Significant Acetylcholinesterase Inhibition Research Articles

Influence of microplastic pollution on the toxicity of potamodromous fish grass carp (Ctenopharyngodon idellus) and its swimming capacity

Microplastics (MPs), as a ubiquitous environmental contaminant in marine and freshwater systems, produced a significant influence on the physiological characteristics of aquatic organisms, and inevitably posed unknown effects on their swimming capacity. Herein, we evaluated the MPs accumulation in potamodromous fish, Ctenopharyngodon idellus, and their potential effects on oxidative stress, neurotoxicity, gut microbial diversity, and swimming capability through a toxic-control experiment. Juvenile fish were exposed to 5 µm polystyrene-MPs (PS-MPs) for 6 days at concentrations of 0.1, 1, and 10 mg/L. Exposure to PS-MPs resulted in significant inhibition of acetylcholinesterase (AChE) in the brain of fish, with significant increases in superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels at 1 and 10 mg/L exposures. Meanwhile, MPs altered grass carp gut microbiota and reduced the Shannon diversity index. In addition, MPs significantly increased induced swimming speed by observing the flow rate at which grass carp happened to produce a reverse current behavioral response. The 1 and 10 mg/L of MPs treatments can significantly reduce the critical swimming speed of grass carp, meaning that the completion of the life history of grass carp may be delayed. Furthermore, there were significant correlations between biomarkers and indicators of swimming capacity. Therefore, the present study suggests that MPs produced a negative effect on the physiological properties of fish, reducing the swimming capacity of migratory fish.

Cyperus rotundus L.: Invasive weed plant with insecticidal potential against Aphis craccivora Koch and Planococcus lilacinus (Cockerell)

Cyperus rotundus L. is a widely distributed invasive weed plant with vast traditional medicinal uses. Herein, the methanolic root extract of C. rotundus and its fractions (n-hexane, chloroform, n-butanol, and aqueous) were evaluated for insecticidal activity against nymphs of Aphis craccivora Koch and crawlers of Planococcus lilacinus (Cockerell) to find promising lead (s). In contact topical assay, among extract/fractions, n-hexane fraction exhibited more toxicity against A. craccivora (LD50 = 1.12 μg/insect) and P. lilacinus (LD50 = 0.94 μg/insect). The chemical analysis of n-hexane fraction revealed a volatile composition similar to that of the essential oil (EO) of C. rotundus roots. Hence, EO was extracted using water and deep eutectic solvents (DESs) as cosolvent, which revealed enhancement in EO yield (from 0.28 to 0.46% w/w) on implementing DESs. A total of 35 diverse volatile metabolites were identified in all EO samples, accounting for 85.0 to 91.8% of chemical composition, having cyperotundone, cyperene mustakone, isolongifolen-5-one, boronia butenal as major constituents. The EO obtained with DES-7 [choline chloride: ethylene glycol (1:4)] and DES-6 [choline chloride: lactic acid (1:3)] were found effective against A. craccivora (LD50 = 0.62–0.87 μg/insect) and P. lilacinus (LD50= 0.59–0.67 μg/insect) after 96 h. NMR analysis of EO revealed cyperotundone as a major compound, which was isolated along with cyperene and cyperene epoxide. All the molecules were found effective against P. lilacinus, whereas against A. craccivora cyperotundone, cyperene and cyperene epoxide showed promising toxicity (LD50 = 0.74–0.86 μg/insect). Extract/fractions, EO, and isolated molecules showed a significant reproductive inhibition rate of A. craccivora at higher concentrations. All the tested concentrations of cyperotundone showed significant inhibition of acetylcholinesterase (AChE) and glutathione-S-transferase (GST) in A. craccivora and P. lilacinus. Based upon the present study, C. rotundus can be recommended to control targeted insects in the greenhouse/field conditions after performing bio-efficacy and phytotoxicity studies.

Efficacy of D-Limonene Nanoemulsion Against Rhipicephalus annulatus and Rhipicephalus sanguineus Ticks.

Ticks infestation has a negative impact against human and animal health through blood sucking, transmission of blood-borne diseases and also caused economic losses. In the present study the adulticidal, ovicidal and larvicidal activity of D-limonene nanoemulsion (DLN) were evaluated against two tick species; Rhipicephalus annulatus and Rhipicephalus sanguineus. Nanoemulsion form of D-limonene was prepared, and its characteristics were evaluated using a UV spectrophotometer and zeta droplet size measurement. Acetylcholinesterase activity was determined. The results revealed significant adulticidal effect with low LC50 and LC90 for D-limonene pure form (DL) against both adult tick spp. (R. annulatus and R. sanguineus) ((0.958 and 1.559%) and (2.26 and 3.51%), respectively). DLN LC50 and LC90 values were ((1.277 and 2.396) and (3.97 and 7.28), respectively) against R. annulatus and R. sanguineus, respectively. DL and DLN showed significant ovicidal effect against R. sanguineus at high concentrations (10 and 5%). In larval packet test, LC50 and LC90 values of DL were ((1.53 and 2.22%) and (6.81 and 12.07%), respectively) against R. annulatus and R. sanguineus, respectively, while LC50 and LC90 values of DLN were ((6.48 and 11.26%) and (7.82 and 13.59%), respectively) against R. annulatus and R. sanguineus, respectively. Significant acetylcholinesterase inhibition percentage was detected for both ticks spp. which treated by DL and DLN. Pure DL is more effective than DLN form against R. annulatus and R. sanguineus.

Melipona scutellaris Geopropolis: Chemical Composition and Bioactivity.

Geopropolis has been used in traditional medicine for centuries. In this study, the botanical origin, physicochemical profile, and biological activities of geopropolis from Melipona scutellaris harvested during rainy and dry seasons were investigated. Palynological analysis identified over 50 pollen types, with Schinus terebinthifolius and Cecropia being the predominant types. The analytical results were in line with those reported in the literature. Rainy-season geopropolis exhibited higher total phenol and flavonoid content (determined using High Performance Liquid Chromatography-25.13% and 3.92%, respectively) compared to the dry season (19.30% and 2.09%); the major peaks (naringin, gallic acid, and catechin) were similar among samples. Antioxidant capacity was assessed via DPPH, reducing power, and β-carotene/linoleic acid discoloration assays. Rainy-season samples displayed superior antioxidant activity across methods. Antimicrobial effects were determined using microdilution, while the impact on the cholinesterase enzyme was quantified using 5-thio-2-nitrobenzoic acid accumulation. Anti-inflammatory and antimutagenic activities were assessed through hyaluronidase enzyme inhibition and by utilizing Saccharomyces cerevisiae ATCC-20113 cells. Both samples exhibited anti-inflammatory and antimutagenic properties. Moreover, a significant inhibition of acetylcholinesterase was observed, with IC50 values of 0.35 µg/mL during the rainy season and 0.28 µg/mL during the dry season. Additionally, the geopropolis displayed antimicrobial activity, particularly against Staphylococcus aureus. These findings suggest the therapeutic potential of M. scutellaris geopropolis in the context of inflammatory, oxidative, and infectious diseases.

Integrated transcriptomic and biochemical characterization of the mechanisms governing stress responses in soil-dwelling invertebrate (Folsomia candida) upon exposure to dibutyl phthalate

Dibutyl phthalate (DBP) is one of the most commonly utilized plasticizers and a frequently detected phthalic acid ester (PAE) compound in soil samples. However, the toxicological effects of DBP on soil-dwelling organisms remain poorly understood. This study employed a multi-biomarker approach to investigate the impact of DBP exposure on Folsomia candida’s survival, reproduction, enzyme activity levels, and transcriptional profiles. Analyses of antioxidant biomarkers, including catalase (CAT) and glutathione S-transferase (GST), as well as detoxifying enzymes such as acetylcholinesterase (AChE), Cytochrome P450 (CYP450), and lipid peroxidation (LPO), revealed significant increases in CAT activity, GST levels, and CYP450 expression following treatment with various doses of DBP for 2, 4, 7, or 14 days. Additionally, LPO induction was observed along with significant AChE inhibition. In total, 3175 differentially expressed genes (DEGs) were identified following DBP treatment that were enriched in six Gene Ontology (GO) terms and 144 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including 85 upregulated and 59 downregulated primarily associated with lipid metabolism, signal transduction, DNA repair, and cell growth and death. Overall these results provide foundational insights for further research into the molecular mechanisms underlying responses of soil invertebrates to DBP exposure.

Effects of Inorganic and Organic Pollutants on the Biomarkers' Response of Cerastoderma edule under Temperature Scenarios.

Currently, there is increased chemical pollution, and climate change is a major concern to scientific, political and social communities globally. Marine systems are very susceptible to changes, and considering the ecological and economic roles of bivalve species, like Cerastoderma edule, studies evaluating the effects of both stressors are of great importance. This study intends to (a) determine the toxicity of copper (Cu) and oxyfluorfen at the lethal level, considering the temperature; (b) assess the changes in the antioxidant defence enzymes as a consequence of the simultaneous exposure to chemical and warming pressures; and (c) determine if lipid peroxidation (LPO) and neurotoxic effects occur after the exposure to chemical and temperature stressors. C. edule was exposed to Cu and oxyfluorfen at different temperatures (15 °C, 20 °C and 25 °C) for 96 h. The ecotoxicological results reveal a higher tolerance of C. edule to oxyfluorfen than to Cu, regardless of the temperature. The antioxidant defence system revealed efficiency in fighting the chemicals' action, with no significant changes in the thiobarbituric reactive species (TBARS) levels to 15 °C and 20 °C. However, a significant inhibition of acetylcholinesterase (AChE) was observed on the organisms exposed to oxyfluorfen at 20 °C, as well as a decreasing trend on the ones exposed to Cu at this temperature. Moreover, the catalase (CAT) showed a significant increase in the organisms exposed to the two highest concentrations of Cu at 15 °C and in the ones exposed to the highest concentration of oxyfluorfen at 20 °C. Looking at the temperature as a single stressor, the organisms exposed to 25 °C revealed a significant increase in the TBARS level, suggesting potential LPO and explaining the great mortality at this condition.

Design, synthesis and pharmacological evaluation of disubstituted 1,3,4 thiadiazoles derivatives for the treatment of cognitive dysfunction

Acetylcholinesterase has emerged as a promising target for the development of potential treatments for cognitive decline. The deleterious effect of oxidative stress on the learning and memory paradigms of an individual has also been well documented. As a result, the current study shows the design, synthesis, and pharmacological evaluation of 2, 5 disubstituted 1,3,4 thiadiazole derivatives. Twenty-seven molecules were designed and the molecular docking study performed to predict the binding mode of the designed compounds also suggested that these compounds bind appreciably to the amino acids present in the active site of the recombinant human acetylcholinesterase (rhAChE). Based on docking analysis, Five novel hybrids (8,14, 22, 24 and 27) have been synthesized by employing suitable synthetic procedures and characterized by various spectral and elemental techniques. Further, these synthesized compounds were studied the pharmacokinetic study and evaluated against behavioral alterations using step-down passive avoidance and escape learning protocol at a dose of 0.5 mg/kg with reference to the standard, donepezil. All the synthesized compounds were evaluated for their in vitro acetylcholinesterase (AChE) inhibition at five different concentrations using mice brain homogenate as the source of the enzyme. Biochemical estimation of markers of oxidative stress has also been carried out to assess the role of synthesized molecules on the oxidative damage induced by ascorbic acid. Compounds 14 and 22 demonstrated significant acetylcholinesterase inhibition activity. These compounds also decreased ascorbic acid-induced oxidative stress, thus serving as promising leads for the amelioration of oxidative stress-induced cognitive decline. The findings suggested that these compounds could be investigated further as AChE and oxidative stress inhibitors for the treatment of cognitive dysfunction.

Abstract A079: The quadruplex-binding compound QN-302 in the MIA-PaCa2 pancreatic adenocarcinoma model shows no evidence of cardiac or neurological liabilities at therapeutic doses

Abstract The human genome contains multiple sites of quadruplex (G4) arrangements, with over-representation in promoter regions of many oncogenes. Small molecule G4 stabilization down-regulates the transcription of these genes, leading to selective inhibition of cancer cell growth and anti-tumor activity. We have developed a number of novel G4-binding small molecules. QN-302, the most potent, has significant in vivo activity in animal models for pancreatic cancer and is currently in pre-clinical development with Qualigen Therapeutics. The effects of QN-302 have been examined on (1) a panel of cardiac function receptors, (2) heart rate in vivo, and (3) on the histopathology of organs from treated animals. QN-302 was initially screened in a series of in vitro industry-standard CEREP receptor binding assays. The few apparent indications of significant receptor binding were examined in vivo by means of ELISA assays. Cardiac function was examined using a cardiac heart-beat monitor attached to animals treated with QN-302 and compared to animals dosed with a vehicle control. QN-302 gave negative results in CEREP assays, apart from micromolar inhibition of acetylcholinesterase (ACE) and muscarinic (MUSC) receptors. There was no significant hERG receptor inhibition. There was no significant inhibition of ACE and MUSC receptors in vivo. Heart rate experiments, run at both the proposed therapeutic dose of 1mg/kg and at elevated levels, did not show significant deviations from values for the vehicle control arm. Histopathology of heart, liver and brain tissues from QN-302 treated animals, did not show any deleterious effects from the drug. The lack of effects on ACE and MUSC receptors in vivo, together with the absence of effects on heart, liver and brain tissue from treated animals and the normality of heart rate during treatment, demonstrate that treatment of MIA-Paca2 tumor-bearing mice with QN-302 does not have a cardio-, nephro- or neurotoxic burden at therapeutic doses. QN-302 is bio-available at therapeutic doses and is currently in pre-clinical development with Qualigen Therapeutics Inc Citation Format: Ahmed Ahmed, Tariq Arshad, Stephen Neidle. The quadruplex-binding compound QN-302 in the MIA-PaCa2 pancreatic adenocarcinoma model shows no evidence of cardiac or neurological liabilities at therapeutic doses [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr A079.

Bioactivation and detoxification of organophosphorus pesticides in freshwater planarians shares similarities with humans.

Organophosphorus pesticides (OPs) are a chemically diverse class of insecticides that inhibit acetylcholinesterase (AChE). Many OPs require bioactivation to their active oxon form via cytochrome P450 to effectively inhibit AChE. OP toxicity can be mitigated by detoxification reactions performed by carboxylesterase and paraoxonase. The relative extent of bioactivation to detoxification varies among individuals and between species, leading to differential susceptibility to OP toxicity. Because of these species differences, it is imperative to characterize OP metabolism in model systems used to assess OP toxicity. We have shown that the asexual freshwater planarian Dugesia japonica is a suitable model to assess OP neurotoxicity and developmental neurotoxicity via rapid, automated testing of adult and developing organisms in parallel using morphological and behavioral endpoints. D. japonica has two cholinesterase enzymes with intermediate properties between AChE and butyrylcholinesterase that are sensitive to OP inhibition. Here, we demonstrate that D. japonica contains the major OP metabolic machinery to be a relevant model for OP neurotoxicity studies. Adult and regenerating D. japonica can bioactivate chlorpyrifos and diazinon into their respective oxons. Significant AChE inhibition was only observed after in vivo metabolic activation but not when the parent OPs were directly added to planarian homogenate using the same concentrations and timing. Using biochemical assays, we found that D. japonica has both carboxylesterase (24nmol/(min*mg protein)) and paraoxonase (60pmol/(min*mg protein)) activity. We show that planarian carboxylesterase activity is distinct from cholinesterase activity using benzil and tacrine. These results further support the use of D. japonica for OP toxicity studies.

Exploration of essential oil from Psychotria poeppigiana as an anti-hyperalgesic and anti-acetylcholinesterase agent: Chemical composition, biological activity and molecular docking

Ethnopharmacological relevanceLeaves from Psychotria poeppigiana Müll. Arg. (accepted as Palicourea tomentosa (Aubl.) Borhidi), Rubiaceae, has traditionally been used in medicine for treatments of inflammation and pain; Synonymously, Cephaelis elata for the treatment of dementia; However, few scientific studies have been evidence demonstrating this activity. Aim of the studyThe aim of this study was to investigate the chemical composition of P. poeppigiana essential oil obtained from leaves (EOPP) and its antioxidant, anti-inflammatory and acetylcholinesterase (AChE) activities. Molecular docking simulations were carried out with the main constituents. Materials and methodsEOPP (hydrodistillation) was analysed by gas chromatography-mass spectrometry (GC–MS). The fractionation of EOPP afforded germacrene D and bicyclogermacrene. The antioxidant activity of EOPP was determined by MDA assay. The inflammatory parameters were evaluated using CFA model (with paw edema, mechanical, thermal hyperalgesia, MPO and NAG) in EOPP (30, 100 and 300 mg/kg), germacrene D and bicyclogermacrene (30 mg/kg). The AChE inhibition was evaluated in rat brain structures and molecular docking simulations were carried out using Autodock v.4.3.2. ResultsGC-MS analysis identified 19 compounds, and the major compounds were germacrene D (29.38%) and bicyclogermacrene (25.21%). EOPP exhibited high antioxidant capacity (IC50 = 12.78 ± 1.36 μg/mL). All the tested doses of EOPP and both major constituents significantly inhibited cold and mechanical hyperalgesia and significantly blocked the increase in MPO activity 24 h after the CFA injection. There was significant AChE inhibition by EOPP and germacrene D in the cerebral cortex and hippocampus (>50%). Enzyme-ligand molecular modelling showed that the major constituents of EOPP interacted differently with AChE. ConclusionsThe chemical compounds of the essential oil from the leaves of P. poeppigiana is based mainly on terpenes, the sesquiterpenes germacrene D (29.38%) and bicyclogermacrene (25.21%) being the major compounds. EOPP presented antioxidant, anti-inflammatory and anti-acetylcholinesterase (AChE) activities. Besides, enzyme-ligand molecular modelling showed the EOPP may act as an anti-hyperalgesic and AChE inhibitory agent. Taken together, these results might be in accordance with if folk use for pain- and inflammation-related symptoms.

Preparation, Characterization, and Acetylcholinesterase Inhibitory Ability of the Inclusion Complex of β-Cyclodextrin–Cedar (Juniperus phoenicea) Essential Oil

The aim of the present study was the encapsulation of cedar (Juniperus phoenicea) essential oil (CEO) of Greek origin in β-cyclodextrin (β-CD) through the formation of inclusion complexes (ICs) using the co-precipitation method with different β-CD-to-CEO weight ratios (90:10, 85:15, 80:20, 70:30 (w/w)). The encapsulation of CEO in β-CD through host–guest interactions was confirmed by Nuclear Magnetic Resonance (NMR) spectroscopy, FT-IR spectroscopy, Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). The obtained ICs exhibited nanoscale size (315.9 nm to 769.6 nm),Polydispersity Index from 0.326 to 0.604 and satisfactory stability in suspension (−37.0 mV to −17.0 mV). The process yield was satisfactory, ranging between 65% and 78%, while the inclusion efficiency ranged from 10% to 27%. The in vitro release study conducted for the IC with the optimal characteristics (β-CD:CEO 80:20 (w/w)) exhibited a sustained release profile, with an initial burst effect in the first 5 h. The release profile could be well expressed by the Higuchi equation: Q = 18.893 t1/2 + 9.5919, R2 = 0.8491. The cedar EO presented significant acetylcholinesterase inhibition (IC50 37 μg/mL), which was prolonged by its encapsulation into the β-CD cavity.

Mosquito larvicidal activity of Annona reticulata extract and its lethal impacts on allelochemicals detoxifying enzymes in wild population dengue vector, Aedes aegypti

The dengue vector Aedes aegypti is exceptionally threatening worldwide as it causes a primary viral disease (dengue), even though the vector species has other viral loads. This study was aimed at investigating the Annona reticulata extract with respect to the larvicidal activity against the 4th instar larvae of Aedes aegypti, the toxicity on a non-target aquatic organism (Chironomus costatus), and the biochemical marker enzymes in the mosquito larvae. Among various solvent tested, ethyl acetate as extraction solvent showed the highest mortality (100%) at 200 ppm against Aedes aegypti with no adverse effect on the non-target aquatic organism tested. Besides, the ethyl acetate extract showed significant inhibition of acetylcholinesterase (19%), α- and β-carboxylesterases (47.2 & 70.3%, respectively), glutathione S-transferase (35.2%), and alkaline phosphatase (22.3%). Moreover, the protein (13.7%) and acid phosphatase (11.2%) were reduced without being significant in the quantitative analyses. In qualitative analyses, we also observed that all enzyme patterns showed differential expression upon exposure to the ethyl acetate extract against the 4th instar larvae of Aedes aegypti at a lethal concentration (LC50: 72.5 ppm) for 24 h. These findings precisely showed that the Annona reticulata active extract (using ethyl acetate) can be used as an alternative in pest and vector control management contributing towards not spreading infectious diseases.

Reproduction and biomarker responses of Eisenia fetida after exposure to imidacloprid in biochar-amended soil

Terrestrial and aquatic ecosystems are increasingly threatened by pesticide pollution resulting from extensive use of pesticides, and due to the lack of regulatory measures in the developing world, there is a need for affordable means to lessen environmental effects. This study aimed to investigate the impact of biochar amendment on the toxicity of imidacloprid to life-cycle parameters and biomarker responses of the earthworm Eisenia fetida. E. fetida was exposed to 10% biochar-amended and non-amended OECD artificial soils spiked with 0, 0.75, 1.5, 2.25 and 3 mg imidacloprid/kg for 28 days. An LC50 of 2.7 mg/kg was only computed in the non-amended soil but not in the biochar-amended soil due to insignificant mortality. The EC50 calculated in the non-amended soil (0.92 mg/kg) for reproduction (fertility) was lower than the one computed in the biochar amended (0.98 mg/kg), indicating a decrease in toxicity in the biochar-amended substrate. Significant weight loss was observed at the two highest imidacloprid treatments in the non-amended soil and only at the highest treatment in the biochar-amended substrate, further highlighting the beneficial effects of biochar. Catalase activity decreased significantly at the two highest concentrations of non-amended soil. Yet, in the amended soil, the activity remained high, especially in the highest concentration, where it was significantly higher than the controls. This indicated more severe oxidative stress in the absence of biochar. In all non-amended treatments, there was a significant acetylcholinesterase inhibition, while lower inhibition percentages were observed in the biochar-amended soil. In most endpoints, the addition of biochar alleviated the toxic effects of imidacloprid, which shows that biochar has the potential to be useful in soil remediation. However, there is still a need for field studies to identify the most effective application rate of biochar for land application.

INFLUÊNCIA DA TEMPERATURA NOS EFEITOS DO INSETICIDA CARBARIL EM GIRINOS DE RÃ TOURO (LITHOBATES CATESBEIANUS).

Inseticidas carbamatos, como o carbaril, exercem efeitos tóxicos em animais por inibirem a atividade de B-esterases, tais como a acetilcolinesterase (AChE) e carboxilesterase (CbE). Carbamatos usados na agricultura podem atingir os ambientes aquáticos afetando organismos não-alvo, tais como animais aquáticos. Anfíbios anuros são particularmente sensíveis aos efeitos de agrotóxicos, por apresentarem fase inicial de vida totalmente aquática e muitas vezes limitada a ambientes próximos à agricultura. Variações na temperatura da água exercem efeitos importantes nas respostas dos organismos às intoxicações, pois alteram a concentração do oxigênio dissolvido na água, as reações metabólicas e a ventilação das brânquias. No presente trabalho, foram caracterizadas as atividades da AChE e da CbE em girinos de rã touro (Lithobates catesbeianus), obtendo-se condições ótimas de ensaio das atividades das enzimas por espectrofotometria e em géis de eletroforese. Foram também caracterizadas as sensibilidades das duas enzimas à inibição pelo carbamato carbaril em testes in vitro, sendo constatado que a AChE é mais sensível que a CbE. Posteriormente, animais foram expostos à duas concentrações (10 e 100 ug/L) do carbaril, por 10 dias, e sob três diferentes temperaturas (20, 25 e 30º C). Em nenhum dos grupos foi observada inibição significativa da AChE ou da CbE; porém esta última aumentou de atividade nos grupos expostos à maior concentração do carbaril nas duas menores temperaturas. Apesar dos efeitos in vitro, os experimentos in vivo demonstraram que os girinos de rã touro apresentam mecanismos eficazes para evitar ou compensar eventuais inibições de suas esterases pelo carbaril.

Mood-related behavioral and neurochemical alterations in mice exposed to low chlorpyrifos levels during the brain growth spurt.

Organophosphates are among the most used pesticides. Particularly, chlorpyrifos (CPF) is responsible for a number of deleterious effects on brain development, which may program behavioral changes later in life. Here, we investigated whether a regimen of early low level CPF exposure that did not result in a significant inhibition of acetylcholinesterase (AChE) had deleterious effects on mood-related behaviors, as well as on cholinergic and serotonergic biomarkers in the mice brain. From the 3rd to 9th postnatal day (PN), male and female Swiss mice were subcutaneously injected with CPF. Mice were submitted to a battery of behavioral tests from PN60 to PN63: open field, elevated plus maze and forced swimming tests. The cholinergic and serotonergic biomarkers were assessed at PN10 and PN63. Our data indicated that early CPF exposure increased anxiety-like behavior in females and altered decision-making behavior in both sexes. Most biochemical alterations were sex-dependent and restricted to females. At PN10, CPF female mice showed increased serotonin and choline transporter binding in cerebral cortex. Distinctively, in adult females, the effects indicated a hypoactive state: CPF exposure reduced 5-HT1a receptor binding in cerebral cortex, as well as serotonin transporter binding and choline acetyltransferase activity in brainstem. Our results indicate that CPF exposure during the brain growth spurt deregulates serotonergic and cholinergic biomarkers. The effects are consistent with impaired synaptic function, may be related to long-term mood disorders and point out to higher female susceptibility.

Design and Microwave-Assisted Synthesis of Aza-Resveratrol Analogs with Potent Cholinesterase Inhibition

Currently approved Alzheimer's disease medications mainly comprise acetylcholinesterase inhibitors. Many of these inhibitors are either natural compounds or synthetic molecules inspired in natural compounds. Hybrid molecules that can interact with different target sites of the enzyme could lead to the discovery of effective multitarget drugs. To design, synthesize, and evaluate a series of new aza-resveratrol analogs as in vitro acetyl- and butyrylcholinesterase inhibitors. The synthesis is achieved by a simple and efficient microwave-assisted method, from commercially available starting materials. Compounds are designed as hybrids of an aza-stilbene nucleus (Schiff base) connected to a tertiary amine by a hydrocarbon chain of variable length, designed to interact both with the peripheric anionic site and the catalytic site of the enzyme. All the derivatives inhibit both enzymes in a concentration-dependent manner, acting as moderate to potent cholinesterase inhibitors. The most potent inhibitors are compounds 12b (IC50 = 0.43 μM) and 12a (IC50 = 0.31 μM) for acetyl- and butyrylcholinesterase, respectively. Compounds 12a and 12b also exhibit significant acetylcholinesterase inhibition in SH-SY5Y human neuroblastoma cells without cytotoxic properties. Enzyme kinetic studies and molecular modeling reveal that inhibitor 12b targets both the catalytic active site and the peripheral anionic site of acetylcholinesterase what makes it able to modulate the self-induced β-amyloid aggregation. Furthermore, the molecular modeling analysis helps to assess the impact of the linker length in the inhibitory activity of this family of new cholinesterase inhibitors. These compounds have the potential to serve as a dual binding site inhibitor and might provide a useful template for the development of new anti-Alzheimer's disease agents.

Macrolobin: A new unusual C-glycoside chromone from Macrolobium latifolium and its anticholinesterase and antimicrobial activities

Abstract This work describes the chemical and biological investigations of leaves and stems of Macrolobium latifolium (Vogel). The DCM, EtOAc soluble fractions obtained by liquid-liquid partition the crude methanolic extract of this species were submitted to usual chromatographic techniques which permitted to isolate an unusual 5,7-dihydroxychromone-3α- d -C-glucoside, named macrolobin, along with the known compounds identified as β-taraxerol, friedelin, stigmasterol, β-sitosterol, campesterol, and apigenin. The structures of all compounds were elucidated by 1H, 13C, HSQC and HMBC NMR spectra, IR spectra data analysis, and MS. Furthermore, the chemical profile from fatty acids and/or triglycerides fraction was also determined after transesterification. The reaction products were subjected to GC-FID and GC–MS permitted to detected methyl palmitate as the main fatty acid derivate present in the oil and, lauric (7.52 %), octadecanoic (17.15 %), docosanoic (5.36 %), tricosanoic (11.83 %) and tetracosanoic as minor methyl esters. Concerning the biological activities, the organic soluble fractions and macrolobin displayed antimicrobial activity against Salmonella enterica, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli (MIC values 125−1000 μg.mL−1) and, macrolobin exhibited significant acetylcholinesterase inhibition (IC50 0.8 μM). These findings indicate M. latifolium can contribute with the development of new bioactive compounds, especially the AChE inhibition.

Learning and memory retention deficits in prepubertal guinea pigs prenatally exposed to low levels of the organophosphorus insecticide malathion

High doses of malathion, an organophosphorus (OP) insecticide ubiquitously used in agriculture, residential settings, and public health programs worldwide, induce a well-defined toxidrome that results from the inhibition of acetylcholinesterase (AChE). However, prenatal exposures to malathion levels that are below the threshold for AChE inhibition have been associated with increased risks of neurodevelopmental disorders, including autism spectrum disorder with intellectual disability comorbidity. The present study tested the hypothesis that prenatal exposures to a non-AChE-inhibiting dose of malathion are causally related to sex-biased cognitive deficits later in life in a precocial species. To this end, pregnant guinea pigs were injected subcutaneously with malathion (20 mg/kg) or vehicle (peanut oil, 0.5 ml/kg) once daily between approximate gestational days 53 and 63. This malathion dose regimen caused no significant AChE inhibition in the brain or blood of dams and offspring and had no significant effect on the postnatal growth of the offspring. Around postnatal day 30, locomotor activity and habituation, a form of non-associative learning, were comparable between malathion- and peanut oil-exposed offspring. However, in the Morris water maze, malathion-exposed offspring presented significant sex-dependent spatial learning deficits in addition to memory impairments. These results are far-reaching as they indicate that: (i) malathion is a developmental neurotoxicant and (ii) AChE inhibition is not an adequate biomarker to derive safety limits of malathion exposures during gestation. Continued studies are necessary to identify the time and dose dependence of the developmental neurotoxicity of malathion and the mechanisms underlying the detrimental effects of this insecticide in the developing brain.

Neuroprotective effects of Flaveria bidentis and Lippia salsa extracts on SH-SY5Y cells

Halophyte plants have to survive in a hostile environment by developing adaptive responses. One of these strategies is the production of several protective molecules which make these plants an interesting source of bioactive compounds. Significant acetylcholinesterase inhibition was observed for ethanolic extracts obtained from Lippia salsa Griseb. (Verbenaceae) and Flaveria bidentis (L.) Kuntze (Asteraceae), two plants that are widely distributed in the salt marsh Salitral de la Vidriera. These results encouraged us to further study the active constituents and the potential neuroprotective properties of these plants. The flavonoids luteolin (1) and apigenin (2) were identified as the active components of L. salsa, while 6-methoxykaempferol-3-sulfate (3) was obtained from F. bidentis. In addition, we investigated the cytotoxicity, cellular protection against K+-depolarization and antioxidant activity in SH-SY5Y neuroblastoma cells for these extracts and compound 3. Results demonstrated that beyond acting as acetylcholinesterase inhibitors, they also exhibited neuroprotective effects against KCl-induced-Ca2+ overload and oxidative stress.

Acute toxicity of essential oil compounds (thymol and 1,8-cineole) to insectivorous guppy, Poecilia reticulata Peters, 1859

Thymol and 1,8-cineole are now known bioinsecticidal monoterpenes occurring in many essential oils. The present study determined their toxicity on insectivorous guppy fish, Poecilia reticulata Peters, 1859 known to feed on mosquito larvae. The toxicity was recorded post 24 h treatment in experimental aquaria. The estimated median lethal concentration (LC50) values of thymol and 1,8-cineole for female fish were 12.51 and 3997.07 mg/L, respectively, and for males the concentration required was 10.99 and 1701.93 mg/L, respectively. There was significant inhibition of acetylcholinesterase (AChE) and carboxylesterase (CarE) in treated male fish after 1,8-cineole treatment, whereas thymol induced CarE in both sexes but induced only AChE in females. Overall, thymol and 1,8-cineole were moderately toxic to guppies compared to synthetic pesticides.