Inhibition kinetics of acetylcholinesterase and butyrylcholinesterase from various species by 2-(2-cresyl)-4H-1,3,2-benzodioxaphosphorin-2-oxide (CBDP)

The aerotoxic syndrome has been associated with exposure to tricresyl phosphate (TCP), which is used as additive in hydraulic fluids and engine lubricants. The toxic metabolite 2-(2-cresyl)-4H-1,3,2-benzodioxaphosphorin-2-oxide (CBDP) is formed from the TCP isomer tri-ortho-cresyl phosphate (TOCP) in vivo and is known to react with the active site serine in acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) resulting in the inhibition of the enzymes. Previous in vitro studies showed pronounced species differences in the inhibition kinetics of cholinesterases by organophosphorus compounds (OP), which must be considered in the development of relevant animal models for the investigation of OP poisoning and the aerotoxic syndrome. The present study was designed to investigate the inhibition kinetics of human, Cynomolgus monkey, pig, mini pig, guinea pig, mouse, and rat AChE as well as BChE by CBDP under standardized conditions. There were similar rate constants for the inhibition (ki) of human, Cynomolgus monkey and mouse AChE by CBDP. In contrast, the ki values obtained for guinea pig, mini pig, pig, and rat AChE were 2.8- to 5.9-fold lower than that of human AChE. The results of the present study confirmed CBDP as one of the most potent inhibitors of human BChE, indicating a ki value of 3.24 ± 0.33 ×108M-1min-1, which was about 1,140-fold higher than that of human AChE. Accordingly, a markedly more pronounced inhibition rate of BChE from the species guinea pig, mini pig, pig, rat, Cynomolgus monkey, and mouse by CBDP was found as compared to those of AChE from the respective sources, indicating 2.0- to 89.6-fold higher ki values.

Hypoglycemic, anti-inflammatory, and neuroprotective potentials of crude methanolic extract from Acacia nilotica L. - results of an in vitro study

Acacia nilotica L., also known as babul, belonging to the Fabaceae family and the Acacia genus, is typically used for ornamental purposes and also as a medicinal plant found in tropical and subtropical areas. This plant is a rich source of bioactive compounds. The current study aimed to elucidate the hypoglycemic, anti-inflammatory, and neuroprotective potential of A. nilotica's crude methanolic extract. The results of the in vitro antidiabetic assay revealed that methanolic extract of A. nilotica inhibited the enzyme α-glucosidase (IC50: 33 μg mL-1) and α-amylase (IC50: 17 μg mL-1) in a dose-dependent manner. While in the anticholinesterase enzyme inhibitory assay, maximum inhibition was shown by the extract against acetylcholinesterase (AChE) (637.01 μg mL-1) and butyrylcholinesterase (BChE) (491.98 μg mL-1), with the highest percent inhibition of 67.54% and 71.50% at 1000 μg mL-1, respectively. This inhibitory potential was lower as compared to the standard drug Galantamine that exhibited 82.43 and 89.50% inhibition at the same concentration, respectively. Moreover, the methanolic extract of A. nilotica also significantly inhibited the activities of cyclooxygenase 2 (COX-2) and 5-lipoxygenase (5-LOX) in a concentration-dependent manner. The percent inhibitory activity of 5-LOX and COX-2 ranged from 42.47% to 71.53% and 43.48% to 75.22%, respectively. Furthermore, in silico, in vivo, and clinical investigations must be planned to validate the above-stated bioactivities of A. nilotica.

New Charged Cholinesterase Inhibitors: Design, Synthesis, and Characterization

Triazoles and triazolium salts are very common subunits in the structures of various drugs. Medicaments with a characteristic 1,2,3-triazole core are also being developed to treat neurodegenerative disorders associated with cholinesterase enzyme activity. Several naphtho- and thienobenzo-triazoles from our previous research emerged as being particularly promising in that sense. For this reason, in this research, new naphtho- and thienobenzo-triazoles 23-34, as well as 1,2,3-triazolium salts 44-51, were synthesized and tested. Triazolium salts 44-46 showed excellent activity while salts 47 and 49 showed very good inhibition toward both butyrylcholinesterase (BChE) and acetylcholinesterase (AChE) enzymes. In contrast, neutral photoproducts were shown to be selective towards BChE but with very good inhibition potential as molecules 24-27. The representative of newly prepared compounds, 45 and 50, were stable in aqueous solution and revealed intriguing fluorimetric properties, characterized by a strong Stokes shift of >160 nm. Despite their condensed polycyclic structure shaped similarly to well-known DNA-intercalator ethidium bromide, the studied compounds did not show any interaction with ds-DNA, likely due to the unfavorable steric hindrance of substituents. However, the studied dyes bind proteins, particularly showing very diverse inhibition properties toward AChE and BChE. In contrast, neutral photoproducts were shown to be selective towards a certain enzyme but with moderate inhibition potential. The molecular docking of the best-performing candidates to cholinesterases' active sites identified cation-π interactions as the most responsible for the stability of the enzyme-ligand complexes. As genotoxicity studies are crucial when developing new active substances and finished drug forms, in silico studies for all the compounds synthesized have been performed.

Fused thiophene as a privileged scaffold: A review on anti-Alzheimer's disease potentials via targeting cholinesterases, monoamine oxidases, glycogen synthase kinase-3, and Aβ aggregation

As a "silent threat," Alzheimer's disease (AD) is quickly rising to the top of the list of costly and troublesome diseases facing humanity. It is growing to be one of the most troublesome and expensive conditions, with annual health care costs higher than those of cancer and comparable to those of cardiovascular disorders. One of the main pathogenic characteristics of AD is the deficiency of the neurotransmitter acetylcholine (ACh) which plays a vital role in memory, learning, and attention. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) play a crucial role in hydrolyzing ACh. Consequently, a frequent therapy approach for AD is the suppression of AChE and BChE to improve cholinergic neurotransmission and reduce cognitive symptoms. The accumulation of amyloid plaques (Aβ) is a primary factor contributing to neurodegenerative diseases, particularly AD. Glycogen synthase kinase-3β (GSK3-β) is regarded as a pivotal player in the pathophysiology of AD since dysregulation of this kinase affects all major hallmarks of the disease, such as tau phosphorylation, Aβ aggregation, memory, neurogenesis, and synaptic function. One of the most challenging and risky issues in modern medicinal chemistry is the urgent and ongoing need for the study and development of effective therapeutic candidates for the treatment of AD. A significant class of heterocyclic molecules that can target the complex and multifactorial pathogenesis of AD are fused thiophene derivatives. The goal of the current review is to demonstrate the advancements made in fused thiophene derivatives' anti-AD activity. It also covers their mechanisms of action and studies of the structure-activity relationships in addition to the compilation of significant synthetic routes for fused thiophene derivatives with anti-AD potential. This review is intended to stimulate new ideas in the search for more rationale designs of derivatives based on fused thiophene, hoping to be more potent in treating AD.

Environmental exposure to glyphosate does not inhibit human acetylcholinesterase and butyrylcholinesterase

Glyphosate has remained the leading herbicide on the global market to date, despite the continuous debate between consumers, scientific community, and regulatory agencies over its carcinogenicity, genotoxicity, environmental persistence, and the role in the development of neurodegenerative disorders. Chemically, glyphosate belongs to a large family of organophosphorus pesticides, which exert a neurotoxic effect by inhibiting acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), enzymes of the cholinergic system essential for maintaining neurotransmission. Although research shows that glyphosate is a weak cholinesterase inhibitor in fish and mammals compared to other OP compounds, no conclusive data exist concerning the inhibition of human AChE and BChE. In our study we analysed its inhibitory potency on human AChE and BChE, by establishing its IC50 and reversible inhibition in terms of dissociation inhibition constants. Glyphosate concentration of 40 mmol/L caused near total inhibition of enzyme activity (approx. 10 % activity remaining). Inhibition dissociation constants (K i) of glyphosate-AChE and -BChE complexes were 28.4±2.7 mmol/L and 19.3±1.8 mmol/L, respectively. In conclusion, glyphosate shows a slight binding preference for BChE but exhibits inhibition only in a high concentration range. Our results are in line with studies reporting that its neurotoxic effect is not primarily linked to the cholinergic system.

Progressions of the correlation between lipid metabolism and immune infiltration characteristics in gastric cancer and identification of BCHE as a potential biomarker

Background

Globally, gastric cancer (GC) is a category of prevalent malignant tumors. Its high occurrence and fatality rates represent a severe threat to public health. According to recent research, lipid metabolism (LM) reprogramming impacts immune cells' ordinary function and is critical for the onset and development of cancer. Consequently, the article conducted a sophisticated bioinformatics analysis to explore the potential connection between LM and GC.

Methods

We first undertook a differential analysis of the TCGA queue to recognize lipid metabolism-related genes (LRGs) that are differentially expressed. Subsequently, we utilized the LASSO and Cox regression analyses to create a predictive signature and validated it with the GSE15459 cohort. Furthermore, we examined somatic mutations, immune checkpoints, tumor immune dysfunction and exclusion (TIDE), and drug sensitivity analyses to forecast the signature's immunotherapy responses.

Results

Kaplan-Meier (K-M) curves exhibited considerably longer OS and PFS (p<0.001) of the low-risk (LR) group. PCA analysis and ROC curves evaluated the model's predictive efficacy. Additionally, GSEA analysis demonstrated that a multitude of carcinogenic and matrix-related pathways were much in the high-risk (HR) group. We then developed a nomogram to enhance its clinical practicality, and we quantitatively analyzed tumor-infiltrating immune cells (TIICs) using the CIBERSORT and ssGSEA algorithms. The low-risk group has a lower likelihood of immune escape and more effective in chemotherapy and immunotherapy. Eventually, we selected BCHE as a potential biomarker for further research and validated its expression. Next, we conducted a series of cell experiments (including CCK-8 assay, Colony formation assay, wound healing assay and Transwell assays) to prove the impact of BCHE on gastric cancer biological behavior.

Discussion

Our research illustrated the possible consequences of lipid metabolism in GC, and we identified BCHE as a potential therapeutic target for GC. The LRG-based signature could independently forecast the outcome of GC patients and guide personalized therapy.

Phenyl-quinoline derivatives as lead structure of cholinesterase inhibitors with potency to reduce the GSK-3β level targeting Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder that leads to cognitive decline and memory loss. Unfortunately, there is no effective treatment for this condition, so there is a growing interest in developing new anti-AD agents. In this research project, a series of phenyl-quinoline derivatives were designed as potential anti-AD agents. These derivatives were substituted at two different positions on benzyl and phenyl rings. The structures of the derivatives were characterized using techniques such as IR spectroscopy, 1H NMR, 13C NMR, and elemental analysis. During the in vitro screening, the derivatives were tested against both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). It was observed that most of the derivatives showed higher selectivity against BChE compared to AChE. Among the derivatives, analog 7n (with a methoxy group at R1 and a 4-bromine substituent at R2 exhibited the highest potency, with a 75-fold improvement in the activity compared to the positive control. Importantly, this potent analog demonstrated no toxicity at the tested concentration on SH-SY5Y cells, indicating its potential as a safe anti-AD agent. The level of GSK-3β was also reduced after treatments with 7n at 50 μM. Overall, this study highlights the design and evaluation of phenyl-quinoline derivatives as promising candidates for developing novel anti-AD agents.

Profiling Novel Quinuclidine-Based Derivatives as Potential Anticholinesterase Drugs: Enzyme Inhibition and Effects on Cell Viability

The cholinergic system, relying on the neurotransmitter acetylcholine (ACh), plays a significant role in muscle contraction, cognition, and autonomic nervous system regulation. The enzymes acetylcholinesterase, AChE, and butyrylcholinesterase, BChE, responsible for hydrolyzing ACh, can fine-tune the cholinergic system's activity and are, therefore, excellent pharmacological targets to address a range of medical conditions. We designed, synthesized, and profiled 14 N-alkyl quaternary quinuclidines as inhibitors of human AChE and BChE and analyzed their impact on cell viability to assess their safety in the context of application as potential therapeutics. Our results showed that all of the 14 tested quinuclidines inhibited both AChE and BChE in the micromolar range (Ki = 0.26 - 156.2 μM). The highest inhibition potency was observed for two bisquaternary derivatives, 7 (1,1'-(decano)bis(3-hydroxyquinuclidinium bromide)) and 14 (1,1'-(decano)bis(3-hydroxyiminoquinuclidinium bromide)). The cytotoxic effect within 7-200 μM was observed only for monoquaternary quinuclidine derivatives, especially those with the C12-C16 alkyl chain. Further analysis revealed a time-independent mechanism of action, significant LDH release, and a decrease in the cells' mitochondrial membrane potential. Taking all results into consideration, we can confirm that a quinuclidine core presents a good scaffold for cholinesterase binding and that two bisquaternary quinuclidine derivatives could be considered as candidates worth further investigations as drugs acting in the cholinergic system. On the other hand, specific cell-related effects probably triggered by the free long alkyl chain in monoquaternary quinuclidine derivatives should not be neglected in future N-alkyl quaternary quinuclidine derivative structure refinements. Such an effect and their potential to interact with other specific targets, as indicated by a pharmacophore model, open up a new perspective for future investigations of these compounds' scaffold in the treatment of specific conditions and diseases other than cholinergic system-linked disorders.

Customized fluorescent probe for peering into the expression of butyrylcholinesterase in thyroid cancer

BACKGROUND

Thyroid cancer has been increasingly prevalent in recent years. The main diagnostic methods for thyroid are B-ultrasound scan, serum detection and puncture detection. However, these methods are invasive and complex. It is a pressing need to develop non-invasive or minimally invasive methods for thyroid cancer diagnosis. Fluorescence method as a non-invasive detection method has attracted much attention. Butyrylcholinesterase (BChE) is a common enzyme in the human body, and many diseases affect its reduction. We found that BChE is also a marker for thyroid cancer. Therefore, it is of certain clinical value to explore the expression of BChE in thyroid cancer cells through a customized fluorescent probe to provide valuable experimental data and clues for studying the expression of thyroid cancer marker to reflect thyroid status.

RESULTS

In this study, we customized a fluorescent probe named Kang-BChE, which is easy to synthesize with a high yield. The experimental results show that the probe Kang-BChE can detect BChE in the linear range of 0-900 U L-1 (R2 = 0.9963), and the detection limit is as low as 3.93 U L-1 (λex/em = 550/689 nm). In addition, Kang-BChE probes have low cytotoxicity, good specificity, and can completely eliminate interference from acetylcholinesterase (AChE). Kang-BChE showed excellent stability in the detection of complex biological samples in serum recovery experiments (95.64-103.12 %). This study was the first time using Kang-BChE to study the low expression of BChE in thyroid cancer cells (Tpc-1 cells). In addition, we observed that H2O2 concentration in Tpc-1 cells was positively correlated with BChE activity.

SIGNIFICANCE

Kang-BChE is expected to be an important tool for monitoring the change of BChE content in complex biological environments due to its excellent performance. Kang-BChE can also be used to explore the influence of molecules in more organisms on the change of BChE content due to its excellent anti-interference ability. We expect that Kang-BChE can play a significant role in the clinical diagnosis and treatment of thyroid cancer.

Costunosides A-C: cytotoxic sesquiterpene lactones from the rhizomes of Aucklandia costus Falc

Three new eudesmane type rare sesquiterpene lactone galactosides, costunosides A-C (1-3) were isolated from the rhizomes of Aucklandia costus along with ten known compounds (4-13). Costunosides A-C (1-3) are the first example of naturally eudesmane glycosides containing a β-galactopyranoside moiety. The structure and relative configurations of these compounds were established by comprehensive analysis of MS and, in particular 1D/2D NMR spectroscopic data. The isolated compounds were tested against a panel of human cancer cell lines, where compounds 3, 6 and 7 have shown promising cytotoxic activity against PC-3, HCT-116 and A549 cell lines with IC50 values in the range of 3.4 µM to 9.3 µM, respectively. Costunosides A-C (1-3) were also screened for inhibition assay of acetyl-cholinesterase (AChE), and butyrylcholinesterase (BChE) and found inactive at a concentration of 10 µM.

Construction of a Label-Free Ratiometric Biosensor Based on Target Recycling Amplification and Hg-ZnSe QDs for Assay of BChE and OPs

Herein, we constructed a label-free ratiometric fluorescence biosensing strategy for the determination of butyrylcholinesterase (BChE) activity and organophosphorus (OPs) concentration. BChE promoted the hydrolysis of iodized s-butyrylthiocholine (BTCh) into a reducing substance thiocholine, which can decompose CoOOH nanosheets (CoOOH NSs) to Co2+. Subsequently, the single-stranded DNA (ssDNA) on the surface of CoOOH NSs was released. Then, ssDNA hybridized with hairpin DNA (h-DNA) and triggered the target recycling amplification process, producing large amounts of G-quadruplex. After adding thioflavin T (ThT), the target BChE was converted into activatable G-quadruplex/ThT with an amplified yellow fluorescence signal. The addition of OPs could significantly inhibit the hydrolysis of BTCh by BChE and thus unable to produce the yellow fluorescence G-quadruplex/ThT complex. Throughout the entire process, the fluorescence intensity of Hg-ZnSe QDs as a reference signal remained unchanged at 630 nm. Furthermore, this work provided an effective approach for detecting the BChE activity in serum samples and OPs in fruits and vegetables.

In silico exploration of promising heterocyclic molecules against both acetylcholinesterase and butyrylcholinesterase enzymes

We aimed to further explore the relationship between heterocyclic molecules and their associated biological activities for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. A dataset of 36 heterocycles was used to predict the activity of AChE and BChE inhibitors (the pIC50 values ranged from 7.84 to 12.49). A quantitative structure-activity relationship (QSAR) study was generated with the help of four different models (BMA, MNLR, MLR, and ANN). Four of the models were statistically acceptable based on both internal and external validation. The descriptors used in the models were similar to the X-ray structures of the target-ligand complexes, which made it possible to predict the pIC50 for AChE and BChE enzymes. Five selected molecules (compounds 6 (C₂₁H₂₁F₃N₄O), compound 7 (C₂₂H₂₃F₃N₄O), and compound 8 (C₂₂H₂₃F₃N₄O₂) belong to the oxadiazole derivative group; compound 16 (C₁₇H₁₃ClN₂O₃) is classified into the chemical structures of different N, O, and S-based heterocycle groups; and compound 25 (C₁₉H₁₇NO₂) pertains to the pyrimidine derivative group) possessed high pIC50 values for AChE and BChE enzymes (pIC50 values for AChE and BChE ranged from 9.01 to 10.32). The range of docking scores between the AChE and BChE receptors and their respective candidates was from -8.1 to -9.2 kcal/mol. The pharmacokinetics, biological activities, and physicochemical properties of five selected compounds supported their ability to protect against AD because they are not toxic, have a cholinergic effect, can cross the blood-brain barrier, and are well absorbed by the gastrointestinal tract.Communicated by Ramaswamy H. Sarma.

Anti-Alzheimer's Activity of Polyphenolic Stilbene-Rich Acetone Fraction of the Oil-Removed Seeds of Passiflora edulis: in Vivo and in Silico Studies

The stilbene-rich acetone fraction in high yield (6.6 %, PEAS) of Passiflora edulis Sims was prepared and evaluated for neuroprotective activity in murine Alzheimer's disease model induced by aluminum chloride and D-galactose. The phytochemical and HPLC-DAD-MS analysis of the polyphenolic stilbene-rich acetone fraction showed that it contained different stilbenes including trans-piceatannol, scirpusins A-B and cassigarol E. The total phenolic content (TPC) of PEAS was 413.87±1.71 mg GAE eqv/g. The neuroprotective activity of PEAS is typically presented in the Morris water maze-reference Spatial Memory test, where the Alzheimer's mice treated at 100 mg/kg (Alz-ED1) and 200 mg/kg (Alz-ED2) spent less than 47 % and 66 % of the time, respectively, than the Alzheimer's model mice (Alz). Two simple stilbenes, trans-piceatannol and trans-resveratrol, showed selectively inhibitory activity in silico against acetylcholinesterase (AChE). Two stilbene dimers, cassigarol E and scirpusin A, exhibited low nanomolar inhibitory potential against AChE and butyrylcholinesterase (BChE), significantly lower than those of the positive control, donepezil and tacrine. These findings suggest that the stilbenes from P. edulis seeds, particularly the stilbene dimers, warrant further investigation as potential neuroprotective candidates in the prevention of cognitive deficits associated with Alzheimer's disease.

New indole derivatives as multitarget anti-Alzheimer's agents: synthesis, biological evaluation and molecular dynamics

Background: Alzheimer's disease is a neurological disorder that causes brain cells to shrink and die. Aim: Thirteen novel 'oxathiolanyl', 'pyrazolyl' and 'pyrimidinyl' indole derivatives were designed and synthesized as anti-Alzheimer's disease treatment. Method: In vitro enzyme assay was performed against both AChE and BChE enzymes. In addition, antioxidant assay and cytotoxicity on a normal cell line were determined. Molecular docking and dynamic simulations were conducted to confirm the binding mode in both esterases' active sites. In silico absorption, distribution, metabolism, excretion and toxicity studies were also carried out. Results & conclusion: Compounds 5, 7 and 11 exhibited superior inhibitory activity against acetylcholinesterase and butyrylcholinesterase, with IC₅₀ values of 0.042 and 3.003 μM, 2.54 and 0.207 μM and 0.052 and 2.529 μM, respectively, compared with donepezil.

Phytochemical investigation and biological activity of Doronicum pardalianches L. roots against Alzheimer's disease

The methanol extract of Doronicum pardalianches L. was fractionated using n-hexane, chloroform, and ethyl acetate to evaluate their cholinesterase (ChE) inhibitory activity via modified Ellman's method. It was perceived that only the ethyl acetate fraction was active toward acetylcholinesterase (AChE) with IC₅₀ value of 172.21 µg/mL. Also, all fractions showed no butyrylcholinesterase (BChE) inhibitory activity. The ethyl acetate fraction was also investigated for its neuroprotectivity and metal chelating ability (Zn²⁺, Fe²⁺, and Cu²⁺) which demonstrated desired activity. Phytochemical analysis of the ethyl acetate fraction led to isolation and identification of formononetin 7-O-β-D-glucopyranoside which has not been previously reported for this plant.

Phytochemical analysis and anticholinesterase activity of aril of Myristica fragrans Houtt

In this study, the ethyl acetate fraction of Myristica fragrans Houtt. was investigated for its in vitro anticholinesterase activity as well as neuroprotectivity against H₂O₂-induced cell death in PC12 neuronal cells and the ability to chelate bio-metals (Zn²⁺, Fe²⁺, and Cu²⁺). The fraction was inactive toward acetylcholinesterase (AChE); however, it inhibited the butyrylcholinesterase (BChE) with IC₅₀ value of 68.16 µg/mL, compared with donepezil as the reference drug (IC₅₀ = 1.97 µg/mL) via Ellman's method. It also showed good percentage of neuroprotection (86.28% at 100 µg/mL) against H₂O₂-induced neurotoxicity and moderate metal chelating ability toward Zn²⁺, Fe²⁺, and Cu²⁺. The phytochemical study led to isolation and identification of malabaricone A (1), malabaricone C (2), 4-(4-(3,4-dimethoxyphenyl)-2,3-dimethylbutyl)benzene-1,2-diol (3), nectandrin B (4), macelignan (5), and 4-(4-(benzo[d][1,3]dioxol-5-yl)-1-methoxy-2,3-dimethylbutyl)-2-methoxyphenol (6) which were assayed for their cholinesterase (ChE) inhibitory activity. Compounds 1 and 3 were not previously reported for M. fragrans. Among isolated compounds, compound 2 showed the best activity toward both AChE and BChE with IC₅₀ values of 25.02 and 22.36 μM, respectively, compared with donepezil (0.07 and 4.73 μM, respectively).

Polyphenolic compounds: Synthesis, assessment of antimicrobial effect and enzymes inhibition against important medicinal enzymes with computational details

Phenolic compounds mainly benefit human health and have many biological activities. Their activities are related to their structure, which allows them to interact with enzymes. The inhibition potencies of synthesized polyphenolic compounds (3a and 3b) were investigated on cholinesterases, α‑Gly, and tyrosinase activities. The structures of 3a and 3b were determined based on spectral data (NMR, UV-vis, XRD pattern, SEM, and EDX). The compounds have effective inhibitory potential with IC₅₀ value between 2.25 ± 0.35-5.66 ± 0.75 µM and Ki values 2.95 ± 0.37-14.86 ± 4.99 µM for AChE, BChE, and tyrosinase. It was determined that the synthesized compounds have biological activities by the MIC and cytotoxicity tests, and they have IC₅₀ values of 16.15 µg/mL and 12.16 µg/mL for the PC-3 cell line, respectively. According to the calculated molecular docking results, these compounds showed the highest binding energy against AChE and tyrosinase enzymes (-11.3 and -10.4 kcal/mol, respectively). The compounds have synthetic accessibility scores of 2.75 and 4.55 based on the drug-likeness properties.

Comparative in-vitro anti-inflammatory, anticholinesterase and antidiabetic evaluation: computational and kinetic assessment of succinimides cyano-acetate derivatives

This research was planned to synthesize cyano-acetate derivatives of succinimide and evaluate its comparative biological efficacy as anti-inflammatory, anti-cholinesterase and anti-diabetic, which was further validated by molecular docking studies. The three cyano-acetate derivatives of succinimide including compound 23 Methyl 2-cyano-2-(2,5-dioxopyrrolidin-3-yl)acetate, compound 31 Methyl 2-cyano-2-(1-methyl-2,5-dioxopyrrolidin-3-yl)acetate and compound 44 Methyl 2-cyano-2-(1-ethyl-2,5-dioxopyrrolidin-3-yl) acetate were synthesized. The mentioned compounds were checked for in vitro anti-inflammatory, anti-cholinesterase and anti-diabetic (α-amylase inhibition) activity. To validate the in vitro results, computational studies were carried out using molecular operating environment to analyse the BE, i.e. binding energies of all synthesized compounds against the respective enzymes. The Compounds 23, 31, 44 exhibited anti-inflammatory via inhibiting COX-2 (IC50 value of 204.08, 68.60 and 50.93 µM, respectively), COX-1 (IC50 value of 287, 185, and 143 µM, respectively) and 5-LOX (IC50 value of 138, 50.76 and 20, 87 µM respectively). They exhibited choline-mimetic potential, such as compound 23, 31 and 44 inhibited AChE enzyme (IC50 value of 240, 174, and 134 µM, respectively) and BChE enzyme (IC50 value of 203, 134 and 97 µM, respectively). The Compounds 23, 31, 44 exhibited anti-diabetic effect via inhibiting α-amylase enzyme (IC50 values of 250, 106 and 60 µM, respectively). Molecular docking studies revealed that the synthesized compounds have good binding affinity in the binding pockets of AChE, BChE, COX-2, 5-LOX and α-amylase enzyme and showed high binding energies. The synthesized succinimide derivatives, i.e. compound 23, 31, 44 showed marked inhibitory activities against cyclooxygenase, lipoxygenase, α-amylase and cholinesterase enzymes. Among these three, compound 44 and 31 showed strong anti-inflammatory and anti-diabetic activity while they displayed moderate anti-cholinesterase activity supported by molecular docking results.Communicated by Ramaswamy H. Sarma.

Ghrelin Acylation-A Post-Translational Tuning Mechanism Regulating Adult Hippocampal Neurogenesis

Adult hippocampal neurogenesis—the generation of new functional neurones in the adult brain—is impaired in aging and many neurodegenerative disorders. We recently showed that the acylated version of the gut hormone ghrelin (acyl-ghrelin) stimulates adult hippocampal neurogenesis while the unacylated form of ghrelin inhibits it, thus demonstrating a previously unknown function of unacyl-ghrelin in modulating hippocampal plasticity. Analysis of plasma samples from Parkinson’s disease patients with dementia demonstrated a reduced acyl-ghrelin:unacyl-ghrelin ratio compared to both healthy controls and cognitively intact Parkinson’s disease patients. These data, from mouse and human studies, suggest that restoring acyl-ghrelin signalling may promote the activation of pathways to support memory function. In this short review, we discuss the evidence for ghrelin’s role in regulating adult hippocampal neurogenesis and the enzymes involved in ghrelin acylation and de-acylation as targets to treat mood-related disorders and dementia.

New 4-phenylpiperazine-carbodithioate-N-phenylacetamide hybrids: Synthesis, in vitro and in silico evaluations against cholinesterase and α-glucosidase enzymes

A series of novel 4-phenylpiperazine-carbodithioate-N-phenylacetamide hybrids (6a-n) was designed, synthesized, and evaluated for their in vitro inhibitory activity against the metabolic enzymes, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glucosidase. The obtained results showed that most of the synthesized compounds exhibited high to good anti-AChE and anti-BChE activity in the range of nanomolar concentrations in comparison to tacrine as a positive control. Molecular modeling of the most potent compounds 6e and 6i demonstrated that these compounds interacted with important residues of the AChE and BChE active sites. Moreover, all the newly synthesized compounds 6a-n had significant K_i values against α-glucosidase when compared with the positive control acarbose. Representatively, N-2-fluorophenylacetamide derivative 6l, with a K_i value of 0.98 nM as the most potent compound, was 126 times more potent than acarbose with a K_i value of 123.70 nM. This compound also fitted in the α-glucosidase active site and interacted with key residues. An in silico study of the druglikeness/absorption, distribution, metabolism, and excretion (ADME)/toxicity profile of the selected compounds 6e, 6i, and 6l predicts that these compounds are drug-like and have the appropriate properties in terms of ADME and toxicity.

Profile of Phenolic Compounds of Prunus armeniaca L. Leaf Extract Determined by LC-ESI-QTOF-MS/MS and Their Antioxidant, Anti-Diabetic, Anti-Cholinesterase, and Anti-Inflammatory Potency

In view of the limited information available in the literature concerning leaves as by-products of Prunus armeniaca cultivation, the aim of this work was to identify and characterize their principal polyphenolic constituents by LC-ESI-QTOF-MS/MS and screening in vitro biological potency as antioxidant capacity (ABTS, online ABTS, FRAP, ORAC), antidiabetic (α-amylase, α-glucosidase), anti-obesity (pancreatic lipase), anti-cholinesterase (AChE and BChE), and anti-inflammatory (COX-1 and COX-2) inhibitory activity. Comparison of different polyphenolic extracts of P. armeniaca cultivar leaves according to their quantitative composition revealed them to be exceptional sources of hydroxycinnamic acids, and to a lesser extent as sources of flavonols. Polyphenol-rich apricot leaf extract (PrALe) showed the most effective anti-obesity action through inhibition of pancreatic lipase, COX-1 and antioxidant capacity, especially the oxygen radical absorbance capacity, which was particularly correlated with polyphenolic compounds. Online ABTS radical UPLC-PDA-PDA analysis clearly demonstrated that the three predominant compounds of PrALe are quercetin-3-O-rutinoside > 5-O- and 3-O-caffeoylquinic acid, which basically contribute to antioxidant potential. These results assist in the evaluation of plant sources of potential new raw materials for application in different commercial sectors, especially for food, cosmetics and pharmaceuticals production.

New Uncharged 2-Thienostilbene Oximes as Reactivators of Organophosphate-Inhibited Cholinesterases

The inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) by organophosphates (OPs) as nerve agents and pesticides compromises normal cholinergic nerve signal transduction in the peripheral and central nervous systems (CNS) leading to cholinergic crisis. The treatment comprises an antimuscarinic drug and an oxime reactivator of the inhibited enzyme. Oximes in use have quaternary nitrogens, and therefore poorly cross the brain–blood barrier. In this work, we synthesized novel uncharged thienostilbene oximes by the Wittig reaction, converted to aldehydes by Vilsmeier formylation, and transformed to the corresponding uncharged oximes in very high yields. Eight trans,anti- and trans,syn-isomers of oximes were tested as reactivators of nerve-agent-inhibited AChE and BChE. Four derivatives reactivated cyclosarin-inhibited BChE up to 70% in two hours of reactivation, and docking studies confirmed their productive interactions with the active site of cyclosarin-inhibited BChE. Based on the moderate binding affinity of both AChE and BChE for all selected oximes, and in silico evaluated ADME properties regarding lipophilicity and CNS activity, these compounds present a new class of oximes with the potential for further development of CNS-active therapeutics in OP poisoning.

Butyrylcholinesterase-Protein Interactions in Human Serum

Measuring various biochemical and cellular components in the blood is a routine procedure in clinical practice. Human serum contains hundreds of diverse proteins secreted from all cells and tissues in healthy and diseased states. Moreover, some serum proteins have specific strong interactions with other blood components, but most interactions are probably weak and transient. One of the serum proteins is butyrylcholinesterase (BChE), an enzyme existing mainly as a glycosylated soluble tetramer that plays an important role in the metabolism of many drugs. Our results suggest that BChE interacts with plasma proteins and forms much larger complexes than predicted from the molecular weight of the BChE tetramer. To investigate and isolate such complexes, we developed a two-step strategy to find specific protein–protein interactions by combining native size-exclusion chromatography (SEC) with affinity chromatography with the resin that specifically binds BChE. Second, to confirm protein complexes′ specificity, we fractionated blood serum proteins by density gradient ultracentrifugation followed by co-immunoprecipitation with anti-BChE monoclonal antibodies. The proteins coisolated in complexes with BChE were identified by mass spectroscopy. These binding studies revealed that BChE interacts with a number of proteins in the human serum. Some of these interactions seem to be more stable than transient. BChE copurification with ApoA-I and the density of some fractions containing BChE corresponding to high-density lipoprotein cholesterol (HDL) during ultracentrifugation suggest its interactions with HDL. Moreover, we observed lower BChE plasma activity in individuals with severely reduced HDL levels (≤20 mg/dL). The presented two-step methodology for determination of the BChE interactions can facilitate further analysis of such complexes, especially from the brain tissue, where BChE could be involved in the pathogenesis and progression of AD.

Evaluation of γ-carboline-phenothiazine conjugates as simultaneous NMDA receptor blockers and cholinesterase inhibitors

Alzheimer's disease (AD) is the most common form of dementia. It is associated with the impairment of memory and other cognitive functions that are mainly caused by progressive defects in cholinergic and glutamatergic signaling in the central nervous system. Inhibitors of acetylcholinesterase (AChE) and ionotropic glutamate receptors of the N-methyl-d-aspartate (NMDA) receptor family are currently approved as AD therapeutics. We previously showed using a cell-based assay of NMDA receptor-mediated glutamate-induced excitotoxicity that bis-γ-carbolinium conjugates are useful NMDA receptor blockers. However, these compounds also act as subnanomolar AChE inhibitors, which may cause serious anticholinergic side effects when applied in vivo. Here, we evaluated new structures containing γ-carbolines linked to phenothiazine via a propionyl spacer. These compounds were superior to the previously characterized bis-γ-carbolinium conjugates because they blocked NMDA receptors without requiring a quaternary pyridine N-atom and inhibited AChE with moderate IC₅₀ values of 0.54-5.3 µM. In addition, these new compounds displayed considerable selectivity for the inhibition of butyrylcholinesterase (BChE; IC₅₀ = 0.008-0.041 µM), which may be favorable for AD treatment. Inhibitory activities towards the NMDA receptors and AChE were in the same micromolar range, which may be beneficial for equal dosing against multiple targets in AD patients.

Release of protein-bound nerve agents by excess fluoride from whole blood: GC-MS/MS method development, validation, and application to a real-life denatured blood sample

In analogy to the fluoride-induced regeneration of butyrylcholinesterase (BChE) inhibited by nerve agents a method was developed and optimized for whole blood samples. Compared to the plasma method, regeneration grade was found to be higher for cyclosarin (GF), i-butylsarin from VR, and n-butylsarin from CVX, but lower for sarin (GB), fluorotabun from tabun (GA), and ethylsarin from VX. Regeneration grade of soman (GD) is the same for both matrices because it is released from serum albumin and not from cholinesterases. The method was fully validated for GB and GF to prove selectivity, linearity (n = 6), limit of determination (LOD1), reproducibility (within day (n = 8) and from day to day (n = 8)), effectiveness of extraction, matrix effect, and sample stability (after sample preparation and during three freeze/thaw cycles). The other agents were tested for selectivity, linearity (n = 2), limit of determination, and stability after sample preparation. The method showed high selectivity, good linearity up to the protein's saturation concentration (GB: R² = 0.9995, GF: 0.9968), and high reproducibility (GB: C.V. 5.9-13.7%, GF: 4.9-10.3%). The limits of determination (calculated from the spiked amount of the original agent) were found with 0.3 ng/mL VX, 0.5 ng/mL GB, 1 ng/mL VR, 0.5 ng/mL GA, 1 ng/mL CVX, and 8 ng/mL GD. In the case of GF, it was found with 4 ng/mL using Isolute ENV + SPE cartridges as for the other analytes and with 2.5 ng/mL using Isolute C8 EC SPE cartridges instead. This method was then applied to a denatured whole blood sample obtained from an individual exposed to GB. While previously only the GB metabolite isopropyl methylphosphonic acid (IMPA) could be detected in this blood sample it was now possible to successfully release GB from the blood proteins by excess fluoride.

Hypericum triquetrifolium and H. neurocalycinum as Sources of Antioxidants and Multi-Target Bioactive Compounds: A Comprehensive Characterization Combining In Vitro Bioassays and Integrated NMR and LC-MS Characterization by Using a Multivariate Approach

Hypericum triquetrifolium and H. neurocalycinum were evaluated for their phytochemical content and in vitro bioactivity. NMR analyses were performed on the methanol extract of the aerial parts of H. triquetrifolium to establish the main classes of phytoconstituents. Then, LC-DAD-MSⁿ analyses were performed in order to compare the composition of aerial parts and roots extracts of both Hypericum species, obtained using either methanol or water as solvents. Results, processed using multivariate data analysis, showed a significantly higher phenolic content of methanol extracts compared to water extracts, while minor qualitative differences were observed between the two. Distinctive flavonoid and PAC patterns were observed for H. triquetrifolium and H. neurocalycinum, and specific compounds were exclusively detected in one or the other species. Specifically, the phloroglucinols 7-epiclusianone, hyperfirin and hyperforin were present only in H. neurocalycinum, while hyperforin was detected only in H. triquetrifolium. Extracts were assayed using different in vitro tests to evaluate their antioxidant properties and their inhibitory activity against several enzymes, showing significant antioxidant and metal chelating activities. Furthermore, inhibitory properties against acetylcholinesterase, butyrylcholinesterase and tyrosinase were observed. Multivariate approaches were used to correlate biological data with the phytochemical composition of the different extracts. The results, showing positive correlations between specific chemical constituents and the measured bioactivities, represent preliminary data that could guide future studies aimed at isolating bioactive constituents from H. neurocalycinum and H. triquetrifolium for further pharmacological evaluations.

Effect of pesticide exposure on total antioxidant capacity and biochemical parameters in Brazilian soybean farmers

Farmers represent a population highly vulnerable to the toxic effects of pesticide exposure. Antioxidant capacity and biochemical parameters have been used as biomarkers of occupational exposure to pesticides. The aim of this study was to evaluate hepatic and renal parameters as well as butyrylcholinesterase (BChE) activity and ferric-reducing ability of plasma (FRAP) considering high and low exposure periods in soybean farmers in southern Brazil. The exposed group consisted of 50 soybean farmers. Two control groups were used, composed by 35 (Novo Hamburgo control group) and 28 (Sertão control group) subjects not exposed to pesticides. Farmers blood samples were collected during the high and low pesticide exposure periods. BChE, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), urea, and creatinine levels were determined. The FRAP assay was carried out to evaluate the antioxidant potential in the exposed group. Considering the exposed group, significantly lower BChE and increased AST activity were observed during high pesticide exposure period as well as higher FRAP, urea and creatinine levels; however, ALT and GGT did not differ between the two periods. When compared with the control groups, only urea and creatinine were higher in the exposed group. The present results indicate that occupational exposure to mixtures of pesticides might elicit adverse effects at the biochemical level. In addition, the study highlights the importance in considering periods of a same crop season with different degree of pesticide exposure during biologic monitoring of these biochemical parameters.

The Role of Butyrylcholinesterase and Iron in the Regulation of Cholinergic Network and Cognitive Dysfunction in Alzheimer's Disease Pathogenesis

Alzheimer’s disease (AD), the most common form of dementia in elderly individuals, is marked by progressive neuron loss. Despite more than 100 years of research on AD, there is still no treatment to cure or prevent the disease. High levels of amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain are neuropathological hallmarks of AD. However, based on postmortem analyses, up to 44% of individuals have been shown to have high Aβ deposits with no clinical signs, due to having a “cognitive reserve”. The biochemical mechanism explaining the prevention of cognitive impairment in the presence of Aβ plaques is still unknown. It seems that in addition to protein aggregation, neuroinflammatory changes associated with aging are present in AD brains that are correlated with a higher level of brain iron and oxidative stress. It has been shown that iron accumulates around amyloid plaques in AD mouse models and postmortem brain tissues of AD patients. Iron is required for essential brain functions, including oxidative metabolism, myelination, and neurotransmitter synthesis. However, an imbalance in brain iron homeostasis caused by aging underlies many neurodegenerative diseases. It has been proposed that high iron levels trigger an avalanche of events that push the progress of the disease, accelerating cognitive decline. Patients with increased amyloid plaques and iron are highly likely to develop dementia. Our observations indicate that the butyrylcholinesterase (BChE) level seems to be iron-dependent, and reports show that BChE produced by reactive astrocytes can make cognitive functions worse by accelerating the decay of acetylcholine in aging brains. Why, even when there is a genetic risk, do symptoms of the disease appear after many years? Here, we discuss the relationship between genetic factors, age-dependent iron tissue accumulation, and inflammation, focusing on AD.

Cholinesterase inhibitory activity of highly functionalized fluorinated spiropyrrolidine heterocyclic hybrids

Two series of dimethoxyindanone imbedded novel fluorinated spiropyrrolidine heterocyclic hybrids were synthesized employing two different less explored azomethine ylides and were measured for their efficiency as inhibitors for Alzheimer’s disease. Among the spiropyrrolidine heterocyclic hybrids, the indole based fluorinated compound with a methoxy substituent at the meta- position of the aryl ring exhibited the utmost potent AChE and BChE inhibitory activities with an IC₅₀ of 1.97 ± 0.19 µM and 7.08 ± 0.20 µM respectively. The plausible mechanism of inhibition on ChE receptors was unveiled via molecular docking studies.

A Novel Chemical Profile of a Selective In Vitro Cholinergic Essential Oil from Clinopodium taxifolium (Kunth) Govaerts (Lamiaceae), a Native Andean Species of Ecuador

A novel chemical profile essential oil, distilled from the aerial parts of Clinopodium taxifolium (Kunth) Govaerts (Lamiaceae), was analysed by Gas Chromatography-Mass Spectrometry (GC-MS, qualitative analysis) and Gas Chromatography with Flame Ionization Detector (GC-FID, quantitative analysis), with both polar and non-polar stationary phase columns. The chemical composition mostly consisted of sesquiterpenes and sesquiterpenoids (>70%), the main ones being (E)-β-caryophyllene (17.8%), α-copaene (10.5%), β-bourbonene (9.9%), δ-cadinene (6.6%), cis-cadina-1(6),4-diene (6.4%) and germacrene D (4.9%), with the non-polar column. The essential oil was then submitted to enantioselective GC analysis, with a diethyl-tert-butyldimethylsilyl-β-cyclodextrin diluted in PS-086 chiral selector, resulting in the following enantiomeric excesses for the chiral components: (1R,5S)-(-)-α-thujene (67.8%), (1R,5R)-(+)-α-pinene (85.5%), (1S,5S)-(-)-β-pinene (90.0%), (1S,5S)-(-)-sabinene (12.3%), (S)-(-)-limonene (88.1%), (S)-(+)-linalool (32.7%), (R)-(-)-terpinen-4-ol (9.3%), (S)-(-)-α-terpineol (71.2%) and (S)-(-)-germacrene D (89.0%). The inhibition activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) of C. taxifolium essential oil was then tested, resulting in selective activity against BChE with an IC50 value of 31.3 ± 3.0 μg/mL (positive control: donepezil, IC50 = 3.6 μg/mL).

Vitamin B3-Based Biologically Active Compounds as Inhibitors of Human Cholinesterases

We evaluated the potential of nine vitamin B3 scaffold-based derivatives as acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors, as a starting point for the development of novel drugs for treating disorders with cholinergic neurotransmission-linked pathology. As the results indicate, all compounds reversibly inhibited both enzymes in the micromolar range pointing to the preference of AChE over BChE for binding the tested derivatives. Molecular docking studies revealed the importance of interactions with AChE active site residues Tyr337 and Tyr124, which dictated most of the observed differences. The most potent inhibitor of both enzymes with K_i of 4 μM for AChE and 8 μM for BChE was the nicotinamide derivative 1-(4′-phenylphenacyl)-3-carbamoylpyridinium bromide. Such a result places it within the range of several currently studied novel cholinesterase inhibitors. Cytotoxicity profiling did not classify this compound as highly toxic, but the induced effects on cells should not be neglected in any future detailed studies and when considering this scaffold for drug development.

In vitro antioxidant, anticholinesterases, anti-α-amylase, and anti-α-glucosidase effects of Algerian Salvia aegyptiaca and Salvia verbenaca

In this study, Salvia aegyptiaca and Salvia verbenaca aerial part decoction and methanol extracts (SAE DE, SAE ME, SVR DE, and SVR ME) were screened for their in vitro antioxidant, anti-Alzheimer, and antidiabetic enzymes inhibition activities. The antioxidant properties of Salvia extracts were determined using DPPH radical scavenging, ABTS radical scavenging, Alkaline DMSO superoxide radical scavenging, β-carotene bleaching, reducing power, and metal chelating activity assays. All extracts showed high antioxidant capacity and the antioxidant properties with the best performance were detected in the SAE ME and SVR ME. The extracts of S. aegyptiaca and S. verbenaca showed a low inhibitory activity of acetylcholinesterase (AChE), whereas, the methanol extract of S. aegyptiaca had the highest inhibitory activity on butyrylcholinesterase (BChE) (71.60 ± 4.33% for 100 µg/ml) compared to the other extracts. In vitro inhibitory effect on diabetic enzymes showed that the ME inhibited α-amylase enzyme with an IC₅₀ 86 and 101 µg/ml for SAE and SVR, respectively. Similarly, both extracts inhibited α-glucosidase with (IC₅₀ 97 and 150 µg/ml, respectively). The decoction extracts exhibited lower activity on both enzymes. PRACTICAL APPLICATIONS: It is becoming evident that oxidative stress is involved in several acute and chronic diseases. Counteracting free radical generation has become one of the widest fields of research worldwide. This study deals with the in vitro antioxidant activity of two plants from the Salvia genus as well as the assessment of their in vitro inhibitory properties of four key enzymes implicated in diabetes and Alzheimer's disease. Concerning the practical applications of our work, it can be explored in its antioxidant part as a food supplement to prevent the excess of free radicals in the body and also in other industrial practices. Another potential use is in the prevention and amelioration of both diabetes and Alzheimer's disease symptoms for the extracts that had enzyme inhibitory activity, but this deserves further toxicological and in vivo studies.

Phytochemical investigation and anticholinesterase activity of ethyl acetate fraction of Myristica fragrans Houtt. seeds

In this work, n-hexane, chloroform, and ethyl acetate fractions of the methanol extract of Myristica fragrans Houtt. seeds were evaluated against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) via Ellman's method. It was found that all fractions depicted no anti-AChE activity, however, they were active toward BChE with IC₅₀ values of 361.8, 215.0, and 145.8 µg/mL, respectively comparing with donepezil as the reference drug (IC₅₀ = 1.97 µg/mL). The ethyl acetate fraction which also showed high neuroprotectivity and metal chelating ability was selected for the phytochemical analysis. Our results confirmed the presence of trimyristin and 5,7-diacetyl chrysin (reported for the first time in M. fragrans) in the corresponding fraction.

Honey as the Potential Natural Source of Cholinesterase Inhibitors in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized, among others by abnormal levels of acetyl- and butyrylcholinesterase in the brain. In this study, 47 types of Polish honeys were examined (using colorimetric method) as a source of acetyl- and butyrylcholinesterase inhibitors. The highest potential for AChE inhibition was observed in the case of buckwheat honey (39.51% inhibition), while multi-floral honey showed the highest capacity for BChE inhibition (39.76%). Our study revealed that honeys can be a rich source of cholinesterase inhibitors and therefore may play a role in AD treatment.

Assessment of DNA damage and cholinesterase activity in soybean farmers in southern Brazil: High versus low pesticide exposure

The aim of this study was to evaluate the DNA damage in soybean growers during two agricultural periods of a crop season (high and low exposure) and a control group, as well as butyrylcholinesterase (BChE) activity during these exposure periods in order to estimate the degree of BChE inhibition for the exposed group. DNA damage in peripheral whole blood was evaluated by the comet assay and plasma BChE activity was accessed as a measure of exposure to cholinesterase inhibitors. None of the soybean growers reported using full Personal Protective Equipment (PPE). BChE was lower in high exposure period than in low exposure period and DNA damage index was significantly increased in the high exposure period than in the low exposure period. In addition, DNA damage in both exposure periods was higher than control group. No correlation was found between exposure time and DNA damage and BChE activity. However, negative correlation was observed between DNA damage in high and low exposure periods. The results indicate that soybean growers are exposed to cholinesterase inhibitors and to pesticides mixtures with genotoxic potential.

Chemical Composition, Enantiomeric Distribution, and Sensory Evaluation of the Essential Oils Distilled from the Ecuadorian Species Myrcianthes myrsinoides (Kunth) Grifo and Myrcia mollis (Kunth) DC. (Myrtaceae)

The essential oils of Myrcianthes myrsinoides and Myrcia mollis, belonging to the Myrtaceae family, were obtained by steam distillation. They were analyzed by gas chromatography-mass spectrometry (GC-MS), gas chromatography-flame ionization detector (GC-FID), enantioselective gas chromatography, and gas chromatography-olfactometry (GC-O). A total of 58 compounds for Myrcianthes myrsinoides essential oil (EO) and 22 compounds for Myrcia mollis EO were identified and quantified by GC-MS with apolar and polar columns (including undetermined components). Major compounds (>5.0%) were limonene (5.3%–5.2%), 1,8-cineole (10.4%–11.6%), (Z)-caryophyllene (16.6%–16.8%), trans-calamenene (15.9%–14.6%), and spathulenol (6.2%–6.5%). The enantiomeric excess of eight chiral constituents was determined, being (+)-limonene and (+)-germacrene D enantiomerically pure. Eight components were identified as determinant in the aromatic profile: α-pinene, β-pinene, (+)-limonene, γ-terpinene, terpinolene, linalool, β-elemene and spathulenol. For M. mollis, the major compounds (>5.0%) were α-pinene (29.2%–27.7%), β-pinene (31.3%–30.0%), myrcene (5.0%–5.2%), 1,8-cineole (8.5%–8.7%), and linalool (7.7%–8.2%). The enantiomeric excess of five chiral constituents was determined, with (S)-α-pinene and (+)-germacrene D enantiomerically pure. The metabolites β-pinene, 1,8-cineole, γ-terpinene, terpinolene, linalool, and (E)-β-caryophyllene were mainly responsible for the aroma of the EO. Finally, the M. myrsinoides essential oil has an inhibitory activity for cholinesterase enzymes (IC₅₀ of 78.6 μg/mL and 18.4 μg/mL vs. acethylcholinesterase (AChE) and butyrylcholinesterase (BChE) respectively). This activity is of interest to treat Alzheimer’s disease.

Chemical, Enantioselective, and Sensory Analysis of a Cholinesterase Inhibitor Essential Oil from Coreopsis triloba S.F. Blake (Asteraceae)

The fresh leaves of Coreopsis triloba S.F. Blake, collected at Cerro Villonaco in Loja, Ecuador, were investigated with respect to their essential oil (EO). The chemical composition was determined qualitatively through gas chromatography coupled with mass spectrometry (GC-MS) and quantitatively by gas chromatography coupled with flame ionization (GC-FID), using relative response factors (RRF) based on the enthalpy of combustion. The essential oil contained between 92.5% and 93.4% of monoterpene hydrocarbons, with (E)-β-ocimene being the main component (35.2–35.9%), followed by β-phellandrene (24.6–25.0%), α-pinene (15.3–15.9%), myrcene (10.9–11.0%), sabinene (2.2–2.4%), (Z)-β-ocimene (1.5%), and germacrene D (1.2–1.3%). The enantiomeric distribution of α-pinene, β-pinene, limonene, and germacrene D was also determined. The main components responsible for the aroma were identified through aroma extract dilution analysis (AEDA), a gas chromatography-olfactometry (GC-O) based technique, being α-pinene, β-pinene (0.6%), terpinolene (0.1%), α-copaene (0.1–0.3%), β-phellandrene, and (E)-4,8-dimethyl-1,3,7-nonatriene (0.1–0.2%) the main olfactory constituents according to the decreasing factor of dilution (FD) order. The biological tests showed IC₅₀ inhibition values of 42.2 and 6.8 µg/mL for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), respectively.

Butyrylcholinesterase Protein Ends in the Pathogenesis of Alzheimer's Disease-Could BCHE Genotyping Be Helpful in Alzheimer's Therapy?

Late-onset Alzheimer’s disease (AD) is clinically characterized by a progressive decline of memory and other cognitive functions leading to the loss of the ability to perform everyday activities. Only a few drugs have been approved to treat AD dementia over the past century since the first AD patient was diagnosed. Drugs increasing the availability of neurotransmitters at synapses in the brain are used clinically in the treatment of AD dementia, and cholinesterase inhibitors (ChEIs) are the mainstay of the therapy. A detrimental effect on cognitive function has been reported in patients with pharmacological inhibition of acetylcholinesterase (AChE) by ChEIs and reduced butyrylcholinesterase (BChE) activity due to the single nucleotide polymorphisms. The BChE K-variant (rs1803274), the most common genetic variant of the BCHE gene, was thought to reduce enzyme activity reflecting the lower clinical response to rivastigmine in AD patients. During ChEIs therapy, patients carrying reduced-activity BChE do not present such improved attention like patients with the wild-type enzyme. On the other hand, alterations in the BCHE gene causing enzyme activity reduction may delay AD onset in patients at risk by preserving the level of cortical acetylcholine (ACh). Based on our previous results, we conclude that SNPs localized outside of the coding sequence, in 5’UTR (rs1126680) and/or intron 2 (rs55781031) of the BCHE gene, but not solely K-variant alteration (p.A539T) itself, are responsible for reduced enzyme activity. Therefore, we suspect that not BChE-K itself, but these coexisting SNPs (rs1126680 and rs55781031), could be associated with deleterious changes in cognitive decline in patients treated with ChEIs. Based on the results, we suggest that SNPs (rs1126680) and/or (rs55781031) genotyping should be performed to identify subjects at risk for lowered efficacy ChEIs therapy, and such patients should be treated with a lower rivastigmine dosage. Finally, our sequence analysis of the N-terminal end of N-BChE revealed evolutionarily conserved amino acid residues that can be involved in disulfide bond formation and anchoring of N-BChE in the cell membrane.

Novel AChE and BChE inhibitors using combined virtual screening, text mining and in vitro binding assays

In the current work, we developed a computational pipeline method for predicting the binding affinities of studied compounds at the specific target sites. Since many approved therapeutic compounds involve indole or indole-derivative rings, in the current study we focused compounds including these fingerprints. Initially, 212520 compounds were retrieved from Specs-SC library and after the conversion of IUPAC text file format, compounds that include 'indol' keyword (5194 compounds) were used in binary QSAR-based models to screen against a defined therapeutic activity "Alzheimer's disease" (AD). The molecules that have higher AD therapeutic activity values (>0.5) were then used in the 26 different toxicity-QSAR models. Binary QSAR models resulted 89 hits that have high AD therapeutic activity and no toxicity. Selected 89 molecules were then screened against acetylcholinesterase (AChE) targets using molecular docking and top-docking poses of compounds were used in initially short (10 ns) molecular dynamics (MD) simulations. Molecular Mechanics/Generalized Born Surface Area (MM/GBSA) binding free energy calculations were performed for 89 ligands and tightly bound 17 ligands based on average MM/GBSA scores were selected for long (100 ns) MD simulations. The same protocol was also applied for the known 4 AChE inhibitors. Selected hits were also docked to the binding pocket of butyrylcholinesterase (BChE). Finally, based on MM/GBSA scores, as well as their corresponding docking scores and metabolite production profiles, 7 compounds were selected and their in vitro tests were performed. Out of 7 compounds, 6 of them showed μM-level inhibition for both AChE and BChE targets.Communicated by Ramaswamy H. Sarma.

Haplotypes of butyrylcholinesterase K-variant and their influence on the enzyme activity

Butyrylcholinesterase (BChE) is a serine hydrolase widely distributed throughout the body. It provides protection against administrated or inhaled poisons by hydrolyzing or sequestering the toxic compounds. The most frequent genetic variant of BCHE gene - K variant (p.A539T) is located in the C-terminal tetramerization domain, outside of the catalytic center. Many studies tried to reveal the nature of the lower activity of BChE K-variant but results and conclusions were often contradictory. The aim of this study is to estimate K allele frequency and its coexisting alterations in BCHE gene in a population of 162 individuals, as well as, assess influence on the enzyme activity in serum. We present three haplotypes of BChE-K variant, two of them coexist in strong linkage disequilibrium with alterations in 5'UTR (rs1126680), intron 2 (rs55781031) or in exon 2 (rs1799807). We demonstrate a negative role of these alterations on enzyme activity. By oneself BCHE-K (with no other alterations in BCHE gene) haplotype exhibits wild type enzyme activity. Based on our previous and presented results we conclude that SNPs localized outside the coding sequence, in 5'UTR or/and in intron 2 of BCHE gene, but not solely in K-variant alteration (p.A539T) itself, are responsible for reduced enzyme activity.

Occupational exposure to pesticides and thyroid function in Brazilian soybean farmers

INTRODUCTION

Agriculture production has been supported especially by the use of pesticides for crop protection and pest control. Although the agricultural production has been increased by pesticides use, these substances also reach non-target organisms and may become a risk to the health of farmers. Several epidemiological studies in human have investigated the association between exposure to pesticides and altered serum levels of thyroid hormones, reporting both positive and negative results. Overall, the impact of pesticides on human thyroid function is still limited.

OBJECTIVE

The aim of this study was to access serum levels of free thyroxin (FT4), total triiodothyronine (TT3), thyroid-stimulating hormone (TSH), and butyrylcholinesterase (BChE) in soybean farmers in southern Brazil.

METHODS

The exposed group was composed by 46 rural workers and 27 subjects not exposed to pesticides composed the control group. All subjects had blood samples collected by venipuncture in order to analyze the serum levels of FT4, TT3, TSH and BChE.

RESULTS

The results showed a significant decreasing in TSH and increasing in TT3 and FT4 in rural workers, compared to control group. BChE levels were lower in exposed group than in control group. The results suggest that farmers are exposed to mixtures of pesticides with endocrine disruptor properties.

High-performance counter-current chromatography isolation and initial neuroactivity characterization of furanocoumarin derivatives from Peucedanum alsaticum L (Apiaceae)

BACKGROUND

Medicinal plants are a proven source of drug-like small molecules with activity towards targets relevant for diseases of the central nervous system (CNS). Plant species of the Apiaceae family have to date yielded a number of neuroactive metabolites, such as coumarin derivatives with acetylcholinesterase inhibitory activity or anti-seizure activity.

PURPOSE

To accelerate the discovery of neuroactive phytochemicals with potential as CNS drug leads, we sought to rapidly isolate furanocoumarins, primary constituents of the dichloromethane (DCM) extract of the fruits of Peucedanum alsaticum L. (Apiaceae), using high-performance counter-current chromatography (HPCCC) and to evaluate their neuroactivity using both in vitro and in vivo microscale bioassays based on cholinesterase ELISAs and zebrafish epilepsy models.

RESEARCH METHODS AND PROCEDURE

In this study the DCM extract was subjected to HPCCC for the efficient separation (60 min) and isolation of furanocoumarins. Isolated compounds were identified with TOF-ESI-MS and NMR techniques and examined as inhibitors of AChE and BChE using ELISA microtiter assays. Anti-seizure properties of the extract and of the isolated compounds were evaluated using a zebrafish epilepsy model based on the GABA_A antagonist pentylenetetrazol (PTZ), which induces increased locomotor activity and seizure-like behavior.

RESULTS

The solvent system, composed of n-heptane, ethyl acetate, methanol and water (3:1:3:1, v/v/v/v), enabled the isolation of 2.63 mg lucidafuranocoumarin A (purity 98%) and 8.82 mg bergamottin (purity 96%) from 1.6 g crude DCM extract. The crude extract, at a concentration of 100 µg/ml, exhibited a weak inhibitory activity against acetylcholinesterase (AChE) (9.63 ± 1.59%) and a moderate inhibitory activity against butyrylcholinestrase (BChE) (49.41 ± 2.19%). Lucidafuranocoumarin A (100 µg/ml) was inactive against AChE but showed moderate inhibition towards BChE (40.66 ± 1.25%). The DCM extract of P. alsaticum fruits (0.62-1.75 µg/ml) and bergamottin (2-10 µm) exhibited weak anti-seizure activity, while lucidafuranocoumarin A (10-16 µm) was found to significantly inhibit PTZ-induced seizures. The percentage of seizure inhibition for the isolated compounds, at their most bioactive concentration, was 26% for bergamottin and 69% for lucidafuranocoumarin A.

CONCLUSION

Our findings underscore the utility of HPCCC for the rapid isolation of rare coumarin derivatives, and the potential of microscale in vivo bioassays based on zebrafish disease models for the rapid assessment of neuroactivity of these drug-like natural products.

Synthesis, preliminarily biological evaluation and molecular docking study of new Olaparib analogues as multifunctional PARP-1 and cholinesterase inhibitors

A series of new Olaparib derivatives was designed and synthesized, and their inhibitory activities against poly (ADP-ribose) polymerases-1 (PARP-1) enzyme and cancer cell line MDA-MB-436 in vitro were evaluated. The results showed that compound 5l exhibited the most potent inhibitory effects on PARP-1 enzyme (16.10 ± 1.25 nM) and MDA-MB-436 cancer cell (11.62 ± 2.15 μM), which was close to that of Olaparib. As a PARP-1 inhibitor had been reported to be viable to neuroprotection, in order to search for new multitarget-directed ligands (MTDLs) for the treatment of Alzheimer’s disease (AD), the inhibitory activities of the synthesized compounds against the enzymes AChE (from electric eel) and BChE (from equine serum) were also tested. Compound 5l displayed moderate BChE inhibitory activity (9.16 ± 0.91 μM) which was stronger than neostigmine (12.01 ± 0.45 μM) and exhibited selectivity for BChE over AChE to some degree. Molecular docking studies indicated that 5l could bind simultaneously to the catalytic active of PARP-1, but it could not interact well with huBChE. For pursuit of PARP-1 and BChE dual-targeted inhibitors against AD, small and flexible non-polar groups introduced to the compound seemed to be conducive to improving its inhibitory potency on huBChE, while keeping phthalazine-1-one moiety unchanged which was mainly responsible for PARP-1 inhibitory activity. Our research gave a clue to search for new agents based on AChE and PARP-1 dual-inhibited activities to treat Alzheimer’s disease.

Genetic underpinnings in Alzheimer's disease - a review

In this review, we discuss the genetic etiologies of Alzheimer's disease (AD). Furthermore, we review genetic links to protein signaling pathways as novel pharmacological targets to treat AD. Moreover, we also discuss the clumps of AD-m ediated genes according to their single nucleotide polymorphism mutations. Rigorous data mining approaches justified the significant role of genes in AD prevalence. Pedigree analysis and twin studies suggest that genetic components are part of the etiology, rather than only being risk factors for AD. The first autosomal dominant mutation in the amyloid precursor protein (APP) gene was described in 1991. Later, AD was also associated with mutated early-onset (presenilin 1/2, PSEN1/2 and APP) and late-onset (apolipoprotein E, ApoE) genes. Genome-wide association and linkage analysis studies with identified multiple genomic areas have implications for the treatment of AD. We conclude this review with future directions and clinical implications of genetic research in AD.

Pesticide exposure and health conditions among orange growers in Southern Brazil

This study aimed to evaluate the exposure to pesticides through the biomarkers analysis, as well as life habits and use of Personal Protective Equipment (PPE) in a group of farmers who grow citrus in the Vale do Caí region, in Rio Grande do Sul, southern Brazil. The study population consisted of 73 volunteer farmers, 45 males and 28 females, aged between 13 and 69 years old. The control group consisted of 30 individuals who were not exposed to pesticides. Measures of urea, creatinine, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), plasma cholinesterase (BChE) activity, and hematological parameters were analyzed. The study population also answered a structured questionnaire on life habits and health. The results showed that BChE activity was significantly lower in the exposed group than in the control group. AST, ALT, and creatinine were increased in the group of women exposed to pesticides when compared to the control group. GGT, urea, and hematological parameters did not show statistical differences for both male and female group. The most prevalent symptom reported by farmers after exposure to pesticides was headache. Furthermore, it was verified that the use of complete PPE is only made by 38% of the studied population.

Blood cholinesterase activity levels of farmers in winter and hot season of Mae Taeng District, Chiang Mai Province, Thailand

Organophosphate and carbamate pesticides have been widely used by farmers for crop protection and pest control. Inhibition of acetylcholinesterase (AChE) in erythrocyte and butyrylcholinesterase (BChE) in plasma is the predominant toxic effect of organophosphate and carbamate pesticides. Mae Taeng District, Chiang Mai Province, is one of the large areas of growing vegetables and fruits. Due to their regular exposure to these pesticides, the farmers are affected by this toxicity. The objective of the study was to examine the AChE and the BChE activity levels in the blood of 102 farmers for comparison of exposure in two cropping seasons, winter and hot. Blood samples were collected in December 2013 (winter) and April-June 2014 (hot). A total of 102 farmers joined the study, represented by 76 males (74.5 %) and 26 females (25.5 %). The age of most of the farmers was 53.4 ± 8.7 years. Out of 102, 21 farmers used carbamate pesticides. The results showed that the AChE and the BChE activity levels of all the farmers were 3.27 ± 0.84 Unit/mL and 2.15 ± 0.58 Unit/mL, respectively. The AChE and the BChE activity levels in males were 3.31 ± 0.88 Unit/mL and 1.97 ± 0.60 U/mL, respectively, during winter and 3.27 ± 0.82 Unit/mL and 2.15 ± 0.58 U/mL, respectively, during the hot season, and AChE and the BChE activity levels in females were 3.27 ± 0.82 U/mL and 2.44 ± 0.56 U/mL, respectively, during the hot season. The cholinesterase activity levels, both AChE and BChE, in the male farmers' blood had significant difference between the two seasons, while in the case of the female farmers, there was significant difference in the BChE activity levels, at p < 0.05. The BChE activity level was found to significantly correlate with self-spray (p < 0.05), which implies that the BChE activity decreased when they sprayed by themselves. The cholinesterase activity levels of the present study were lower than those of the other studies, which may be an indication of some chronic effect of exposure to anticholinesterase pesticides. Thus, it is recommended that the use of pesticides be decreased, together with increase in the awareness of the impact of pesticides on health; also recommended is regular monitoring of blood cholinesterase.

Bioscavenger is effective as a delayed therapeutic intervention following percutaneous VX poisoning in the guinea-pig

The prolonged systemic exposure that follows skin contamination with low volatility nerve agents, such as VX, requires treatment to be given over a long time due to the relatively short half-lives of the therapeutic compounds used. Bioscavengers, such as butyrylcholinesterase (BChE), have been shown to provide effective post-exposure protection against percutaneous nerve agent when given immediately on signs of poisoning and to reduce reliance on additional treatments. In order to assess the benefits of administration of bioscavenger at later times, its effectiveness was assessed when administration was delayed for 2h after the appearance of signs of poisoning in guinea-pigs challenged with VX (4×LD₅₀). VX-challenged animals received atropine, HI-6 and avizafone on signs of poisoning and 2h later the same combination with or without bioscavenger. Five out of 6 animals which received BChE 2h after the appearance of signs of poisoning survived to the end of the study at 48h, compared with 6 out of 6 which received BChE immediately on signs. All the animals (n=6+6) that received only MedCM, without the addition of BChE, died within 10h of poisoning. The toxicokinetics of a sub-lethal challenge of percutaneous VX were determined in untreated animals. Blood VX concentration peaked at approximately 4h after percutaneous dosing with 0.4×LD₅₀; VX was still detectable at 36h and had declined to levels below the lower limit of quantification (10pg/mL) by 48h in 7 of 8 animals, with the remaining animal having a concentration of 12pg/mL. These studies confirm the persistent systemic exposure to nerve agent following percutaneous poisoning and demonstrate that bioscavenger can be an effective component of treatment even if its administration is delayed.

Post-exposure treatment with the oxime RS194B rapidly reactivates and reverses advanced symptoms of lethal inhaled paraoxon in macaques

Fatalities from organophosphate (OP) insecticide result from both occupational and deliberate exposure; significantly impacting human health. Like nerve agents, insecticides are neurotoxins which target and inhibit acetylcholinesterases (AChE) in central and peripheral synapses in the cholinergic nervous system. Post-exposure therapeutic countermeasures generally include administration of atropine with a pyridinium aldoxime e.g. pralidoxime, to reactivate the OP-inhibited AChE. However, commonly used oximes inefficiently cross the bloodbrain barrier and are rapidly cleared and their benefit is debated. Recent findings have demonstrated the ability of a novel zwitterionic, centrally acting, brain penetrating oxime (RS194B) to reverse severe symptoms and rapidly reactivate sarin-inhibited AChE in macaques, but it has not been tested following OP pesticide poisoning. In the present study, the symptoms following a lethal dose of inhaled paraoxon (100ug/kg), were shown to mimic those in insecticide poisoned individuals and were also rapidly reversed in macaques by post-exposure IM administration of 80mg/kg of RS194B. This occurred with a concomitant reactivation of AChE to 40-100% in<1hr and BChE (40% in 8h). These findings will be used to develop a macaque model with RS194B as a post-exposure treatment for insecticide poisoning and generate efficacy data for approval under the FDA Animal rule.

Macbr

This study investigated the chemical composition, physical proprieties, biological activity, and enantiomeric analysis of the essential oil from the aerial parts of Niphogeton dissecta (culantrillo del cerro) from Ecuador, obtained by steam distillation. The qualitative and quantitative analysis of the essential oil was realized by gas chromatographic and spectroscopic techniques (GC-MS and GC-FID). Acorenone B was identified by GC-MS and NMR experiments. The enantiomeric distribution of some constituents has been assessed by enantio-GC through the use of a chiral cyclodextrin-based capillary column. We identified 41 components that accounted for 96.46% of the total analyzed, the major components were acorenone B (41.01%) and (E)-β-ocimene (29.64%). The enantiomeric ratio of (+)/(−)-β-pinene was 86.9:13.1, while the one of (+)/(−)-sabinene was 80.9:19.1. The essential oil showed a weak inhibitory activity, expressed as Minimal Inhibitory Concentration (MIC), against Enterococcus faecalis (MIC 10 mg/mL) and Staphylococcus aureus (MIC 5 mg/mL). Furthermore, it inhibited butyrylcholinesterase with an IC₅₀ value of 11.5 μg/mL. Pure acorenone B showed inhibitory activity against both acetylcholinesterase and butyrylcholinesterase, with IC₅₀ values of 40.8 μg/mL and 10.9 μg/mL, respectively.

An Efficient Synthesis of bi-Aryl Pyrimidine Heterocycles: Potential New Drug Candidates to Treat Alzheimer's Disease

A series of 13 novel pyrimidine-based sulfonamides 6a-m were synthesized in short periods of time under microwave conditions in good to excellent yield (54-86%). The chemical structures of these heterocycles consist of a central pyrimidine ring having a phenyl group and pyrimidine groups with sulfonamide motifs. The enzyme inhibitory potential of these compounds was investigated against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) because these enzymes play a crucial role in the treatment of Alzheimer's disease. As compared to the reference compound eserine (IC₅₀  = 0.04 ± 0.0001 μM for AChE and IC₅₀  = 0.85 ± 0.0001 μM for BChE), the IC₅₀ values of the synthesized compounds ranged from 3.73 ± 0.61 μM to 57.36 ± 0.22 μM for AChE and 4.81 ± 0.16 μM to 111.61 ± 0.53 μM for BChE. Among these tested compounds, 6j having a -CH₃ group was found to be the most potent one against both enzymes (AChE, IC₅₀  = 3.73 ± 0.61 μM; BChE, IC₅₀  = 4.81 ± 0.16 μM). Quantitative structure-activity relationship (QSAR) and molecular docking studies of the synthesized compounds were also performed.