Neurobiology of butyrylcholinesterase

Naphthyl-functionalized acetamide derivatives: Promising agents for cholinesterase inhibition and antioxidant therapy in Alzheimer's disease

This study presents the synthesis and characterization of a series of 13 novel acetamides. These were subjected to Ellman's assay to determine the efficacy of the AChE and BChE inhibitors. Finally, we report their antioxidant activity as an alternative approach for the search for drugs to treat AD. These studies revealed that compounds 1a-1k and 2l-2m were obtained in moderate yield. Four amides (1h, 1j, 1k, and 2l) were selective for one of the enzymes (BChE); thus, those that inhibited BChE were more active than the positive control (galantamine) and showed better IC50 values (3.30-5.03 µM). The theoretical free binding energies calculated by MM-GBSA indicated that all inhibitors were more stable than rivastigmine, and the inhibition mechanisms involved the entire active site: peripheral anionic site, oxyanion hole, acyl-binding pockets, and catalytic site. We examined the cytotoxicity of compounds 1h, 1j, 1k, and 2l in human dermal cells and found that they did not exhibit any toxic effects under the tested conditions. Additionally, these compounds, which also inhibited BChE, displayed mixed inhibition and did not exhibit hemolytic effects on human erythrocytes. Furthermore, the ABTS and DPPH assays indicated that, although none of the compounds showed activity in the DPPH assay, the EC50 values for radical trapping by the ABTS method showed that compounds 1a, 1d, 1e, and 1g had EC50 values lower than 10 µg/mL, indicating their strong radical scavenging capacity. We also report the crystal structures of compounds 1c, 1d, 1f, and 1g, which are found in monoclinic crystal systems.

Naringin and Naringenin: Potential Multi-Target Agents for Alzheimer's Disease

Alzheimer's disease (AD) is one of the most common forms of neurodegenerative dementia. The etiology of AD is multifactorial, and its complex pathophysiology involves tau and amyloid-β deposition, increased oxidative stress, neuroinflammation, metabolic disorders, and massive neuronal loss. Due to its complex pathology, no effective cure for AD has been found to date. Therefore, there is an unmet clinical need for the development of new drugs against AD. Natural products are known to be good sources of compounds with pharmacological activity and have potential for the development of new therapeutic agents. Naringin, a naturally occurring flavanone glycoside, is predominantly found in citrus fruits and Chinese medicinal herbs. Mounting evidence shows that naringin and its aglycone, naringenin, have direct neuroprotective effects on AD, such as anti-amyloidogenic, antioxidant, anti-acetylcholinesterase, and anti-neuroinflammatory effects, as well as metal chelation. Furthermore, they are known to improve disordered glucose/lipid metabolism, which is a high risk factor for AD. In this review, we summarize the latest data on the impact of naringin and naringenin on the molecular mechanisms involved in AD pathophysiology. Additionally, we provide an overview of the current clinical applications of naringin and naringenin. The novel delivery systems for naringin and naringenin, which can address their widespread pharmacokinetic limitations, are also discussed. The literature indicates that naringin and naringenin could be multilevel, multitargeted, and multifaceted for preventing and treating AD.

Synthesis, Characterization, and Biological Evaluation of N-Methyl Derivatives of Norbelladine

Norbelladine derivatives have garnered attention in recent years due to their diverse biological activities and pivotal role in the biosynthetic pathway of Amaryllidaceae alkaloids. This study reports the synthesis and biological evaluation of four O,N-methylated derivatives of norbelladine. These derivatives were synthesized through a three-step process: forming imine intermediates from benzaldehydes with tyramine, hydrogenating them to secondary amines, and N-methylating these amines. The products were purified and characterized by 1H and 13C NMR spectroscopy. Their biological activities were assessed by evaluating their ability to inhibit Alzheimer's disease-related enzymes acetylcholinesterase and butyrylcholinesterase. Additionally, the cytotoxic activity of the novel derivatives was tested against cancer cell lines derived from hepatocarcinoma (Huh7), adenocarcinoma (HCT-8), and acute myeloid leukemia (THP-1) cells, and their antiviral properties against a human coronavirus (HCoV-OC43), a flavivirus (dengue virus), and a lentivirus (pseudotyped HIV-1). Docking analysis was performed to understand the impact of the N-methylation on their pharmacological relevance. The results indicate that while N-methylation does not significantly affect antiviral activity, it enhances butyrylcholinesterase inhibition for N-methylnorbelladine and 4'-O,N-dimethylnorbelladine. Overall, this work enhances our understanding of norbelladine derivatives, provides new tools for Alzheimer's disease research, and lays the groundwork for future pharmaceutical developments.

Synthesis, biological and computational evaluation of benzoxazole hybrid analogs as potential anti-Alzheimer's agents

Aim: Current study aims exploration of bis-benzoxazole bearing bis-Schiff base scaffolds (1-16) as anti-Alzheimer's agents.Materials & methods: 2-aminophenol is used as starting materials which react with different reagents in different step to give us bis-benzoxazole bearing bis-Schiff base analogs. NMR and HREI-MS techniques were used for characterization. All derivatives demonstrated varied range of activities with IC50 values 1.10 ± 0.40-24.50 ± 0.90 μM against acetylcholinesterase (AChE) and 1.90 ± 0.70-28.60 ± 0.60 μM against butyrylcholinesterase (BuChE) in contrast to donepezil. In both cases, analog-3 was found most potent. Molecular docking explored modes of interactions between scaffolds and receptor sites of targeted enzymes.Conclusion: This study offering promising approach for optimization and development of potent inhibitors of cholinesterase enzymes.

Reactivators of butyrylcholinesterase inhibited by organophosphorus compounds

In this review, the current progress in the research and development of butyrylcholinesterase (BChE) reactivators is summarised and the advantages or disadvantages of these reactivators are critically discussed. Organophosphorus compounds such as nerve agents (sarin, tabun, VX) or pesticides (chlorpyrifos, diazinon) cause irreversible inhibition of acetylcholinesterase (AChE) and BChE in the human body. While AChE inhibition can be life threatening due to cholinergic overstimulation and crisis, selective BChE inhibition has presumably no adverse effects. Because BChE is mostly found in plasma, its activity is important for the scavenging of organophosphates before they can reach AChE in the central nervous system. Therefore, this enzyme in combination with its reactivator can be used as a pseudo-catalytic scavenger of organophosphates. Three structural types of BChE reactivators were found, i.e. bisquaternary salts, monoquaternary salts and uncharged compounds. Although the reviewed reactivators have certain limitations, the promising candidates for BChE reactivation were found in each structural group.

Cholinergic Inhibition and Antioxidant Potential of Gongronema latifolium Benth Leaf in Neurodegeneration: Experimental and In Silico Study

The use of Gongronema latifolium for the management of various forms of neurological disorders has generated a lot of interest in the need to further investigate its neurotherapeutic constituents. This work, therefore, focused on assessing the inhibitory potential of selected bioactive components derived from G. latifolium against key neurotherapeutic targets and oxidant species associated with neurodegeneration using in vitro analysis and biomolecular modelling. G. latifolium methanol extract (GLME), solvent partition, chromatographic fractions (A-F) of GLME and pregnane compounds (Iloneoside and marsectohexol) derived from fraction-B with the highest activity were investigated for in vitro acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and monoamine oxidase (MAO) inhibition in addition to their in vitro antioxidant activities. The interactions of iloneoside, marsectohexol, and reference drugs with human acetylcholinesterase, butyrylcholinesterase, and β-secretase (BACE-1) were further assessed using molecular docking, binding free energy calculations, cluster analysis, and molecular dynamics simulations. The GLME and fractions inhibited the activities of both acetylcholinesterase and butyrylcholinesterase in a dose-dependent manner. Iloneoside and marsectohexol exhibited in vitro concentration-dependent inhibitory activities against acetylcholinesterase (IC50 = 19.28, 184.9 µM, respectively) and butyrylcholinesterase (IC50 = 30.75, 43.4 µM, respectively). These compounds also possess ferric ion-reducing, hydroxyl, and superoxide radical-scavenging activities. Iloneoside had the highest docking scores of -9.8, -9.9 -9.4 Kcal for AChE, BChE, and BACE1, respectively. The stability of the interaction of the bioactive compounds with the catalytic residues of the protein targets was preserved in a 100 ns molecular dynamics simulation. Iloneoside, a rare pregnane glycoside, was identified as a neurotherapeutic constituent of G. latifolium leaf. Further studies are suggested to investigate the neurotherapeutic potential in animal models.

Identification of potential inhibitors of cholinergic and β-secretase enzymes from phytochemicals derived from Gongronema latifolium Benth leaf: an integrated computational analysis

Neurodegenerative disorders (NDDs) are associated with increased activities of the brain acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and β-secretase enzyme (BACE1). Inhibition of these enzymes affords therapeutic option for managing NDDs such as Alzheimer's disease (AD) and Parkinson's disease (PD). Although, Gongronema latifolium Benth (GL) has been widely documented in ethnopharmacological and scientific reports for the management of NDDs, there is paucity of information on its underlying mechanism and neurotherapeutic constituents. Herein, 152 previously reported Gongronema latifolium derived-phytochemicals (GLDP) were screened against hAChE, hBChE and hBACE-1 using molecular docking, molecular dynamics (MD) simulations, free energy of binding calculations and cluster analysis. The result of the computational analysis identified silymarin, alpha-amyrin and teraxeron with the highest binding energies (-12.3, -11.2, -10.5 Kcal/mol) for hAChE, hBChE and hBACE-1 respectively as compared with those of the reference inhibitors (-12.3, -9.8 and - 9.4 for donepezil, propidium and aminoquinoline compound respectively). These best docked phytochemicals were found to be orientated in the hydrophobic gorge where they interacted with the choline-binding pocket in the A-site and P-site of the cholinesterase and subsites S1, S3, S3' and flip (67-75) residues of the pocket of the BACE-1. The best docked phytochemicals complexed with the target proteins were stable in a 100 ns molecular dynamic simulation. The interactions with the catalytic residues were preserved during the simulation as observed from the MMGBSA decomposition and cluster analyses. The presence of these phytocompounds most notably silymarin, which demonstrated dual high binding tendencies to both cholinesterases, were identified as potential neurotherapeutics subject to further investigation.

Organophosphate toxicity patterns: A new approach for assessing organophosphate neurotoxicity

Organophosphorus compounds or organophosphates (OPs) are widely used as flame retardants, plasticizers, lubricants and pesticides. This contributes to their ubiquitous presence in the environment and to the risk of human exposure. The persistence of OPs and their bioaccumulative characteristics raise serious concerns regarding environmental and human health impacts. To address the need for safer OPs, this study uses a New Approach Method (NAM) to analyze the neurotoxicity pattern of 42 OPs. The NAM consists of a 4-step process that combines computational modeling with in vitro and in vivo experimental studies. Using spherical harmonic-based cluster analysis, the OPs were grouped into four main clusters. Experimental data and quantitative structure-activity relationships (QSARs) analysis were used in conjunction to provide information on the neurotoxicity profile of each group. Results showed that one of the identified clusters had a favorable safety profile, which may help identify safer OPs for industrial applications. In addition, the 3D-computational analysis of each cluster was used to identify meta-molecules with specific 3D features. Toxicity was found to correspond to the level of phosphate surface accessibility. Substances with conformations that minimize phosphate surface accessibility caused less neurotoxic effect. This multi-assay NAM could be used as a guide for the classification of OP toxicity, helping to minimize the health and environmental impacts of OPs, and providing rapid support to the chemical regulators, whilst reducing reliance on animal testing.

Sequential Contrastive and Deep Learning Models to Identify Selective Butyrylcholinesterase Inhibitors

Butyrylcholinesterase (BChE) is a target of interest in late-stage Alzheimer's Disease (AD) where selective BChE inhibitors (BIs) may offer symptomatic treatment without the harsh side effects of acetylcholinesterase (AChE) inhibitors. In this study, we explore multiple machine learning strategies to identify BIs in silico, optimizing for precision over all other metrics. We compare state-of-the-art supervised contrastive learning (CL) with deep learning (DL) and Random Forest (RF) machine learning, across single and sequential modeling configurations, to identify the best models for BChE selectivity. We used these models to virtually screen a vendor library of 5 million compounds for BIs and tested 20 of these compounds in vitro. Seven of the 20 compounds displayed selectivity for BChE over AChE, reflecting a hit rate of 35% for our model predictions, suggesting a highly efficient strategy for modeling selective inhibition.

Onset of Alzheimer disease in apolipoprotein ɛ4 carriers is earlier in butyrylcholinesterase K variant carriers

BACKGROUND

The authors sought to examine the impact of the K-variant of butyrylcholinesterase (BCHE-K) carrier status on age-at-diagnosis of Alzheimer disease (AD) in APOE4 carriers.

METHODS

Patients aged 50-74 years with cerebrospinal fluid (CSF) biomarker-confirmed AD, were recruited to clinical trial (NCT03186989 since June 14, 2017). Baseline demographics, disease characteristics, and biomarkers were evaluated in 45 patients according to BCHE-K and APOE4 allelic status in this post-hoc study.

RESULTS

In APOE4 carriers (N = 33), the mean age-at-diagnosis of AD in BCHE-K carriers (n = 11) was 6.4 years earlier than in BCHE-K noncarriers (n = 22, P < .001, ANOVA). In APOE4 noncarriers (N = 12) there was no observed influence of BCHE-K. APOE4 carriers with BCHE-K also exhibited slightly higher amyloid and tau accumulations compared to BCHE-K noncarriers. A predominantly amyloid, limited tau, and limbic-amnestic phenotype was exemplified by APOE4 homozygotes with BCHE-K. In the overall population, multiple regression analyses demonstrated an association of amyloid accumulation with APOE4 carrier status (P < .029), larger total brain ventricle volume (P < .021), less synaptic injury (Ng, P < .001), and less tau pathophysiology (p-tau181, P < .005). In contrast, tau pathophysiology was associated with more neuroaxonal damage (NfL, P = .002), more synaptic injury (Ng, P < .001), and higher levels of glial activation (YKL-40, P = .01).

CONCLUSION

These findings have implications for the genetic architecture of prognosis in early AD, not the genetics of susceptibility to AD. In patients with early AD aged less than 75 years, the mean age-at-diagnosis of AD in APOE4 carriers was reduced by over 6 years in BCHE-K carriers versus noncarriers. The functional status of glia may explain many of the effects of APOE4 and BCHE-K on the early AD phenotype.

TRIAL REGISTRATION

NCT03186989 since June 14, 2017.

Rational design of a near-infrared fluorescent probe for monitoring butyrylcholinesterase activity and its application in development of inhibitors

Butyrylcholinesterase (BChE) is widely expressed in multiple tissues and has a vital role in several key human disorders, such as Alzheimer's disease and tumorigenesis. However, the role of BChE in human disorders has not been investigated. Thus, to quantitatively detect and visualize dynamical variations in BChE activity is essential for exploring the biological roles of BChE in the progression of a number of human disorders. Herein, based on the substrate characteristics of BChE, we customized and synthesized three near-infrared (NIR) fluorescent probe substrates with cyanine-skeleton, and finally selected a NIR fluorescence probe substrate named CYBA. The CYBA demonstrated a significant increase in fluorescence when interacting with BChE, but mainly avoided AChE. Upon the addition of BChE, CYBA could be specifically hydrolyzed to TBO, resulting in a significant NIR fluorescence signal enhancement at 710 nm. Systematic evaluation revealed that CYBA exhibited exceptional chemical stability in complex biosamples and possessed remarkable selectivity and sensitivity towards BChE. Moreover, CYBA was successfully applied for real-time imaging of endogenous BChE activity in two types of nerve-related living cells. Additionally, CYBA demonstrated exceptional stability in the detection of complex biological samples in plasma recovery studies (97.51%-104.01%). Furthermore, CYBA was used to construct a high-throughput screening (HTS) method for BChE inhibitors using human plasma as the enzyme source. We evaluated inhibitory effects of a series of natural products and four flavonoids were identified as potent inhibitors of BChE. Collectively, CYBA can serve as a practical tool to track the changes of BChE activity in complicated biological environments due to its excellent capabilities.

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.

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.

Optical imaging probes for selective detection of butyrylcholinesterase

Butyrylcholinesterase (BChE), a member of the human serine hydrolase family, is an essential enzyme for cholinergic neurotransmission as it catalyzes the hydrolysis of acetylcholine. It also plays central roles in apoptosis, lipid metabolism, and xenobiotic detoxification. On the other side, abnormal levels of BChE are directly associated with the formation of pathogenic states such as neurodegenerative diseases, psychiatric and cardiovascular disorders, liver damage, diabetes, and cancer. Thus, selective and sensitive detection of BChE level in living organisms is highly crucial and is of great importance to further understand the roles of BChE in both physiological and pathological processes. However, it is a very complicated task due to the potential interference of acetylcholinesterase (AChE), the other human cholinesterase, as these two enzymes share a very similar substrate scope. To this end, optical imaging probes have attracted immense attention in recent years as they have modular structures, which can be tuned precisely to satisfy high selectivity toward BChE, and at the same time they offer real time and nondestructive imaging opportunities with a high spatial and temporal resolution. Here, we summarize BChE selective imaging probes by discussing the critical milestones achieved during the development process of these molecular sensors over the years. We put a special emphasis on design principles and biological applications of highly promising new generation activity-based probes. We also give a comprehensive outlook for the future of BChE-responsive probes and highlight the ongoing challenges. This collection marks the first review article on BChE-responsive imaging agents.

Recent Developments in Coumarin Derivatives as Neuroprotective Agents

BACKGROUND

Neurodegenerative diseases are among the diseases that cause the foremost burden on the health system of the world. The diseases are multifaceted and difficult to treat because of their complex pathophysiology, which includes protein aggregation, neurotransmitter breakdown, metal dysregulation, oxidative stress, neuroinflammation, excitotoxicity, etc. None of the currently available therapies has been found to be significant in producing desired responses without any major side effects; besides, they only give symptomatic relief otherwise indicated off-episode relief. Targeting various pathways, namely choline esterase, monoamine oxidase B, cannabinoid system, metal chelation, β-secretase, oxidative stress, etc., may lead to neurodegeneration. By substituting various functional moieties over the coumarin nucleus, researchers are trying to produce safer and more effective neuroprotective agents.

OBJECTIVES

This study aimed to review the current literature to produce compounds with lower side effects using coumarin as a pharmacophore.

METHODS

In this review, we have attempted to compile various synthetic strategies that have been used to produce coumarin and various substitutional strategies used to produce neuroprotective agents from the coumarin pharmacophore. Moreover, structure-activity relationships of substituting coumarin scaffold at various positions, which could be instrumental in designing new compounds, were also discussed.

RESULTS

The literature review suggested that coumarins and their derivatives can act as neuroprotective agents following various mechanisms.

CONCLUSION

Various studies have demonstrated the neuroprotective activity of coumarin due to an oxaheterocyclic loop, which allows binding with a broad array of proteins, thus motivating researchers to explore its potential as a lead against various neurodegenerative diseases.

Extractions of aerial parts of Hippomarathrum scabrum with conventional and green methodologies: Chemical profiling, antioxidant, enzyme inhibition, and anti-cancer effects

Hippomarathrum scabrum L. is an endemic medicinal plant in Turkey; however, there have been few studies investigating the phytochemistry and biological properties of these plants has not been investigated. The aim of this work is to determine the chemical composition of different extracts (extracts obtained by using supercritical carbon dioxide extraction, accelerated solvent extraction, homogenizer-assisted extraction, microwave-assisted extraction, and ultrasound-assisted extraction from Hippomarathrum scabrum L., and evaluate their biological properties. The analysis revealed that 5-O-caffeoylquinic acid, rutin, and isorhamnetin 3-O-rutinoside were the main bioactive compounds. The extract obtained by accelerated extraction contains the highest concentration of 5-O-Caffeoylquinic acid (7616.74 ± 63.09 mg/kg dry extract) followed by the extract obtained by homogenizer-assisted extraction (6682.53 ± 13.04 mg/kg dry extract). In antioxidant tests, all extracts expressed significant antioxidant activity. Also, cytotoxic and anticancer effects of these plant extracts were detected in the human prostate cancer cell line. Intrinsic apoptotic genes were up-regulated and anti-apoptotic genes were down-regulated in human prostate cancer cells after inhibition concentration dose treatment. The findings are promising, and suggest the use of these plant extracts could be used as natural sources with different biological activities, as well as anticancer agents.

Enzyme ChE, cholinergic therapy and molecular docking: Significant considerations and future perspectives

Enzyme Che plays an essential role in cholinergic and non-cholinergic functions. It is present in the fertilized/unfertilized eggs and sperm of different species. Inclusion criteria for data collection from electronic databases NCBI and Google Scholar are enzyme AChE/BChE, cholinergic therapy, genomic organization and gene transcription, enzyme structure, biogenesis, transport, processing and localization, molecular signaling and biological function, polymorphism and influencing factors. Enzyme Che acts as a signaling receptor during hematopoiesis, protein adhesion, amyloid fiber formation, neurite outgrowth, bone development, and maturation, explaining the activity out of synaptic neurotransmission. Polymorphism in the Che genes correlates to various diseases and diverse drug responses. In particular, change accompanies cancer, neurodegenerative, and cardiovascular disease. Literature knowledge indicates the importance of Che inhibitors that influence biochemical and molecular pathways in disease treatment, genomic organization, gene transcription, structure, biogenesis, transport, processing, and localization of Che enzyme. Enzyme Che polymorphism changes indicate the possibility of efficient and new inhibitor drug target mechanisms in diverse research areas.

The Art of Building Living Tissues: Exploring the Frontiers of Biofabrication with 3D Bioprinting

The scope of three-dimensional printing is expanding rapidly, with innovative approaches resulting in the evolution of state-of-the-art 3D bioprinting (3DbioP) techniques for solving issues in bioengineering and biopharmaceutical research. The methods and tools in 3DbioP emphasize the extrusion process, bioink formulation, and stability of the bioprinted scaffold. Thus, 3DbioP technology augments 3DP in the biological world by providing technical support to regenerative therapy, drug delivery, bioengineering of prosthetics, and drug kinetics research. Besides the above, drug delivery and dosage control have been achieved using 3D bioprinted microcarriers and capsules. Developing a stable, biocompatible, and versatile bioink is a primary requisite in biofabrication. The 3DbioP research is breaking the technical barriers at a breakneck speed. Numerous techniques and biomaterial advancements have helped to overcome current 3DbioP issues related to printability, stability, and bioink formulation. Therefore, this Review aims to provide an insight into the technical challenges of bioprinting, novel biomaterials for bioink formulation, and recently developed 3D bioprinting methods driving future applications in biofabrication research.

Galantamine-memantine hybrids for Alzheimer's disease: The influence of linker rigidity in biological activity and pharmacokinetic properties

Neurodegenerative processes characterizing Alzheimer's disease (AD) are strictly related to the impairment of cholinergic and glutamatergic neurotransmitter systems which provoke synaptic loss. These experimental evidences still represent the foundation of the actual standard-of-care treatment for AD, albeit palliative, consisting on the coadministration of an acetylcholinesterase inhibitor and the NMDAR antagonist memantine. In looking for more effective treatments, we previously developed a series of galantamine-memantine hybrids where compound 1 (ARN14140) emerged with the best-balanced action toward the targets of interest paired to neuroprotective efficacy in a murine AD model. Unfortunately, it showed a suboptimal pharmacokinetic profile, which required intracerebroventricular administration for in vivo studies. In this work we designed and synthesized new hybrids with fewer rotatable bonds, which is related to higher brain exposure. Particularly, compound 2, bearing a double bond in the tether, ameliorated the biological profile of compound 1 in invitro studies, increasing cholinesterases inhibitory potencies and selective antagonism toward excitotoxic-related GluN1/2B NMDAR over beneficial GluN1/2A NMDAR. Furthermore, it showed increased plasma stability and comparable microsomal stability in vitro, paired with lower half-life and faster clearance in vivo. Remarkably, pharmacokinetic evaluations of compound 2 showed a promising increase in brain uptake in comparison to compound 1, representing the starting point for further chemical optimizations.

A method for the efficient evaluation of substrate-based cholinesterase imaging probes for Alzheimer's disease

Cholinesterase (ChE) enzymes have been identified as diagnostic markers for Alzheimer disease (AD). Substrate-based probes have been synthesised to detect ChEs but they have not detected changes in ChE distribution associated with AD pathology. Probes are typically screened using spectrophotometric methods with pure enzyme for specificity and kinetics. However, the biochemical properties of ChEs associated with AD pathology are altered. The present work was undertaken to determine whether the Karnovsky-Roots (KR) histochemical method could be used to evaluate probes at the site of pathology. Thirty thioesters and esters were synthesised and evaluated using enzyme kinetic and KR methods. Spectrophotometric methods demonstrated all thioesters were ChE substrates, yet only a few provided staining in the brain with the KR method. Esters were ChE substrates with interactions with brain ChEs. These results suggest that the KR method may provide an efficient means to screen compounds as probes for imaging AD-associated ChEs.

Butyrylcholinesterase signal sequence self-aggregates and enhances amyloid fibril formation in vitro

Alzheimer's disease (AD) pathogenesis has been attributed to extracellular aggregates of amyloid β (Aβ) plaques and neurofibrillary tangles in the human brain. It has been reported that butyrylcholinesterase (BChE) also accumulates in the brain Aβ plaques in AD. We have previously found that the BChE substitution in 5'UTR caused an in-frame N-terminal extension of 41 amino acids of the BChE signal peptide. The resultant variant with a 69 amino acid signal peptide, designated N-BChE, could play a role in AD development. Here, we report that the signal sequence of the BChE, if produced in an extended 69 aa version, can self-aggregate and could form seeds that enhance amyloid fibril formation in vitro in a dose-dependent manner and create larger co-aggregates. Similar phenomena could have been observed in the human brain if such an extended form of the signal sequence had been, in some circumstances, translated.

Hydrazone-sulfonate hybrids as potential cholinesterase inhibitors: design, synthesis and molecular modeling simulation

Aim: Design and synthesis of a series of hydrazone-sulfonate hybrids, 5a-r. Methodology: The inhibitory properties of the synthesized compounds against acetylcholinesterase and butyrylcholinesterase were evaluated using donepezil as the reference standard. Results & conclusion: Compound 5e was identified as the most potent inhibitor of acetylcholinesterase (IC50 = 9.30 μM), and compound 5i was the most potent inhibitor of butyrylcholinesterase (IC50 = 11.82 μM). To confirm the safety of the most potent hits at the used doses, toxicological bioassays were conducted. Molecular docking was performed and the tested derivatives were found to fit well in the active sites of both enzymes. This study provides valuable insights into the potential of hydrazone-sulfonate hybrids as drug candidates.

Drug and pro-drug substrates and pseudo-substrates of human butyrylcholinesterase

Butyrylcholinesterase (BChE) is present in plasma and numerous cells and organs. Its physiological function(s) is(are) still unclear. However, this enzyme is of pharmacological and toxicological importance. It displays a broad specificity and is capable of hydrolyzing a wide range of substrates with turnovers differing by several orders of magnitude. Nowaday, these substrates include more than two dozen carboxyl-ester drugs, numerous acetylated prodrugs, and transition state analogues of acetylcholine. In addition, BChE displays a promiscuous hydrolytic activity toward amide bonds of arylacylamides, and slowly hydrolyzes carbamyl- and phosphoryl-esters. Certain pseudo-substrates like carbamates and organophosphates are major drugs of potential medical interest. The existence of a large genetic poly-allelism, affecting the catalytic properties of BChE is at the origin of clinical complications in the use of certain drugs catabolized by BChE. The number of drugs and prodrugs hydrolyzed by BChE is expected to increase in the future. However, very few quantitative data (Km, kcat) are available for most marketed drugs, and except for myorelaxants like succinylcholine and mivacurium, the impact of BChE genetic mutations on catalytic parameters has not been evaluated for most of these drugs.

Serum butyrylcholinesterase activity in healthy dogs with and without exposure to diazinon

BACKGROUND

Cholinesterase is a biomarker for poisonings by anticholinesterase agents, but its reference values are scarce, and possible interaction with collars containing parasiticides has not been studied.

OBJECTIVES

We aimed to evaluate the serum cholinesterase activity of healthy dogs without a history of contact with anticholinesterase agents and healthy animals exposed to commercial collars containing organophosphate.

METHODS

Ninety-nine dogs were used and included healthy animals without recent exposure to anticholinesterase agents and healthy animals previously exposed to diazinon collars. Serum quantification of the enzyme butyrylcholinesterase (BuchE) through spectrophotometry was conducted on all samples. In experiment 1, BuchE activity was quantified at time 0 and 7 days after, a time when the samples were kept at -18°C. In experiment 2, sampling times were 0, 7, 14, 21, 28, and 56 days.

RESULTS

Time 0 values were 4622.38 ± 1311.53 U/L. After 7 days, a significant decay was observed, with a mean of 3934.45 ± 1430.45 U/L. Spearman's test was performed, finding a weak correlation between ALT, creatinine, total plasma proteins, age, weight, red blood cells, platelets, leukocytes, and BuchE activities. In experiment 2, the mean at time 0 was 4753 ± 454.8 U/L. With exposure to the collar, there was a decay of up to 93% after 14 days.

CONCLUSIONS

Normality values of serum BuchE in healthy dogs without a history of exposure to anticholinesterase agents were 4360.8-4883.96 U/L. Freezing serum caused a decrease in BuchE activity. Exposure to commercial collars containing diazinon also reduced BuchE activity without clinical signs, indicating that previously exposed animals should be evaluated carefully.

Clinical enzymology of the dog and cat

Clinical enzymology studies the enzyme activity in serum or other body fluids for the diagnosis, prognosis or monitoring of a variety of diseases. Clinical enzymology has greatly benefited from advances in technology and is now an integral part of laboratory analysis. However, to maximise the clinical benefits of serum enzyme measurement, clinicians and clinical pathologists must have a good understanding of the pathophysiology behind serum enzyme alterations. They must also be aware of the preanalytical and analytical factors that can affect the accuracy of serum enzyme activity measurement. This review article first covers the basic concepts of clinical enzymology and the general mechanisms related to serum enzyme alterations. Then, the review discusses the potential effects of various preanalytical and analytical factors on enzyme activity measurement. Lastly, it explores the pathophysiology and clinical use of various serum enzymes in canine and feline medicine. The present review article aims to be a comprehensive one-stop source for clinical pathologists and small animal practitioners.

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.

A Multitarget Approach against Neuroinflammation: Alkyl Substituted Coumarins as Inhibitors of Enzymes Involved in Neurodegeneration

Neurodegenerative disorders (NDs) include a large range of diseases characterized by neural dysfunction with a multifactorial etiology. The most common NDs are Alzheimer's disease and Parkinson's disease, in which cholinergic and dopaminergic systems are impaired, respectively. Despite different brain regions being affected, oxidative stress and inflammation were found to be common triggers in the pathogenesis and progression of both diseases. By taking advantage of a multi-target approach, in this work we explored alkyl substituted coumarins as neuroprotective agents, capable to reduce oxidative stress and inflammation by inhibiting enzymes involved in neurodegeneration, among which are Carbonic Anhydrases (CAs), Monoamine Oxidases (MAOs), and Cholinesterases (ChEs). The compounds were synthesized and profiled against the three targeted enzymes. The binding mode of the most promising compounds (7 and 9) within MAO-A and -B was analyzed through molecular modeling studies, providing and explanation for the different selectivities observed for the MAO isoforms. In vitro biological studies using LPS-stimulated rat astrocytes showed that some compounds were able to counteract the oxidative stress-induced neuroinflammation and hamper interleukin-6 secretion, confirming the success of this multitarget approach.

Dopaminergic and serotoninergic neurotoxicity of lanthanide phosphate (TbPO4) in developing zebrafish

Rare earth elements (REEs) are exploited for global use in manufacturing. Such activities result in their release into the environment and the transformation into more stable phosphate deposition. The objective of this study was to evaluate molecular and behavioral changes of zebrafish exposed to the synthesized terbium phosphate (TbPO4) at concentrations of 10, 20, and 50 mg/L and to determine its potential for neurotoxicity. Metabolomics related to neurotransmitters, and assessment of transcripts and proteins were conducted to uncover the molecular mechanisms underlying TbPO4 with emphasis on neurotransmitter systems. Exposure to 20 mg/L TbPO4 induced larval hyperactivity and perturbed the cholinergic system in zebrafish. Based on metabolomics related to neurotransmitters, dopamine (DA), serotonin (5-HT), and many of their precursors and metabolites were decreased in abundance by TbPO4. In addition, the expression levels of transcripts related to the synthesis, transport, receptor binding, and metabolism of DA and 5-HT were analyzed at the mRNA and protein levels. Transcript and protein levels for tyrosine hydroxylase (TH), the rate-limiting enzyme for DA synthesis, were down-regulated in larval fish. Monoamine oxidase (MAO), an enzyme that catabolizes monoamines DA and 5-HT, was also reduced in mRNA abundance. We hypothesize that DA synthesis and monoamine metabolism are associated with behavioral alterations. This study elucidates putative mechanisms and exposure risks to wildlife and humans by characterizing phosphatic REE-induced neurotoxicity in developing zebrafish.

Design, synthesis and molecular docking and ADME studies of novel hydrazone derivatives for AChE inhibitory, BBB permeability and antioxidant effects

Alzheimer's disease (AD) is a progressive and fatal neurodegenerative disease that is characterized by memory and cognitive impairments that predominantly affects the elderly and is the most common cause of dementia. As is known, the AChE enzyme consists of two parts. In this work, 10 new hydrazones (3a-3j) were designed and synthesized. Naphthalene, indole, benzofuran and benzothiophene rings were used to interact with the PAS region. 4-fluorophenyl and 4-fluorobenzyl structures were preferred for interaction with the CAS region. In biological activity studies, the AChE and BChE inhibitory potentials of all compounds were evaluated using the in vitro Ellman method. The biological evaluation showed that compounds 3i and 3j displayed significant activity against AChE. The compounds 3i and 3j displayed IC50 values of 0.034 and 0.027 µM against AChE, respectively. The reference drug donepezil (IC50 = 0.021 µM) also displayed a significant inhibition against AChE. In addition, the antioxidant activities of the compounds were also evaluated. Derivatives 3i and 3j, which emerged active from both in vitro activity studies, were subjected to in vitro PAMPA tests to determine BBB permeability. Further docking simulation also revealed that these compounds (3i, 3j and donepezil) interacted with the enzyme active site in a similar manner to donepezil. A few parameters derived from MD simulation trajectories were computed and validated for the protein-ligand complex's stability under the dynamic conditions.Communicated by Ramaswamy H. Sarma.

Synthesis of phenylethanoid glycosides from acrylic esters of glucose and aryldiazonium salts via palladium-catalyzed cross-coupling reactions and evaluation of their anti-Alzheimer activity

Cinnamic acid-containing sugar compounds such as phenylethanoid glycosides are widely present in nature and display various biological activities. In this work, the synthesis of trans-cinnamic acid containing phenylethanoid glycosides was achieved via palladium-catalyzed cross-coupling reactions between glycosyl acrylic esters and aryldiazonium salts. A wide range of functionalized aryldiazonium salts were successfully coupled with 6-O- and 4-O-acrylic esters of glucose under optimized conditions. The reactions proceeded at room temperature in the absence of additives and base. The desired products were obtained in good to excellent yields. Selected compounds from the library were screened for anti-Alzheimer activity, while compound 16 displayed significant inhibitory activities against butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) enzymes.

Benzenesulfonamide as a novel, pharmaceutical small molecule inhibitor on Aβ gene expression and oxidative stress in Alzheimer's Wistar rats

Alzheimer's disease (AD) is the most prevalent acute neurodegenerative disease described by memory loss and other cognitive functions. Benzenesulfonamide, a novel, potent, and small organic molecule, was synthesized to investigate its effects on the levels of oxidative biomarkers (GPx, ROS, and MDA) and expression of beta-amyloid peptides (Aβ40 and Aβ42) in the pathology of AD. The results were compared with the rivastigmine drug. Applying benzenesulfonamide to Alzheimer's-induced Wistar rats showed a significant increase in the level of oxidative biomarkers (GPx, ROS, and MDA) in both the brain and blood serum as well as amyloid-β40 and 42 gene expressions. Therefore, benzenesulfonamide could be considered a novel therapeutic agent against AD.

Under the umbrella of depression and Alzheimer's disease physiopathology: Can cannabinoids be a dual-pleiotropic therapy?

Depression and Alzheimer´s disease (AD) are two disorders highly prevalent worldwide. Depression affects more than 300 million people worldwide while AD affects 60-80% of the 55 million cases of dementia. Both diseases are affected by aging with high prevalence in elderly and share not only the main brain affected areas but also several physiopathological mechanisms. Depression disease is already ascribed as a risk factor to the development of AD. Despite the wide diversity of pharmacological treatments currently available in clinical practice for depression management, they remain associated to a slow recovery process and to treatment-resistant depression. On the other hand, AD treatment is essentially based in symptomatology relieve. Thus, the need for new multi-target treatments arises. Herein, we discuss the current state-of-art regarding the contribution of the endocannabinoid system (ECS) in synaptic transmission processes, synapses plasticity and neurogenesis and consequently the use of exogenous cannabinoids in the treatment of depression and on delaying the progression of AD. Besides the well-known imbalance of neurotransmitter levels, including serotonin, noradrenaline, dopamine and glutamate, recent scientific evidence highlights aberrant spine density, neuroinflammation, dysregulation of neurotrophic factor levels and formation of amyloid beta (Aβ) peptides, as the main physiopathological mechanisms compromised in depression and AD. The contribution of the ECS in these mechanisms is herein specified as well as the pleiotropic effects of phytocannabinoids. At the end, it became evident that Cannabinol, Cannabidiol, Cannabigerol, Cannabidivarin and Cannabichromene may act in novel therapeutic targets, presenting high potential in the pharmacotherapy of both diseases.

The structural modification and biological evaluation of tetrahydrothienopyridine derivatives as selective BChE inhibitors

A series of tetrahydrothienopyridine derivatives have been designed, synthesized, and evaluated as selective BChE inhibitors. Compounds were analyzed via HRMS, 1H NMR, and 13C NMR. The inhibitory effects were evaluated according to the method of Ellman et al. 6n was the most potent and selective inhibitor against BChE (eeAChE IC50 = 686.4 ± 478.6 μM, eqBChE IC50 = 10.5 ± 5.0 nM, SI = 6.5*104, hBChE IC50 = 32.5 ± 6.5 nM). Cell-based assays have confirmed the low neurotoxicity of 6a and 6n and their moderate neuroprotective effects. Compounds 6a and 6n provide novel chemical entities for the treatment of Alzheimer's disease.

The Association of Selected GWAS Reported AD Risk Loci with CSF Biomarker Levels and Cognitive Decline in Slovenian Patients

Alzheimer's disease (AD) is the most common neurodegenerative disease, with a complex genetic background. Apart from rare, familial cases, a combination of multiple risk loci contributes to the susceptibility of the disease. Genome-wide association studies (GWAS) have identified numerous AD risk loci. Changes in cerebrospinal fluid (CSF) biomarkers and imaging techniques can detect AD-related brain changes before the onset of clinical symptoms, even in the presence of preclinical mild cognitive impairment. In this study, we aimed to assess the associations between SNPs in well-established GWAS AD risk loci and CSF biomarker levels or cognitive test results in Slovenian patients with cognitive decline. The study included 82 AD patients, 28 MCI patients with pathological CSF biomarker levels and 35 MCI patients with normal CSF biomarker levels. Carriers of at least one polymorphic TOMM40 rs157581 C allele had lower Aβ42 (p = 0.033) and higher total tau (p = 0.032) and p-tau181 levels (p = 0.034). Carriers of at least one polymorphic T allele in SORCS1 rs1358030 had lower total tau (p = 0.019), while polymorphic SORCS1 rs1416406 allele was associated with lower total tau (p = 0.013) and p-tau181 (p = 0.036). In addition, carriers of at least one polymorphic T allele in BCHE rs1803274 had lower cognitive test scores (p = 0.029). The study findings may contribute to the identification of genetic markers associated with AD and MCI and provide insights into early disease diagnostics.

Anti-AChE and Anti-BuChE Screening of the Fermentation Broth Extracts from Twelve Aspergillus Isolates and GC-MS and Molecular Docking Studies of the Most Active Extracts

Nowadays, the administration of cholinesterase enzyme (acetylcholinesterase: AChE and butyrylcholinesterase: BuChE) inhibitors is very common for the symptomatic treatment of Alzheimer's disease and the other forms of dementia and CNS disorders. In this paper, the anti-AChE and anti-BuChE activities of the fermentation broth ethyl acetate extracts from twelve Aspergillus isolates were evaluated by Ellman method. The results showed that A1 (Aspergillus flavus) and A5 (Aspergillus tubingensis, isolate 1) extracts with IC50 values of 46.77 μg/mL and 75.85 μg/mL possess the greatest ability to inhibit AChE and BuChE, respectively. GC-MS analysis of the extracts (A1 and A5) demonstrated that two alkaloids named 14-methyl-16-azabicyclo[10.3.1]hexadeca-1(15),12(16),13-triene (MAHT) and 6-chloro-2-methyl-7,8,9,10-tetrahydro-phenanthridine (CMTP) account for the highest percentage of A1 (26.95%) and A5 (25.5%) extracts, respectively. A 2-pyrazoline derivative, 5-hydroxy-3-(4-pyridinyl)-5-trifluoromethyl-1-(2,4,6-trimethylphenoxyacetyl)- (PHPTT), also constituted the high percentage (9.54%) of A5 extract. The anticholinesterase and neuroprotective effects of some 2-pyrazoline derivatives have been previously reported. The interaction study of MAHT with human AChE and CMTP and PHPTT with human BuChE using molecular docking indicated that these alkaloids bind to the active site gorge of the enzymes with high affinity. The best docking scores of MAHT, CMTP, and PHPTT were -7.1, -8.2, and -9.7 kcal/mol, respectively.

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.

Insights into the Role of Erythrina corallodendron L. in Alzheimer's Disease: in Vitro and in Silico Approach

Alzheimer's disease (AD) is a major health problem. Cholinergic transmission is greatly affected in AD. Phytochemical investigation of the alkaloid rich fraction (AF) of Erythrina corallodendron L leaves resulted in isolation of five known alkaloids: erysodine, erythrinine, 8-oxoerythrinine, erysovine N-oxide and erythrinine N-oxide. In this study, eysovine N-oxide was reported for the second time in nature. AF was assayed for cholinesterase inhibition at the concentration of 100 μg mL-1 . AF showed a higher percent inhibition for butyrylcholinesterase enzyme (BuChE) (83.28 %) compared to acetylcholinesterase enzyme (AChE) (64.64 %). The isolated alkaloids were also assayed for their anti-BuChE effect. In-silico docking study was done for the isolated compounds at the binding sites of AChE and BuChE to determine their binding pattern and interactions, also molecular dynamics were estimated for the compound displaying the best fit for AChE and BuChE. In addition, ADME parameters and toxicity were predicted for the isolated alkaloids compared to donepezil.

Real-time visualization of butyrylcholinesterase activity using a highly selective and sensitive chemiluminescent probe

Butyrylcholinesterase (BChE), one of the critical human cholinesterases, plays crucial roles in numerous physiological and pathological processes. Accordingly, it is a striking and at the same time challenging target for bioimaging studies. Herein, we developed the first ever example of a 1,2-dixoetane-based chemiluminescent probe (BCC) for monitoring BChE activity in native biological contexts such as living cells and animals. BCC was initially shown to exhibit a highly selective and sensitive turn-on response in its luminescence signal upon reacting with BChE in aqueous solutions. Later, BCC was utilized to image endogenous BChE activity in normal and cancer cell lines. It was also shown through inhibition experiments that BChE can detect fluctuations of BChE levels successfully. In vivo imaging ability of BCC was demonstrated in healthy and tumor-bearing mice models. BCC enabled us to visualize the BChE activity in different regions of the body. Furthermore, it was successfully employed to monitor tumors derived from neuroblastoma cells with a very high signal to noise ratio. Thus, BCC appears as a highly promising chemiluminescent probe, which can be used to further understand the contribution of BChE to regular cellular processes and the formation of diseased states.

Investigation of Novel Benzoxazole-Oxadiazole Derivatives as Effective Anti-Alzheimer's Agents: In Vitro and In Silico Approaches

Alzheimer's disease (AD) is a progressive neurological illness that is distinguished clinically by cognitive and memory decline and adversely affects the people of old age. The treatments for this disease gained much attention and have prompted increased interest among researchers in this field. As a springboard to explore new anti-Alzheimer's chemical prototypes, the present study was carried out for the synthesis of benzoxazole-oxadiazole analogues as effective Alzheimer's inhibitors. In this research work, we have focused our efforts to synthesize a series of benzoxazole-oxadiazole (1-19) and evaluating their anti-Alzheimer properties. In addition, the precise structures of synthesized derivatives were confirmed with the help of various spectroscopic techniques including ¹H-NMR, ¹³C-NMR and HREI-MS. To find the anti-Alzheimer potentials of the synthesized compounds (1-19), in vitro acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), inhibitory activities were performed using Donepezil as the reference standard. From structure-activity (SAR) analysis, it was confirmed that any variation found in inhibitory activities of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes were due to different substitution patterns of substituent(s) at the variable position of both acetophenone aryl and oxadiazole aryl rings. The results of the anti-Alzheimer assay were very encouraging and showed moderate to good inhibitory potentials with IC₅₀ values ranging from 5.80 ± 2.18 to 40.80 ± 5.90 µM (against AChE) and 7.20 ± 2.30 to 42.60 ± 6.10 µM (against BuChE) as compared to standard Donepezil drug (IC₅₀ = 33.65 ± 3.50 µM (for AChE) and 35.80 ± 4.60 µM (for BuChE), respectively. Specifically, analogues 2, 15 and 16 were identified to be significantly active, even found to be more potent than standard inhibitors with IC₅₀ values of 6.40 ± 1.10, 5.80 ± 2.18 and 6.90 ± 1.20 (against AChE) and 7.50 ± 1.20, 7.20 ± 2.30 and 7.60 ± 2.10 (against BuChE). The results obtained were compared to standard drugs. These findings reveal that benzoxazole-oxadiazole analogues act as AChE and BuChE inhibitors to develop novel therapeutics for treating Alzheimer's disease and can act as lead molecules in drug discovery as potential anti-Alzheimer agents.

Dual-Mode Ratiometric Electrochemical and Turn-On Fluorescent Detection of Butyrylcholinesterase Utilizing a Single Probe for the Diagnosis of Alzheimer's Disease

Biomarkers detection in blood with high accuracy is crucial for the diagnosis and treatment of many diseases. In this study, the proof-of-concept fabrication of a dual-mode sensor based on a single probe (Re-BChE) using a dual-signaling electrochemical ratiometric strategy and a "turn-on" fluorescent method is presented. The probe Re-BChE was synthesized in a single step and demonstrated dual mode response toward butyrylcholinesterase (BChE), a promising biomarker of Alzheimer's disease (AD). Due to the specific hydrolysis reaction, the probe Re-BChE demonstrated a turn-on current response for BChE at -0.28 V, followed by a turn-off current response at -0.18 V, while the fluorescence spectrum demonstrated a turn-on response with an emission wavelength of 600 nm. The developed ratiometric electrochemical sensor and fluorescence detection demonstrated high sensitivity with BChE concentrations with a low detection limit of 0.08 μg mL^-1 and 0.05 μg mL^-1, respectively. Importantly, the dual-mode sensor presents the following advantages: (1) dual-mode readout can correct the impact of systematic or background error, thereby achieving more accurate results; (2) the responses of dual-mode readout originate from two distinct mechanisms and relatively independent signal transduction, in which there is no interference between two signaling routes. Additionally, compared with the reported single-signal electrochemical assays for BChE, both redox potential signals were detected in the absence of biological interference within a negative potential window. Furthermore, it was discovered that the outcomes of direct dual-mode electrochemical and fluorescence quantifications of the level of BChE in serum were in agreement with those obtained from the use of commercially available assay kits for BChE sensing. This method has the potential to serve as a useful point-of-care tool for the early detection of AD.

Xylopia aethiopica suppresses markers of oxidative stress, inflammation, and cell death in the brain of Wistar rats exposed to glyphosate

The herbicide "Roundup" is used extensively in agriculture to control weeds. However, by translocation, it can be deposited in plants, their proceeds, and the soil, thus provoking organ toxicities in exposed individuals. Neurotoxicity among others is one of the side effects of roundup which has led to an increasing global concern about the contamination of food by herbicides. Xylopia aethiopica is known to have medicinal properties due to its antioxidative and anti-inflammatory properties, and it is hypothesized to neutralize roundup-induced neurotoxicity. Thirty-six (36) Wistar rats were used for this study. The animals were shared equally into six groups with six rats each. Glyphosate administration to three of the six groups was done orally and for 1 week. Either Xylopia aethiopica or vitamin C was co-administered to two of the three groups and also administered to two other groups and the final group served as the control. Our studies demonstrated that glyphosate administration led to a significant decrease in antioxidants such as catalase, superoxide dismutase, glutathione, and glutathione peroxidase. We also observed a significant increase in inflammatory markers such as tumor necrosis factor-α, interleukin 6, C-reactive protein, and immunohistochemical expression of caspase-3, cox-2, and p53 proteins (p < 0.05). However, Xylopia aethiopica co-administration with glyphosate was able to ameliorate the aforementioned changes when compared to the control (p < 0.05). Degenerative changes were also observed in the cerebellum, hippocampus, and cerebral cortex upon glyphosate administration. These changes were not observed in the groups treated with Xylopia aethiopica and vitamin C. Taken together, Xylopia aethiopica could possess anti-oxidative and anti-inflammatory properties that could be used in combating glyphosate neurotoxicity.

Immunohistochemistry for acetylcholinesterase and butyrylcholinesterase in the dorsal motor nucleus of the vagus (DMNV) of formalin-fixed, paraffin-embedded tissue: comparison with reported literature

The majority of research regarding the expression of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in the brain has been conducted using histochemistry to identify enzymatic activity in frozen fixed tissue. However, retrospective human neurochemistry studies are generally restricted to formalin-fixed, paraffin-embedded (FFPE) tissues that are not suitable for histochemical procedures. The availability of commercially available antibody formulations provides the means to study such tissues by immunohistochemistry (IHC). In this study, we optimised IHC conditions for evaluating the expression of AChE and BuChE in the brainstem, focusing on the dorsal motor nucleus of the vagus, in human and piglet FFPE tissues, using commercially available antibodies. Our results were compared to published reports of histochemically determined AChE and BuChE expression. We varied antibody concentrations and antigen retrieval methods, and evaluated different detection systems, with the overall aim to optimise immunohistochemical staining. The primary findings, consistent across both species, are: (1) AChE and BuChE expression dominated in the neuronal somata, specifically in the neuronal cytoplasm; and (2) no change in the protocol resulted in axonal/neuropil expression of AChE. These results indicate that IHC is a suitable tool to detect AChE and BuChE in FFPE tissue using commercial antibodies, albeit the staining patterns obtained differed from those using histochemistry in frozen tissue. The underlying cause(s) for these differences are discussed in detail and may be associated with the principal components of the staining method, the antibody protein target and/or limitations to the detection of epitopes by tissue fixation.

Integrated in silico and experimental discovery of trimeric peptide ligands targeting Butyrylcholinesterase

Butyrylcholinesterase (BChE) is recognized as a high value biotherapeutic in the treatment of Alzheimer's disease and drug addiction. This study presents the rational design and screening of an in-silico library of trimeric peptides against BChE and the experimental characterization of peptide ligands for purification. The selected peptides consistently afforded high BChE recovery (> 90 %) and purity, yielding up to a 1000-fold purification factor. This study revealed a marked anti-correlated conformational movement governed by the ionic strength and pH of the aqueous environment, which ultimately controls BChE binding and release during chromatographic purification; and highlighted the role of residues within and allosteric to the catalytic triad of BChE in determining biorecognition, thus providing useful guidance for ligand design and affinity maturation.

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

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

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.

Molecular and Computational Analysis Identify Statins as Selective Inhibitors of Human Butyrylcholinesterase

Cholinesterase enzyme family consists of acetylcholinesterase (AChE, 3.1.1.7), the major enzyme responsible for hydrolysis of acetylcholine at cholinergic synapses, and butyrylcholinesterase (BChE, 3.1.1.8) a detoxification enzyme of plasma. Statins are cholesterol-lowering medications utilized as protective medicaments in stroke and Alzheimer's disease, which cholinesterases are associated with. Thus, in this study, we characterized the inhibitory effects and mechanisms of common statins, rosuvastatin, atorvastatin, simvastatin and lovastatin, on human erythrocyte AChE and purified serum BChE using in vitro and in silico methods. Kinetic assays identified statins as selective non-competitive inhibitors of human serum BChE. The IC₅₀ and K_m values were found as 194.7 ± 55.2 µM and 1.03 ± 0.2 µM for rosuvastatin, 492.5 ± 55.1 µM and 7.2 ± 0.3 µM for atorvastatin, 14.2 ± 0.3 µM and 202.7 ± 23.2 µM for lovastatin, and 17.6 ± 0.1 µM and 207.2 ± 13.2 µM for simvastatin, respectively. The compounds did not display considerable inhibition against AChE. Molecular docking predicted good affinity and strong interactions with the BChE active site for atorvastatin and rosuvastatin. Current study identifies rosuvastatin as the most specific and selective inhibitor of human BChE among the tested statins. As selective inhibitors of BChE statins have the potential to be re-evaluated as medicaments due to their pleiotropic effects.

Catalytic activities of a highly efficient cocaine hydrolase for hydrolysis of biologically active cocaine metabolites norcocaine and benzoylecgonine

Cocaine is a widely abused, hepatotoxic drug without an FDA-approved pharmacotherapy specific for cocaine addiction or overdose. It is recognized as a promising therapeutic strategy to accelerate cocaine metabolism which can convert cocaine to pharmacologically inactive metabolite(s) using an efficient cocaine-metabolizing enzyme. Our previous studies have successfully designed and discovered a highly efficient cocaine hydrolase, denoted as CocH5-Fc(M6), capable of rapidly hydrolyzing cocaine at the benzoyl ester moiety. In the present study, we determined the kinetic parameters of CocH5-Fc(M6) against norcocaine (k_cat = 9,210 min^-1, K_M = 20.9 μM, and k_cat/K_M = 1.87 × 10⁵ min^-1 M^-1) and benzoylecgonine (k_cat = 158 min^-1, K_M = 286 μM, and k_cat/K_M = 5.5 × 10⁵ min^-1 M^-1) for the first time. Further in vivo studies have demonstrated that CocH5-Fc(M6) can effectively accelerate clearance of not only cocaine, but also norcocaine (known as a cocaine metabolite which is more toxic than cocaine itself) and benzoylecgonine (known as an unfavorable long-lasting metabolite with some long-term toxicity concerns) in rats. Due to the desired high catalytic activity against norcocaine, CocH5-Fc(M6) is capable of quickly detoxifying both cocaine and its more toxic metabolite norcocaine after intraperitoneally administering lethal dose of 60 or 180 mg/kg cocaine. In addition, the ability of CocH5-Fc(M6) to accelerate clearance of benzoylecgonine should also be valuable for the use of CocH5-Fc(M6) in treatment of cocaine use disorder.