Rapid screening of acetylcholinesterase active contaminants in water: A solid phase microextraction-based ligand fishing approach

Effect-directed analysis (EDA) has been increasingly used for screening toxic contaminants in the environment, but conventional EDA procedures are often time-consuming and labor-extensive. This challenges the use of EDA for toxicant identification in the scenarios when quick answers are demanded. Herein, a solid phase microextraction ligand fishing (SPME-LF) strategy has been proposed as a rapid EDA approach for identifying acetylcholinesterase (AChE) active compounds in water. The feasibility of ligand fishing techniques for screening AChE active chemicals from environmental mixtures was first verified by a membrane separation method. Then, SPME fibers were prepared through self-assembly of boronic acid groups with AChE via co-bonding and applied for SPME-LF. As AChE coated SPME fibers selectively enriched AChE-active compounds from water, comparing sorbing compounds by the SPME fibers with and without AChE coating can quickly distinguish AChE toxicants in mixtures. Compared with conventional EDA, SPME-LF does not require repeating sample separations and bioassays, endowing SPME-LF with the merits of low-cost, labor-saving, and user-friendly. It is believed that cost-efficient and easy-to-use SPME-LF strategy can potentially be a rapid EDA method for screening receptor-specific toxicants in aquatic environment, especially applicable in time-sensitive screening.

Nanoplasmonic biosensors for multicolor visual analysis of acetylcholinesterase activity and drug inhibitor screening in point-of-care testing

The monitoring of acetylcholinesterase (AChE) activity and the screening of its inhibitors are significance of the diagnosis and drug therapy of nervous diseases. A metal ions-mediated signal amplification strategy was developed for the highly sensitive and multicolor assay of AChE activity and visually screening its drug inhibitors. After the specific reaction between AChE and acetylthiocholine (ATCh), the hydrolysis product thiocholine (TCh) can directly and decompose the α-FeOOH nanorods (NRs) to release amounts of Fe2+, which was regarded as Fenton reagent to efficiently catalyze H2O2 to produce ·OH. Then, the as-formed ·OH can further largely shorten the gold nanobipyramids (Au NBPs), generating a series of palpable color variations. The linear range for AChE activity was 0.01-500.0 U/L with the limit of detection as low as 0.0074 U/L. The vivid visual effects could be easily distinguished for the multicolor assay of AChE activity by naked eye in visible light. To achieve the point-of-care testing, Au NBPs were further assembled on polymeric electrospun nanofibrous films (ENFs) surface as test strips for the easy-to-use test of AChE activity by RGB values with a smartphone. Fascinatingly, this proposed strategy can be used for the visual screening AChE inhibitors or non-inhibitors. Comparing with the clinical drugs (rivastigmine tartrate, and donepezil), some natural alkaloids such as evodiamine, caffeine, camptothecin, and berberine hydrochloride were selected as inhibitor modes to confirm the drug screening capability of this method. This proposed strategy may have great potential in the other disease-related enzymatic biomarkers assay and the rapid screening of drug therapy.

Composition and Anti-Acetylcholinesterase Properties of the Essential Oil of the Ecuadorian Endemic Species Eugenia valvata McVaugh

Alzheimer's disease is a global health problem due to the scarcity of acetylcholinesterase inhibitors, the basis for symptomatic treatment of this disease; this requires new approaches to drug discovery. In this study, we investigated the chemical composition and anticholinesterase activity of Eugenia valvata McVaugt (Myrtaceae) collected in southern Ecuador, which was obtained as an essential oil (EO) with a yield of 0.124 ± 0.03% (w/w); as a result of the chemical composition analysis, a total of 58 organic compounds were identified-representing 95.91% of the total volatile compounds-using a stationary phase based on 5% phenyl-methylpolysiloxane, as analyzed via gas chromatography coupled to mass spectrometry (GC-MS) and flame ionization detection (GC-FID). The main groups were hydrocarbon sesquiterpenes (37.43%), oxygenated sesquiterpenes (31.08%), hydrocarbon monoterpenes (24.14%), oxygenated monoterpenes (0.20%), and other compounds (3.058%). Samples were characterized by the following compounds: α-pinene (22.70%), α-humulene (17.20%), (E)-caryophyllene (6.02%), citronellyl pentanoate (5.76%), 7-epi-α-eudesmol (4.34%) and 5-iso-cedranol (3.64%); this research was complemented with an enantioselective analysis carried out using 2,3-diethyl-6-tert-butyldimethylsilyl-β-cyclodextrin as a stationary phase chiral selector. As a result, α-pinene, limonene, and α-cadinene enantiomers were identified; finally, in the search for new active principles, the EO reported strong anticholinesterase activity with an IC50 of 53.08 ± 1.13 µg/mL, making it a promising candidate for future studies of Alzheimer's disease.

In Vitro Antibacterial, Antioxidant, Anticholinesterase, and Antidiabetic Activities and Chemical Composition of Salvia balansae

CONTEXT

Salvia balansae de Noé (S. balansae) (Lamiaceae) is known to be an important plant used in folk medicine as an herbal remedy in Algeria.

OBJECTIVE

The purpose of the present study was to demonstrate the phytochemical composition, antioxidant activities, enzyme inhibitory activities, and antimicrobial activities of S. balansae extracts.

MATERIALS AND METHODS

A methanolic extract and a petroleum ether extract from the aerial parts of the plant were assessed for their chemical composition. HPLC-MS and HPLC-DAD assessed the content of phenols, GC-MS the fatty acid composition, and ICP-MS the mineral profiles of the plant. Additionally, we evaluated the bioactivities of S. balansae extracts by the DPPH, ABTS, and CUPRAC assays, including the antioxidant potential against AChE, BChE, α-amylase, and α-glucosidase for enzyme inhibition. The antibacterial and antifungal activities of the methanolic extract were determined by the disc diffusion test against several strains of bacteria and yeasts.

RESULTS

Our findings revealed that the aerial parts of S. balansae were rich in phytochemical components and contained large amounts of minerals. Quantitative analysis of phenolic compounds by HPLC-DAD revealed the presence of 12 compounds in three major classes, flavonoids, hydroxycinnamic acid, and phenolic acid derivatives, with 0.61, 0.45, and 0.29 mg/g of extract, respectively. Nine phenolic constituents were quantified by HPLC-MS analysis; catechin (72.5%) was the main compound, followed by myricetin (21.7%). The fatty acid composition of the S. balansae petroleum ether extract by GC-MS analysis was quantified. Seventeen compounds, including palmitic acid, were identified as the major fatty acids. The antioxidant activity of the S. balansae extracts was measured by three different methods: the methanol extract provided better results than the petroleum ether extract, and interesting values were noted for the DPPH, ABTS, and CUPRAC assays of 242.7 ± 7.44, 124.1 ± 9.70, and 222.9 ± 6.05 µg/mL, respectively. The enzyme inhibition activity of the plant could not be determined. The antimicrobial results of the methanolic extract obtained from the disc diffusion method, followed by measurements of MIC, MBC, and MFC against several bacteria and yeasts, indicated that S. balansae exhibited noticeable antimicrobial and antifungal activities.

CONCLUSIONS

These results provided new data about the main phenolic compounds and biological activities of extracts of the aerial parts of S. balansae, which might be an alternative source for synthetic bioactive compounds.

Efficient Combination of Complex Chromatography, Molecular Docking and Enzyme Kinetics for Exploration of Acetylcholinesterase Inhibitors from Poria cocos

Poria cocos (P. cocos) is a traditional Chinese medicinal product with the same origin as medicine and food. It has diuretic, anti-inflammatory and liver protection properties, and has been widely used in a Chinese medicine in the treatment of Alzheimer's disease (AD). This study was conducted to explore the activity screening, isolation of acetylcholinesterase inhibitors (AChEIs), and in vitro inhibiting effect of P. cocos. The aim was to develop a new extraction process optimization method based on the Matlab genetic algorithm combined with a traditional orthogonal experiment. Moreover, bio-affinity ultrafiltration combined with molecular docking was used to screen and evaluate the activity of the AChEIs, which were subsequently isolated and purified using high-speed counter-current chromatography (HSCCC) and semi-preparative high-performance liquid chromatography (semi-preparative HPLC). The change in acetylcholinesterase (AChE) activity was tested using an enzymatic reaction kinetics experiment to reflect the inhibitory effect of active compounds on AChE and explore its mechanism of action. Five potential AChEIs were screened via bio-affinity ultrafiltration. Molecular docking results showed that they had good binding affinity for the active site of AChE. Meanwhile, the five active compounds had reversible inhibitory effects on AChE: Polyporenic acid C and Tumulosic acid were non-competitive inhibitors; 3-Epidehydrotumulosic acid was a mixed inhibitor; and Pachymic acid and Dehydrotrametenolic acid were competitive inhibitors. This study provided a basis for the comprehensive utilization of P. cocos and drug development for the treatment of AD.

In-vitro antioxidant potential and acetylcholinesterase inhibitory effect of Ficus benghalensis aerial root extract

Aim and objective: The aim of the current study was to evaluate the antioxidant effect, acetylcholinesterase (AChE) inhibitory effect and phytochemical screening of different extracts of aerial root extract of Ficus benghalensis using in-vitro methods. Methods: The aerial root extract was prepared by successive extraction method using different organic solvents having increasing order of polarity. FB aerial root extract was screened for preliminary phytochemical analysis. FB aerial root extracts were evaluated for in-vitro acetylcholinesterase inhibitory effect by the Ellman’s method and anti-oxidant potential by DPPH assay and hydroxyl radical neutralizing assay. Results: Preliminary phytochemical screening of FB extracts indicate the existence of the phytochemicals such as phenols, alkaloids, flavonoids, glycosides, anthraquinones, tannins and steroids. The results of the DPPH assay, hydroxyl radical scavenging assay and AChE inhibitory assay show that chloroform and ethyl acetate extracts are having significant antioxidant activity and acetylcholinesterase inhibitory effect as compared to the other extracts, respectively. Conclusion: The results of the current study suggest that the aerial root extract of FB might be a potential drug source for treatment of neurodegenerative disorders like Alzheimer disease. Keywords: Ficus benghalensis; antioxidant; DPPH; acetylcholinesterase; neurodegenerative disorder.

High-performance thin-layer chromatography in combination with an acetylcholinesterase-inhibition bioassay with pre-oxidation of organothiophosphates to determine neurotoxic effects in storm, waste, and surface water

Pesticides such as organothiophosphates (OTPs) are neurotoxically active and enter the aquatic environment. Bioassays, using acetylcholinesterase (AChE), a suitable substrate and reactant, can be applied for the photometric detection of AChE-inhibiton (AChE-I) effects. The oxidized forms of OTPs, so-called oxons, have higher inhibition potentials for AChE. Therefore, a higher sensitivity is achieved for application of oxidized samples to the AChE assay. In this study, the oxidation of malathion, parathion, and chlorpyrifos by n-bromosuccinimide (NBS) was investigated in an approach combining high-performance thin-layer chromatography (HPTLC) with an AChE-I assay. Two AChE application approaches, immersion and spraying, were compared regarding sensitivity, precision, and general feasibility of the OTP effect detection. The oxidation by NBS led to an activation of the OTPs and a strong increase in sensitivity similar to the oxons tested. The sensitivity and precision of the two application techniques were similar, although the spray method was slightly more sensitive to the oxidized OTPs. The 10% inhibition concentrations (IC10) for the spray approach were 0.26, 0.75, and 0.35 ng/spot for activated malathion, parathion, and chlorpyrifos, respectively. AChE-I effect recoveries in samples from a stormwater retention basin and receiving stream were between 69 and 92% for malathion, parathion, and chlorpyrifos. The overall workflow, including sample enrichment by solid-phase extraction, HPTLC, oxidation of OTPs, and AChE-I assay, was demonstrated to be suitable for the detection of AChE-I effects in native water samples. An effect of unknown origin was found in a sample from a stormwater retention basin.

A critical comparison between an ultra-high-performance liquid chromatography triple quadrupole mass spectrometry (UHPLC-QqQ-MS) method and an enzyme assay for anti-cholinesterase pesticide residue detection in cereal matrices

Analytical method development for the control of pesticide residues occurring in significant dietary foodstuffs is of utmost importance considering their potential impact on consumer health and food market sustainability. Depending on the purpose, either instrumental analysis, mainly chromatographic methods, or screening assays, mostly using biorecognition affinity, are commonly used, featuring different advantages and drawbacks. To practically compare these two different types of analytical strategies, we applied them for the detection of (i) 97 organophosphate (OP) and carbamate (CM) pesticide residues in wheat flour and (ii) carbofuran (a carbamate insecticide) in wheat, rye and maize flour samples. Regarding high-end analysis, an ultra-high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC-QqQ-MS) method was developed and validated achieving low limits of quantification (LOQs, from 0.002 to 0.040 mg kg^-1) and a short chromatographic run (12 min). In terms of bioanalytical methods, a fast (17 min) and cost-efficient (∼0.01€ per sample) acetylcholinesterase (AChE) microplate assay for carbofuran screening was utilized. Importantly, carbofuran was the strongest of the 11 OP and CM tested pesticides achieving a half maximal inhibitory concentration (IC₅₀) of 0.021 μM whilst the assay detectability was at the parts per billion level in all three cereal matrices. Based on the attained results, a critical discussion is presented providing the analytical merits and bottlenecks for each case and a wider outlook related to the application of analytical methods in the food safety control analytical scheme.

UPLC-PDA-ESI-QTOF-MS/MS fingerprint of purified flavonoid enriched fraction of Bryophyllum pinnatum; antioxidant properties, anticholinesterase activity and in silico studies

CONTEXT

Bryophyllum pinnatum (Lam.) Oken (Crassulaceae) is used traditionally to treat many ailments.

OBJECTIVES

This study characterizes the constituents of B. pinnatum flavonoid-rich fraction (BPFRF) and investigates their antioxidant and anticholinesterase activity using in vitro and in silico approaches.

MATERIALS AND METHODS

Methanol extract of B. pinnatum leaves was partitioned to yield the ethyl acetate fraction. BPFRF was isolated from the ethyl acetate fraction and purified. The constituent flavonoids were structurally characterized using UPLC-PDA-MS². Antioxidant activity (DPPH), Fe²⁺-induced lipid peroxidation (LP) and anticholinesterase activity (Ellman's method) of the BPFRF and standards (ascorbic acid and rivastigmine) across a concentration range of 3.125-100 μg/mL were evaluated in vitro for 4 months. Molecular docking was performed to give insight into the binding potentials of BPFRF constituents against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE).

RESULTS

UPLC-PDA-MS² analysis of BPFRF identified carlinoside, quercetin (most dominant), luteolin, isorhamnetin, luteolin-7-glucoside. Carlinoside was first reported in this plant. BPFRF significantly inhibited DPPH radical (IC₅₀ = 7.382 ± 0.79 µg/mL) and LP (IC₅₀ = 7.182 ± 0.60 µg/mL) better than quercetin and ascorbic acid. Also, BPFRF exhibited potent inhibition against AChE and BuChE with IC₅₀ values of 22.283 ± 0.27 µg/mL and 33.437 ± 1.46 µg/mL, respectively compared to quercetin and rivastigmine. Docking studies revealed that luteolin-7-glucoside, carlinoside and quercetin interact effectively with crucial amino acid residues of AChE and BuChE through hydrogen bonds.

DISCUSSION AND CONCLUSIONS

BPFRF possesses an excellent natural source of cholinesterase inhibitor and antioxidant. The material could be further explored for the potential treatment of oxidative damage and cholinergic dysfunction in Alzheimer's disease.

Electrochemical Biosensor for Markers of Neurological Esterase Inhibition

A novel, integrated experimental and modeling framework was applied to an inhibition-based bi-enzyme (IBE) electrochemical biosensor to detect acetylcholinesterase (AChE) inhibitors that may trigger neurological diseases. The biosensor was fabricated by co-immobilizing AChE and tyrosinase (Tyr) on the gold working electrode of a screen-printed electrode (SPE) array. The reaction chemistry included a redox-recycle amplification mechanism to improve the biosensor's current output and sensitivity. A mechanistic mathematical model of the biosensor was used to simulate key diffusion and reaction steps, including diffusion of AChE's reactant (phenylacetate) and inhibitor, the reaction kinetics of the two enzymes, and electrochemical reaction kinetics at the SPE's working electrode. The model was validated by showing that it could reproduce a steady-state biosensor current as a function of the inhibitor (PMSF) concentration and unsteady-state dynamics of the biosensor current following the addition of a reactant (phenylacetate) and inhibitor phenylmethylsulfonylfluoride). The model's utility for characterizing and optimizing biosensor performance was then demonstrated. It was used to calculate the sensitivity of the biosensor's current output and the redox-recycle amplification factor as a function of experimental variables. It was used to calculate dimensionless Damkohler numbers and current-control coefficients that indicated the degree to which individual diffusion and reaction steps limited the biosensor's output current. Finally, the model's utility in designing IBE biosensors and operating conditions that achieve specific performance criteria was discussed.

Colorimetric detection of acetylcholinesterase and its inhibitor based on thiol-regulated oxidase-like activity of 2D palladium square nanoplates on reduced graphene oxide

A convenient and sensitive colorimetric assay for acetylcholinesterase (AChE) and its inhibitor has been designed based on the oxidase-like activity of {100}-faceted Pd square nanoplates which are grown in situ on reduced graphene oxide (PdSP@rGO). PdSP@rGO can effectively catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) without the assistance of H₂O₂ to generate blue oxidized TMB (oxTMB) with a characteristic absorption peak at 652 nm. In the presence of AChE, acetylthiocholine (ATCh), a typical AChE substrate, is hydrolyzed to thiocholine (TCh). The generated TCh can effectively inhibit the PdSP@rGO-triggered chromogenic reaction of TMB via cheating with Pd, resulting in color fading and decrease in absorbance. Thus, a sensitive probe for AChE activity is constructed with a working range of 0.25-5 mU mL^-1 and  a limit of detection (LOD) of 0.0625 mU mL^-1. Furthermore, because of the inhibition effect of tacrine on AChE, tacrine is also detected through the colorimetric AChE assay system within the concentrations range 0.025-0.4 μM with a LOD of 0.00229 μM. Hence, a rapid and facile colorimetric procedure to sensitively detect AChE and its inhibitor can be anticipated through modulating the oxidase-like activity of PdSP@rGO. Colorimetric method for detection of AChE and its inhibitor is established by modulating the oxidase mimetic activity of {100}-faceted Pd square nanoplates on reduced graphene oxide (PdSP@rGO).

Functional characterisation and sensory evaluation of a novel synbiotic okara beverage

This study aimed to produce four different beverages from okara (soybean by-product) previously hydrolyzed by Cynara cardunculus enzymes and fermented by probiotic bacteria or unfermented beverage. The probiotic viable cells, the isoflavones profile and organic acids were evaluated in the okara beverage. In addition, total phenolic content, antioxidant and ACE inhibitory activities were evaluated at storage time and during in vitro gastrointestinal digestion of all beverages. The probiotic was viable throughout storage in all fermented beverages. The significant bioconversion of the isoflavone glycosides into their corresponding bioactive aglycones was observed in fermented beverage. Furthermore, the beverages showed a good ACE inhibitory activity. After gastrointestinal tract, all beverages showed an increase in the antioxidant and ACE inhibitory activities. In conclusion, this study shows that the application of okara for a multifunctional beverage could be a promising strategy in the disease prevention and contribution to a zero waste approach in food industry.

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).

Qualitative enzymatic detection of organophosphate and carbamate insecticides

In this study, new polymers containing amides (TrisPS-Ntaa, and TrisPS-Ntaa-Fc) were synthesized by condensation reaction for qualitative identification of insecticides. The synthesized polymers, including amides were investigated by infrared spectroscopy (IR), scanning electron microscopy-energy dispersion X- ray spectrometry (SEM-EDX), and gel permeation chromatography (GPC). Then, acetylcholinesterase enzyme (AChE) was covalently immobilized on these polymers to improve properties (including activity, reusability, and storage stability). Accordingly, organophosphate (malathion, acephate, chlorpyrifos methyl) and carbamate (carbofuran, methiocarb, methomyl), which are used to prevent harmful organisms in some agricultural products were enzymatically determined based on their inhibitory activity on AChE.

An Overview on the Mechanisms and Applications of Enzyme Inhibition-Based Methods for Determination of Organophosphate and Carbamate Pesticides

Acetylcholinesterase inactivating compounds, such as organophosphate (OP) and carbamate (CM) pesticides, are widely used in agriculture to ensure sustainable production of food and feed. As a consequence of their applications, they would result in neurotoxicity, even death. In this essence, the development of enzyme inhibition methods still shows great significance as rapid detection techniques for on-site large-scale screening of OPs and CMs. Initially, mechanisms and applications of various enzyme-inhibition-based methods and devices, including optical colorimetric assay, fluorometric assays, electrochemical biosensors, rapid test card, and microfluidic device, are highlighted in the present overview. Further, to enhance the enzyme sensitivity for detection; alternative enzyme sources or high yield enrichment methods (such as abzyme, artificial enzyme, and recombinant enzyme), as well as enzyme reactivation and identification, are also addressed in this comprehensive overview.

Efficient identification of Acetylcholinesterase and Hyaluronidase inhibitors from Paeonia parnassica extracts through a HeteroCovariance Approach

ETHNOPHARMACOLOGICAL RELEVANCE

On the basis of the relevant reference in the poem Theriaca of the ancient Greek physician Nicander and its traditional use, Paeonia parnassica was selected for the evaluation of two extracts obtained from the roots and aerial parts to inhibit hydrolytic enzymes involved in snake envenomation. The secondary metabolites which contribute to these activities were detected through a novel HeteroCovariance NMR based approach. Afterwards these ingredients were isolated, identified and evaluated for their inhibitory potency.

AIM OF THE STUDY

The identification of acetylcholinesterase and hyaluronidase inhibitors from Paeonia parnassica extracts was used as a case study for the introduction of a recently developed methodology to evaluate ethnopharmacological data and exploit them for the discovery of bioactive natural compounds. This process is based on the fractionation of the selected extracts and the simultaneous phytochemical analysis and biological assessment of the resulting fractions, which permits the rapid detection of the specified secondary metabolites prior to any laborious and time-consuming purification.

MATERIALS AND METHODS

The roots and aerial parts of P. parnassica were extracted using methanol: water 50:50 and the two resulted extracts were fractionated by Centrifugal Partition Chromatography. The obtained fractions were evaluated in-vitro for their ability to inhibit acetylcholinesterase and hyaluronidase enzymes and their ¹H NMR spectra were recorded. The biological activity was statistically correlated with the spectral data through the HeteroCovariance Approach (HetCA). Finally the purification, identification and biological evaluation of targeted secondary metabolites were carried out.

RESULTS

The general chemical structures and some explicit secondary metabolites which contribute (e.g. gallotannins, gallic acid derivatives) or not (characteristic "cage-like" monoterpenes of the genus, glycosylated flavonoids) to the anti-acetylcholinesterase and anti-hyaluronidase activities were detected through HetCA. The consequent isolation and biological evaluation of targeted compounds were performed in order to validate the effectiveness and precision of the methodology. This procedure revealed the most active ingredients of both extracts obtained from roots and aerial parts against the above mentioned biological targets, as well as other compounds possessing moderate activity.

CONCLUSIONS

The results of this study contributed to the verification of the ancient text Theriaca regarding the use of Paeonia parnassica to treat the snake bite symptoms. Furthermore, the ingredients of the Paeonia parnassica extracts, which were responsible for their anti-cholinesterase and anti-hyaluronidase activities, were determined applying a HetCA methodology before their isolation. Therefore, the current work provides clear evidence that HetCA could consist an efficient tool for the exploitation of traditional medicine information in order to discover bioactive natural compounds and develop new pharmacotherapies which serve the needs of contemporary medicine.

Walnut (Juglans regia L.) Septum: Assessment of Bioactive Molecules and In Vitro Biological Effects

Walnut (Juglans regia L.) septum represents an interesting bioactive compound source by-product. In our study, a rich phenolic walnut septum extract, previously selected, was further examined. The tocopherol content determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed higher amounts of α-tocopherol compared to γ- and δ-tocopherols. Moreover, several biological activities were investigated. The in vitro inhibiting assessment against acetylcholinesterase, α-glucosidase, or lipase attested a real management potential in diabetes or obesity. The extract demonstrated very strong antimicrobial potential against Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella enteritidis. It also revealed moderate (36.08%) and strong (43.27%) antimutagenic inhibitory effects against TA 98 and TA 100 strains. The cytotoxicity of the extract was assessed on cancerous (A549, T47D-KBluc, MCF-7) and normal (human gingival fibroblasts (HGF)) cell lines. Flow cytometry measurements confirmed the cytotoxicity of the extract in the cancerous cell lines. Additionally, the extract demonstrated antioxidant activity on all four cell types, as well as anti-inflammatory activity by lowering the inflammatory cytokines (interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-1 β (IL-1β)) evaluated in HGF cells. To the best of our knowledge, most of the cellular model analyses were performed for the first time in this matrix. The results prove that walnut septum may be a potential phytochemical source for pharmaceutical and food industry.

An Acetylcholinesterase Inhibition-Based Biosensor for Aflatoxin B1 Detection Using Sodium Alginate as an Immobilization Matrix

In this study, we investigated a novel aflatoxin biosensor based on acetylcholinesterase (AChE) inhibition by aflatoxin B1 (AFB1) and developed electrochemical biosensors based on a sodium alginate biopolymer as a new matrix for acetylcholinesterase immobilization. Electrochemical impedance spectroscopy was performed as a convenient transduction method to evaluate the AChE activity through the oxidation of the metabolic product, thiocholine. Satisfactory analytical performances in terms of high sensitivity, good repeatability, and long-term storage stability were obtained with a linear dynamic range from 0.1 to 100 ng/mL and a low detection limit of 0.1 ng/mL, which is below the recommended level of AFB1 (2 µg/L). The suitability of the proposed method was evaluated using the samples of rice supplemented with AFB1 (0.5 ng/mL). The selectivity of the AChE-biosensor for aflatoxins relative to other sets of toxic substances (OTA, AFM 1) was also investigated.

Promoting Active Sites in MOF-Derived Homobimetallic Hollow Nanocages as a High-Performance Multifunctional Nanozyme Catalyst for Biosensing and Organic Pollutant Degradation

Nanozymes are one of the ideal alternatives to natural enzymes for various applications. The rational design of nanozymes with improved catalytic activity stimulates increasing attention to address the low activity of current nanozymes. Here, we reported a general strategy to fabricate the Co-based homobimetallic hollow nanocages (HNCs) (C-CoM-HNC, M = Ni, Mn, Cu, and Zn) by ion-assistant solvothermal reaction and subsequent low-temperature calcination from metal-organic frameworks. The C-CoM-HNCs are featured with HNCs composed of interlaced nanosheets with homogeneous bimetallic oxide dispersion. The hierarchical structure and secondary metallic doping endow the C-CoM-HNC highly active sites. In particular, the Cu-doped C-CoCu-HNCs nanostructures exhibit superior performances over the other C-CoM-HNC as both the oxidase mimicking and peroxymonosulfate (PMS) activator. A sensitive bioassay for acetylcholinesterase (AChE) was established based on the excellent oxidase-like activity of C-CoCu-HNC, offering a linear detection range from 0.0001 to 1 mU/mL with an ultralow detection limit of 0.1 mU/L. As the PMS activator, the C-CoCu-HNC was applied for targeted organic pollutant (rhodamine B, RhB) degradation. A highly efficient RhB degradation was realized, along with good adaptability in a wide pH range and good reusability during the eight-cycle run. The results suggest that C-CoCu-HNC holds a practical potential for clinical diagnostics and pollution removal. Further density functional theory calculation reveals that Cu doping leads to a tighter connection and more negative adsorption energy for O₂/PMS, as well as an upshifted d-band center in the C-CoCu-HNCs nanostructures. These changes facilitated the adsorption of O₂/PMS on the C-CoCu-HNC surface for dissociation. This work not only offers a promising multifunctional nanozyme catalyst for clinical diagnostics and pollution removal but also gives some clues for the further development of novel nanozymes with high catalytic activities.

Colorimetric assay of acetylcholinesterase inhibitor tacrine based on MoO2 nanoparticles as peroxidase mimetics

Molybdenum dichalcogenides MoX₂ (X=S, Se) have been found to possess intrinsic peroxidase-like activity. However, molybdenum oxides (MoO₂) as peroxidase mimetics have not been exploited yet. Herein, MoO₂ nanoparticles were synthesized by a simple hydrothermal method and found to possess the peroxidase-like activity for the first time. MoO₂ nanoparticles could catalyze the oxidation of 3,3',5,5'-tetrametylbenzidine (TMB) by H₂O₂ to produce a blue-color product (oxTMB). The catalytic property and mechanism were investigated by stead-state kinetics experiment and free radicals scavenging experiment, respectively. Acetylcholinesterase (AChE) could catalyze the hydrolysis of acetylthiocholine chloride (ATCh) into thiocholine (TCh), which could reduce oxTMB to decrease the absorbance in solution. In the presence of AChE inhibitor tacrine, the generation of TCh was inhibited and the absorbance was preserved. Based on these properties, a colorimetric assay method was developed for AChE inhibitor tacrine. This work not only broadens the application of the peroxidase mimetics, but also overcome the disadvantages of traditional methods such as expensive, complex and vulnerable to background interference for colorimetric assay of AChE inhibitor.

Simple Colorimetric Method for Cholinesterase-inhibitor Screening in Gastric Content by Using Phytoesterase Enzyme from Kidney Bean

BACKGROUND AND OBJECTIVE

Diagnosis of cholinesterase inhibitor insecticide ingestion is based on clinical suspicious and should be confirmed by cholinesterase essay. However, serum cholinesterase activity test requires specific instruments and procedure. This study aimed to develop simple colorimetric test to detect cholinesterase inhibitors in the gastric content, using phytoesterase and alpha naphthyl acetate as a chromogenic substrate.

MATERIALS AND METHODS

Methomyl and chlorpyrifos were selected for the phytoesterase enzyme inhibition assay. The experiment was conducted using pooled insecticide-free gastric content sample from ten cadavers. The gastric content samples were prepared by simple filtration procedure or liquid-liquid extraction procedure with dichloromethane or ethyl acetate. The inhibitor concentrations measured by the developed phytoesterase enzyme inhibition assay were compared with those analyzed by the LC-MS/MS and the GC-FPD.

RESULTS

Different sample preparation procedures, sensitivity and specificity and specificity of the test were investigated. Sample extracted with dichloromethane reduced the effect of matrix in gastric content as same as ethyl acetate. The developed color test method of detection showed 56.52% sensitivity and 100% specificity for methomyl, 100% sensitivity and 96.30% specificity for chlorpyrifos. The limit of detection of the assay was 422.6 ng mL-1 for methomyl and was 339.8 ng mL-1 for chlorpyrifos.

CONCLUSION

This developed method could be used an alternative diagnostic test for methomyl and chlorpyrifos self-ingestion.

Detection and identification of acetylcholinesterase inhibitors in Annona cherimola Mill. by effect-directed analysis using thin-layer chromatography-bioassay-mass spectrometry

INTRODUCTION

Acetylcholinesterase (AChE) inhibitors are considered an important strategy in the treatment of neurological disorders such as Alzheimer's disease. A simple and fast planar chromatography-bioassay methodology has been established to detect bioactive molecules in cherimoya fruit.

OBJECTIVE

Detect and identify AChE inhibitors in cherimoya by high-performance thin-layer chromatography (HPTLC)-bioassay-mass spectrometry (MS) and related techniques.

METHODOLOGY

Effect-directed analysis by planar chromatography-bioassay-mass spectrometry was applied to detect and identify AChE inhibitors in pulp, peel and cherimoya seed. Bioassay was optimised establishing the following conditions: enzymatic solution (1.0 U mL^-1 ), 1-naphtyl acetate substrate (1.5 mg mL^-1 ) and Fast Blue B salt (1.0 mg mL^-1 ). TLC-MS interface was used to directly elute the active zones into a mass spectrometer or to a micro-vial for further off-line studies.

RESULTS

Two AChE inhibitory bands were detected in peel extracts. An analysis via HPTLC-MS and high-performance liquid chromatography diode array detector tandem mass spectrometry (HPLC-DAD-MS/MS) allowed to characterise three potential AChE inhibitors: anonaine (m/z 266 [M + H]⁺ ; UV λ_max = 269.6 nm), glaucine (m/z 256 [M + H]⁺ ; UV λ_max = 282.9 and 300.6 nm) and xylopine (m/z 296 [M + H]⁺ ; UV λ_max = 278.5 nm).

CONCLUSIONS

The application of this optimised high throughput method allowed to establish the presence of three potential AChE inhibitors in cherimoya peel. For the first time AChE inhibitory capacity of these alkaloids is reported.

Capillary electrophoresis-immobilized enzyme microreactors for acetylcholinesterase assay with surface modification by highly-homogeneous microporous layer

We propose a new capillary electrophoresis (CE)-based open-tubular immobilized enzyme microreactor (OT-IMER) and its application in acetylcholinesterase (AChE) assays. The IMER is fabricated at the capillary inlet (reactor length of ∼1 cm) with the inner surface modified by a micropore-structured layer (thickness of ∼220 nm, pore size of ∼15-20 nm). The use of IMER accomplishes the enzymatic reaction and separation/detection of the products in the same capillary within 3 min. The feasibility of the proposed method is evaluated via online analysis of the activity and inhibition of AChE enzymes. Such method exhibits good reproducibility with relative standard deviation (RSD) of less than 4% for 20 runs, and the enzyme remains over 82% of the initial activity after usage of 7 days. The IMERs are successfully applied to detect the organophosphorus pesticide, paraoxon, in three types of vegetable juice samples with a limit of detection of as low as 61 ng mL^-1. Results show that the spiked samples are in the range of 89.6-105.9% with RSD less than 2.7%, thereby indicating its satisfactory level of accurate and reliable analysis of real samples by using the proposed method. Our study indicates that, with combination of advantages of both porous-layer capillary and CE OT-IMER, the proposed method is capable to enhance enzymatic reactions and to achieve rapid analysis with simple instrumentation and operation, thus would pave the way for extensive application of CE-based IMERs in a variety of bioanalysis.

A Luminescence Turn-On Assay for Acetylcholinesterase Activity and Inhibitor Screening Based on Supramolecular Self-Assembly of Alkynylplatinum(II) Complexes on Coordination Polymer

A new approach toward acetylcholinesterase (AChE) detection has been demonstrated based on the electrostatic interactions between anionic alkynylplatinum(II) complex molecules and cationic coordination polymer, together with the spectroscopic and emission characteristics of alkynylplatinum(II) complexes upon supramolecular self-assembly. This process involves strengthening of distinct noncovalent Pt(II)···Pt(II) and π-π stacking interactions, which is evidenced by UV-vis absorption, emission, and resonance light scattering results. Such a method has been applied to AChE inhibitor screening, which is important as the demand for AChE inhibitor assays arises along with the drug development for Alzheimer's disease. It affords an emission turn-on response and operates in a continuous and label-free fashion. The low-energy red emission and large Stokes shift of alkynylplatinum(II) complexes are advantageous to biological applications.

Screening and determination for potential acetylcholinesterase inhibitory constituents from ginseng stem-leaf saponins using ultrafiltration (UF)-LC-ESI-MS2

INTRODUCTION

Previous studies have demonstrated that several ginsenosides have remarkable inhibitory effect on acetylcholinesterase (AChE). In the present study, ginseng stem-leaf saponins (GSLS) can improve learning and memory of Alzheimer's disease patients. However, much comprehensive information regarding AChE inhibition of GSLS and its metabolites is yet unknown.

OBJECTIVE

The present study aims to screen and determine the potential of AChE inhibitors (AChEIs) from GSLS.

METHODOLOGY

The active fraction of the GSLS detected in vitro AChE inhibition assays was selected as a starting material for the screening of the potential of AChEIs using ultrafiltration liquid chromatography coupled to electrospray ionisation tandem mass spectrometry (UF-LC-ESI-MS² ).

RESULTS

The results showed that 31 ginsenosides were identified with analysis using rapid resolution liquid chromatography with a diode array detector combined with electrospray ionisation tandem mass spectrometry (RRLC-DAD-ESI-MS² ) from the active fraction, and there are 27 compounds with AChE binding activity. Among them, 11 ginsenosides were evaluated and confirmed using in vitro enzymatic assay, and ginsenosides F₁ , Rd, Rk₃ , 20(S)-Rg₃ , F₂ and Rb₂ were found to possess strong AChE inhibitory activities.

CONCLUSION

The proposed UF-LC-ESI-MS² method was a powerful tool for the discovery of AChEIs from traditional Chinese medicine (TCM).

Dual-Channel Enzymatic Inhibition Measurement (DEIM) Coupling Isotope Substrate via Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry

A novel dual-channel enzymatic inhibition measurement (DEIM) method was developed to improve the repeatability with light/heavy isotope substrates, producing reliable relative standard deviations (< 3%) by employing acetylcholinesterase (AChE) as the model enzyme. The matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) was adapted for enzyme-inhibited method due to its good salt-tolerance and high throughput; meanwhile, dual-channel enzymatic reactions were performed to improve the repeatability of each well. The acetylcholinesterase inhibition measurement was conducted by mixing the quenched enzyme reaction solution of blank group (with heavy isotope as substrate) and experimental group (with light isotope as substrate), of which the inhibition rate might be affected by isotope effects. Hence, inverse study and Km measurement were implemented to validate the method. The inverse study shows similar inhibition rate (68.9 and 70.3%) and the Km of isotope substrates are analogous (0.139 and 0.135 mM), which demonstrated that the novel method is feasible to AChE inhibition measurement. Finally, the method was applied to herb extracts, half of which exhibit inhibition to AChE. The precise dual-channel enzymatic inhibition measurement (DEIM) method could be regarded as a promising approach to potential enzyme inhibitor screening. Graphical Abstract ᅟ.

Ultra-thin bimetallic alloy nanowires with porous architecture/monolayer MoS2 nanosheet as a highly sensitive platform for the electrochemical assay of hazardous omethoate pollutant

A novel electrochemical biosensor was designed for sensitive detection of organophosphate pesticides based on three-dimensional porous bimetallic alloy architecture with ultrathin nanowires (PdCo NWs, PdCu NWs, PdNi NWs) and monolayer MoS₂ nanosheet (m-MoS₂). The bimetallic alloy NWs/m-MoS₂ nanomaterials were used as a sensing platform for electrochemical analysis of omethoate, a representative organophosphate pesticide, via acetylcholinesterase inhibition pathway. We demonstrated that all three bimetallic alloy NWs enhanced electrochemical responses of enzymatic biosensor, benefited from bimetallic synergistic action and porous structure. In particular, PdNi NWs outperformed other two bimetallic alloy. Moreover, PdNi NWs/m-MoS₂ as an electronic transducer is superior to the corresponding biosensor in the absence of monolayer MoS₂ nanosheet, which arise from synergistic signal amplification effect between different components. Under optimized conditions, the developed biosensor on the basis of PdNi NWs/m-MoS₂ shows outstanding performance for the electrochemical assay of omethoate, such as a wide linear range (10^-13 M∼10^-7 M), a low detection limit of 0.05 pM at a signal-to-noise ratio of 3, high sensitivity and long-time stability. The results demonstrate that bimetallic alloy NWs/m-MoS₂ nanocomposites could be excellent transducers to promote electron transfer for the electrochemical reactions, holding great potentials in the construction of current and future biosensing devices.

Mass spectrometry for characterization of homologous piperidine alkaloids and their activity as acetylcholinesterase inhibitors

RATIONALE

Piperidine alkaloids from Senna spectabilis constitute a rare class of natural products with several biological activities. However, the absence of chromophores makes their structural elucidation by conventional methods a great challenge. In this context, mass spectrometry emerges as a powerful tool for metabolomics studies.

METHODS

The piperidine alkaloids (-)-cassine and (-)-spectaline and the semisynthetic derivatives (-)-3-O-acetylcassine and (-)-3-O-acetylspectaline were investigated by electrospray ionization tandem mass spectrometry (ESI-MS/MS) in the positive mode and electron ionization mass spectrometry (EI-MS). ESI fragmentation studies were performed with a quadrupole time-of-flight instrument; N₂ was used as collision gas. The acetylcholinesterase inhibitory activity of the investigated compounds was evaluated by bioautography and microplate screening assays.

RESULTS

ESI-MS/MS and EI-MS provided valuable and complementary information about the structure of the piperidine compounds. Collision-induced dissociation experiments (MS/MS) revealed that neutral elimination of water or acetic acid is the major fragmentation pathway, which agrees with the stereochemistry proposed for (-)-cassine and (-)-spectaline and the semisynthetic derivatives (-)-3-O-acetylcassine and (-)-3-O-acetylspectaline.

CONCLUSIONS

The ESI-MS/MS and EI-MS studies allowed us to propose fragmentation mechanisms for piperidine alkaloids and derivatives. Therefore, mass spectrometry is an important tool for characterizing the structure of these compounds and for supporting further metabolomics studies.

Accumulation, tissue distribution, and biochemical effects of polystyrene microplastics in the freshwater fish red tilapia (Oreochromis niloticus)

While the presence of microplastics (MPs) in marine environments has been detected worldwide, the importance of MPs pollution in freshwater environments has also been emphasized in recent years. However, the body of knowledge regarding the biological effects of MPs on freshwater organisms is still much more limited than on marine organisms. The aim of the present study was to evaluate the accumulation and tissue distribution of MPs in the freshwater fish red tilapia (Oreochromis niloticus), as well as the biochemical effects of MPs on O. niloticus. During 14 days of exposure to 0.1 μm polystyrene-MPs at concentrations of 1, 10, and 100 μg L^-1, the MPs concentrations in various tissues of O. niloticus generally increased over time following the order gut > gills > liver ≈ brain. Moreover, the acetylcholinesterase (AChE) activity in the fish brain was inhibited by MPs exposure, with a maximum inhibition rate of 37.7%, suggesting the potential neurotoxicity of MPs to freshwater fish. The activities of cytochrome P450 (CYP) enzymes [7-ethoxyresorufin O-deethylase (EROD) and 7-benzyloxy-4-trifluoromethyl-coumarin O-dibenzyloxylase (BFCOD)] in the fish liver exhibited clear temporal variabilities, with significant decreases followed by elevations compared to the control. The alterations of the EROD and BFCOD activities indicate the potential involvement of CYP enzymes for the metabolism of MPs. The activity of antioxidative enzyme superoxide dismutase (SOD) in the liver was significantly induced throughout the exposure period, while the malondialdehyde (MDA) content did not vary with MPs exposure, suggesting that the antioxidative enzymatic system in O. niloticus could prevent oxidative damage. These results highlight the ingestion and accumulation of MPs in different tissues of freshwater fish, which lead to perturbations in fish biological systems and should be considered in environmental risk assessment.

Chemometrics-assisted spectrophotometric green method for correcting interferences in biowaiver studies: Application to assay and dissolution profiling study of donepezil hydrochloride tablets

A green, simple and cost effective chemometric UV-Vis spectrophotometric method has been developed and validated for correcting interferences that arise during conducting biowaiver studies. Chemometric manipulation has been done for enhancing the results of direct absorbance, resulting from very low concentrations (high incidence of background noise interference) of earlier points in the dissolution timing in case of dissolution profile using first and second derivative (D1 & D2) methods and their corresponding Fourier function convoluted methods (D1/FF& D2/FF). The method applied for biowaiver study of Donepezil Hydrochloride (DH) as a representative model was done by comparing two different dosage forms containing 5mg DH per tablet as an application of a developed chemometric method for correcting interferences as well as for the assay and dissolution testing in its tablet dosage form. The results showed that first derivative technique can be used for enhancement of the data in case of low concentration range of DH (1-8μgmL^-1) in the three different pH dissolution media which were used to estimate the low drug concentrations dissolved at the early points in the biowaiver study. Furthermore, the results showed similarity in phosphate buffer pH6.8 and dissimilarity in the other 2pH media. The method was validated according to ICH guidelines and USP monograph for both assays (HCl of pH1.2) and dissolution study in 3pH media (HCl of pH1.2, acetate buffer of pH4.5 and phosphate buffer of pH6.8). Finally, the assessment of the method greenness was done using two different assessment techniques: National Environmental Method Index label and Eco scale methods. Both techniques ascertained the greenness of the proposed method.

Effect-directed analysis of ginger (Zingiber officinale) and its food products, and quantification of bioactive compounds via high-performance thin-layer chromatography and mass spectrometry

Decision makers responsible for quality management along the food chain need to reflect on their analytical tools that should ensure quality of food and especially superfood. The "4ables" in target analysis (stable, extractable, separable, detectable) focusing on marker compounds do not cover all relevant information about the sample. On the example of ginger, a streamlined quantitative bioprofiling was developed for effect-directed analysis of 17 commercially available ginger and ginger-containing products via high-performance thin-layer chromatography (HPTLC-UV/Vis/FLD-bioassay). The samples were investigated concerning their active profile as radical scavengers, antimicrobials, estrogen-like activators and acetylcholinesterase/tyrosinase inhibitors. The [6]-gingerol and [6]-shogaol content of the different products ranged 0.2-7.4mg/g and 0.2-3.0mg/g, respectively. Further, multipotent compounds were discovered, characterized, and for example, assigned as [8]- and [10]-gingerol via HPTLC-ESI-HRMS. The developed bioprofiling is a step forward to new analytical methods needed to inform on the true product quality influenced by cultivation, processing, and storage.

HPLC-DAD finger printing, antioxidant, cholinesterase, and α-glucosidase inhibitory potentials of a novel plant Olax nana

BACKGROUND

The medicinal importance of a novel plant Olax nana Wall. ex Benth. (family: Olacaceae) was revealed for the first time via HPLC-DAD finger printing, qualitative phytochemical analysis, antioxidant, cholinesterase, and α-glucosidase inhibitory assays.

METHODS

The crude methanolic extract of O. nana (ON-Cr) was subjected to qualitative phytochemical analysis and HPLC-DAD finger printing. The antioxidant potential of ON-Cr was assessed via 1,1-diphenyl,2-picrylhydrazyl (DPPH), 2,2-azinobis[3-ethylbenzthiazoline]-6-sulfonic acid (ABTS) and hydrogen peroxide (H2O2) free radical scavenging assays. Furthermore, acetylcholinesterase (AChE) & butyrylcholinesterase (BChE) inhibitory activities were performed using Ellman's assay, while α- glucosidase inhibitory assay was carried out using a standard protocol.

RESULTS

The qualitative phytochemical analysis of ON-Cr revealed the presence of secondary metabolites like alkaloids, flavonoids, tannins, sterols, saponins and terpenoids. The HPLC-DAD finger printing revealed the presence of 40 potential compounds in ON-Cr. Considerable anti-radical activities was revealed by ON-Cr in the DPPH, ABTS and H2O2 free radical scavenging assays with IC50 values of 71.46, 72.55 and 92.33 μg/mL, respectively. Furthermore, ON-Cr showed potent AChE and BChE inhibitory potentials as indicated by their IC50 values of 33.2 and 55.36 μg/mL, respectively. In the α-glucosidase inhibition assay, ON-Cr exhibited moderate inhibitory propensity with an IC50 value of 639.89 μg/mL.

CONCLUSIONS

This study investigated Olax nana for the first time for detailed qualitative phytochemical tests, HPLC-DAD finger printing analysis, antioxidant, anticholinesterase and α-glucosidase inhibition assays. The antioxidant and cholinesterase inhibitory results were considerable and can provide scientific basis for further studies on the neuroprotective and anti-Alzheimer's potentials of this plant. ON-Cr may further be subjected to fractionation and polarity guided fractionation to narrow down the search for isolation of bioactive compounds.

Analysis of acetylcholinesterase inhibitors by extraction in choline saccharinate aqueous biphasic systems

Ionic liquid-based aqueous biphasic systems (IL-ABS) formed by ILs composed of ions of low toxicity, choline ([Chol]⁺) coupled with saccharinate ([Sac]^-) and acesulfamate ([Ace]^-), and inorganic salts with distinct water-structuring properties were employed for simultaneous extraction and concentration of acetylcholinesterase (AChE) inhibitors - galantamine (gal), N-desmethyl galantamine (des) and ungiminorine (ung). Comprehensive experiments aimed to assess the influence of salt and IL type and concentration, as well as the pH and temperature on the phase-forming ability and distribution of the target alkaloids between the two phases formed reveled that the IL anion and pH are the most important factors. At the optimal conditions found a quantitative recovery into the IL-rich phase of gal, des and ung was achieved in a single extractive step. These results were further used as a platform for the development of a simple and safer sample pretreatment method for analysis of the three analytes, followed by RP-HPLC/UV detection. The method showed satisfactory analytical performance, the latter allowing quantitative determination of these AChE inhibitors in pharmaceutical dosage form and in human urine.

Antioxidant and acetylcholinesterase inhibitory activities of ginger root (Zingiber officinale Roscoe) extract

Background Zingiber officinale Roscoe has been used in traditional medicine for the treatment of neurological disorder. This study aimed to investigate the phenolic contents, antioxidant, acetylcholinesterase enzyme (AChE) inhibitory activities of different fraction of Z. officinale root grown in Vietnam. Methods The roots of Z. officinale are extracted with ethanol 96 % and fractionated with n-hexane, ethyl acetate (EtOAc) and butanol (BuOH) solvents. These fractions evaluated the antioxidant activity by 1,1-Diphenyl -2-picrylhydrazyl (DPPH) assay and AChE inhibitory activity by Ellman's colorimetric method. Results Our data showed that the total phenolic content of EtOAc fraction was highest equivalents to 35.2±1.4 mg quercetin/g of fraction. Our data also demonstrated that EtOAc fraction had the strongest antioxidant activity with IC50 was 8.89±1.37 µg/mL and AChE inhibitory activity with an IC50 value of 22.85±2.37 μg/mL in a dose-dependent manner, followed by BuOH fraction and the n-hexane fraction is the weakest. Detailed kinetic analysis indicated that EtOAc fraction was mixed inhibition type with Ki (representing the affinity of the enzyme and inhibitor) was 30.61±1.43 µg/mL. Conclusions Our results suggest that the EtOAc fraction of Z. officinale may be a promising source of AChE inhibitors for Alzheimer's disease.

[Decontamination of organophosphorus compounds: Towards new alternatives]

Organophosphorus coumpounds (OP) are toxic chemicals mainly used for agricultural purpose such as insecticides and were also developed and used as warfare nerve agents. OP are inhibitors of acetylcholinesterase, a key enzyme involved in the regulation of the central nervous system. Chemical, physical and biological approaches have been considered to decontaminate OP. This review summarizes the current and emerging strategies that are investigated to tackle this issue with a special emphasis on enzymatic remediation methods. During the last decade, many studies have been dedicated to the development of biocatalysts for OP removal. Among these, recent reports have pointed out the promising enzyme SsoPox isolated from the archaea Sulfolobus solfataricus. Considering both its intrinsic stability and activity, this hyperthermostable enzyme is highly appealing for the decontamination of OP.

Oxidase-mimicking activity of ultrathin MnO2 nanosheets in colorimetric assay of acetylcholinesterase activity

In the present study, a novel colorimetric sensing platform was constructed for quantitative detection of acetylcholinesterase (AChE) activity and its inhibitor. Manganese dioxide (MnO₂) nanosheets as an oxidase-mimicking nanomaterial could directly oxidize 3,3',5,5'-tetramethylbenzidine (TMB) into oxTMB without the need for horseradish peroxidase and H₂O₂. When AChE was introduced, acetylthiocholine could be catalytically hydrolyzed to produce thiocholine, which easily triggers the decomposition of MnO₂ nanosheets, causing the decrease of solution absorbance. Owing to the inhibition effect of organophosphorus pesticides, the enzymatic activity was suppressed, preventing the decomposition of MnO₂ and resulting in the increase of absorbance. Under optimal conditions, the colorimetric platform shows sensitive responses to AChE and paraoxon in the range of 0.1-15 mU mL^-1 and 0.001-0.1 μg mL^-1, respectively. The detection limits of AChE and paraoxon reached 35 μU mL^-1 and 1.0 ng mL^-1, respectively. Furthermore, the MnO₂-TMB platform has been used to fabricate test strips for rapid and convenient visual detection of AChE and its inhibitor with highly promising performance.

Research Advances and Detection Methodologies for Microbe-Derived Acetylcholinesterase Inhibitors: A Systemic Review

Acetylcholinesterase inhibitors (AChEIs) are an attractive research subject owing to their potential applications in the treatment of neurodegenerative diseases. Fungi and bacteria are major producers of AChEIs. Their active ingredients of fermentation products include alkaloids, terpenoids, phenylpropanoids, and steroids. A variety of in vitro acetylcholinesterase inhibitor assays have been developed and used to measure the activity of acetylcholinesterases, including modified Ellman's method, thin layer chromatography bioautography, and the combined liquid chromatography-mass spectrometry/modified Ellman's method. In this review, we provide an overview of the different detection methodologies, the microbe-derived AChEIs, and their producing strains.

Chlorpyrifos pollution: its effect on brain acetylcholinesterase activity in rat and treatment of polluted soil by indigenous Pseudomonas sp

The study was aimed to evaluate the levels of chlorpyrifos (CPF) pollution in agricultural soil of Punjab, India, its detrimental effects on acetylcholinesterase (AChE) activity in rat brain and bioremediation of soils polluted with CPF using indigenous and adapted bacterial lab isolate. The analysis revealed that soil samples of Bathinda and Amritsar regions are highly contaminated with chlorpyrifos showing 19 to 175 mg/kg concentrations of CPF. The non-targeted animals may get poisoned with CPF by its indirect dermal absorption, inhalation of toxic fumes and regular consumption of soiled food grains. The study indicated that even the lowermost concentrations of CPF, 19 and 76 mg/kg of soil found in the Amritsar and Bathinda regions respectively can significantly inhibit the AChE activity in rat brain within 24 h of its treatment. This represents the antagonistic effect of CPF on AChE which is a prime neurotransmitter present in all living beings including humans. In light of this, an attempt was made to remediate the polluted soil, a major reservoir of CPF, using Pseudomonas sp. (ChlD), an indigenous bacterial isolate. The culture efficiently degraded 10 to 100 mg/kg chlorpyrifos supplemented in the soil and utilized it as sole source of carbon and energy for its growth. Thus, this study provides a detailed insight regarding the level of CPF pollution in Punjab, its detrimental effects on mammals and bio-based solution to remediate the sites polluted with CPF.

Combined effects of chlorpyriphos, copper and temperature on acetylcholinesterase activity and toxicokinetics of the chemicals in the earthworm Eisenia fetida

In polluted environments organisms are commonly exposed to a combination of chemicals with different modes of action, and their effects can be additionally modified by natural abiotic conditions. One possible mechanism for interactions in mixtures is via toxicokinetics, as chemicals may alter the uptake, distribution, biotransformation and/or elimination of each other, and all these processes can be affected by temperature. In this study, the effect of temperature (T) on the toxicokinetics of copper (Cu) and chlorpyriphos (CHP), applied either singly or in binary mixtures, was studied in the earthworm Eisenia fetida. The experiments were conducted at 10 or 20 °C and the earthworms were exposed to environmentally realistic concentrations of Cu and/or CHP for 16 d, followed by a depuration period of 4 d in uncontaminated soil. The earthworms were sampled for body Cu and/or CHP concentrations and acetylcholinesterase (AChE) activity measurements. The CHP degradation rate in the soil was substantially higher at 20 °C and in soil treated with Cu. The significant (p < 0.05) inhibition of AChE activity in the earthworms exposed to CHP was found. The effect of Cu was significant only at p < 0.1. No synergistic effect of the parallel CHP and Cu exposure was found. Four days after transferring the earthworms to uncontaminated soil, the AChE activity recovered to the level observed in control animals. The temperature effect on the toxicokinetic parameters was more pronounced for CHP than for Cu. In the case of CHP, the assimilation rate constant (k_A) was significantly higher at 20 °C than at 10 °C, both in CHP-only and CHP + Cu treatments. A similar trend was found for the elimination rate constant (k_E), but the difference was statistically significant only for non-Cu treatments. In the case of Cu, the general trend of higher k_A and k_E at 20 °C and in the absence of CHP was observed.

Fumigant and contact toxicity of 22 wooden essential oils and their major components against Drosophila suzukii (Diptera: Drosophilidae)

Fumigant and contact toxicities of 22 plant essential oils (EOs) from 14 families and their constituents against the adult spotted wing drosophila (SWD), Drosophila suzukii were examined. Analyses by GC, GC-MS, and NMR led to the identification of 2, 16, 13, 4, 6, 9, and 10 compounds from Gaultheria fragrantissima, Croton anistatum, Illicium verum, Liquidamabar orientalis, Cinnamomum cassia, Rosa damasena, and Santalum album, respectively. In fumigant toxicity test, G. fragrantissima, C. anistatum, and I. verum exhibited 100, 93.8, and 95.8, and 100, 70.0, and 80.0% mortalities against the adult male and female SWD at 4.41mg/L air, respectively. LC₅₀ values (mg/L air) of G. fragrantissima, C. anistatum, and I. verum were 3.46, 3.67, and 3.16 against male, and 3.48, 4.31, and 4.01 against female SWD. LC₅₀ values (mg/L air) of methyl salicylate and trans-anethole were 2.17 and 1.75 against male and 2.65 and 3.00 against female SWD, respectively. In contact toxicity tests, L. orientalis, C. cassia, R. damasena, and S. album showed insecticidal activity with LD₅₀ values (μg/fly) of 2.64, 1.84, 3.40 and 2.18 against male SWD and of 3.74, 2.24, 8.91 and 5.61 against female SWD, respectively. 2-Phehy-1-ethanol, 3-phenyl-1-propanol, trans-cinnamaldehyde, trans-cinnamyl alcohol, and α-santalol also exhibited insecticidal activity with LD₅₀ values of 9.79, 5.52, 2.39, 3.02 and 2.37 against male SWD and of 11.77, 7.04, 2.94, 3.32, and 3.99 against female SWD, respectively. trans-Cinnamaldehyde exhibited the highest AChE inhibition but its inhibition is likely due to a non-specific chemical inhibition. Our results indicate that wooden EOs and their components can be used as fumigants or spray-type control agents against SWD.

Identification of petrogenic produced water components as acetylcholine esterase inhibitors

Effect-directed analysis (EDA) was applied to identify acetylcholine esterase (AChE) inhibitors in produced water. Common produced water components from oil production activities, such as polycyclic aromatic hydrocarbons (PAHs), alkylphenols, and naphthenic acids were tested for AChE inhibition using a simple mixture of PAHs and naphthenic acids. Produced water samples collected from two offshore platforms in the Norwegian sector of the North Sea were extracted by solid phase extraction and fractionated by open-column liquid solid chromatography and high-performance liquid chromatography (HPLC) before being tested using a high-throughput and automated AChE assay. The HPLC fractions causing the strongest AChE inhibition were analysed by gas chromatography coupled to a high-resolution time-of-flight mass spectrometry (GC-HR-ToF-MS). Butylated hydroxytoluene and 4-phenyl-1,2-dihydronaphthalene were identified as two produced water components capable of inhibiting AChE at low concentrations. In order to assess the potential presence of such compounds discharged into aquatic ecosystems, AChE activity in fish tissues was measured. Saithe (Pollachius virens) caught near two offshore platforms showed lower enzymatic activity than those collected from a reference location. Target analysis of saithe did not detected the presence of these two putative AChE inhibitors and suggest that additional compounds such as PAHs, naphthenic acids and yet un-identified compounds may also contribute to the purported AChE inhibition observed in saithe.

Automated high-throughput in vitro screening of the acetylcholine esterase inhibiting potential of environmental samples, mixtures and single compounds

A high-throughput and automated assay for testing the presence of acetylcholine esterase (AChE) inhibiting compounds was developed, validated and applied to screen different types of environmental samples. Automation involved using the assay in 96-well plates and adapting it for the use with an automated workstation. Validation was performed by comparing the results of the automated assay with that of a previously validated and standardised assay for two known AChE inhibitors (paraoxon and dichlorvos). The results show that the assay provides similar concentration-response curves (CRCs) when run according to the manual and automated protocol. Automation of the assay resulted in a reduction in assay run time as well as in intra- and inter-assay variations. High-quality CRCs were obtained for both of the model AChE inhibitors (dichlorvos IC50=120µM and paraoxon IC50=0.56µM) when tested alone. The effect of co-exposure of an equipotent binary mixture of the two chemicals were consistent with predictions of additivity and best described by the concentration addition model for combined toxicity. Extracts of different environmental samples (landfill leachate, wastewater treatment plant effluent, and road tunnel construction run-off) were then screened for AChE inhibiting activity using the automated bioassay, with only landfill leachate shown to contain potential AChE inhibitors. Potential uses and limitations of the assay were discussed based on the present results.

Environmentally-friendly in situ plated bismuth-film electrode for the quantification of the endocrine disruptor parathion in skimmed milk

An in situ bismuth-film electrode (BiFE) together with square-wave cathodic voltammetry (SWCV) was used to determine the concentration of the endocrine disruptor parathion in skimmed milk. The experimental conditions (deposition time, deposition potential and Bi (III) concentration) were optimized for the preparation of the BiFE. A glassy carbon electrode was used as the substrate. The selection of the chemical composition of the supporting electrolyte and the solution pH was aimed at improving the reduction of parathion at the BiFE surface. In addition, the parameters of the square-wave cathodic voltammetry were adjusted to improve the sensor performance. A cathodic current identified at -0.523 V increased linearly with the parathion concentration in the range of 0.2-2.0 μmol L(-1) (R=0.999). The sensitivity of the calibration curve obtained was 4.09 μA L μmol(-1), and the limits of detection (LOD) and quantification (LOQ) were 55.7 nmol L(-1) and 169.0 nmol L(-1), respectively. The performance of the sensor was tested using a sample of skimmed milk with parathion added. The same determination was carried out by UV-vis spectroscopy and the results obtained were used for the statistical evaluation of the data obtained.

A Workflow to Investigate Exposure and Pharmacokinetic Influences on High-Throughput in Vitro Chemical Screening Based on Adverse Outcome Pathways

BACKGROUND

Adverse outcome pathways (AOPs) link adverse effects in individuals or populations to a molecular initiating event (MIE) that can be quantified using in vitro methods. Practical application of AOPs in chemical-specific risk assessment requires incorporation of knowledge on exposure, along with absorption, distribution, metabolism, and excretion (ADME) properties of chemicals.

OBJECTIVES

We developed a conceptual workflow to examine exposure and ADME properties in relation to an MIE. The utility of this workflow was evaluated using a previously established AOP, acetylcholinesterase (AChE) inhibition.

METHODS

Thirty chemicals found to inhibit human AChE in the ToxCast™ assay were examined with respect to their exposure, absorption potential, and ability to cross the blood-brain barrier (BBB). Structures of active chemicals were compared against structures of 1,029 inactive chemicals to detect possible parent compounds that might have active metabolites.

RESULTS

Application of the workflow screened 10 "low-priority" chemicals of 30 active chemicals. Fifty-two of the 1,029 inactive chemicals exhibited a similarity threshold of ≥ 75% with their nearest active neighbors. Of these 52 compounds, 30 were excluded due to poor absorption or distribution. The remaining 22 compounds may inhibit AChE in vivo either directly or as a result of metabolic activation.

CONCLUSIONS

The incorporation of exposure and ADME properties into the conceptual workflow eliminated 10 "low-priority" chemicals that may otherwise have undergone additional, resource-consuming analyses. Our workflow also increased confidence in interpretation of in vitro results by identifying possible "false negatives."

CITATION

Phillips MB, Leonard JA, Grulke CM, Chang DT, Edwards SW, Brooks R, Goldsmith MR, El-Masri H, Tan YM. 2016. A workflow to investigate exposure and pharmacokinetic influences on high-throughput in vitro chemical screening based on adverse outcome pathways. Environ Health Perspect 124:53-60; http://dx.doi.org/10.1289/ehp.1409450.

Direct determination of methyl parathion insecticide in rice samples by headspace solid-phase microextraction-gas chromatography-mass spectrometry

BACKGROUND

The organophosphorus insecticides, especially those based on methyl parathion as active principle, have been used extensively in the protection of rice in Maranhão State, in the north-east of Brazil. This paper describes the optimisation of a solid-phase microextraction (SPME) procedure in confined atmosphere (headspace, HS) for the determination of methyl parathion in rice organic samples by gas chromatography with mass spectrometry detection (GC/MS).

RESULTS

The proposed HS-SPME-GC/MS method has been shown to be appropriate for direct analysis of the insecticide in polished rice, with satisfactory results for the following parameters: linearity (correlation coefficient 0.9985), sensitivity (LOD and LOQ of 0.026 and 0.078 µg kg(-1) respectively), precision (coefficients of variation between 6.1 and 22.4%) and accuracy (recoveries varying from 73.2 to 90.0%). Although the efficiency of the proposed GC/MS does not differ statistically (P < 0.05) from the conventional GC/NPD method, given its low cost, speed and also the fact that a minimum volume of toxic effluent is generated, this method can be considered an on-line procedure based on green chemistry.

CONCLUSIONS

Thus, the analytical methodology satisfies the minimum requirements for control of residues of such insecticides in rice samples destined for human consumption.

Thin Layer Chromatography-Autography-High Resolution Mass Spectrometry Analysis: Accelerating the Identification of Acetylcholinesterase Inhibitors

INTRODUCTION

The prevailing treatment for Alzheimer's disease is the use of acetylcholinesterase (AChE) inhibitors. Natural extracts are the principal source of AChE's inhibitors. However, their chemical complexity demands for simple, selective and rapid assays.

OBJECTIVE

To develop a strategy for identification of AChE inhibitors present in mixtures employing high resolution mass spectrometry (HRMS) and thin layer chromatography (TLC)-biological staining.

METHODOLOGY

The strategy uses an autographic assay based on the α-naphthyl acetate - fast blue B system for the detection of AChE activity. The immobilisation of AChE in agar allowed the extraction of the compounds for analysis by HRMS. Three TLC experiments employing different solvent systems were used in parallel and the mass spectra of the compounds extracted from the inhibition halos, were compared. The analysis was performed under MatLab environment.

RESULTS

The strategy was used to detect the presence of physostigmine in an extract of Brassica rapa L. spiked with the inhibitor. Similarly, caffeine was straightforwardly spotted as responsible for the inhibitory properties of an extract of Ilex paraguariensis Saint-Hilaire. Comparison of the HRMS profiles lead to the facile identification of the [M+H](+) and [M+Na](+) of the compounds responsible for the inhibition.

CONCLUSION

The proposed methodology, coupling TLC-AChE autography-HRMS, illustrates the feasibility of assigning molecular formulas of active compounds present in complex mixtures directly from autography. The new AChE agar-immobilised assay presented a more homogenous colour and a better definition than direct spraying methods, reducing the cost of the assay and improving its sensitivity.

Guaiasistanol: A new guaiane sesquiterpenoid from Teucrium persicum Boiss

In this study, a new guaiane type skeleton sesquiterpenoid named guaiasistanol (6α, 10α-epoxy-4α-hydroxyguaiane) was isolated from chloroform part of the Teucrium persicum extract, also chrysothol. Spectroscopic means explained the structures. This compound was evaluated for inhibitory activity against acetylcholinesterase and it showed a moderate activity with 28% inhibition.

A highly stable minimally processed plant-derived recombinant acetylcholinesterase for nerve agent detection in adverse conditions

Although recent innovations in transient plant systems have enabled gram quantities of proteins in 1-2 weeks, very few have been translated into applications due to technical challenges and high downstream processing costs. Here we report high-level production, using a Nicotiana benthamiana/p19 system, of an engineered recombinant human acetylcholinesterase (rAChE) that is highly stable in a minimally processed leaf extract. Lyophylized clarified extracts withstand prolonged storage at 70 °C and, upon reconstitution, can be used in several devices to detect organophosphate (OP) nerve agents and pesticides on surfaces ranging from 0 °C to 50 °C. The recent use of sarin in Syria highlights the urgent need for nerve agent detection and countermeasures necessary for preparedness and emergency responses. Bypassing cumbersome and expensive downstream processes has enabled us to fully exploit the speed, low cost and scalability of transient production systems resulting in the first successful implementation of plant-produced rAChE into a commercial biotechnology product.

Chemical Compositions and Biological Activities of Essential Oils of Beilschmiedia glabra

This study was designed to examine the chemical compositions of essential oils from Beilschmiedia glabra and their antioxidant, antimicrobial, antityrosinase, acetylcholinesterase and anti-inflammatory activities. In total, 47 components were identified in the essential oils, which made up 86.8% and 89.7% of the leaf and bark oils, respectively. The leaf oil is composed mainly of β-eudesmol (15.4%), β-selinene (12.2%), caryophyllene oxide (8.1%) and γ-gurjunene (5.2%), while the bark oil contains high percentages of β-eudesmol (19.3%), β-selinene (16.9%), δ-cadinene (15.8%), germacrene D (9.8%) and β-caryophyllene (5.5%). Antioxidant activity showed that the leaf oil has the highest phenolic content at 233.4 mg GA/g, while the bark oil showed potent activity in the β- carotene/linoleic acid bleaching assay. However, both oils showed weak activity in the DPPH and ABTS assays. For antimicrobial activity, the leaf and bark oils displayed strong activity against Candida glabrata and Saccharomyces cerevisiae with MIC values of 31.3 and 62.5 μg/mL, respectively. Percentage inhibitions against tyrosinase (leaf 73.7%; bark 76.0%) and acetylcholinesterase (leaf 48.1%; bark 45.2%) were tested at a concentration of 1 mg/mL, while anti-inflammatory activity (leaf 59.7%; bark 48.9%) was evaluated at a concentration of 100 μM. Evaluation of these assays indicated moderate levels of activity.

Acetylcholinesterase inhibitors from a marine fungus Talaromyces sp. strain LF458

Two new oxaphenalenone dimers, talaromycesone A (1) and talaromycesone B (2), and a new isopentenyl xanthenone, talaroxanthenone (3), together with six known diphenyl ether derivatives, e.g., Δ(1',3'),-1'-dehydroxypenicillide (4), 1',2'-dehydropenicillide (5), vermixocin A (6), vermixocin B (7), 3'-methoxy-1'2'-dehydropenicillide (8), and AS-186c (9), were isolated from the culture broth and mycelia of a marine fungus Talaromyces sp. strain LF458. Compound 2 represents the first example of 1-nor oxaphenalenone dimer carbon skeleton. All isolated compounds were subjected to bioactivity assays. Compounds 1, 2, and 9 exhibited potent antibacterial activities with IC50 3.70, 17.36, and 1.34 μM, respectively, against human pathogenic Staphylococcus strains. Compounds 1, 3, and 9 displayed potent acetylcholinesterase inhibitory activities with IC50 7.49, 1.61, and 2.60 μM, respectively. Interestingly, phosphodiesterase PDE-4B2 was inhibited by compounds 3 (IC50 7.25 μM) and 9 (IC50 2.63 μM).