Evaluation of N-alkyl isatins and indoles as acetylcholinesterase and butyrylcholinesterase inhibitors

Two series of N-alkyl isatins and N-alkyl indoles varying in size of the alkyl group were synthesised and evaluated for inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Among the N-alkyl isatins 4a-j, the addition of the N-alkyl group improved inhibition potency towards AChE and BChE compared to isatin. Selectivity towards inhibition of BChE was observed, and the increase in size of the N-alkyl group positively correlated to improved inhibition potency. The most potent inhibitor for BChE was 4i (IC50 = 3.77 µM, 22-fold selectivity for BChE over AChE). N-alkyl indoles 5a-j showed similar inhibition of AChE, the most potent being 5g (IC50 = 35.0 µM), but 5a-j lost activity towards BChE. This suggests an important role of the 3-oxo group on isatin for BChE inhibition, and molecular docking of 4i with human BChE indicates a key hydrogen bond between this group and Ser198 and His438 of the BChE catalytic triad.

4-Amidophenol Quinone Methide Precursors: Effective and Broad-Scope Nonoxime Reactivators of Organophosphorus-Inhibited Cholinesterases and Resurrectors of Organophosphorus-Aged Acetylcholinesterase

Acetylcholinesterase (AChE) inhibition by organophosphorus (OP) compounds poses a serious health risk to humans. While many therapeutics have been tested for treatment after OP exposure, there is still a need for efficient reactivation against all kinds of OP compounds, and current oxime therapeutics have poor blood-brain barrier penetration into the central nervous system, while offering no recovery in activity from the OP-aged forms of AChE. Herein, we report a novel library of 4-amidophenol quinone methide precursors (QMP) that provide effective reactivation against multiple OP-inhibited forms of AChE in addition to resurrecting the aged form of AChE after exposure to a pesticide or some phosphoramidates. Furthermore, these QMP compounds also reactivate OP-inhibited butyrylcholinesterase (BChE) which is an in vivo, endogenous scavenger of OP compounds. The in vitro efficacies of these QMP compounds were tested for reactivation and resurrection of soluble forms of human AChE and BChE and for reactivation of cholinesterases within human blood as well as blood and brain samples from a humanized mouse model. We identify compound 10c as a lead candidate due to its broad-scope efficacy against multiple OP compounds as well as both cholinesterases. With methylphosphonates, compound 10c (250 μM, 1 h) shows >60% recovered activity from OEt-inhibited AChE in human blood as well as mouse blood and brain, thus highlighting its potential for future in vivo analysis. For 10c, the effective concentration (EC50) is less than 25 μM for reactivation of three different methylphosphonate-inhibited forms of AChE, with a maximum reactivation yield above 80%. Similarly, for OP-inhibited BChE, 10c has EC50 values that are less than 150 μM for two different methylphosphonate compounds. Furthermore, an in vitro kinetic analysis show that 10c has a 2.2- and 92.1-fold superior reactivation efficiency against OEt-inhibited and OiBu-inhibited AChE, respectively, when compared to an oxime control. In addition to 10c being a potent reactivator of AChE and BChE, we also show that 10c is capable of resurrecting (ethyl paraoxon)-aged AChE, which is another current limitation of oximes.

Butyrylcholinesterase in lipid metabolism: A new outlook

Cholinesterase enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are traditionally associated with the termination of acetylcholine mediated neural signaling. The fact that these ubiquitous enzymes are also found in tissues not involved in neurotransmission has led to search for alternative functions for these enzymes. Cholinesterases are reported to be involved in many lipid related disease states. Taking into view that lipases and cholinesterases belong to the same enzyme class and by comparing the catalytic sites, we propose a new outlook on the link between BChE and lipid metabolism. The lipogenic substrates of BChE that have recently emerged in contrast to traditional cholinesterase substrates are explained through the hydrolytic capacity of BChE for ghrelin, 4-methyumbelliferyl (4-mu) palmitate, and arachidonoylcholine and through endogenous lipid mediators such as cannabinoids like anandamide and essential fatty acids. The abundance of BChE in brain, intestine, liver, and plasma, tissues with active lipid metabolism, supports the idea that BChE may be involved in lipid hydrolysis. BChE is also regulated by various lipids such as linoleic acid, alpha-linolenic acid or dioctanoylglycerol, whereas AChE is inhibited. The finding that BChE is able to hydrolyze 4-mu palmitate at a pH where lipases are less efficient points to its role as a backup in lipolysis. In diseases such as Alzheimer, in which elevated BChE and impaired lipid levels are observed, the lipolytic activity of BChE might be involved. It is possible to suggest that fatty acids such as 4-mu palmitate, ghrelin, arachidonoylcholine, essential fatty acids, and other related lipid mediators regulate cholinesterases, which could lead to some sort of compensatory mechanism at high lipid concentrations.

Prolonged duration of action of suxamethonium in pregnant and postpartum patients: A registry study

BACKGROUND

Suxamethonium is hydrolysed by butyrylcholinesterase (BChE) and a low BChE activity can result in a prolonged duration of action of suxamethonium. The BChE activity is reduced during pregnancy and postpartum period by up to 33%. However, it can also be reduced by mutations in the BChE gene. In this study, we assessed BChE activity and mutations in the BChE gene in pregnant and postpartum patients with prolonged duration of action of suxamethonium. It was hypothesised that at least 30% of patients with a low BChE activity did not have a mutation in the BChE gene.

METHODS

In this registry study we focused on pregnant and postpartum patients with a history of prolonged duration of action of suxamethonium referred to the Danish Cholinesterase Research Unit (DCRU) between March 2007 and January 2023. Primary outcome was the proportion of patients without a mutation among patients with a low BChE activity. Secondary outcomes were the proportion of patients with a low BChE activity and the proportion of patients with a mutation out of the total number of patients.

RESULTS

A total of 40 patients were included and among patients with a low BChE activity, 6% (95% CI: 1%-21%) did not have a mutation. Out of the total number of included patients referred to the DCRU, 90% (95% CI: 76%-97%) had a mutation and 94% (95% CI: 80%-99%) had a low BChE activity.

CONCLUSION

Among pregnant and postpartum patients with a history of prolonged duration of action of suxamethonium and a low BChE activity, 6% did not have a mutation in the BChE gene. Our findings suggest that during pregnancy and postpartum clinically relevant prolonged duration of action of suxamethonium rarely occurs in genotypically normal patients.

Bioactive cholinesterase inhibitions of clerodanes from the flowers of Croton krabas and molecular docking studies

The first investigation of the phytochemical profile of the flowers of Croton krabas led to the isolation of two new clerodane diterpenes, 6S-crotocaudin (1) and crotocaudin B (2), together with two known clerodanes, 6S-crotoeurin C (3) and isoteucvin (4). The structures and absolute configurations of isolated clerodanes were elucidated by extensive analysis of NMR spectroscopic data, mass spectrometry and ECD calculations. Compounds 1-4 demonstrated significant inhibitory activity towards acetylcholinesterase (AChE). Notably, compound 2 exhibited the strongest AChE inhibition (IC50 1.01 µM). Compounds 3 and 4 showed potent butyrylcholinesterase (BChE) inhibitory activity with IC50 values of 1.09 and 1.12 µM, respectively. The molecular docking results revealed that 2 bound to the catalytic anionic site (CAS) and peripheral anionic site (PAS) of AChE, while 3 occupied in the CAS of BChE.

Interactions between forsythoside E and two cholinesterases at the different conditions: fluorescence sections

Forsythoside E is one secondary metabolite ofForsythia suspensa(Thunb.) Vahl. In the study, the interactions between forsythoside E and two types of cholinesterases, acetylcholinesterase and butyrylcholinesterase were investigated in the different conditions. Forsythoside E increased the fluorescence intensity of acetylcholinesterase but quenched the fluorescence of butyrylcholinesterase. Aβ25-35used in the study may not form complexes with cholinesterases, and did not affect the interaction between forsythoside E and cholinesterases. The charged quaternary group of AsCh interacted with the 'anionic' subsite in acetylcholinesterase, which did not affect the interaction between forsythoside E and acetylcholinesterase. The enhancement rate of forsythoside E to acetylcholinesterase fluorescence from high to low was acid solution (pH 6.4), neutral solution (pH 7.4) and alkaline solution (pH 8.0), while the reduction rate of forsythoside E to butyrylcholinesterase fluorescence was in reverse order. Metal ions may interact with cholinesterases, and increased the effects of forsythoside E to cholinesterases fluorescence, in order that Fe3+was the highest, followed by Cu2+, and Mg2+. A forsythoside E-butyrylcholinesterase complex at stoichiometric ratio of 1:1 was spontaneously formed, and the static quenching was the main quenching mode in the process of forsythoside E binding with butyrylcholinesterase. TheKvalues of two complexes were pretty much the same, suggesting that the interaction between cholinesterases and forsythoside E was almost unaffected by acid-base environment and metal ions. Thennumbers of two cholinesterases approximately equaled to one, indicating that there was only one site on each cholinesterase applicable for forsythoside E to bind to.

Machine learning-based virtual screening and molecular modelling studies for identification of butyrylcholinesterase inhibitors as anti-Alzheimer's agent

Butyrylcholinesterase (BChE) is a hydrolase involved in the metabolism and detoxification of specific esters in the blood. It is also implicated in the progression of Alzheimer's disease, a type of dementia. As the disease progresses, the level of BChE tends to increase, opting for a major role as an acetylcholine-degrading enzyme and surpassing the role of acetylcholinesterase. Hence, the development of BChE inhibitors could be beneficial for the latter stages of the disease. In the present study, machine learning (ML) models were developed and employed to identify new BChE inhibitors. Further, the identified molecules were subjected to molecular property filters. The filtered ligands were studied through molecular modelling techniques, viz. molecular docking and molecular dynamics (MD). Support vector machine-based ML models resulted in the identification of 3291 compounds that would have predicted IC50 values less than 200 nM. The docking study showed that compounds ART13069594, ART17350769 and LEG19710163 have mean binding energies of -9.62, -9.26 and -8.93 kcal/mol, respectively. The MD study displayed that all the selected ligands showed stable complexes with BChE. The trajectories of all the ligands were stable similar to the standard BChE inhibitors.Communicated by Ramaswamy H. Sarma.

Cholinesterase activities and sepsis-associated encephalopathy in viral versus nonviral sepsis

PURPOSE

There is evidence that cholinergic imbalance secondary to neuroinflammation plays a role in the pathophysiology of sepsis-associated encephalopathy (SAE). Blood acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities have been proposed as surrogate parameters for the cholinergic function of the central nervous system. Viral sepsis is associated with systemic inflammation and BChE has been reported to be of prognostic value in a small cohort of COVID-19 patients. Nevertheless, the prognostic value of AChE in patients with viral sepsis remains unclear.

METHODS

We investigated the role of AChE and BChE activities as prognostic biomarkers of SAE and mortality in patients with viral vs nonviral sepsis enrolled in two prospective cohort studies. We quantified the AChE and BChE activities in whole blood of patients at two time points in the acute phase of viral sepsis (N = 108) and compared them with the activities in patients with nonviral sepsis (N = 117) and healthy volunteers (N = 81). Patients were observed until discharge from the intensive care unit (ICU).

RESULTS

Three days after sepsis onset, the median [interquartile range] levels of AChE and BChE were reduced in both patients with viral sepsis (AChE, 5,105 [4,010-6,250] U·L-1; BChE, 1,943 [1,393-2,468] U·L-1) and nonviral sepsis (AChE, 4,424 [3,630-5,055] U·L-1; BChE, 1,095 [834-1,526] U·L-1) compared with healthy volunteers (AChE, 6,693 [5,401-8,020] U·L-1; BChE, 2,645 [2,198-3,478] U·L-1). Patients with viral sepsis with SAE during their ICU stay had lower AChE activity three days after sepsis onset than patients without SAE (4,249 [3,798-5,351] U·L-1 vs 5,544 [4,124-6,461] U·L-1). Butyrylcholinesterase activity seven days after sepsis onset was lower in patients with viral sepsis who died in the ICU than in surviving patients (1,427 [865-2,181] U·L-1 vs 2,122 [1,571-2,787] U·L-1).

CONCLUSION

Cholinesterase activities may be relevant prognostic markers for the occurrence of SAE and mortality in the ICU in patients with viral sepsis.

STUDY REGISTRATION

This study constitutes an analysis of data from the ongoing studies ICROS (NCT03620409, first submitted 15 May 2018) and ICROVID (DRKS00024162, first submitted 9 February 2021).

Diethoxyphosphoryloxy-oleanolic acid is a nanomolar-inhibitor of butyrylcholinesterase

A series of new betulin, lupeol, erythrodiol, and oleanolic acid phosphoryloxy- and furoyloxy-derivatives has been synthesized and their structure was confirmed by NMR spectroscopy. Synthesized compounds were subjected to Ellman's assays to determine their ability to inhibit the enzymes AChE and BChE. Among them, diethoxyphosphoryloxy-oleanolic acid inhibited BChE with a value of 99%, thereby acting as a mixed-type inhibitor holding very low Ki values of Ki = 6.59 nM and Ki ' = 1.97 nM, respectively.

Design, synthesis, and activity evaluation of novel multitargeted l-tryptophan derivatives with powerful antioxidant activity against Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial neurological disease, and the multitarget directed ligand (MTDL) strategy may be an effective approach to delay its progression. Based on this strategy, 27 derivatives of l-tryptophan, 3a-1-3d-1, were designed, synthesized, and evaluated for their biological activity. Among them, IC50 (inhibitor concentration resulting in 50% inhibitory activity) values of compounds 3a-18 and 3b-1 were 0.58 and 0.44 μM for human serum butyrylcholinesterase (hBuChE), respectively, and both of them exhibited more than 30-fold selectivity for human serum acetylcholinesterase. Enzyme kinetics studies showed that these two compounds were mixed inhibitors of hBuChE. In addition, these two derivatives possessed extraordinary antioxidant activity in OH radical scavenging and oxygen radical absorption capacity fluorescein assays. Meanwhile, these compounds could also prevent β-amyloid (Aβ) self-aggregation and possessed low toxicity on PC12 and AML12 cells. Molecular modeling studies revealed that these two compounds could interact with the choline binding site, acetyl binding site, and peripheral anionic site to exert submicromolar BuChE inhibitory activity. In the vitro blood-brain barrier permeation assay, compounds 3a-18 and 3b-1 showed enough blood-brain barrier permeability. In drug-likeness prediction, compounds 3a-18 and 3b-1 showed good gastrointestinal absorption and a low risk of human ether-a-go-go-related gene toxicity. Therefore, compounds 3a-18 and 3b-1 are potential multitarget anti-AD lead compounds, which could work as powerful antioxidants with submicromolar selective inhibitory activity for hBuChE as well as prevent Aβ self-aggregation.

Targeting Alzheimer's Disease: Evaluating the Efficacy of C-1 Functionalized N-Aryl-Tetrahydroisoquinolines as Cholinergic Enzyme Inhibitors and Promising Therapeutic Candidates

We have synthesized 22 C-1 functionalized-N-aryl-1,2,3,4-tetrahydroisoquinoline derivatives showing biological activities towards cholinergic enzymes. Synthesis was performed using visible-light-promoted photo-redox chemistry, starting from a common intermediate, and the application of this synthetic methodology drastically simplified synthetic routes and purification of desired compounds. All synthesized derivates were divided into four groups based on the substituents in the C-1 position, and their inhibition potencies towards two cholinergic enzymes, acetyl- and butyrylcholinesterase were evaluated. Most potent derivatives were selected, and kinetic analysis was further carried out to obtain insights into the mechanisms of inhibition of these two enzymes. Further validation of the mode of inhibition of cholinergic enzymes by the two most potent THIQ compounds, 3c and 3i, was performed using fluorescence-quenching titration studies. Molecular docking studies further confirmed the proposed mechanism of enzymes' inhibition. In silico predictions of physicochemical properties, pharmacokinetics, drug-likeness, and medicinal chemistry friendliness of the selected most potent derivatives were performed using Swiss ADME tool. This was followed by UPLC-assisted log P determination and in vitro BBB permeability studies performed in order to assess the potential of the synthesized compounds to pass the BBB.

New 3-amino-2-thioxothiazolidin-4-one-based inhibitors of acetyl- and butyryl-cholinesterase: synthesis and activity

Aim: 2-Thioxothiazolidin-4-one represents a versatile scaffold in drug development. The authors used it to prepare new potent acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors that can be utilized, e.g., to treat Alzheimer's disease. Materials & methods: 3-Amino-2-thioxothiazolidin-4-one was modified at the amino group or active methylene, using substituted benzaldehydes. The derivatives were evaluated for inhibition of AChE and BChE (Ellman's method). Results & conclusion: The derivatives were obtained with yields of 52-94%. They showed dual inhibition with IC50 values from 13.15 μM; many compounds were superior to rivastigmine. The structure-activity relationship favors nitrobenzylidene and 3,5-dihalogenosalicylidene scaffolds. AChE was inhibited noncompetitively, whereas BChE was inhibited with a mixed type of inhibition. Molecular docking provided insights into molecular interactions. Each enzyme is inhibited by a different binding mode.

The First-Known Case of Hereditary Heterozygous Butyrylcholinesterase Deficiency in a Patient on Dialysis

Serum levels of butyrylcholinesterase (BChE) are commonly used to assess liver function. Its levels have been reported to be significantly lower in patients undergoing dialysis. To the best of our knowledge, this is the first report of hereditary heterozygous BChE deficiency in a patient undergoing dialysis. Medical staff involved in the care of patients with BChE deficiency should be aware of anesthetic usage, because prolonged neuromuscular paralysis following the administration of succinylcholine or mivacurium may occur. However, in the heterozygotes, BChE activity is not completely absent. Therefore, differentiating patients undergoing dialysis is challenging. A 52-year-old man underwent living-related kidney transplantation for focal segmental glomerulosclerosis at 22 years of age. As the renal function gradually worsened, the patient began to receive combined hemodialysis and peritoneal dialysis therapy. No problems with anesthesia were observed in past surgeries. The patient's BChE levels fluctuated between 76 and 170 U/L (reference range: 198-495 U/L); however, they had never been previously investigated. We suspected hereditary heterozygous BChE deficiency because the patient's sister was also diagnosed with it. DNA sequencing revealed a heterozygous missense mutation (Gly365Arg) and a K-variant (Ala539Thr). Patients on dialysis with low serum BChE levels often present with low albumin levels which may be overlooked as malnutrition. Thus, BChE deficiency should be suspected in patients on dialysis with unexplained low serum BChE levels. In the case of heterozygous BChE deficiency, the reference value is low, and continuous monitoring is crucial.

Rivastigmine-Bambuterol Hybrids as Selective Butyrylcholinesterase Inhibitors

Selective butyrylcholinesterase inhibitors are considered promising drug candidates for the treatment of Alzheimer's disease. In this work, one rivastigmine-bambuterol hybrid (MTR-1) and fourteen of its analogues were synthesized, purified, and characterized. In vitro cholinesterase assays showed that all the compounds were more potent inhibitors of BChE when compared to AChE. Further investigations indicated that MTR-3 (IC50(AChE) > 100,000 nM, IC50(BChE) = 78 nM) was the best compound in the series, showing high butyrylcholinesterase selectivity and inhibition potency, the potential to permeate the blood-brain barrier, and longer-lasting BChE inhibition than bambuterol. These compounds could be used to discover novel specific BChE inhibitors for the treatment of Alzheimer's disease.

Investigation of microwave extraction of red cabbage and its neurotherapeutic potential

In the pursuit of bioactive compounds with health benefits from food and medicinal plants, optimization of process to reduce solvent, raw material, energy and time consumption has been a valuable research objective. Sustainable management and efficient use of natural resources are of critical importance for sustainability goals. In this manner, microwave extraction of red cabbage which has been a mass cultivated plant for food purposes, was optimized for maximizing acetylcholinesterase, butyrylcholinesterase, tyrosinase inhibitory activity and bioactive content. Quantitative analysis of total phenol, flavonoid and anthocyanin content were performed using spectrophotometry and UPLC-DAD-ESI-MS/MS. Optimum conditions were determined as 600 W, 100% ethanol, 12 min for butyrylcholinesterase inhibitory and 800 W, 50% ethanol, 4 min for tyrosinase inhibitory activity. Microwave extraction outperformed conventional solvent extracts (hexane, dichloromethane, 2-methyl tetrahydrofuran, ethanol, 70% ethanol and water) in terms of activity and content. The isolated fraction containing major anthocyanins as cyanidin-3-sophoroside-5-glucoside and cyanidin-3-(sinapoyl)-sophoroside-5-glucoside was identified as the responsible portion for tyrosinase inhibitory activity. The dominant anthocyanins rich fraction of the optimum microwave extract can be considered for the production of antityrosinase products, while the identification of inhibitor metabolites for acetylcholinesterase and butyrylcholinesterase can be targeted for future studies considering red cabbage as a valuable source.

Cytotoxic and oxidative changes in individuals occupationally exposed to recyclable municipal solid waste

aste collectors are exposed to a wide variety of bacteria, endotoxins, fungi, allergens, particulate matter, irritating inhalants, and vehicle exhaust, making them more prone to development of chronic diseases. Although several studies described the impact of occupational exposure on the overall health of waste collectors, few investigations were conducted regarding cellular and molecular changes that may occur due to exposure. The aim of this study was to assess biomarkers of oxidative stress such as levels of reactive oxygen species (ROS), lipoperoxidation, total antioxidant capacity (TAC), apoptosis, butyrylcholinesterase (BChE) activity and mitochondrial function (MitoTrackerTM Green FM and MitoTrackerTM Red) using the peripheral blood from individuals occupationally exposed to recyclable solid waste in Southern Brazil. The study included 30 waste collectors and 30 control individuals, who did not perform activities with recognized exposure to biological and chemical substances. Waste collectors were found to exhibit in peripheral blood leukocytes (PBL) higher rates of apoptosis, increased production of ROS, and reduced mitochondrial membrane potential (MMP), associated with decreased total antioxidant capacity (TAC) and elevated activity of BChE in plasma. Therefore, evidence indicates that cytotoxicity, oxidative stress, and inflammatory responses may be involved in the multiplicity of adverse health outcomes related to contaminant exposure in waste collectors. It is thus necessary to implement and/or improve occupational health programs aimed at workers as well as mandatory inspections for the use of personal protective equipment.

A New Clerodane from the Leaves of Croton krabas and Its Cholinesterase Inhibitory Activities

Chromatographic separation of the leaves of Croton krabas resulted in the isolation of one new clerodane, crotoeurin D (1), along with two known compounds, 6S-crotoeurin C (2) and blumenol A (3). Their structures were determined based on extensive nuclear magnetic resonance spectroscopic data analysis and mass spectrometry. The absolute configuration of the new clerodane was assigned by nuclear overhauser effect spectroscopy correlations and electronic circular dichroism calculations. Compound 1 exhibited significant acetylcholinesterase and butyrylcholinesterase inhibitory activities. Moreover, the binding modes of 1 revealed that its structure formed strong hydrogen bonds and hydrophobic interactions with the active sites of both enzymes.

Identification of Indazole-Based Thiadiazole-Bearing Thiazolidinone Hybrid Derivatives: Theoretical and Computational Approaches to Develop Promising Anti-Alzheimer's Candidates

A hybrid library of compounds based on indazole-based thiadiazole containing thiazolidinone moieties (1-17) was synthesized. The synthesized compounds were screened in vitro for their inhibition profile against targetedacetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities. All the derivatives demonstrated a varied range of inhibitory activities having IC50 values ranging from 0.86 ± 0.33 μM to 26.73 ± 0.84 μM (AChE) and 0.89 ± 0.12 μM to 27.08 ± 0.19 μM (BuChE), respectively. The results obtained were compared with standard Donepezil drugs (IC50 = 1.26 ± 0.18 μM for AChE) and (1.35 ± 0.37 μM for BuChE), respectively. Specifically, the derivatives 1-17, 1, 9, and 14 were found to be significantly active, with IC50 values of 0.86 ± 0.30, 0.92 ± 0.10, and 1.10 ± 0.37 μM (against AChE) and 0.89 ± 0.12, 0.98 ± 0.48 and 1.19 ± 0.42 μM (against BuChE), respectively.The structure-activity relationship (SAR) studies revealed that derivatives bearing para-CF3, ortho-OH, and para-F substitutions on the phenyl ring attached to the thiadiazole skeleton, as well as meta-Cl, -NO2, and para-chloro substitutions on the phenyl ring, having a significant effect on inhibitory potential. The synthesized scaffolds have been further characterized by using 1H-NMR, 13C-NMR, and (HR-MS) to confirm the precise structures of the synthesized compounds. Additionally, the molecular docking approach was carried out for most active compounds to explore the binding interactions established by most active compounds, with the active sites of targeted enzymes and obtained results supporting the experimental data.

Quantitative Structure-Activity Relationship Modeling of Pea Protein-Derived Acetylcholinesterase and Butyrylcholinesterase Inhibitory Peptides

The aim of this work was to determine the structural requirements for peptides that inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities. The data set used consisted of 19 oligopeptides that had been identified through mass spectrometry analysis of enzymatic digests of yellow field pea protein. The structure-function relationship was analyzed by partial least squares regression using the 5z scores. A nine-component model was created from 16 peptides for AChE inhibitory peptides (Q2 = 67.2% and R2 = 0.9974), while three data sets were prepared for BuChE inhibitory peptides to improve the quality of the models (Q2 = 26.7-46.4% and R2 = 0.9577-0.9958). The most active peptides from the PLS models have threonine, leucine, alanine, and valine at the N terminal, asparagine, histidine, proline, and arginine at the second position, with aspartic acid and serine at the third, and arginine at the C terminal.

Structure-based design of new N-benzyl-piperidine derivatives as multitarget-directed AChE/BuChE inhibitors for Alzheimer's disease

The pathogenic complexity of Alzheimer's disease (AD) demands the development of multitarget-directed agents aiming at improving actual pharmacotherapy. Based on the cholinergic hypothesis and considering the well-established role of butyrylcholinesterase (BuChE) in advanced stages of AD, the chemical structure of the acetylcholinesterase (AChE) inhibitor drug donepezil (1) was rationally modified for the design of new N-benzyl-piperidine derivatives (4a-d) as potential multitarget-direct AChE and BuChE inhibitors. The designed analogues were further studied through the integration of in silico and in vitro methods. ADMET predictions showed that 4a-d are anticipated to be orally bioavailable, able to cross the blood-brain barrier and be retained in the brain, and to have low toxicity. Computational docking and molecular dynamics indicated the formation of favorable complexes between 4a-d and both cholinesterases. Derivative 4a presented the lowest binding free energy estimation due to interaction with key residues from both target enzymes (-36.69 ± 4.47 and -32.23 ± 3.99 kcal/mol with AChE and BuChE, respectively). The in vitro enzymatic assay demonstrated that 4a was the most potent inhibitor of AChE (IC50 2.08 ± 0.16 µM) and BuChE (IC50 7.41 ± 0.44 µM), corroborating the in silico results and highlighting 4a as a novel multitarget-directed AChE/BuChE inhibitor.

Phenolic and bisamide derivatives from Aglaia odorata and their biological activities

Three new compounds (1-3), including two bisamide derivatives (1 and 2) and a lignin (3), along with 15 known compounds were isolated from Aglaia odorata. Compound 2 was a pair of enantiomers and successfully resolved into the anticipated enantiomers. Their structures were elucidated by extensive spectroscopic analysis, electronic circular dichroism (ECD) calculations, and X-ray crystallography. Three compounds showed excellent inhibitory activities on α-glucosidase with IC50 values ranging from 54.48 to 240.88 μM, better than that of the positive control (acarbose, IC50 = 590.94 μM). Moreover, compounds 3, 13, and 15 presented moderate inhibitory activities against butyrylcholinesterase. Compound 17 exhibited potent PTP1B inhibitory activity with an IC50 value of 179.45 μM. Representative active compounds were performed for the molecular docking study. Herein, we described the isolation, structure elucidation, the inhibitory effects on three enzymes, and molecular docking of the isolates from the title plant.

Evaluation of Carbonic Anhydrase, Acetylcholinesterase, Butyrylcholinesterase, and α-Glycosidase Inhibition Effects and Antioxidant Activity of Baicalin Hydrate

Baicalin is the foremost prevalent flavonoid found in Scutellaria baicalensis. It also frequently occurs in many multi-herbal preparations utilized in Eastern countries. The current research has assessed and compared the antioxidant, antidiabetic, anticholinergic, and antiglaucoma properties of baicalin hydrate. Baicalin hydrate was tested for its antioxidant capacity using a variety of techniques, including N,N-dimethyl-p-phenylenediamine dihydrochloride radical (DMPD•+) scavenging activity, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical (ABTS•+) scavenging activity, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) scavenging activity, potassium ferric cyanide reduction ability, and cupric ions (Cu2+) reducing activities. Also, for comparative purposes, reference antioxidants, such as butylated hydroxyanisole (BHA), Trolox, α-Tocopherol, and butylated hydroxytoluene (BHT) were employed. Baicalin hydrate had an IC50 value of 13.40 μg/mL (r2: 0.9940) for DPPH radical scavenging, whereas BHA, BHT, Trolox, and α-Tocopherol had IC50 values of 10.10, 25.95, 7.059, and 11.31 μg/mL for DPPH• scavenging, respectively. These findings showed that baicalin hydrate had comparably close and similar DPPH• scavenging capability to BHA, α-tocopherol, and Trolox, but it performed better than BHT. Additionally, apart from these studies, baicalin hydrate was tested for its ability to inhibit a number of metabolic enzymes, including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), carbonic anhydrase II (CA II), and α-glycosidase, which have been linked to several serious illnesses, such as Alzheimer's disease (AD), glaucoma, and diabetes, where the Ki values of baicalin hydrate toward the aforementioned enzymes were 10.01 ± 2.86, 3.50 ± 0.68, 19.25 ± 1.79, and 26.98 ± 9.91 nM, respectively.

In silico identification of colchicine derivatives as novel and potential inhibitors based on molecular docking and dynamic simulations targeting multifactorial drug targets involved in Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, characterized by a gradual and steady deterioration in cognitive function over time. At least 50 million people worldwide are considered to have AD or another form of dementia. AD is marked by a gradual decline in cognitive abilities, memory deterioration and neurodegenerative transformations within the brain. The intricate and multifaceted nature of polygenic AD presents significant challenges within the landscape of drug development. The pathophysiology of AD unfolds in a non-linear and dynamic pattern, encompassing various systems and giving rise to a multitude of factors and hypotheses that contribute to the disease's onset. These encompass theories such as the beta-amyloid hypothesis, cholinergic hypothesis, tau hypothesis, oxidative stress and more. In the realm of drug development, polypharmacological drug profiles have emerged as a strategy that can yield combined or synergistic effects, effectively mitigating undesirable side effects and significantly enhancing the therapeutic efficacy of essential medications. With this concept in mind, our in-silico study sought to delve into the binding interactions of a diverse array of colchicine derivative compounds. These derivatives are chosen for their potential anti-inflammatory, antioxidant, anti-neurodegenerative and neuroprotective properties against Alzheimer's and other neurodegenerative diseases. We investigated compound interactions with AD-related targets, utilizing comprehensive molecular docking and dynamic simulations. COM111X showed impressive docking with acetylcholinesterase, indicating potential as an anti-Alzheimer's drug. COM112Y displayed strong docking scores with PDE4D and butyrylcholinesterase, suggesting dual inhibition for Alzheimer's treatment. Further in vitro and in vivo studies are warranted to explore these findings.Communicated by Ramaswamy H. Sarma.

Inhibitory properties of quinopimaric acid derivatives towards cholinesterases

A series of new diterpene quinopimaric acid derivatives modified at the hydroxyl group with different pharmacophore fragments has been synthesised and their (along with previously obtained compounds) inhibitory properties towards cholinesterases were studied. Thereby an indole-3-acetyl derivative 7 and a propargyl substituted compound 28 were shown to be excellent and acetylcholinesterase-selective inhibitors. Both compounds inhibited the enzyme as a mixed type inhibitor, and Ki values of 0.41 and 0.44 µM and Ki' values of 0.98 and 2.26 µM were determined. The binding interactions between all active compounds and ligands protein were confirmed through molecular docking study.

Elettaria cardamomum (L.) Maton Essential Oil: An Interesting Source of Bioactive Specialized Metabolites as Inhibitors of Acetylcholinesterase and Butyrylcholinesterase

Elettaria cardamomum (L.) Maton (Zingiberaceae family) is a plant traditionally used in Ayurvedic and Chinese medicine. In this work, the essential oil of E. cardamomum was found to inhibit the enzymes AChE (62.6% of inhibition, IC50 24.9 μg/mL) and BChE (55.8% of inhibition, IC50 25.9 μg/mL) by performing an in vitro colorimetric assay using the Ellman method. A bio-guided fractionation approach was used to isolate fractions/pure compounds that were tested individually to evaluate their activity. The resulting oxygenated fraction was found to be active against both AChE (percentage inhibition 42.8%) and BChE (percentage inhibition 63.7%), while the hydrocarbon fraction was inactive. The activity was attributed to a pool of oxygenated terpenes (α-terpinyl acetate, 1,8-cineole, linalool, linalyl acetate, and α-terpineol) that synergistically contributed to the overall activity of the essential oil.

Association of Reduced Maternal Plasma Cholinesterase Activity With Preeclampsia: A Meta-Analysis

Blood butyrylcholinesterase (BChE) activity has been found to decrease during pregnancy and reportedly decrease even more in preeclampsia (PE). The purpose of the present meta-analysis was to answer a specific question of whether BChE activity (in the plasma, serum, or whole blood) is reduced in pregnant women suffering from PE compared to those with normal pregnancy. The meta-analysis included 15 studies with 20 records of BChE activity in 608 women compared to 569 healthy pregnant (control) ones. The studies were subjected to quality assessment using the Newcastle-Ottawa Scale (NOS). Using the Meta-Essentials software program 1.5, the one-group random effects model and forest plot revealed that the percentage of BChE activity in pregnant women with PE was 84.84% of the control value, with a standard error of 4.09 and 95% C.I. of 76.28, 93.41, indicating a significant 15.16% reduction in BChE activity in comparison to healthy pregnancy. No significant heterogeneity was seen in the analyzed data and the funnel plot did show publication bias. Subgroup (mild, severe, and unclassified PE) forest plot analysis revealed that the % BChE activities in PE compared to respective healthy pregnancies were 96.28%, 97.08%, and 76.62%, respectively with no heterogeneity. The median NOS score of the 15 studies included in the meta-analysis was 7, ranging from 5 to 8 (medium to high quality), and the forest plot showed an effect size of 0.735. This meta-analysis shows that BChE activity is reduced in PE compared with normal pregnancy and its value as a biomarker warrants further clinical studies.

Structure-Dependent Mechanism of Organophosphate Release from Albumin and Butyrylcholinesterase Adducts When Exposed to Fluoride Ion: A Comprehensive In Silico Study

The most favorable targets for retrospectively determining human exposure to organophosphorus pesticides, insecticides, retardants, and other industrial organophosphates (OPs) are adducts of OPs with blood plasma butyrylcholinesterase (BChE) and human serum albumin (HSA). One of the methods for determining OP exposure is the reactivation of modified BChE using a concentrated solution of KF in an acidic medium. It is known that under the action of fluoride ion, OPs or their fluoroanhydrides can be released not only from BChE adducts but also from the adducts with albumin; however, the contribution of albumin to the total pool of released OPs after plasma treatment with KF has not yet been studied. The efficiency of OP release can be affected by many factors associated with the experimental technique, but first, the structure of the adduct must be taken into account. We report a comparative analysis of the structure and conformation of organophosphorus adducts on HSA and BChE using molecular modeling methods and the mechanism of OP release after fluoride ion exposure. The conformational analysis of the organophosphorus adducts on HSA and BChE was performed, and the interaction of fluoride ions with modified proteins was studied by molecular dynamics simulation. The geometric and energy characteristics of the studied adducts and their complexes with fluoride ion were calculated using molecular mechanics and semiempirical approaches. The structural features of modified HSA and BChE that can affect the efficiency of OP release after fluoride ion exposure were revealed. Using the proposed approach, the expediency of using KF for establishing exposure to different OPs, depending on their structure, can be assessed.

Lobeline: A multifunctional alkaloid modulates cholinergic and glutamatergic activities

Developing drugs for Alzheimer's disease (AD) is an extremely challenging task due to its devastating pathology. Previous studies have indicated that natural compounds play a crucial role as lead molecules in the development of drugs. Even though, there are remarkable technological advancements in the isolation and synthesis of natural compounds, the targets for many of them are still unknown. In the present study, lobeline, a piperidine alkaloid has been identified as a cholinesterase inhibitor through chemical similarity assisted target fishing method. The structural similarities between lobeline and donepezil, a known acetylcholinesterase (AChE) inhibitor encouraged us to hypothesize that lobeline may also exhibit AChE inhibitory properties. It was further confirmed by in silico, in vitro and biophysical studies that lobeline could inhibit cholinesterase. The binding profiles indicated that lobeline has a higher affinity for AChE than BChE. Since excitotoxicity is one of the major pathological events associated with AD progression, we also investigated the neuroprotective potential of lobeline against glutamate mediated excitotoxicity in rat primary cortical neurons. The cell based NMDA receptor (NMDAR) assay with lobeline suggested that neuroprotective potential of lobeline is mediated through the blockade of NMDAR activity.

Design, Synthesis, and Proof of Concept of Balanced Dual Inhibitors of Butyrylcholinesterase (BChE) and Histone Deacetylase 6 (HDAC6) for the Treatment of Alzheimer's Disease

Concomitant inhibition of butyrylcholinesterase (BChE) and histone deacetylase 6 (HDAC6) is supposed to be effective in the treatment of Alzheimer's disease (AD). Inspired by our previous efforts in designing BChE inhibitors, herein, selective BChE and HDAC6 dual inhibitors were successfully identified through the fusion of the core pharmacophoric moiety of BChE and HDAC6 inhibitors. After the structure-activity relationship (SAR) studies, two compounds (24g and 29a) were confirmed to have superior inhibitory activity against BChE (the IC50 against hBChE are 4.0 and 1.8 nM, respectively) and HDAC6 (the IC50 against HDAC6 are 8.9 and 71.0 nM, respectively). These two compounds showed prominently neuroprotective effects in vitro, potent reactive oxygen species (ROS) scavenging effects, and effective metal ion (Fe2+ and Cu2+) chelation. In addition, they exhibited pronounced inhibition of phosphorylated tau and a moderate immunomodulatory effect, with a lack of neurotoxicity at the cellular level. In vivo studies showed that both 24g and 29a ameliorated the cognitive impairment in an Aβ1-42-induced mouse model at a low dosage (2.5 mg/kg). Our data demonstrated that BChE/HDAC6 dual inhibitors could establish the basis for a potential new symptomatic and disease-modifying strategy to treat AD.

Derivatives of 9-phosphorylated acridine as butyrylcholinesterase inhibitors with antioxidant activity and the ability to inhibit β-amyloid self-aggregation: potential therapeutic agents for Alzheimer's disease

We investigated the inhibitory activities of novel 9-phosphoryl-9,10-dihydroacridines and 9-phosphorylacridines against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carboxylesterase (CES). We also studied the abilities of the new compounds to interfere with the self-aggregation of β-amyloid (Aβ42) in the thioflavin test as well as their antioxidant activities in the ABTS and FRAP assays. We used molecular docking, molecular dynamics simulations, and quantum-chemical calculations to explain experimental results. All new compounds weakly inhibited AChE and off-target CES. Dihydroacridines with aryl substituents in the phosphoryl moiety inhibited BChE; the most active were the dibenzyloxy derivative 1d and its diphenethyl bioisostere 1e (IC50 = 2.90 ± 0.23 µM and 3.22 ± 0.25 µM, respectively). Only one acridine, 2d, an analog of dihydroacridine, 1d, was an effective BChE inhibitor (IC50 = 6.90 ± 0.55 μM), consistent with docking results. Dihydroacridines inhibited Aβ42 self-aggregation; 1d and 1e were the most active (58.9% ± 4.7% and 46.9% ± 4.2%, respectively). All dihydroacridines 1 demonstrated high ABTS•+-scavenging and iron-reducing activities comparable to Trolox, but acridines 2 were almost inactive. Observed features were well explained by quantum-chemical calculations. ADMET parameters calculated for all compounds predicted favorable intestinal absorption, good blood-brain barrier permeability, and low cardiac toxicity. Overall, the best results were obtained for two dihydroacridine derivatives 1d and 1e with dibenzyloxy and diphenethyl substituents in the phosphoryl moiety. These compounds displayed high inhibition of BChE activity and Aβ42 self-aggregation, high antioxidant activity, and favorable predicted ADMET profiles. Therefore, we consider 1d and 1e as lead compounds for further in-depth studies as potential anti-AD preparations.

Azole derivatives inhibit wildtype butyrylcholinesterase and its common mutants

Azoles, which have been used for antifungal chemotherapy for decades, have recently been of interest for their efficacy against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). There is little known about the potential of azoles against BChE, however there is none regarding their inhibitory effects against mutants of BChE. In the current study, an azole library of 1-aryl-2-(1H-imidazol-1-yl)ethanol/ethanone oxime esters were tested against AChE and BChE, which yielded derivates more potent than the positive control, galantamine, against both isoforms. Kinetic analyses were performed for wildtype and mutant (A328F and A328Y) inhibition for the two most potent BChE inhibitors, pivalic and 3-bezoylpropanoic acid esters of 2-(1H-imidazol-1-yl)-1-(2-naphthyl)ethanol, which were found to have great affinity to the wildtype and mutant BChE types with Ki values as low as 0.173 ± 0.012 µM. The compounds were identified to show linear competitive or mixed type inhibition. Molecular modeling confirmed these kinetic data and provided further insights regarding molecular basis of BChE inhibition by the active derivatives. Thus, current study suggests new azole derivatives with promising cholinesterase inhibitory effects and reveals the first set of information to promote our understanding for the inhibitory behavior of this class against the mutant BChE forms.

Comparison of Biochemical, Haematological and Plasmatic Butyrylcholinesterase Parameters in Farmers and Non-Farmers, Morocco

Background

The long-term use of pesticides can cause harmful consequences to both human health and the environment. In the present research, we aimed to compare biochemical, hematological, and plasmatic measurements of butyrylcholinesterase (BChE) between farmers and non-farmers.

Materials and Methods

The study is cross-sectional and included 270 participants, with 135 farmers using pesticides and a control population of 135 non-farmers. The recruitment of the participants was conducted from August 2017 to the end of December 2019. Blood samples from participants were collected for the evaluation of biochemical markers of the function of the liver and determination of BChE activity. A whole blood sample with ethylenediamine tetraacetic anticoagulant (EDTA) was also taken for a complete blood count.

Results

The results showed a statistically significant (P = 0.03) decrease in mean corpuscular hemoglobin (MCH) in the cases (28.45 ± 2.94 pg) as compared with controls (29.17 ± 2.54 pg). The statistical analysis of the renal parameters between the two groups determined that the uremia value was significantly higher in cases (34 ± 12 mg/dL) when compared to the control group (29 ± 8 mg/dL) P < 0.001. The cases recorded a significant increase in aspartate aminotransferase (AST) (26.22 ± 11.59 U/L) and alanine aminotransferase (ALT) (25.63 ± 13.47 U/L) enzyme activities among cases versus controls. The results obtained showed a significantly decreased BChE activity in the group of cases exposed to pesticides (7554.52 ± 2107 U/l) compared to the unexposed control group (10135.58 ± 1909 U/l) (t-test, P < 0.001).

Conclusion

The education of the farmers on correct practices concerning phytosanitary use has the potential of reducing their exposure to these products.

N-Methyl Costaricine and Costaricine, Two Potent Butyrylcholinesterase Inhibitors from Alseodaphne pendulifolia Gamb

Studies have been conducted over the last decade to identify secondary metabolites from plants, in particular those from the class of alkaloids, for the development of new anti-Alzheimer's disease (AD) drugs. The genus Alseodaphne, comprising a wide range of alkaloids, is a promising source for the discovery of new cholinesterase inhibitors, the first-line treatment for AD. With regard to this, a phytochemical investigation of the dichloromethane extract of the bark of A. pendulifolia Gamb. was conducted. Repeated column chromatography and preparative thin-layer chromatography led to the isolation of a new bisbenzylisoquinoline alkaloid, N-methyl costaricine (1), together with costaricine (2), hernagine (3), N-methyl hernagine (4), corydine (5), and oxohernagine (6). Their structures were elucidated by the 1D- and 2D-NMR techniques and LCMS-IT-TOF analysis. Compounds 1 and 2 were more-potent BChE inhibitors than galantamine with IC₅₀ values of 3.51 ± 0.80 µM and 2.90 ± 0.56 µM, respectively. The Lineweaver-Burk plots of compounds 1 and 2 indicated they were mixed-mode inhibitors. Compounds 1 and 2 have the potential to be employed as lead compounds for the development of new drugs or medicinal supplements to treat AD.

Naturally Occurring Cholinesterase Inhibitors from Plants, Fungi, Algae, and Animals: A Review of the Most Effective Inhibitors Reported in 2012-2022

Since the development of the "cholinergic hypothesis" as an important therapeutic approach in the treatment of Alzheimer's disease (AD), the scientific community has made a remarkable effort to discover new and effective molecules with the ability to inhibit the enzyme acetylcholinesterase (AChE). The natural function of this enzyme is to catalyze the hydrolysis of the neurotransmitter acetylcholine in the brain. Thus, its inhibition increases the levels of this neurochemical and improves the cholinergic functions in patients with AD alleviating the symptoms of this neurological disorder. In recent years, attention has also been focused on the role of another enzyme, butyrylcholinesterase (BChE), mainly in the advanced stages of AD, transforming this enzyme into another target of interest in the search for new anticholinesterase agents. Over the past decades, Nature has proven to be a rich source of bioactive compounds relevant to the discovery of new molecules with potential applications in AD therapy. Bioprospecting of new cholinesterase inhibitors among natural products has led to the discovery of an important number of new AChE and BChE inhibitors that became potential lead compounds for the development of anti-AD drugs. This review summarizes a total of 260 active compounds from 142 studies which correspond to the most relevant (IC 50 ≤ 15 µM) research work published during 2012-2022 on plant-derived anticholinesterase compounds, as well as several potent inhibitors obtained from other sources like fungi, algae, and animals.

Activation/Inhibition of Cholinesterases by Excess Substrate: Interpretation of the Phenomenological b Factor in Steady-State Rate Equation

Cholinesterases (ChEs) display a non-michaelian behavior with positively charged substrates. In the steady-state rate equation, the b factor describes this behavior: if b > 1 there is substrate activation, if b < 1 there is substrate inhibition. The mechanistic significance of the b factor was investigated to determine whether this behavior depends on acylation, deacylation or on both steps. Kinetics of human acetyl- (AChE) and butyryl-cholinesterase (BChE) were performed under steady-state conditions and using a time-course of complete substrate hydrolysis. For the hydrolysis of short acyl(thio)esters, where acylation and deacylation are partly rate-limiting, steady-state kinetic analysis could not decide which step determines b. However, the study of the hydrolysis of an arylacylamide, 3-(acetamido)-N,N,N-trimethylanilinium (ATMA), where acetylation is rate-limiting, showed that b depends on the acylation step. The magnitude of b and opposite b values between AChE and BChE for the hydrolysis of acetyl(thio)- versus benzoyl-(thio) esters, then indicated that the productive adjustment of substrates in the active center at high concentration depends on motions of both the Ω and the acyl-binding loops. Benzoylcholine was shown to be a poor substrate of AChE, and steady-state kinetics showed a sudden inhibition at high concentration, likely due to the non-dissociation of hydrolysis products. The poor catalytic hydrolysis of this bulky ester by AChE illustrates the importance of the fine adjustment of substrate acyl moiety in the acyl-binding pocket. Molecular modeling and QM/MM simulations should definitively provide evidence for this statement.

Acetylcholinesterase inhibitory activities of some flavonoids from the root bark of Pinus krempfii Lecomte: in vitro and in silico study

From the root bark of Pinus krempfii Lecomte, four flavonoids were isolated and evaluated for their inhibitory activities against AChE and BChE enzymes in vitro and in silico. Tectochrysin (1) was found to inhibit AChE with an IC₅₀ value of 33.69 ± 2.80 μM. The docking study results also showed agreement with the in vitro test results. All four compounds also showed the best binding affinity for the AChE enzyme, characterised by binding energy (ΔG) values as low as -8.1 to -9.3 kcal/mol, in which, the compound tectochrysin had the best binding affinity for the AChE protein with a ΔG value of -9.329 kcal/mol. Tectochrysin (1) was also bound to the amino acid Phe295 of AChE with a bond length of 2.8 Å, similar to the control dihydrotanshinone-I. Galangin (2) also showed its in vitro inhibitory activity against BChE with an IC₅₀ value of 82.21 ± 2.70 μM. In silico, it also had the best binding energy value of -9.072 kcal/mol with BChE and formed hydrogen bonds with the His438 (2.85 Å) residues of BChE like the positive control (tacrine). The steered molecular dynamics (SMD) simulation results of these two complexes revealed a mechanistic insight that the protein-ligand complexes showed stable trajectories throughout the 20 and 150 ns simulations. Moreover, the drug likeliness suggested that both flavonoids (1 and 2) were expected to be drug-like and have an LD₅₀ toxicity level of 5. This study has contributed new results for drug discovery and the development of substances with neuroprotective effects, especially for the treatment of Alzheimer's disease.Communicated by Ramaswamy H. Sarma.

Screening of the Anti-Neurodegenerative Activity of Caffeic Acid after Introduction into Inorganic Metal Delivery Systems to Increase Its Solubility as the Result of a Mechanosynthetic Approach

The proven anti-neurodegenerative properties of caffeic acid in vivo are limited due to its poor solubility, which limits bioavailability. Therefore, caffeic acid delivery systems have been developed to improve caffeic acid solubility. Solid dispersions of caffeic acid and magnesium aluminometasilicate (Neusilin US2-Neu) were prepared using the ball milling and freeze-drying techniques. The solid dispersions of caffeic acid:Neu obtained by ball milling in a 1:1 mass ratio turned out to be the most effective. The identity of the studied system in comparison to the physical mixture was confirmed using the X-Ray Powder Diffractionand Fourier-transform infrared spectroscopy techniques. For caffeic acid with improved solubility, screening tests were carried out to assess its anti-neurodegenerative effect. The obtained results on the inhibition of acetylcholinesterase, butyrylcholinesterase, tyrosinase, and antioxidant potential provide evidence for improvement of caffeic acid's anti-neurodegenerative activity. As a result of in silico studies, we estimated which caffeic acid domains were involved in interactions with enzymes showing expression relevant to the neuroprotective activity. Importantly, the confirmed improvement in permeability of the soluble version of caffeic acid through membranes simulating the walls of the gastrointestinal tract and blood-brain barrier further strengthen the credibility of the results of in vivo anti-neurodegenerative screening tests.

Assessment of Anticholinergic and Antidiabetic Properties of Some Natural and Synthetic Molecules: an In Vitro and In Silico Approach

INTRODUCTION

In this study, it was aimed to determine the in vitro and in silico effects of some natural and synthetic molecules on acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and α-glucosidase enzymes.

BACKGROUND

Alzheimer's disease (AD) and Type II diabetes mellitus (T2DM), which are considered amongst the most important diseases of today's world. However, the side effects of therapeutic agents used in both diseases limit their use. Therefore, it is important to develop drugs with high therapeutic efficacy and better pharmacological profile.

OBJECTIVE

This study sets out to determine the related enzyme inhibitors used in the treatment of AD and T2DM, which are considered amongst the most important diseases of today's world.

METHODS

In the current study, the in vitro and in silico effects of dienestrol, hesperetin, L-thyroxine, 3,3',5-Triiodo-L-thyronine (T3) and dobutamine molecules on AChE, BChE and α-glycosidase enzyme activities were investigated.

RESULTS

All the molecules showed an inhibitory effect on the enzymes. The IC50 and Ki values of the L-Thyroxine molecule, which showed the strongest inhibition effect for the AChE enzyme, were determined as 1.71 µM and 0.83±0.195 µM, respectively. In addition, dienestrol, T3 and dobutamine molecules showed a more substantial inhibition effect than tacrine. Dobutamine molecule showed the most substantial inhibition effect for BChE enzyme, and IC50 and Ki values were determined as 1.83 µM and 0.845±0.143 µM, respectively. The IC50 and Ki values for the hesperetin molecule, which showed the strongest inhibition for the α-glycosidase enzyme, were determined as 13.57 µM and 12.33±2.57 µM, respectively.

CONCLUSION

According to the results obtained, it may be said that the molecules used in the study are potential inhibitor candidates for AChE, BChE and α-glycosidase.

In Vitro and In Silico Investigation of Polyacetylenes from Launaea capitata (Spreng.) Dandy as Potential COX-2, 5-LOX, and BchE Inhibitors

Diverse secondary metabolites are biosynthesized by plants via various enzymatic cascades. These have the capacity to interact with various human receptors, particularly enzymes implicated in the etiology of several diseases. The n-hexane fraction of the whole plant extract of the wild edible plant, Launaea capitata (Spreng.) Dandy was purified by column chromatography. Five polyacetylene derivatives were identified, including (3S,8E)-deca-8-en-4,6-diyne-1,3-diol (1A), (3S)-deca-4,6,8-triyne-1,3-diol (1B), (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1,3-diol (2), bidensyneoside (3), and (3S)-(6E,12E)-tetradecadiene-8,10-diyne-1-ol-3-O-β-D-glucopyranoside (4). These compounds were investigated for their in vitro inhibitory activity against enzymes involved in neuroinflammatory disorders, including cyclooxygenase-2 (COX-2), 5-lipoxygenase (5-LOX), and butyrylcholinesterase (BchE) enzymes. All isolates recorded weak-moderate activities against COX-2. However, the polyacetylene glycoside (4) showed dual inhibition against BchE (IC₅₀ 14.77 ± 1.55 μM) and 5-LOX (IC₅₀ 34.59 ± 4.26 μM). Molecular docking experiments were conducted to explain these results, which showed that compound 4 exhibited greater binding affinity to 5-LOX (-8.132 kcal/mol) compared to the cocrystallized ligand (-6.218 kcal/mol). Similarly, 4 showed a good binding affinity to BchE (-7.305 kcal/mol), which was comparable to the cocrystallized ligand (-8.049 kcal/mol). Simultaneous docking was used to study the combinatorial affinity of the unresolved mixture 1A/1B to the active sites of the tested enzymes. Generally, the individual molecules showed lower docking scores against all the investigated targets compared to their combination, which was consistent with the in vitro results. This study demonstrated that the presence of a sugar moiety (in 3 and 4) resulted in dual inhibition of 5-LOX and BchE enzymes compared to their free polyacetylenes analogs. Thus, polyacetylene glycosides could be suggested as potential leads for developing new inhibitors against the enzymes involved in neuroinflammation.

Two new dilactonized glycerol glycosides of the dual anticholinesterase active extract from Ocotea daphnifolia using bioguided fractionation and molecular docking studies

The dual inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) is considered as an important strategy for the treatment of Alzheimer's disease. In this study, we applied the bioguided fractionations of Ocotea daphinifolia ethyl acetate active extract to furnish a fraction with high inhibitory activity for AChE and BuChE (82% and 92%, respectively). High-performance liquid chromatography semipreparative purification of this fraction provided two new natural products: 1-β-D-galactopyranosyl-glycerol-2,3-heptanedionate, (1) whose complete chemical structural elucidation was made with spectrometric analysis (MS, 1D, and 2D NMR) and its minor derivative 1-β-D-gulopyranosyl-glycerol-2,3-heptanedionate; (2) which could be characterized by 2D ¹ H-¹³ C heteronuclear single-quantum correlation spectra analysis. Investigation of the intermolecular interactions with cholinesterases was carried out by molecular docking studies, and results suggested that both compounds are capable to interact with the catalytic site of both enzymes. Compounds 1 and 2 interact with residues of catalytic domains and the peripheral anionic binding site of AChE and BuChE. The results are comparable to those achieved with rivastigmine and galantamine. Thus, this study provides evidence for consideration of the glycosylglycerol from O. daphnifolia as new valuable dual cholinesterases inhibitor.

Identification of Natural Compounds of the Apple as Inhibitors against Cholinesterase for the Treatment of Alzheimer's Disease: An In Silico Molecular Docking Simulation and ADMET Study

Alzheimer's disease (AD), the most common type of dementia in older people, causes neurological problems associated with memory and thinking. The key enzymes involved in Alzheimer's disease pathways are acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Because of this, there is a lot of interest in finding new AChE inhibitors. Among compounds that are not alkaloids, flavonoids have stood out as good candidates. The apple fruit, Malus domestica (Rosaceae), is second only to cranberries regarding total phenolic compound concentration. Computational tools and biological databases were used to investigate enzymes and natural compounds. Molecular docking techniques were used to analyze the interactions of natural compounds of the apple with enzymes involved in the central nervous system (CNS), acetylcholinesterase, and butyrylcholinesterase, followed by binding affinity calculations using the AutoDock tool. The molecular docking results revealed that CID: 107905 exhibited the best interactions with AChE, with a binding affinity of -12.2 kcal/mol, and CID: 163103561 showed the highest binding affinity with BuChE, i.e., -11.2 kcal/mol. Importantly, it was observed that amino acid residue Trp286 of AChE was involved in hydrogen bond formation, Van Der Walls interactions, and Pi-Sigma/Pi-Pi interactions in the studied complexes. Moreover, the results of the Molecular Dynamics Simulation (MDS) analysis indicated interaction stability. This study shows that CID: 12000657 could be used as an AChE inhibitor and CID: 135398658 as a BuChE inhibitor to treat Alzheimer's disease and other neurological disorders.

Synthesis, in vitro biological screening and docking study of benzo[d]oxazole bis Schiff base derivatives as a potent anti-Alzheimer agent

We have synthesized benzo[d]oxazole derivatives (1-21) through a multistep reaction. Alteration in the structure of derivatives was brought in the last step via using various substituted aromatic aldehydes. In search of an anti-Alzheimer agent, all derivatives were evaluated against acetylcholinesterase and butyrylcholinesterase enzyme under positive control of standard drug donepezil (IC₅₀ = 0.016 ± 0.12 and 4.5 ± 0.11 µM) respectively. In case of acetylcholinesterase enzyme inhibition, derivatives 8, 9 and 18 (IC₅₀ = 0.50 ± 0.01, 0.90 ± 0.05 and 0.3 ± 0.05 µM) showed very promising inhibitory potentials. While in case of butyrylcholinesterase enzyme inhibition, most of the derivatives like 6, 8, 9, 13, 15, 18 and 19 (IC₅₀ = 2.70 ± 0.10, 2.60 ± 0.10, 2.20 ± 0.10, 4.25 ± 0.10, 3.30 ± 0.10, 0.96 ± 0.05 and 3.20 ± 0.10 µM) displayed better inhibitory potential than donepezil. Moreover, derivative 18 is the most potent one among the series in both inhibitions. The binding interaction of derivatives with the active gorge of the enzyme was confirmed via a docking study. Furthermore, the binding interaction between derivatives and the active site of enzymes was correlated through the SAR study. Structures of all derivatives were confirmed through spectroscopic techniques such as ¹H-NMR, ¹³C-NMR and HREI-MS, respectively.Communicated by Ramaswamy H. Sarma.

Effect of sulfonamide derivatives of phenylglycine on scopolamine-induced amnesia in rats

Alzheimer's disease is a neurodegenerative disease responsible for dementia and other neuropsychiatric symptoms. In the present study, compounds 30 and 33, developed earlier in our laboratory as selective butyrylcholinesterase inhibitors, were tested against scopolamine-induced amnesia to evaluate their pharmacodynamic effect. The efficacy of the compounds was determined by behavioral experiments using the Y-maze and the Barnes maze and neurochemical testing. Both compounds reduced the effect of scopolamine treatment in the behavioral tasks at a dose of 20 mg/kg. The results of the neurochemical experiment indicated a reduction in cholinesterase activity in the prefrontal cortex and the hippocampus. The levels of antioxidant enzymes superoxide dismutase and catalase were restored compared to the scopolamine-treated groups. The docking study on rat butyrylcholinesterase (BChE) indicated tight binding, with free energies of -9.66 and -10.23 kcal/mol for compounds 30 and 33, respectively. The two aromatic amide derivatives of 2-phenyl-2-(phenylsulfonamido) acetic acid produced stable complexes with rat BChE in the molecular dynamics investigation.

Vinyl functionalized 5,6-dimethylbenzimidazolium salts: Synthesis and biological activities

A series of vinyl functionalized 5,6-dimethylbenzimidazolium salts are synthesized. All compounds were fully characterized by elemental analyses, MS, ¹ H-NMR, ¹³ C-NMR, and IR spectroscopy techniques. Enzyme inhibition is a very active area of research in drug design and development. In this study, the synthesized novel benzimidazolium salts were evaluated toward the human erythrocyte carbonic anhydrase I (hCA I), and II (hCA II) isoenzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. They demonstrated highly potent inhibition ability against hCA I with K_i values of 484.8 ± 62.6-1389.7 ± 243.2 nM, hCA II with K_i values of 298.9 ± 55.7-926.1 ± 330.0 nM, α-glycosidase with K_i values of 170.3 ± 27-760.1 ± 269 μM, AChE with K_i values of 27.1 ± 3-77.6 ± 1.7 nM, and BChE with K_i values of 21.0 ± 5-61.3 ± 15 nM. As a result, novel vinyl functionalized 5,6-dimethylbenzimidazolium salts (1a-g) exhibited effective inhibition profiles toward studied metabolic enzymes. Therefore, we believe that these results may contribute to the development of new drugs particularly to treat some global disorders including glaucoma, Alzheimer's disease, and diabetes.

Acetylcholinesterase Activity Staining in Freshwater Planarians

The serine hydrolase acetylcholinesterase (AChE) is an important neuronal enzyme which catalyzes the hydrolysis of the neurotransmitter acetylcholine and other choline esters. The breakdown of acetylcholine by AChE terminates synaptic transmission and regulates neuromuscular communication. AChE inhibition is a common mode of action of various insecticides, such as carbamates and organophosphorus pesticides. Freshwater planarians, especially the species Dugesia japonica, have been shown to possess AChE activity and to be a suitable alternative model for studying the effects of pesticides in vivo. AChE activity can be quantified in homogenates using the Ellman assay. However, this biochemical assay requires specialized equipment and large numbers of planarians. Here, we present a protocol for visualizing AChE activity in individual planarians. Activity staining can be completed in several hours and can be executed using standard laboratory equipment (a fume hood, nutator, and light microscope with imaging capability). We describe the steps for preparing the reagents, and the staining and imaging of the planarians. Planarians are treated with 10% acetic acid and fixed with 4% paraformaldehyde and then incubated in a staining solution containing the substrate acetylthiocholine. After incubation in the staining solution for 3.5 hr on a nutator at 4°C, or stationary on ice, planarians are washed and mounted for imaging. Using exposure to an organophosphorus pesticide as an example, we show how AChE inhibition leads to a loss of staining. Thus, this simple method can be used to qualitatively evaluate AChE inhibition due to chemical exposure or RNA interference, providing a new tool for mechanistic studies of effects on the cholinergic system. © 2023 Wiley Periodicals LLC. Basic Protocol 1: Preparing the staining solution Basic Protocol 2: Fixing, staining, and imaging whole-mount planarian specimens for visualization of acetylcholinesterase activity.

Multitargeted C9-substituted ester and ether derivatives of berberrubine for Alzheimer's disease: Design, synthesis, biological evaluation, metabolic stability, and pharmacokinetics

Berberrubine is a naturally occurring isoquinoline alkaloid and a bioactive metabolite of berberine. Berberine exhibits a wide range of pharmacological activities, including cholinesterase inhibition. The cholinesterase inhibitors provide symptomatic treatment for Alzheimer's disease; however, multitarget-directed ligands have the potential as disease-modifying therapeutics. Herein, we prepared a series of C9-substituted berberrubine derivatives intending to discover dual cholinesterase and beta-site amyloid-precursor protein cleaving enzyme 1 (BACE-1) inhibitors. Most synthesized derivatives possessed balanced dual inhibition (AChE and BChE) activity in the submicromolar range and a moderate inhibition against BACE-1. Two most active ester derivatives, 12a and 11d, display inhibition of AChE, BChE, and BACE-1. The 3-methoxybenzoyl ester derivative, 12a, inhibits electric eel acetylcholinesterase (EeAChE), equine serum butyrylcholinesterase (eqBChE), and human hBACE-1 with IC₅₀ values of 0.5, 4.3, and 11.9 μM, respectively and excellent BBB permeability (P_e  = 8 × 10^-6  cm/s). The ester derivative 12a is metabolically unstable; however, its ether analog 13 is stable in HLM and exhibits inhibition of AChE, BChE, and BACE-1 with IC₅₀ values of 0.44, 3.8, and 17.9 μM, respectively. The ether analog also inhibits self-aggregation of Aβ and crosses BBB (P_e  = 7.3 × 10^-6  cm/s). Administration of 13 at 5 mg/kg (iv) in Wistar rats showed excellent plasma exposure with AUC_0-∞ of 28,834 ng min/ml. In conclusion, the multitargeted berberrubine ether derivative 13 is CNS permeable and has good ADME properties.

Piperazine derivatives with potent drug moiety as efficient acetylcholinesterase, butyrylcholinesterase, and glutathione S-transferase inhibitors

Cholinesterases catalyze the breakdown of the neurotransmitter acetylcholine (ACh), a naturally occurring neurotransmitter, into choline and acetic acid, allowing the nervous system to function properly. In the human body, cholinesterases come in two types, including acetylcholinesterase (AChE; E.C.3.1.1.7) and butyrylcholinesterase (BChE; E.C.3.1.1.8). Both cholinergic enzyme inhibitors are essential in the biochemical processes of the human body, notably in the brain. On the other hand, GSTs are found all across nature and are the principal Phase II detoxifying enzymes in eukaryotes and prokaryotes. Specific isozymes are identified as therapeutic targets because they are overexpressed in various malignancies and may have a role in the genesis of other diseases such as neurological disorders, multiple sclerosis, asthma, and especially cancer cell. Piperazine chemicals have a role in many biological processes and have fascinating pharmacological properties. As a result, therapeutically effective piperazine research is becoming more prominent. Half maximal inhibition concentrations (IC₅₀ ) of piperazine derivatives were found in ranging of 4.59-6.48 µM for AChE, 4.85-8.35 µM for BChE, and 3.94-8.66 µM for GST. Also, piperazine derivatives exhibited Ki values of 8.04 ± 5.73-61.94 ± 54.56, 0.24 ± 0.03-32.14 ± 16.20, and 7.73 ± 1.13-22.97 ± 9.10 µM toward AChE, BChE, and GST, respectively. Consequently, the inhibitory properties of the AChE/BChE and GST enzymes have been compared to Tacrine (for AChE and BChE) and Etacrynic acid (for GST).

Novel Organoruthenium(II) Complex C1 Selectively Inhibits Butyrylcholinesterase without Side Effects on Neuromuscular Transmission

Enzyme butyrylcholinesterase (BChE) shows increased activity in some brain regions after progression of Alzheimer's disease and is therefore one of the therapeutic targets for symptomatic treatment of this neurodegenerative disorder. The organoruthenium(II) complex [(η⁶-p-cymene)Ru(II)(1-hydroxy-3-methoxypyridine-2(1H)-thionato)pta]PF₆ (C1) was designed based on the results of our previous structure-activity studies. Inhibitory activity toward cholinesterase enzymes shows that this complex selectively, competitively, and reversibly inhibits horse serum BChE (hsBChE) with an IC₅₀ value of 2.88 µM. When tested at supra-pharmacological concentrations (30, 60, 90, and 120 µM), C1 had no significant effect on the maximal amplitude of nerve-evoked and directly elicited single-twitch and tetanic contractions. At the highest tested concentration (120 µM), C1 had no effect on resting membrane potential, but significantly decreased the amplitude of miniature end-plate potentials (MEPP) without reducing their frequency. The same concentration of C1 had no effect on the amplitude of end-plate potentials (EPP), however it shortened the half-decay time of MEPPs and EPPs. The decrease in the amplitude of MEPPs and shortening of the half-decay time of MEPPs and EPPs suggest a possible weak inhibitory effect on muscle-type nicotinic acetylcholine receptors (nAChR). These combined results show that, when applied at supra-pharmacological concentrations up to 120 µM, C1 does not importantly affect the physiology of neuromuscular transmission and skeletal muscle contraction.

Conjugates of Tacrine and Salicylic Acid Derivatives as New Promising Multitarget Agents for Alzheimer's Disease

A series of previously synthesized conjugates of tacrine and salicylamide was extended by varying the structure of the salicylamide fragment and using salicylic aldehyde to synthesize salicylimine derivatives. The hybrids exhibited broad-spectrum biological activity. All new conjugates were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with selectivity toward BChE. The structure of the salicylamide moiety exerted little effect on anticholinesterase activity, but AChE inhibition increased with spacer elongation. The most active conjugates were salicylimine derivatives: IC₅₀ values of the lead compound 10c were 0.0826 µM (AChE) and 0.0156 µM (BChE), with weak inhibition of the off-target carboxylesterase. The hybrids were mixed-type reversible inhibitors of both cholinesterases and displayed dual binding to the catalytic and peripheral anionic sites of AChE in molecular docking, which, along with experimental results on propidium iodide displacement, suggested their potential to block AChE-induced β-amyloid aggregation. All conjugates inhibited Aβ₄₂ self-aggregation in the thioflavin test, and inhibition increased with spacer elongation. Salicylimine 10c and salicylamide 5c with (CH₂)₈ spacers were the lead compounds for inhibiting Aβ₄₂ self-aggregation, which was corroborated by molecular docking to Aβ₄₂. ABTS^•+-scavenging activity was highest for salicylamides 5a-c, intermediate for salicylimines 10a-c, low for F-containing salicylamides 7, and non-existent for methoxybenzoylamides 6 and difluoromethoxybenzoylamides 8. In the FRAP antioxidant (AO) assay, the test compounds displayed little or no activity. Quantum chemical analysis and molecular dynamics (MD) simulations with QM/MM potentials explained the AO structure-activity relationships. All conjugates were effective chelators of Cu²⁺, Fe²⁺, and Zn²⁺, with molar compound/metal (Cu²⁺) ratios of 2:1 (5b) and ~1:1 (10b). Conjugates exerted comparable or lower cytotoxicity than tacrine on mouse hepatocytes and had favorable predicted intestinal absorption and blood-brain barrier permeability. The overall results indicate that the synthesized conjugates are promising new multifunctional agents for the potential treatment of AD.

An Overview of 1,2,3-triazole-Containing Hybrids and Their Potential Anticholinesterase Activities

Acetylcholine (ACh) neurotransmitter of the cholinergic system in the brain is involved in learning, memory, stress responses, and cognitive functioning. It is hydrolyzed into choline and acetic acid by two key cholinesterase enzymes, viz., acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). A loss or degeneration of cholinergic neurons that leads to a reduction in ACh levels is considered a significant contributing factor in the development of neurodegenerative diseases (NDs) such as Alzheimer's disease (AD). Numerous studies have shown that cholinesterase inhibitors can raise the level of ACh and, therefore, enhance people's quality of life, and, at the very least, it can temporarily lessen the symptoms of NDs. 1,2,3-triazole, a five-membered heterocyclic ring, is a privileged moiety, that is, a central scaffold, and is capable of interacting with a variety of receptors and enzymes to exhibit a broad range of important biological activities. Recently, it has been clubbed with other pharmacophoric fragments/molecules in hope of obtaining potent and selective AChE and/or BuChE inhibitors. The present updated review succinctly summarizes the different synthetic strategies used to synthesize the 1,2,3-triazole moiety. It also highlights the anticholinesterase potential of various 1,2,3-triazole di/trihybrids reported in the past seven years (2015-2022), including a rationale for hybridization and with an emphasis on their structural features for the development and optimization of cholinesterase inhibitors to treat NDs.