CHOLINESTERASES, A TARGET OF PHARMACOLOGY AND TOXICOLOGY

Development, biological evaluation, and molecular modelling of novel isocytosine and guanidine derivatives as BACE1 inhibitors using a fragment growing strategy

Alzheimer's disease (AD) is a neurodegenerative condition characterized by significant synaptic loss and neuronal death in brain regions critical for cognitive functions. The disease is characterized by the formation of amyloid plaques, which are extracellular constructs consisting mainly of aggregated Aβ42. The latter is a peptide formed by the proteolytic cleavage of β-amyloid precursor protein (APP) by two enzymes, β- and γ-secretase. Therefore, inhibition of the aspartic protease β-secretase (BACE1) is considered a promising therapeutic approach for the treatment and prevention of Alzheimer's disease. Unfortunately, a limited number of β-secretase inhibitors have reached human trials and eventually failed due to inconclusive therapeutic and/or safety profiles. In this study, we developed drug-like molecules with a β-secretase inhibitory activity using a fragment growing strategy on isocytosine and acyl guanidine warheads. Our approach is based on optimizing the hydrophobic part of the molecules to obtain a conformationally restrained scaffold complementary to the hydrophobic pockets within the enzyme active site. We developed 32 compounds with promising in vitro inhibitory activity against BACE1 down to sub-micromolar IC50. Docking simulation studies were performed to understand the mode of binding of the prepared compounds. We demonstrated that compounds with superior activities, such as 16b and 16g, are able to provide the best balance between the steric shape and position of the polar substituent for achieving preferential anchoring into the S1, S3, S1', and S2' sub-pockets. Further, in vivo characterization of selected drug-like candidates of the benzimidazole series AMK-IV, namely 16a and 16k, demonstrated their ability to reduce oxidation stress and their safety within brain and liver tissues.

Monoamine alterations in Alzheimer's disease and their implications in comorbid neuropsychiatric symptoms

Alzheimer's disease (AD) is a devastating neurodegenerative disorder characterized by relentless cognitive decline and the emergence of profoundly disruptive neuropsychiatric symptoms. As the disease progresses, it unveils a formidable array of neuropsychiatric manifestations, including debilitating depression, anxiety, agitation, and distressing episodes of psychosis. The intricate web of the monoaminergic system, governed by serotonin, dopamine, and norepinephrine, significantly influences our mood, cognition, and behavior. Emerging evidence suggests that dysregulation and degeneration of this system occur early in AD, leading to notable alterations in these critical neurotransmitters' levels, metabolism, and receptor function. However, how the degeneration of monoaminergic neurons and subsequent compensatory changes contribute to the presentation of neuropsychiatric symptoms observed in Alzheimer's disease remains elusive. This review synthesizes current findings on monoamine alterations in AD and explores how these changes contribute to the neuropsychiatric symptomatology of the disease. By elucidating the biological underpinnings of AD-related psychiatric symptoms, we aim to underscore the complexity and inform innovative approaches for treating neuropsychiatric symptoms in AD.

Design of reversible cholinesterase inhibitors: Fine-tuning of enzymatic activity by PAMAM-calix-dendrimers

Reversible cholinesterase (ChE) inhibitors are widely used drugs for the therapy of various cognitive and neurodegenerative disorders. The development of a "universal drug" with easily tunable ChE inhibition activity is a relevant interdisciplinary problem. Here we propose for the first time the design of novel "fine-tuned" ChE inhibitors based on dendrimers with a thiacalix[4]arene core (PAMAM-calix-dendrimers). A series of first-generation PAMAM-calix-dendrimers with different terminal fragments were designed and synthesized. The human acetylcholinesterase and butyrylcholinesterase inhibition by PAMAM-calix-dendrimers was confirmed by molecular docking and in vitro studies. PAMAM-calix-dendrimers were found to have IC50 values for acetylcholinesterase and butyrylcholinesterase in the range of 0.076-5400 μM. Relationships between the structure of PAMAM-calix-dendrimers and the ChE inhibitory activity were established. The conformation of the macrocyclic core and the nature of the terminal groups were found to exert a direct impact on the inhibitory activity of dendrimers. We anticipate our study to be a starting point for creation of "universal drug" with tunable ChE inhibitory activity to specific therapeutic targets, and more sophisticated in vivo studies of such systems.

Climatic fluctuations alter the preference of stingless bees (Apidae, Meliponini) towards food contaminated with acephate and glyphosate

The global decline of pollinators has become a major concern for the scientific community, policymakers, and the general public. Among the main drivers of diminishing bee populations is the widespread use of agrochemicals. To gain a comprehensive understanding of the foraging dynamics of bees at agrochemical-contaminated areas, it is essential to consider both environmental conditions and the specific foraging ecology of bee species. For the first time, we conducted a semi-field study to investigate whether stingless bees exhibit a preference for food contaminated with agrochemicals compared to non- contaminated food, under natural weather conditions. Colonies of Plebeia lucii Moure, 2004 were placed in a greenhouse and subjected to a preference test, where bees were given the freedom to choose between contaminated or non-contaminated food sources following a preliminary training period. Within the greenhouse, we placed feeders containing realistic concentrations of an insecticide (acephate: 2 mg a.i./L), a herbicide (glyphosate: 31.3 mg a.i./L), or a mixture of both, alongside non-contaminated food. Environmental variables (temperature, humidity, and light intensity) were monitored throughout the experiment. At higher temperatures, the foragers preferred food containing the mixture of both agrochemicals or uncontaminated food over the other treatments. At lower temperatures, by contrast, the bees preferred food laced with a single agrochemical (acephate or glyphosate) over uncontaminated food or the agrochemical mixture. Our findings indicate that agrochemical residues in nectar pose a significant threat to P. lucii colonies, as foragers do not actively avoid contaminated food, despite the detrimental effects of acephate and glyphosate on bees. Furthermore, we demonstrate that even minor, natural fluctuations in environmental conditions can alter the colony exposure risk. Despite the interplay between temperature and bees' preference for contaminated food, foragers consistently collected contaminated food containing both agrochemicals, whether isolated or in combination, throughout the whole experiment.

Microplastics and silver nanoparticles compromise detrital food chains in streams through effects on microbial decomposers and invertebrate detritivores

Abundance of microplastics (MPs) in freshwater ecosystems has become an emerging concern due to their persistence, toxicity and potential interactions with other contaminants. Silver nanoparticles (Ag-NPs), which share common sources with MPs (e.g., personal care products), are also a subject of concern. Thus, the high probability of co-occurrence of both contaminants raises additional apprehensions. This study assessed, for the first time, the impacts of MPs and Ag-NPs, alone or in mixtures, on stream detritus food webs. Physiological and ecological responses of aquatic fungal communities, invertebrate shredders (Allogamus sp.) and collectors (Chironomus riparius) were examined. Additionally, antioxidant enzymatic responses of microbes and shredders were analyzed to unravel the mechanisms of toxicity; also, neuronal stress responses of Allogamus sp. were assessed based on the activities of cholinesterases. Organisms were exposed to environmentally realistic concentrations of polyethylene MPs, extracted from a personal care product (0.1, 0.5 and 10 mg L-1), for 7 days, in the absence or presence of Ag-NPs (0.1 mg L-1 and 1 mg L-1). The exposure to both contaminants reduced the growth rates of all tested organisms. MPs, Ag-NPs, and their mixtures led to a decrease in leaf litter decomposition by fungi and shredders. The availability of fine particulate organic matter, released by the shredders, increased when exposed to these contaminants. The negative effects of these contaminants were further strengthened by the responses of antioxidant enzymes that revealed high level of oxidative stress in both fungi and Allogamus sp. Moreover, the activities of cholinesterases showed that Allogamus sp. were under neuronal stress upon exposure to both contaminants. The impacts in mixtures were stronger than those of individual contaminants suggesting interactive effects. Overall, our study showed adverse effects of MPs and Ag-NPs across trophic levels and indicated that they may compromise key processes, such as organic matter decomposition in streams.

Effect of Dalbergiella welwitschi alkaloid-rich extracts on neuroprotective in streptozotocin-induced diabetic rats

The neuroprotective ability of alkaloid-rich leaf extract of Dalbergiella welwitschii in streptozotocin-induced type 2 diabetic rats were investigated in this study. Dalbergiella welwitshii leaf alkaloid-rich extract was obtained using standard procedure. Streptozotocin was injected into the experimental animals intraperitoneally at a dose of 45 mg/mg body weight. Prior to this, the animals were given 20% (w/v) fructose for one week. The animals were grouped into five (n = 8), comprising of normal control (NC), diabetic control (DC), diabetic rats treated with low (50 mg/mg body weight) and high (100 mg/kg body weight) doses of Dalbergiella welwitschii alkaloid-rich leaf extracts (i.e., DWL and DWH respectively) and 200 mg/kg body weight of metformin (MET). The animals were sacrificed on the 21st day, blood and brain tissue were harvested and used for the determination of neurotransmitters, cholinesterase, some ATP activities, oxidative stress biomarkers and histological examination. The results show that diabetic rats placed on DWL, DWH and MET significantly (p < 0.05) reduced cholinergic, elevated some ATPase activities and ameliorated oxidative stress biomarkers. These were supported by the histological examination by improving neuroprotective effects in diabetic rats administered DWL, DWH and MET. Hence, it can be presumed that DWL and DWH could be beneficial in treating diabetic neurodegenerative diseases.

Characterization of Phenolic Profile and Biological Properties of Astragalus membranaceus Fisch. ex Bunge Commercial Samples

Astragalus membranaceus Fisch. ex Bunge (syn. Astragalus mongholicus Bunge) is one of the notable medicinal and food plants. Therefore, the aim of this study was to calculate the phenolic composition and antioxidant, antimicrobial, as well as enzyme inhibitory [acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and tyrosinase (TYR)] activities with chemometric approaches of the hydromethanolic and water extracts of commercial A. membranaceus samples. Ten individual phenolic compounds were determined using high-performance liquid chromatography (HPLC), and only quercetin was found at a level of above 80 µg/g DW in both extracts. Moreover, the highest antioxidant activity in DPPH, FRAP, ABTS, and CUPRAC assays was found in the sample containing the roots in loose form from USA. A. membranaceus extracts displayed the inhibition zone diameters within the range from 10 to 22 mm antimicrobial activity against S. aureus, while there were no inhibition zones in any extracts in case of E. coli. The extracts of A. membranaceous showed an inhibition rate below 40% against TYR, and among tested extracts, only two samples were able to inhibit BChE with IC50 values of above 30 µg/mL. Correlation analysis showed a highly positive relationship between their phenolic composition and antioxidant activity. Concluding, the obtained results confirmed that A. membranaceus commercial samples could be an important dietary source of natural antioxidants.

New 1,2,4-oxadiazole derivatives as potential multifunctional agents for the treatment of Alzheimer's disease: design, synthesis, and biological evaluation

A series of new 1,2,4-oxadiazole-based derivatives were synthesized and evaluated for their anti-AD potential. The results revealed that eleven compounds (1b, 2a-c, 3b, 4a-c, and 5a-c) exhibited excellent inhibitory potential against AChE, with IC50 values ranging from 0.00098 to 0.07920 µM. Their potency was 1.55 to 125.47 times higher than that of donepezil (IC50 = 0.12297 µM). In contrast, the newly synthesized oxadiazole derivatives with IC50 values in the range of 16.64-70.82 µM exhibited less selectivity towards BuChE when compared to rivastigmine (IC50 = 5.88 µM). Moreover, oxadiazole derivative 2c (IC50 = 463.85 µM) was more potent antioxidant than quercetin (IC50 = 491.23 µM). Compounds 3b (IC50 = 536.83 µM) and 3c (IC50 = 582.44 µM) exhibited comparable antioxidant activity to that of quercetin. Oxadiazole derivatives 3b (IC50 = 140.02 µM) and 4c (IC50 = 117.43 µM) showed prominent MAO-B inhibitory potential. They were more potent than biperiden (IC50 = 237.59 µM). Compounds 1a, 1b, 3a, 3c, and 4b exhibited remarkable MAO-A inhibitory potential, with IC50 values ranging from 47.25 to 129.7 µM. Their potency was 1.1 to 3.03 times higher than that of methylene blue (IC50 = 143.6 µM). Most of the synthesized oxadiazole derivatives provided significant protection against induced HRBCs lysis, revealing the nontoxic effect of the synthesized compounds, thus making them safe drug candidates. The results unveiled oxadiazole derivatives 2b, 2c, 3b, 4a, 4c, and 5a as multitarget anti-AD agents. The high AChE inhibitory potential can be computationally explained by the synthesized oxadiazole derivatives' significant interactions with the AChE active site. Compound 2b showed good physicochemical properties. All these data suggest that 2b could be considered as a promising candidate for future development.

Identification of a Novel Inhibitor of Cimex lectularius Acetylcholinesterase

Acetylcholinesterase (AChE) stands as a primary target of commercial insecticides, notably organophosphates and carbamates. Despite their widespread use in agricultural and indoor pest control, concerns over their high toxicity and the emergence of resistance have restricted their efficacy. In this study, we conducted high-throughput virtual screening against both wild-type (WT) and resistant Cimex lectularius AChE utilizing a library encompassing 1 270 000 compounds. From this screening, we identified 100 candidate compounds and subsequently assessed their inhibitory effects on purified AChE enzymes. Among these candidates, AE027 emerged as a potent inhibitor against both WT and resistant AChE, exhibiting IC50 values of 10 and 43 μM, respectively. Moreover, the binding of AE027 significantly stabilized AChE, elevating its melting temperature by approximately 7 °C. Through molecular docking and molecular dynamics simulation, we delineated the binding mode of AE027, revealing its interaction with a site adjacent to the catalytic center, which is distinct from known inhibitors, with differing poses observed between WT and resistant AChE. Notably, the resistance mutation F348Y, positioned at a site directly interfacing with AE027, impedes ligand binding through steric hindrance. Furthermore, we evaluated the toxicity and pharmacokinetic properties of AE027 utilizing bioinformatics tools. These findings lay a crucial foundation for the development of a novel generation of insecticides that can combat both WT and resistant pest populations effectively and safely.

Carltonine-derived compounds for targeted butyrylcholinesterase inhibition

The investigation into human butyrylcholinesterase (hBChE) inhibitors as therapeutic agents for Alzheimer's disease (AD) holds significant promise, addressing both symptomatic relief and disease progression. In the pursuit of novel drug candidates with a selective BChE inhibition pattern, we focused on naturally occurring template structures, specifically Amaryllidaceae alkaloids of the carltonine-type. Herein, we explored a series of compounds implementing an innovative chemical scaffold built on the 3- and 4-benzyloxy-benzylamino chemotype. Notably, compounds 28 (hBChE IC50 = 0.171 ± 0.063 μM) and 33 (hBChE IC50 = 0.167 ± 0.018 μM) emerged as top-ranked hBChE inhibitors. In silico simulations elucidated the binding modes of these compounds within hBChE. CNS availability was predicted using the BBB score algorithm, corroborated by in vitro permeability assessments with the most potent derivatives. Compound 33 was also inspected for aqueous solubility, microsomal and plasma stability. Chemoinformatics analysis validated these hBChE inhibitors for oral administration, indicating favorable gastrointestinal absorption in compliance with Lipinski's and Veber's rules. Safety assessments, crucial for the chronic administration typical in AD treatment, were conducted through cytotoxicity testing on human neuroblastoma (SH-SY5Y) and hepatocellular carcinoma (HepG2) cell lines.

New Multitarget Molecules Derived from Caffeine as Potentiators of the Cholinergic System

Cholinergic deficit is a characteristic factor of several pathologies, such as myasthenia gravis, some types of congenital myasthenic syndromes, and Alzheimer's Disease. Two molecular targets for its treatment are acetylcholinesterase (AChE) and nicotinic acetylcholine receptor (nAChR). In previous studies, we found that caffeine behaves as a partial nAChR agonist and confirmed that it inhibits AChE. Here, we present new bifunctional caffeine derivatives consisting of a theophylline ring connected to amino groups by different linkers. All of them were more potent AChE inhibitors than caffeine. Furthermore, although some of them also activated muscle nAChR as partial agonists, not all of them stabilized nAChR in its desensitized conformation. To understand the molecular mechanism underlying these results, we performed docking studies on AChE and nAChR. The nAChR agonist behavior of the compounds depends on their accessory group, whereas their ability to stabilize the receptor in a desensitized state depends on the interactions of the linker at the binding site. Our results show that the new compounds can inhibit AChE and activate nAChR with greater potency than caffeine and provide further information on the modulation mechanisms of pharmacological targets for the design of novel therapeutic interventions in cholinergic deficit.

The effects of different acetylcholinesterase inhibitors on EEG patterns in patients with Alzheimer's disease: A systematic review

OBJECTIVE

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common type of dementia. The early diagnosis of AD is an important factor for the control of AD progression. Electroencephalography (EEG) can be used for early diagnosis of AD. Acetylcholinesterase inhibitors (AChEIs) are also used for the amelioration of AD symptoms. In this systematic review, we reviewed the effect of different AChEIs including donepezil, rivastigmine, tacrine, physostigmine, and galantamine on EEG patterns in patients with AD.

METHODS

PubMed electronic database was searched and 122 articles were found. After removal of unrelated articles, 24 articles were selected for the present study.

RESULTS

AChEIs can decrease beta, theta, and delta frequency bands in patients with AD. However, conflicting results were found for alpha band. Some studies have shown increased alpha frequency, while others have shown decreased alpha frequency following treatment with AChEIs. The only difference was the type of drug.

CONCLUSIONS

We found that studies reporting the decreased alpha frequency used donepezil and galantamine, while studies reporting the increased alpha frequency used rivastigmine and tacrine. It was suggested that future studies should focus on the effect of different AChEIs on EEG bands, especially alpha frequency in patients with AD, to compare their effects and find the reason for their different influence on EEG patterns. Also, differences between the effects of AChEIs on oligodendrocyte differentiation and myelination may be another important factor. This is the first article investigating the effect of different AChEIs on EEG patterns in patients with AD.

Presence of key cholinergic enzymes in human spermatozoa and seminal fluid†

Little is known about the non-neuronal spermic cholinergic system, which may regulate sperm motility and the acrosome reaction initiation process. We investigated the presence of the key acetylcholine (ACh)-biosynthesizing enzyme, choline acetyltransferase (ChAT), and the acetylcholine-degrading enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and two ACh-receptors in human spermatozoa and seminal plasma. Fresh ejaculates were used for intra- and extracellular flow cytometric analysis of ChAT, AChE, BChE, and alpha-7-nicotinic and M1-muscarinic ACh-receptors in sperm. For determining the source of soluble enzymes, frozen seminal samples (n = 74) were selected on two bases: (1) from vasectomized (n = 37) and non-vasectomized (n = 37) subjects and (2) based on levels of alpha-glucosidase, fructose, or zinc to define sample subgroups with high or low fluid contribution from the epididymis and seminal vesicle, and prostate, respectively. Flow cytometric analyses revealed that ChAT was expressed intracellularly in essentially all spermatozoa. ChAT was also present in a readily membrane-detachable form at the extracellular membrane of at least 18% of the spermatozoa. These were also highly positive for intra- and extracellular BChE (>83%) and M1 (>84%) and α7 (>59%) ACh-receptors. Intriguingly, the sperm was negative for AChE. Analyses of seminal plasma revealed that spermatozoa and epididymides were major sources of soluble ChAT and BChE, whereas soluble AChE most likely originated from epididymides and seminal vesicles. Prostate had relatively minor contribution to the pool of the soluble enzymes in the seminal fluid. In conclusion, human spermatozoa exhibited a cholinergic phenotype and were one of the major sources of soluble ChAT and BChE in ejaculate. We also provide the first evidence for ChAT as an extracellularly membrane-anchored protein.

Myco-fabricated ZnO nanoparticles ameliorate neurotoxicity in mice model of Alzheimer's disease via acetylcholinesterase inhibition and oxidative stress reduction

Alzheimer's disease (AD) is one of the primary health problems linked to the decrease of acetylcholine in cholinergic neurons and elevation in oxidative stress. Myco-fabrication of ZnO-NPs revealed excellent biological activities, including anti-inflammatory and acetylcholinesterase inhibitory potentials. This study aims to determine if two distinct doses of myco-fabricated ZnO-NPs have a positive impact on behavioral impairment and several biochemical markers associated with inflammation and oxidative stress in mice that have been treated by aluminum chloride (AlCl3) to induce AD. Sixty male mice were haphazardly separated into equally six groups. Group 1 was injected i.p. with 0.5 ml of deionized water daily during the experiment. Mice in group 2 received AlCl3 (50 mg/kg/day i.p.). Groups 3 and 4 were treated i.p. with 5 and 10 mg/kg/day of ZnO-NPs only, respectively. Groups 5 and 6 were given i.p. 5 and 10 mg/kg/day ZnO-NPs, respectively, add to 50 mg/kg/day AlCl3. Results showed that the AlCl3 caused an increase in the escape latency time and a reduction in the time spent in the target quadrant, indicating a decreased improvement in learning and memory. Moreover, acetylcholinesterase enzyme (AChE) activity and malondialdehyde (MDA), tumor necrosis factor-alpha (TNF-α), and interleukin 1β (IL-1β) levels were significantly increased, and the content of glutathione (GSH), activities of superoxide dismutase (SOD), catalase (CAT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), as well as levels of serotonin and dopamine, were decreased in brain tissues only in AlCl3 treated mice. However, treatment of mice with myco-fabrication of ZnO-NPs at doses of 5 or 10 mg/kg improves learning and memory function through ameliorate all the previous parameters in the AD mice group. The low dose of 5 mg/kg is more effective than a high dose of 10 mg/kg. In accordance with these findings, myco-fabricated ZnO-NPs could enhance memory and exhibit a protective influence against memory loss caused by AlCl3.

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.

Current therapeutic targets and multifaceted physiological impacts of caffeine

Caffeine, which shares consubstantial structural similarity with purine adenosine, has been demonstrated as a nonselective adenosine receptor antagonist for eliciting most of the biological functions at physiologically relevant dosages. Accumulating evidence supports caffeine's beneficial effects against different disorders, such as total cardiovascular diseases and type 2 diabetes. Conversely, paradoxical effects are also linked to caffeine ingestion in humans including hypertension-hypotension and tachycardia-bradycardia. These observations suggest the association of caffeine action with its ingested concentration and/or concurrent interaction with preferential molecular targets to direct explicit events in the human body. Thus, a coherent analysis of the functional targets of caffeine, relevant to normal physiology, and disease pathophysiology, is required to understand the pharmacology of caffeine. This review provides a broad overview of the experimentally validated targets of caffeine, particularly those of therapeutic interest, and the impacts of caffeine on organ-specific physiology and pathophysiology. Overall, the available empirical and epidemiological evidence supports the dose-dependent functional activities of caffeine and advocates for further studies to get insights into the caffeine-induced changes under specific conditions, such as asthma, DNA repair, and cancer, in view of its therapeutic applications.

Phytochemical screening, biological evaluation, anatomical, and morphological investigation of Ferula tingitana L. (Apiaceae)

Ferula tingitana L. is a high perennial plant and its leaf is an alternate arrangement and yellow, and its flowers are unisexual like other Apiaceae. It has been used as a spice and for various medicinal purposes in the Mediterranean region. The paper reports antidiabetic, antimicrobial, anticholinesterase, antioxidant, and genotoxic activities of leaves, flowers, stems, and fruits methanol extracts of F. tingitana. Also, quantitative determination of some secondary metabolites was also analyzed by LC-MS/MS. Moreover, chemical composition of essential oils was analyzed. Consequently, anatomical, and morphological properties of plant were investigated. Germacrene D (23.6%), 1,3,5-trimethylbenzene (18.4%), and α-pinene (50.0%) were found as the main compounds in flower, leaf, and stem oils, respectively. The cortex in stem, pedicel, and fruit is characterized by angular collenchyma cells and a distinct cambium layer. 6 compounds (quinic acid, fumaric acid, keracyanin chloride, cyanidin-3-O-glucoside, chlorogenic acid, hesperidin) were observed in samples. Leaf extract showed anticholinesterase activity. Leaf and flower extracts showed the highest % inhibition value on ABTS·+ and DPPH•. Leaf extract has the strongest antioxidant effect because it is rich in total phenolic contents. All extracts of F. tingitana were found generally effective against C. albicans. Stem extract was found effective against E. coli and flower extract was found more effective against S. enterica and C. albicans. Bacterial genotoxicity results showed that extracts did not have genotoxic activity on tester strains S. typhimurium and E. coli WP2uvrA. Thus, it revealed that extracts were genotoxic-ally safe at applied concentrations up to 3 mg/plate.

Review of Phytochemical Potency as a Natural Anti-Helicobacter pylori and Neuroprotective Agent

Phytochemicals are plant secondary metabolites that show health benefits for humans due to their bioactivity. There is a huge variety of phytochemicals that have already been identified, and these compounds can act as antimicrobial and neuroprotection agents. Due to their anti-microbial activity and neuroprotection, several phytochemicals might have the potency to be used as natural therapeutic agents, especially for Helicobacter pylori infection and neurodegenerative disease, which have become a global health concern nowadays. According to previous research, there are some connections between H. pylori infection and neurodegenerative diseases, especially Alzheimer's disease. Hence, this comprehensive review examines different kinds of phytochemicals from natural sources as potential therapeutic agents to reduce H. pylori infection and improve neurodegenerative disease. An additional large-scale study is needed to establish the connection between H. pylori infection and neurodegenerative disease and how phytochemicals could improve this condition.

Effects of acephate and glyphosate-based agrochemicals on the survival and flight of Plebeia lucii Moure, 2004 (Apidae: Meliponini)

The conservation of terrestrial ecosystems depends largely on the preservation of pollinators, mainly bees. Stingless bees are among the main pollinators of native plants and crops in tropical regions, where they can be exposed to agrochemicals while foraging on contaminated flowers. In the present study, we investigated the effects on stingless bees of both a commonly used insecticide and herbicide in Brazil. Plebeia lucii Moure, 2004 (Apidae: Meliponini) foragers were orally chronically exposed to food contaminated with different concentrations of commercial formulations of the insecticide acephate or the herbicide glyphosate. Bee mortality increased with increasing agrochemical concentrations. Depending on its concentration, the acephate-based formulation reduced the lifespan and impaired the flight ability of bees. The glyphosate-based formulation was toxic only under unrealistic concentrations. Our results demonstrate that realistic concentrations of acephate-based insecticides harm the survival and alter the mobility of stingless bees. The ingestion of glyphosate-based herbicides was safe for forager bees under realistic concentrations.

New Advances in the Exploration of Esterases with PET and Fluorescent Probes

Esterases are hydrolases that catalyze the hydrolysis of esters into the corresponding acids and alcohols. The development of fluorescent probes for detecting esterases is of great importance due to their wide spectrum of biological and industrial applications. These probes can provide a rapid and sensitive method for detecting the presence and activity of esterases in various samples, including biological fluids, food products, and environmental samples. Fluorescent probes can also be used for monitoring the effects of drugs and environmental toxins on esterase activity, as well as to study the functions and mechanisms of these enzymes in several biological systems. Additionally, fluorescent probes can be designed to selectively target specific types of esterases, such as those found in pathogenic bacteria or cancer cells. In this review, we summarize the recent fluorescent probes described for the visualization of cell viability and some applications for in vivo imaging. On the other hand, positron emission tomography (PET) is a nuclear-based molecular imaging modality of great value for studying the activity of enzymes in vivo. We provide some examples of PET probes for imaging acetylcholinesterases and butyrylcholinesterases in the brain, which are valuable tools for diagnosing dementia and monitoring the effects of anticholinergic drugs on the central nervous system.

Molecular Multi-Target Approach for Human Acetylcholinesterase, Butyrylcholinesterase and β-Secretase 1: Next Generation for Alzheimer's Disease Treatment

Alzheimer's Disease (AD) is a neurodegenerative condition characterized by progressive memory loss and other affected cognitive functions. Pharmacological therapy of AD relies on inhibitors of the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), offering only a palliative effect and being incapable of stopping or reversing the neurodegenerative process. However, recent studies have shown that inhibiting the enzyme β-secretase 1 (BACE-1) may be able to stop neurodegeneration, making it a promising target. Considering these three enzymatic targets, it becomes feasible to apply computational techniques to guide the identification and planning of molecules capable of binding to all of them. After virtually screening 2119 molecules from a library, 13 hybrids were built and further screened by triple pharmacophoric model, molecular docking, and molecular dynamics (t = 200 ns). The selected hybrid G meets all stereo-electronic requirements to bind to AChE, BChE, and BACE-1 and offers a promising structure for future synthesis, enzymatic testing, and validation.

Inhibition of Human Cholinesterases and in vitro β-Amyloid Aggregation by Rationally Designed Peptides

The multifactorial nature of Alzheimer's disease (AD) is now widely recognized, which has increased the interest in compounds that can address more than one AD-associated targets. Herein, we report the inhibitory activity on the human cholinesterases (acetylcholinesterase, hAChE and butyrylcholinesterase, hBChE) and on the AChE-induced β-amyloid peptide (Aβ) aggregation by a series of peptide derivatives designed by mutating aliphatic residues for aromatic ones. We identified peptide W3 (LGWVSKGKLL-NH2 ) as an interesting scaffold for the development of new anti-AD multitarget-directed drugs. It showed the lowest IC50 value against hAChE reported for a peptide (0.99±0.02 μM) and inhibited 94.2 %±1.2 of AChE-induced Aβ aggregation at 10 μM. Furthermore, it inhibited hBChE (IC50 , 15.44±0.91 μM), showed no in vivo toxicity in brine shrimp and had shown moderated radical scavenging and Fe2+ chelating capabilities in previous studies. The results are in line with multiple reports showing the utility of the indole moiety for the development of cholinesterase inhibitors.

Affordable Portable Platform for Classic Photometry and Low-Cost Determination of Cholinesterase Activity

Excessive use of pesticides could potentially harm the environment for a long time. The reason for this is that the banned pesticide is still likely to be used incorrectly. Carbofuran and other banned pesticides that remain in the environment may also have a negative effect on human beings. In order to provide a better chance for effective environmental screening, this thesis describes a prototype of a photometer tested with cholinesterase to potentially detect pesticides in the environment. The open-source portable photodetection platform uses a color-programmable red, green and blue light-emitting diode (RGB LED) as a light source and a TSL230R light frequency sensor. Acetylcholinesterase from Electrophorus electricus (AChE) with high similarity to human AChE was used for biorecognition. The Ellman method was selected as a standard method. Two analytical approaches were applied: (1) subtraction of the output values after a certain period of time and (2) comparison of the slope values of the linear trend. The optimal preincubation time for carbofuran with AChE was 7 min. The limits of detection for carbofuran were 6.3 nmol/L for the kinetic assay and 13.5 nmol/L for the endpoint assay. The paper demonstrates that the open alternative for commercial photometry is equivalent. The concept based on the OS3P/OS3P could be used as a large-scale screening system.

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.

Design, synthesis, and biological evaluation of novel N-Benzyl piperidine derivatives as potent HDAC/AChE inhibitors for Alzheimer's disease

The multitarget-directed ligands approach represents a potential strategy to provide effective treatments for Alzheimer's disease (AD) given its multifactorial pathology. Herein, a series of N-benzyl piperidine derivatives were designed, synthesized, and biologically characterized for dual inhibitions of histone deacetylase (HDAC) and acetylcholinesterase (AChE). Among the compounds tested, d5 and d10 exhibited dual enzyme inhibitions (d5: HDAC_IC50 = 0.17 μM, AChE_IC50 = 6.89 μM, d10: HDAC_IC50 = 0.45 μM, AChE_IC50 = 3.22 μM), and both compounds showed activities on scavenging free radical, metal chelating, and inhibiting Aβ aggregations. More importantly, both compounds exhibited promising neuroprotective activities in PC-12 cells and good AChE selectivity. Collectively, the multifunctional profiles of compound d5 and d10 encourage further optimization and exploration to develop more potent analogues as potential treatments for AD.

Potential revival of cholinesterase inhibitors as drugs in veterinary medicine

The cholinergic system is involved in the regulation of all organ systems and has acetylcholine (ACh) as almost its only neurotransmitter. Any substance is called cholinergic if it can alter the action of acetylcholine. Cholinesterases (ChEs) are enzymes that enable the hydrolysis of acetylcholine and in this way ensure homeostasis in cholinergic synapses. Cholinesterase inhibitors (ChEi) are a group of indirect-acting cholinergic agonists that influence the activity of the cholinergic system. Several compounds that can inhibit cholinesterases are of importance to veterinary medicine from pharmacological and toxicological perspective. The frequency of their use in veterinary medicine has fluctuated over the years and is now reduced to a minimum. They are mainly used in agriculture as pesticides, and some are rarely used as parasiticides for companion animals and livestock. In recent years, interest in the use of new cholinesterase inhibitors has increased since canine cognitive dysfunction (CCD) became a recognized and extensively studied disease. Similar to Alzheimer's disease (AD) in humans, CCD can be treated with cholinesterase inhibitors that cross the blood-brain barrier. In this review, the mammalian cholinergic system and the drugs that interact with cholinesterases are introduced. Cholinesterase inhibitors that can be used for the treatment of CCD are described in detail.

Benzophenone Derivatives with Histamine H3 Receptor Affinity and Cholinesterase Inhibitory Potency as Multitarget-Directed Ligands for Possible Therapy of Alzheimer's Disease

The multitarget-directed ligands demonstrating affinity to histamine H₃ receptor and additional cholinesterase inhibitory potency represent a promising strategy for research into the effective treatment of Alzheimer's disease. In this study, a novel series of benzophenone derivatives was designed and synthesized. Among these derivatives, we identified compound 6 with a high affinity for H₃R (K_i = 8 nM) and significant inhibitory activity toward BuChE (IC₅₀ = 172 nM and 1.16 µM for eqBuChE and hBuChE, respectively). Further in vitro studies revealed that compound 6 (4-fluorophenyl) (4-((5-(piperidin-1-yl)pentyl)oxy)phenyl)methanone) displays moderate metabolic stability in mouse liver microsomes, good permeability with a permeability coefficient value (P_e) of 6.3 × 10^-6 cm/s, and its safety was confirmed in terms of hepatotoxicity in the HepG2 cell line. Therefore, we investigated the in vivo activity of compound 6 in the Passive Avoidance Test and the Formalin Test. While compound 6 did not show a statistically significant influence on memory and learning, it showed analgesic properties in both acute (ED₅₀ = 20.9 mg/kg) and inflammatory (ED₅₀ = 17.5 mg/kg) pain.

Validation of an SH-SY5Y Cell-Based Acetylcholinesterase Inhibition Assay for Water Quality Assessment

The acetylcholinesterase (AChE) inhibition assay has been frequently applied for environmental monitoring to capture insecticides such as organothiophosphates (OTPs) and carbamates. However, natural organic matter such as dissolved organic carbon (DOC) co-extracted with solid-phase extraction from environmental samples can produce false-negative AChE inhibition in free enzyme-based AChE assays. We evaluated whether disturbance by DOC can be alleviated in a cell-based AChE assay using differentiated human neuroblastoma SH-SY5Y cells. The exposure duration was set at an optimum of 3 h considering the effects of OTPs and carbamates. Because loss to the airspace was expected for the more volatile OTPs (chlorpyrifos, diazinon, and parathion), the chemical loss in this bioassay setup was investigated using solid-phase microextraction followed by chemical analysis. The three OTPs were relatively well retained (loss <34%) during 3 h of exposure in the 384-well plate, but higher losses occurred on prolonged exposure, accompanied by slight cross-contamination of adjacent wells. Inhibition of AChE by paraoxon-ethyl was not altered in the presence of up to 68 mg_c /L Aldrich humic acid used as surrogate for DOC. Binary mixtures of paraoxon-ethyl and water extracts showed concentration-additive effects. These experiments confirmed that the matrix in water extracts does not disturb the assay, unlike purified enzyme-based AChE assays. The cell-based AChE assay proved to be suitable for testing water samples with effect concentrations causing 50% inhibition of AChE at relative enrichments of 0.5-10 in river water samples, which were distinctly lower than corresponding cytotoxicity, confirming the high sensitivity of the cell-based AChE inhibition assay and its relevance for water quality monitoring. Environ Toxicol Chem 2022;41:3046-3057. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The use of Gammarus pulex as a model organism for ecotoxicological assessment of ibuprofen and propranolol at environmental relevant concentrations

The aim of this study is to assess the toxicity of ibuprofen (IBU) and propranolol (PRO) drugs usingGammarus pulex as a model organism. Firstly, the 96 h LC₅₀ values of IBU and PRO were determined and then three sublethal concentrations of the drugs were exposed to G. pulex. The activities of superoxide dismutase (SOD), catalase (CAT) and acetylcholinesterase (AChE) were evaluated. SOD activity decreased in G. pulex exposed to IBU and PRO compared to control. In all groups exposed to IBU, CAT activity increased at different concentrations at 24 and 96 h. In the groups exposed to different PRO concentrations, CAT activities increased after 24 h compared to the control group (p < 0.05). AChE activities increased in all application groups exposed to IBU for 96 hours (p < 0.05). In conclusion, exposure to IBU and PRO resulted in increased oxidative damage. PRO has been found to cause neurotoxicity.

The stress effect of atrazine on the inducible defense traits of Daphnia pulex in response to fish predation risk: Evidences from morphology, life history traits, and expression of the defense-related genes

Herbicide pollution is persistent, which not only has a negative impact on individual organisms, but also may endanger the interspecific relationship between predators and prey. Cladocerans, i.e. zooplankton that plays an important role in the energy flow and material circulation in freshwater ecosystem, usually develop induced defense in response to predation risk. We used atrazine, one of the most used herbicides in the world, and Daphnia pulex, a representative cladocerans, to test the possible interference effect of herbicides on the induced defensive traits of cladocerans in response to predator fish (Rhodeus ocellatus) kairomone, including morphological defense, life history strategies, and the expression of defense-related genes. Atrazine reduced the body size, spine size, growth rate, total offspring, and the relative reproductive output of D. pulex, which further affected the response strength of the morphological and life history defenses, i.e., atrazine significantly reduced the spine size, relative spine size, and fecundity of D. pulex in response to R. ocellatus kairomone. Exposure to atrazine affected the expression of defense-related genes, and we speculated that atrazine affected the signaling process in the induced anti-predation defense of cladocerans. Specially, fish kairomone attenuated the negative effects of high concentrations of atrazine on the life history traits of D. pulex. Our results will help to accurately assess the potential risk of artificial compounds in freshwater ecosystems from the perspective of interspecific relationships, and help to understand the impact of environmental changes on the inducible anti-predator defense of prey in aquatic ecosystems.

BChE inhibitors from marine organisms - A review

Acetylcholine is a key neurotransmitter for brain and muscle function, that has its levels decreased in the brain of people with Alzheimer's Disease (AD). Cholinesterase inhibitors are medicines that decrease the breakdown of acetylcholine, through the inhibition of acetyl- and butyrylcholinesterase enzymes. Despite the fact that butyrylcholinesterase activity rises with the disease, while acetylcholinesterase activity declines, the cholinesterase inhibitors that are currently commercialized inhibit either acetylcholinesterase or both enzymes. The development of selective butyrylcholinesterase inhibitors is a promising strategy in the search for new drugs acting against AD. The marine environment is a rich source of molecules with therapeutic potential, which can provide compounds more easily than traditional methods, with reduced toxicity risks compared to synthetic molecules. This review comprises articles from 2003 to 2020, that assessed the butyrylcholinesterase inhibitory activities from marine organisms, considering their crude extracts and isolated compounds. Part of the articles reported a multi-target activity, inhibiting also other AD-related enzymes. Some of the marine compounds reported here have shown an excellent potential for butyrylcholinesterase inhibition compared to standard inhibitors. Further studies of some compounds reported here may lead to the development of a new treatment for AD.

Use of Tox21 Screening Data to Evaluate the COVID-19 Drug Candidates for Their Potential Toxic Effects and Related Pathways

Currently, various potential therapeutic agents for coronavirus disease-2019 (COVID-19), a global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are being investigated worldwide mainly through the drug repurposing approach. Several anti-viral, anti-bacterial, anti-malarial, and anti-inflammatory drugs were employed in randomized trials and observational studies for developing new therapeutics for COVID-19. Although an increasing number of repurposed drugs have shown anti-SARS-CoV-2 activities in vitro, so far only remdesivir has been approved by the US FDA to treat COVID-19, and several other drugs approved for Emergency Use Authorization, including sotrovimab, tocilizumab, baricitinib, paxlovid, molnupiravir, and other potential strategies to develop safe and effective therapeutics for SARS-CoV-2 infection are still underway. Many drugs employed as anti-viral may exert unwanted side effects (i.e., toxicity) via unknown mechanisms. To quickly assess these drugs for their potential toxicological effects and mechanisms, we used the Tox21 in vitro assay datasets generated from screening ∼10,000 compounds consisting of approved drugs and environmental chemicals against multiple cellular targets and pathways. Here we summarize the toxicological profiles of small molecule drugs that are currently under clinical trials for the treatment of COVID-19 based on their in vitro activities against various targets and cellular signaling pathways.

5-Aryl-1,3,4-oxadiazol-2-amines Decorated with Long Alkyl and Their Analogues: Synthesis, Acetyl- and Butyrylcholinesterase Inhibition and Docking Study

2,5-Disubstituted 1,3,4-oxadiazoles are privileged versatile scaffolds in medicinal chemistry that have exhibited diverse biological activities. Acetyl- (AChE) and butyrylcholinesterase (BChE) inhibitors are used, e.g., to treat dementias and myasthenia gravis. 5-Aryl-1,3,4-oxadiazoles decorated with dodecyl linked via nitrogen, sulfur or directly to this heterocycle have been designed as potential inhibitors of AChE and BChE. They were prepared from commercially available or in-house prepared hydrazides by reaction with dodecyl isocyanate to form hydrazine-1-carboxamides 2 (yields 67–98%) followed by cyclization using p-toluenesulfonyl chloride and triethylamine in 41–100% yields. Thiadiazole isostere was also synthesized. The derivatives were screened for inhibition of AChE and BChE using Ellman’s spectrophotometric method. The compounds showed a moderate dual inhibition with IC₅₀ values of 12.8–99.2 for AChE and from 53.1 µM for BChE. All the heterocycles were more efficient inhibitors of AChE. The most potent inhibitor, N-dodecyl-5-(pyridin-4-yl)-1,3,4-thiadiazol-2-amine 3t, was subjected to advanced reversibility and type of inhibition evaluation. Structure–activity relationships were identified. Many oxadiazoles showed lower IC₅₀ values against AChE than established drug rivastigmine. According to molecular docking, the compounds interact non-covalently with AChE and BChE and block entry into enzyme gorge and catalytic site, respectively.

In Silico Investigation of Some Compounds from the N-Butanol Extract of Centaurea tougourensis Boiss. & Reut

Bioinformatics as a newly emerging discipline is considered nowadays a reference to characterize the physicochemical and pharmacological properties of the actual biocompounds contained in plants, which has helped the pharmaceutical industry a lot in the drug development process. In this study, a bioinformatics approach known as in silico was performed to predict, for the first time, the physicochemical properties, ADMET profile, pharmacological capacities, cytotoxicity, and nervous system macromolecular targets, as well as the gene expression profiles, of four compounds recently identified from Centaurea tougourensis via the gas chromatography–mass spectrometry (GC–MS) approach. Thus, four compounds were tested from the n-butanol (n-BuOH) extract of this plant, named, respectively, Acridin-9-amine, 1,2,3,4-tetrahydro-5,7-dimethyl- (compound 1), 3-[2,3-Dihydro-2,2-dimethylbenzofuran-7-yl]-5-methoxy-1,3,4-oxadiazol-2(3H)-one (compound 2), 9,9-Dimethoxybicyclo[3.3.1]nona-2,4-dione (compound 3), and 3-[3-Bromophenyl]-7-chloro-3,4-dihydro-10-hydroxy-1,9(2H,10H)-acridinedione (compound 4). The insilico investigation revealed that the four tested compounds could be a good candidate to regulate the expression of key genes and may also exert significant cytotoxic effects against several tumor celllines. In addition, these compounds could also be effective in the treatment of some diseases related to diabetes, skin pathologies, cardiovascular, and central nervous system disorders. The bioactive compounds of plant remain the best alternative in the context of the drug discovery and development process.

Chemical Composition, Biological Activities and In Silico Analysis of Essential Oils of Three Endemic Prangos Species from Turkey

In this study, the essential oils (EOs) obtained from three endemic Prangos species from Turkey (P. heyniae, P. meliocarpoides var. meliocarpoides, and P. uechtritzii) were studied for their chemical composition and biological activities. β-Bisabolenal (12.2%) and caryophyllene oxide (7.9%) were the principal components of P. heyniae EO, while P. meliocarpoides EO contained sabinene (16.7%) and p-cymene (13.2%), and P. uechtritzii EO contained p-cymene (24.6%) and caryophyllene oxide (19.6%), as the most abundant components. With regard to their antioxidant activity, all the EOs were found to possess free radical scavenging potential demonstrated in both DPPH and ABTS assays (0.43-1.74 mg TE/g and 24.18-92.99 mg TE/g, respectively). Additionally, while no inhibitory activity was displayed by P. meliocarpoides and P. uechtritzii EOs against both cholinesterases (acetyl- and butyryl-cholinesterases). Moreover, all the EOs were found to act as inhibitors of tyrosinase (46.34-69.56 mg KAE/g). Molecular docking revealed elemol and α-bisabolol to have the most effective binding affinity with tyrosinase and amylase. Altogether, this study unveiled some interesting biological activities of these EOs, especially as natural antioxidants and tyrosinase inhibitors and hence offers stimulating prospects of them in the development of anti-hyperpigmentation topical formulations.

Elasmobranchs as bioindicators of pollution in the marine environment

Bioindicator species are increasingly valuable in environmental pollution monitoring, and elasmobranch species include many suitable candidates for that role. By measuring contaminants and employing biomarkers of effect in relevant elasmobranch species, scientists may gain important insights about the impacts of pollution in marine ecosystems. This review compiles biomarkers applied in elasmobranchs to assess the effect of pollutants (e.g., metals, persistent organic pollutants, and plastics), and the environmental changes induced by anthropogenic activities (e.g., shifts in marine temperature, pH, and oxygenation). Over 30 biomarkers measured in more than 12 species were examined, including biotransformation biomarkers (e.g., cytochrome P450 1A), oxidative stress-related biomarkers (e.g., superoxide anion, lipid peroxidation, catalase, and vitamins), stress proteins (e.g., heat shock protein 70), reproductive and endocrine biomarkers (e.g., vitellogenin), osmoregulation biomarkers (e.g., trimethylamine N-oxide, Na⁺/K⁺-ATPase, and plasma ions), energetic and neurotoxic biomarkers (e.g., lactate dehydrogenase, lactate, and cholinesterases), and histopathological and morphologic biomarkers (e.g., tissue lesions and gross indices).

Spatial Distribution and Stability of Cholinesterase Inhibitory Protoberberine Alkaloids from Papaver setiferum

During a research program to identify new cholinesterase inhibitors of natural origin, two new 7,8-didehydroprotoberberine alkaloids (1 and 2) and nine known compounds (3-11) were isolated from the capsules of the common ornamental poppy, Papaver setiferum (previously P. pseudo-orientale). Despite their reported instability, the 7,8-didehydroprotoberberines isolated herein appeared relatively stable, particularly as their trifluoroacetic acid salts. The spatial distributions of the isolated alkaloids were also analyzed using desorption electrospray ionization imaging mass spectrometry. The alkaloids were localized predominantly within the walls and vascular bundles of the capsules, with the highest relative abundances occurring in the lower half of the capsules toward the peduncle. The relative abundances of the alkaloids were also compared across plant development stages. Although most alkaloids did not show clear patterns in their concentration across development stages, the concentration of suspected oxidation products clearly spiked upon plant death. Finally, all isolated natural products were screened for inhibitory activities against a panel of cholinesterases, from both human and animal sources. These studies identified several competitive inhibitors of cholinesterases with potency in the low micromolar range (1-4, 6, 7), offering new lead compounds for the development of cholinesterase inhibitory drugs.

Interactions of human acetylcholinesterase with phenyl valerate and acetylthiocholine: Thiocholine as an enhancer of phenyl valerate esterase activity

Phenyl valerate (PV) is a neutral substrate for measuring the PVase activity of neuropathy target esterase (NTE), a key molecular event of organophosphorus-induced delayed neuropathy. This substrate has been used to discriminate and identify other proteins with esterase activity and potential targets of organophosphorus (OP) binding. A protein with PVase activity in chicken (model for delayed neurotoxicity) was identified as butyrylcholinesterase (BChE). Further studies in human BChE suggest that other sites might be involved in PVase activity. From the theoretical docking analysis, other more favorable sites for binding PV related to the Asn289 residue located far from the catalytic site ("PVsite") were deduced.In this paper, we demonstrate that acetylcholinesterase is also able to hydrolyze PV. Robust kinetic studies of interactions between substrates PV and acetylthiocholine (AtCh) were performed. The kinetics did not fit the classic competition models among substrates. While PV interacts as a competitive inhibitor in AChE activity, AtCh at low concentrations enhances PVase activity and inhibits this activity at high concentrations. Kinetic behavior suggests that the potentiation effect is caused by thiocholine released at the active site, where AtCh could act as a Trojan Horse. We conclude that the products released at the active site could play an important role in the hydrolysis reactions of different substrates in biological systems.

Rational design and synthesis of modified natural peptides from Boana pulchella (anura) as acetylcholinesterase inhibitors and antioxidants

The use of acetylcholinesterase (AChE) inhibitors, antioxidants or multitarget compounds are among the main strategies against Alzheimer's disease (AD). Between AChE inhibitors, those targeting the peripheral anionic site (PAS) are of special interest. Here, we describe the rational design and synthesis of peptide analogs of a natural PAS-targeting sequence that we recently discovered, aiming at increasing its activity against AChE. We also tested their radical scavenging and metal chelating properties. Our design strategy was based on the position-specific, computer-aided insertion of aromatic residues. The analog named as W3 showed a 30-fold higher inhibitory activity than the original sequence and an improved antioxidant activity. W3 is the most potent modified natural peptide against Electrophorus electricus AChE ever reported with an IC₅₀ of 10.42 μM (± 1.02). In addition, it showed a radical scavenging activity of 47.00% ± 3.11 at 50 μM and 93.47% ± 1.53 at 400 μM. Since peptides are receiving increasing interest as drugs, we propose the W3 analog as an attractive sequence for the development of new peptide-based multitarget drugs for AD. Besides, this work sheds light on the importance of the aromatic residues in the modulation of AChE activity and their effect on the radical scavenging activity of a peptide.

A Novel Function of Sphingosylphosphorylcholine on the Inhibitory Effects of Acetylcholinesterase Activity

Acetylcholine (ACh), a quaternary ammonium cation, is known as one of the itch inducer in atopic dermatitis (AD), an inflammatory skin disease with intense itching. Previous research has reported accumulation of ACh in lesional site of AD patients. Generally, ACh is metabolized by cholinesterase (ChE). Therefore, one of the causes of ACh accumulation may be the suppression of ChE activity. Increased levels of the multifunctional bioactive sphingolipid sphingosylphosphorylcholine (SPC) have also been detected in AD. Since SPC possesses a quaternary ammonium cation, like ACh, it is possible that SPC affects the activity of ChE catalyzing ACh metabolization. We investigated whether SPC influences the activity of ChE by performing enzymatic analysis of ChE in the presence of SPC. We found that SPC strongly suppressed acetylcholinesterase (AChE) activity, but the suppression of butyrylcholinesterase by SPC was quite low. The Michaelis constant (K_m) of AChE in the presence of SPC increased, and the maximum velocity (V_max) decreased, indicating that SPC acts as mixed-type inhibitor for AChE. The analysis of SPC analogs clarified the importance of both the quaternary ammonium cation and the carbon chain length of SPC for the AChE inhibitory effect and showed that SPC was unique in AChE inhibition among the sphingolipids in this study. These findings indicate a novel function of SPC on AChE inhibition. Thus, the inhibition activity of SPC may be a factor in the increase of ACh in AD.

Fine Tuning of Cholinesterase and Glutathione-S-Transferase Activities by Organoruthenium(II) Complexes

Cholinesterases (ChEs) show increased activities in patients with Alzheimer’s disease, and remain one of the main therapeutic targets for treatment of this neurodegenerative disorder. A library of organoruthenium(II) complexes was prepared to investigate the influence of their structural elements on inhibition of ChEs, and on another pharmacologically important group of enzymes, glutathione S-transferases (GSTs). Two groups of organoruthenium(II) compounds were considered: (i) organoruthenium(II) complexes with p-cymene as an arene ligand, and (ii) organoruthenium(II) carbonyl complexes as CO-releasing molecules. Eight organoruthenium complexes were screened for inhibitory activities against ChEs and GSTs of human and animal origins. Some compounds inhibited all of these enzymes at low micromolar concentrations, while others selectively inhibited either ChEs or GSTs. This study demonstrates the importance of the different structural elements of organoruthenium complexes for their inhibitory activities against ChEs and GSTs, and also proposes some interesting compounds for further preclinical testing as ChE or GST inhibitory drugs.

Pharmacological Influencing of The Cholinergic Anti-inflammatory Pathway in Infectious Diseases and Inflammatory Pathologies

The cholinergic anti-inflammatory pathway is a part of the parasympathetic nervous system and it can also be entitled as an anti-inflammatory reflex. It consists of terminations of the vagal nerve into blood, acetylcholine released from the terminations, macrophages and other cells having α7 nicotinic acetylcholine receptor (α7 nAChR), calcium ions crossing through the receptor and interacting with nuclear factors, and erythrocytes with acetylcholinesterase (AChE) terminating the neurotransmission. Stopping of inflammatory cytokines production is the major task for the cholinergic antiinflammatory pathway. The cholinergic anti-inflammatory pathway can be stimulated or suppressed by agonizing or antagonizing α7 nAChR or by inhibition of AChE. This review is focused on cholinergic anti-inflammatory pathway regulation by drugs. Compounds that inhibit cholinesterases (for instance, huperzine, rivastigmine, galantamine), and their impact on the cholinergic anti-inflammatory pathway are discussed here and a survey of actual literature is provided.

Cyanobiphenyls: Novel H3 receptor ligands with cholinesterase and MAO B inhibitory activity as multitarget compounds for potential treatment of Alzheimer's disease

Alzheimer's disease (AD) is a complex and incurable illness that requires the urgent approval of new effective drugs. However, since 2003, no new molecules have shown successful results in clinical trials, thereby making the common "one compound - one target" paradigm questionable. Recently, the multitarget-directed ligand (MTDL) approach has gained popularity, as compounds targeting at least two biological targets may be potentially more effective in treating AD. On the basis of these findings, we designed, synthesized, and evaluated through biological assays a series of derivatives of alicyclic amines linked by an alkoxy bridge to an aromatic lipophilic moiety of [1,1'-biphenyl]-4-carbonitrile. The research results revealed promising biological activity of the obtained compounds toward the chosen targets involved in AD pathophysiology; the compounds showed high affinity (mostly low nanomolar range of K_i values) for human histamine H₃ receptors (hH₃R) and good nonselective inhibitory potency (micromolar range of IC₅₀ values) against acetylcholinesterase from electric eel (eeAChE) and equine serum butyrylcholinesterase (eqBuChE). Moreover, micromolar/submicromolar potency against human monoamine oxidase B (hMAO B) was detected for some compounds. The study identified compound 5 as a multiple hH₃R/eeAChE/eqBuChE/hMAO B ligand (5: hH₃R K_i = 9.2 nM; eeAChE IC₅₀ = 2.63 µM; eqBuChE IC₅₀ = 1.30 µM; hMAO B IC₅₀ = 0.60 µM). Further in vitro studies revealed that compound 5 exhibits a mixed type of eeAChE and eqBuChE inhibition, good metabolic stability, and moderate hepatotoxicity effect on HepG2 cells. Finally, compound 5 showed a beneficial effect on scopolamine-induced memory impairments, as assessed by the passive avoidance test, thus revealing the potential of this compound as a promising agent for further optimization for AD treatment.