ihNFs), M. sylvestris (Ms-ihNFs) P. grandiflora var. grandiflora (Pg-ihNFs), and Verbascum sp. (Vs-ihNFs) were characterized by Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX), Fourier transform infrared spectrometry (FTIR), and X-Ray Diffraction (XRD). Also, several enzymes were selected to evaluate the enzyme inhibition activities of the synthesized PE-ihNFs. For the first-time, enzymes, tyrosinase, α-amylase and α-glucosidase, acetyl and butyryl cholinesterase inhibition activities of the PE-ihNFs with comparison to their plain plant extracts were evaluated in vitro. Results show that the among all the analyzed PE-ihNFs, demonstrated better α-glucosidase & α-amylase enzyme inhibition activity compared to the plain extracts. These initial studies are promising for the synthesis of these hybrid nanoflowers containing medicinal plant extracts, which might have commercial applications in the pharmaceutical and dermo-cosmetics industries.

A genetic screen for aldicarb resistance of Caenorhabditiselegans dauer larvae uncovers 2 alleles of dach-1, a cytochrome P450 gene.

Animals exhibit phenotypic plasticity through the interaction of genes with the environment, and little is known about the genetic factors that change synaptic function at different developmental stages. Here, we investigated the genetic determinants of how animal's sensitivity to drugs that alter synaptic activity is regulated at a specific developmental stage using the free-living nematode Caenorhabditis elegans. C. elegans enters the stress-resistant dauer larval stage under harsh conditions. Although dauer is known to have reduced permeability and increased resistance to most known exogenous chemicals, we discovered that dauer is hypersensitive to a cholinesterase inhibitor, aldicarb. To investigate genes regulating dauer-specific acetylcholine transduction, we first screened for aldicarb-resistant mutations in dauer and then performed a secondary screen to rule out aldicarb-resistant mutations that also affect adults. We isolated 2 different mutations of a single gene called cyp-34A4 or dach-1 encoding a cytochrome P450. In the nondauer stages, dach-1 is mainly expressed in the intestine, but its expression is robustly increased in the epidermis of dauers. By tissue-specific rescue experiments, we found that dach-1 modulates aldicarb sensitivity in a cell nonautonomous manner. In addition, dach-1 plays pleiotropic functions in dauers by regulating quiescence and surviving heat shock and hyperosmolar stress. Our study reveals novel functions of the cytochrome P450 in synaptic and physiological changes during the developmental plasticity.

What are the effects of cholinesterase inhibitors for preventing falls in adults with Parkinson's disease?

What are the effects of cholinesterase inhibitors for preventing falls in adults with Parkinson's disease?

Changing spectrum of acute poisoning in North India: A hospital-based descriptive study.

Evaluating local trends and continued monitoring of patterns of acute poisoning are essential for prompt recognition of the toxidromes, the establishment of immediate treatment facilities (e.g., antidote availability), and effective preventive strategies (e.g., governmental regulation on hazardous substances marketing). We aimed to describe the prevalence of the various types of poisoning and associated case fatality in our academic hospital in North India. A prospective observational descriptive study was conducted, enrolling patients aged ≥13 years with acute poisoning for 17 months from December 2016 to December 2017 and from September 2019 to December 2019, for a total of 17 months. Four hundred and two patients were enrolled (median age 28 years; 63.2% males). Majority of the acute poisoning cases resulted from ingestion (n = 391, 97.3%) and the primary intention was most commonly self-harm (n = 314, 78.1%). The major types of poisoning were pesticide (n = 264, 65.7%), drug overdose (n = 77, 19.2%), and corrosive ingestion (n = 31, 7.7%). Pesticides included insecticides (n = 146, 36.3%; cholinesterase inhibitors, n = 91), fungicides (n = 76, 18.9%; all aluminum phosphide), herbicides (n = 22, 5.5%; paraquat, n = 19), and rodenticides (n = 20, 5.0%; coumarin-derived substances, n = 12). Benzodiazepines (n = 33) and opioids (n = 25) were frequent causes of drug overdose. 95.3% (n = 379) received preliminary treatment at the previous health-care center, including gastric lavage (n = 239) and antidotes (n = 73). In-hospital case fatality rate was 17.3% (n = 58). Herbicide ingestion and opioid overdose are emerging threats with a gradual decline in organophosphate and aluminum phosphide poisoning. Despite improving management of acute poisoning, the overall case fatality rate remains substantial.

Synthesis, Biological Evaluation and Machine Learning Prediction Model for Fluorinated Cinchona Alkaloid-Based Derivatives as Cholinesterase Inhibitors.

A series of 46 Cinchona alkaloid derivatives that differ in positions of fluorine atom(s) in the molecule were synthesized and tested as human acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors. All tested compounds reversibly inhibited AChE and BChE in the nanomolar to micromolar range; for AChE, the determined enzyme-inhibitor dissociation constants (Ki) ranged from 3.9–80 µM, and 0.075–19 µM for BChE. The most potent AChE inhibitor was N-(para-fluorobenzyl)cinchoninium bromide, while N-(meta-fluorobenzyl)cinchonidinium bromide was the most potent BChE inhibitor with Ki constant in the nanomolar range. Generally, compounds were non-selective or BChE selective cholinesterase inhibitors, where N-(meta-fluorobenzyl)cinchonidinium bromide was the most selective showing 533 times higher preference for BChE. In silico study revealed that twenty-six compounds should be able to cross the blood-brain barrier by passive transport. An extensive machine learning procedure was utilized for the creation of multivariate linear regression models of AChE and BChE inhibition. The best possible models with predicted R2 (CD-derivatives) of 0.9932 and R2(CN-derivatives) of 0.9879 were calculated and cross-validated. From these data, a smart guided search for new potential leads can be performed. These results pointed out that quaternary Cinchona alkaloids are the promising structural base for further development as selective BChE inhibitors which can be used in the central nervous system.

Pharmacophore based virtual screening of cholinesterase inhibitors: search of new potential drug candidates as antialzheimer agents.

Alzheimer’s disease (AD) is a distinctive medical condition characterized by loss of memory, orientation, and cognitive impairments, which is an exceptionally universal form of neurodegenerative disease. The statistical data suggested that it is the 3rd major cause of death in older persons. Butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) inhibitors play a vital role in the treatment of AD. Coumarins, natural derivatives, are reported as cholinesterase inhibitors and emerges as a promising scaffold for design of ligands targeting enzymes and pathological alterations related to AD. In this regard, the 3D QSAR pharmacophore models were developed for coumarin scaffold containing BChE and AChE inhibitors. Several 3D QSAR pharmacophore models were developed with FAST, BEST, and CEASER methods, and finally, statistically robust models (based on correlation coefficient, cost value, and RMSE value) were selected for further analysis for both targets. The important features ((HBA 1, HBA 2, HY, RA (BChE) HBA 1, HBA 2, HY, PI, (AChE)) were identified for good inhibitory activity of coumarin derivatives. Finally, the selected models were applied to various database compounds to find potential BChE and AChE inhibitors, and we found 13 for BChE and 1 potent compound for AChE with an estimated activity of IC50 < 10 µM. Further, the Lipinski filters, and ADMET analysis supports the selected compounds to become a drug candidate. These selected BChE and AChE inhibitors can be used in the treatment of AD.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s40203-022-00133-1.

Resveratrol-Maltol and Resveratrol-Thiophene Hybrids as Cholinesterase Inhibitors and Antioxidants: Synthesis, Biometal Chelating Capability and Crystal Structure.

New resveratrol–thiophene and resveratrol–maltol hybrids were synthesized as cholinesterase inhibitors and antioxidants. As with photostability experiments, biological tests also found remarkable differences in the properties and behavior of thiophene and maltol hybrids. While resveratrol–thiophene hybrids have excellent inhibitory and antioxidant properties (similar to the activity of reference drug galantamine), maltols have been proven to be weaker inhibitors and antioxidants. The molecular docking of selected active ligands gave insight into the structures of docked enzymes. It enabled the identification of interactions between the ligand and the active site of both cholinesterases. The maltols that proved to be active cholinesterase inhibitors were able to coordinate Fe3+ ion, forming complexes of 1:1 composition. Their formation constants, determined by spectrophotometry, are very similar, lgK = 11.6–12.6, suggesting that Fe3+ binds to the common hydroxy-pyranone moiety and is hardly affected by the other aromatic part of the ligand. Accordingly, the characteristic bands in their individual absorption spectra are uniformly red-shifted relative to those of the free ligands. The crystal structures of two new resveratrol–maltol hybrids were recorded, giving additional information on the molecules’ intermolecular hydrogen bonds and packing. In this way, several functionalities of these new resveratrol hybrids were examined as a necessary approach to finding more effective drugs for complicated neurodegenerative diseases.

Synthesis, biological evaluation, and molecular dynamics of novel coumarin based phosphorothioates as cholinesterase inhibitors

Inhibition of acetylcholinesterase has been validated as an effective target for treatment of Alzheimer's disease by increasing the levels of acetylcholine and improving the communication between the neuronal cells. Literature reports revealed that coumarins and phosphorothioates were shown to be promising scaffolds as acetylcholinesterase inhibitors. A series of novel chroman-4one derivative moieties (6a-6d, 7b-7d, 8–11) were synthesized with good to excellent yield by reactions of coumarin sulfonyl chlorides 1a, b with various di- and trialkylphosphites, Wittig reagents 4a-d, and the new products were evaluated for their cholinesterase (ChE) inhibitory activities. Structure–activity relationship study results showed that 7a is the most potent compound (anti AChE activity; IC50 = 0.73 μg/ ml), indicating the preference for hydrophobic interaction and Pi-stacked at the side chain of the molecule. This was supported further by molecular docking and dynamics studies of the most potent compound (7a against AChE), which revealed favored interactions with the ChE enzyme's binding pockets.

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.

Ring-fused 3β-acetoxyandrost-5-enes as novel neuroprotective agents with cholinesterase inhibitory properties

Alzheimer´s disease (AD) is an intellectual disorder caused by organic brain damage and cerebral atrophy, characterized by the loss of memory, judgment, and abstract thinking followed by declining cognitive functions, language, and the ability to perform daily living activities. Many efforts have been made to decrease the effects of the disease but also to block the neurodegenerative process. Cholinesterase inhibitors (ChEIs) are a group of medicines that act at the neurotransmission of acetylcholine, preventing its excessive breakdown and helping to improve cognitive functions in patients with AD. In this work, 16 chiral steroids, namely ring-fused 3β-acetoxyandrost-5-ene derivatives, their precursor and two 16-dehydroprogesterone-derived dioximes, were assessed as cholinesterase inhibitors and neuroprotective agents. The results demonstrated that some of the tested steroids are cholinesterase inhibitors and the majority selective for acetylcholinesterase inhibition. Albeit, one ring-fused 3β-acetoxyandrost-5-ene containing N-methylpiperidine ring (compound 2g) demonstrated to be a selective and potent inhibitor of the butyrylcholinesterase enzyme. (S)− 4,4a,5,6,7,8-(hexahydronaphthalen-2-one)-fused 3β-acetoxyandrost-5-ene (compound 6) showed high neuroprotective effect, high ability to restore the mitochondrial membrane potential from glutamate intoxication, and dramatic improvement in cell morphology. The described results provided relevant structure-activity relationship data.

Novel Morpholine-Bearing Quinoline Derivatives as Potential Cholinesterase Inhibitors: The Influence of Amine, Carbon Linkers and Phenylamino Groups.

A series of novel 4-N-phenylaminoquinoline derivatives containing a morpholine group were designed and synthesized, and their anti-cholinesterase activities and ABTS radical-scavenging activities were tested. Among them, compounds 11a, 11g, 11h, 11j, 11l, and 12a had comparable inhibition activities to reference galantamine in AChE. Especially, compound 11g revealed the most potent inhibition on AChE and BChE with IC50 values of 1.94 ± 0.13 μM and 28.37 ± 1.85 μM, respectively. The kinetic analysis demonstrated that both the compounds 11a and 11g acted as mixed-type AChE inhibitors. A further docking comparison between the 11a- and 12a-AChE complexes agreed with the different inhibitory potency observed in experiments. Besides, compounds 11f and 11l showed excellent ABTS radical-scavenging activities, with IC50 values of 9.07 ± 1.34 μM and 6.05 ± 1.17 μM, respectively, which were superior to the control, Trolox (IC50 = 11.03 ± 0.76 μM). It is worth noting that 3-aminoquinoline derivatives 12a–12d exhibited better drug-like properties.

Privileged multi-target directed propargyl-tacrines combining cholinesterase and monoamine oxidase inhibition activities

Twenty-four novel compounds bearing tetrahydroacridine and N-propargyl moieties have been designed, synthesised, and evaluated in vitro for their anti-cholinesterase and anti-monoamine oxidase activities. Propargyltacrine 23 (IC50 = 21 nM) was the most potent acetylcholinesterase (AChE) inhibitor, compound 20 (IC50 = 78 nM) showed the best inhibitory human butyrylcholinesterase (hBChE) profile, and ligand 21 afforded equipotent and significant values on both ChEs (human AChE [hAChE]: IC50 = 0.095 ± 0.001 µM; hBChE: IC50 = 0.093 ± 0.003 µM). Regarding MAO inhibition, compounds 7, 15, and 25 demonstrated the highest inhibitory potential towards hMAO-B (IC50 = 163, 40, and 170 nM, respectively). In all, compounds 7, 15, 20, 21, 23, and 25 exhibiting the most balanced pharmacological profile, were submitted to permeability and cell viability tests. As a result, 7-phenoxy-N-(prop-2-yn-1-yl)-1,2,3,4-tetrahydroacridin-9-amine hydrochloride (15) has been identified as a permeable agent that shows a balanced pharmacological profile [IC50 (hAChE) = 1.472 ± 0.024 µM; IC50 (hBChE) = 0.659 ± 0.077 µM; IC50 (hMAO-B) = 40.39 ± 5.98 nM], and consequently, as a new hit-ligand that deserves further investigation, in particular in vivo analyses, as the preliminary cell viability test results reported here suggest that this is a relatively safe therapeutic agent.

Preclinical and randomized clinical evaluation of the p38α kinase inhibitor neflamapimod for basal forebrain cholinergic degeneration

The endosome-associated GTPase Rab5 is a central player in the molecular mechanisms leading to degeneration of basal forebrain cholinergic neurons (BFCN), a long-standing target for drug development. As p38α is a Rab5 activator, we hypothesized that inhibition of this kinase holds potential as an approach to treat diseases associated with BFCN loss. Herein, we report that neflamapimod (oral small molecule p38α inhibitor) reduces Rab5 activity, reverses endosomal pathology, and restores the numbers and morphology of BFCNs in a mouse model that develops BFCN degeneration. We also report on the results of an exploratory (hypothesis-generating) phase 2a randomized double-blind 16-week placebo-controlled clinical trial (Clinical trial registration: NCT04001517/EudraCT #2019-001566-15) of neflamapimod in mild-to-moderate dementia with Lewy bodies (DLB), a disease in which BFCN degeneration is an important driver of disease expression. A total of 91 participants, all receiving background cholinesterase inhibitor therapy, were randomized 1:1 between neflamapimod 40 mg or matching placebo capsules (taken orally twice-daily if weight <80 kg or thrice-daily if weight >80 kg). Neflamapimod does not show an effect in the clinical study on the primary endpoint, a cognitive-test battery. On two secondary endpoints, a measure of functional mobility and a dementia rating-scale, improvements were seen that are consistent with an effect on BFCN function. Neflamapimod treatment is well-tolerated with no study drug associated treatment discontinuations. The combined preclinical and clinical observations inform on the validity of the Rab5-based pathogenic model of cholinergic degeneration and provide a foundation for confirmatory (hypothesis-testing) clinical evaluation of neflamapimod in DLB.

Emerging role of psychosis in Parkinson's disease: From clinical relevance to molecular mechanisms.

Parkinson’s disease (PD) is the second most common neurodegenerative disease. Psychosis is one of the common psychiatric presentations in the natural course of PD. PD psychosis is an important non-motor symptom, which is strongly correlated with a poor prognosis. Increasing attention is being given to PD psychosis. In this opinion review, we summarized and analyzed the identification, screening, epidemiology, mechanisms, risk factors, and therapeutic approaches of PD psychosis based on the current clinical evidence. PD psychosis tends to have a negative effect on patients' quality of life and increases the burden of family caregiving. Screening and identification in the early stage of disease is crucial for establishing tailored therapeutic strategies and predicting the long-term outcome. Development of PD psychosis is believed to involve a combination of exogenous and endogenous mechanisms including imbalance of neurotransmitters, structural and network changes, genetic profiles, cognitive impairment, and antiparkinsonian medications. The therapeutic strategy for PD psychosis includes reducing or ceasing the use of dopaminergic drug, antipsychotics, cholinesterase inhibitors, and non-pharmacological interventions. Ongoing clinical trials are expected to provide new insights for tailoring therapy for PD psychosis. Future research based on novel biomarkers and genetic factors may help inform individualized therapeutic strategies.

Multipotent Cholinesterase Inhibitors for the Treatment of Alzheimer's Disease: Synthesis, Biological Analysis and Molecular Docking Study of Benzimidazole-Based Thiazole Derivatives.

Twenty-four analogues of benzimidazole-based thiazoles (1–24) were synthesized and assessed for their in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory potential. All analogues were found to exhibit good inhibitory potential against cholinesterase enzymes, having IC50 values in the ranges of 0.10 ± 0.05 to 11.10 ± 0.30 µM (for AChE) and 0.20 ± 0.050 µM to 14.20 ± 0.10 µM (for BuChE) as compared to the standard drug Donepezil (IC50 = 2.16 ± 0.12 and 4.5 ± 0.11 µM, respectively). Among the series, analogues 16 and 21 were found to be the most potent inhibitors of AChE and BuChE enzymes. The number (s), types, electron-donating or -withdrawing effects and position of the substituent(s) on the both phenyl rings B & C were the primary determinants of the structure-activity relationship (SAR). In order to understand how the most active derivatives interact with the amino acids in the active site of the enzyme, molecular docking studies were conducted. The results obtained supported the experimental data. Additionally, the structures of all newly synthesized compounds were elucidated by using several spectroscopic methods like 13C-NMR, 1H-NMR and HR EIMS.

Inhibition of Cholinesterases by Benzothiazolone Derivatives

Thirteen benzothiazolone derivatives (M1–M13) were synthesized and evaluated for their inhibitory activity against cholinesterases (ChEs) and monoamine oxidases (MAOs). All the compounds inhibited ChEs more effectively than MAOs. In addition, most of the compounds showed higher inhibitory activities against butyrylcholinesterase (BChE) than acetylcholinesterase (AChE). Compound M13 most potently inhibited BChE with an IC50 value of 1.21 μM, followed by M2 (IC50 = 1.38 μM). Compound M2 had a higher selectivity index (SI) value for BChE over AChE (28.99) than M13 (4.16). The 6-methoxy indole group of M13 was expected to have a greater effect on BChE inhibitory activity than the other groups. Kinetics and reversibility tests showed that M13 was a reversible noncompetitive BChE inhibitor with a Ki value of 1.14 ± 0.21 μM. In a docking simulation, M13 is predicted to form a hydrogen bond with the backbone carbonyl group of Ser287 of BChE through its methoxy indole moiety and π−π interactions between its benzothiazolone group and the side chain of Trp82 with the five-membered pyrrole ring and with the six-membered benzene ring. From these results, it is suggested that M13 is a BChE inhibitor and a potential candidate agent for the treatment of Alzheimer’s disease.

Blood-brain barrier permeable benzylpiperidin-4-yl-linked benzylamino benzamides as dual cholinesterase inhibitors.

Alzheimer's disease (AD) is a multifaceted neurodegenerative disorder involving various pathological events. The existing options for managing the disease utterly rely on cholinesterase (ChE) inhibitors. In recent years, the dual inhibition of ChEs as a potential AD therapeutics has substantially attracted the attention of medicinal chemists. Recently, we reported benzyl piperidinyl-linked methoxy-naphthamides as dual ChE inhibitors. Herein, we investigated the peripheralanionic binding site-binding methoxy-naphthamide fragment that yielded benzyl piperidinyl-linked benzyl aminobenzamide as another class of dual ChE inhibitors. The 3,5-dimethoxy benzyl aminobenzamide, 8c1, exhibits inhibition of acetylcholinesterase(AChE) and butyrylcholinesterase (BChE)with half-maximal inhibitory concentration valuesof 0.61 and 2.04 µM, respectively. The enzyme kinetics and molecular modeling study indicated the noncompetitive and mixed-type mode of inhibition for AChE and BChE with ki values of 0.14 and 0.46 µM, respectively. The derivative 8c1 crosses the blood-brain barrier as indicated by the Pe value of 14.34 × 10-6 cm/s in the parallel artificial membrane permeability assay. Besides this, it also inhibits the self-aggregation of amyloid-β. The results presented herein indicate the potential of benzamide 8c1 for further investigation in preclinical models of AD.