Acetylcholinesterase Activity Research Articles

Determination of Acetylcholinesterase Activity Based on Ratiometric Fluorescence Signal Sensing.

Acetylcholinesterase (AChE) plays an important role in the treatment of human diseases, environmental security and global food supply. In this study, the simple fluorescent indicators and MnO2 nanosheets were developed and integrated to establish a ratiometric fluorescence sensing system for the detection of AChE activity. Two fluorescence signals could be recorded independently at the same excitation wavelength, which extended the detection range and enhanced the visibility of results. Fluorescence of F-PDA was quenched by MnO2 nanosheets on account of inner filtering effect. Meanwhile, the nonfluorescent OPD was catalytically oxidized to 2,3-diaminophenazine by MnO2 nanosheets. The acetylcholine (ATCh) was catalytically hydrolyzed by AChE to enzymatic thiocholine, which decomposed MnO2 to Mn2+, recovered the fluorescence of F-PDA and reduced the emission of ox-OPD. Utilizing the fluorescence intensity ratio F468/F558 as the signal readout, the ratiometric fluorescence method was established to detect AChE activity. Under the excitation wavelength of 410nm, the ratio F460/F558 against the AChE concentration demonstrated two linear relationships in the range 0.05 -1.0 and 1.0-50 U·L- 1 with a limit of detection (LOD) of 0.073 U·L- 1. The method was applied to the detection of AChE activity and the analysis of the inhibitor Huperzine-A. Due to the advantages of high sensitivity and favorable selectivity, the method possesses an application prospect in the activity deteceion of AChE and the screening of inhibitors.

Neurotoxicity of Combined Exposure to the Heavy Metals (Pb and As) in Zebrafish (Danio rerio)

Lead (Pb) and arsenic (As) are commonly occurring heavy metals in the environment and produce detrimental impacts on the central nervous system. Although they have both been indicated to exhibit neurotoxic properties, it is not known if they have joint effects, and their mechanisms of action are likewise unknown. In this study, zebrafish were exposed to different concentrations of Pb (40 μg/L, 4 mg/L), As (32 μg/L, 3.2 mg/L) and their combinations (40 μg/L + 32 μg/L, 4 mg/L + 3.2 mg/L) for 30 days. The histopathological analyses showed significant brain damage characterized by glial scar formation and ventricular enlargement in all exposed groups. In addition, either Pb or As staining inhibited the swimming speed of zebrafish, which was enhanced by their high concentrations in a mixture. To elucidate the underlying mechanisms, we examined changes in acetylcholinesterase (AChE) activity, neurotransmitter (dopamine, 5-hydroxytryptamine) levels, HPI axis-related hormone (cortisol and epinephrine) contents and neurodevelopment-related gene expression in zebrafish brain. The observations suggest that combined exposure to Pb and As can cause abnormalities in swimming behavior and ultimately exacerbate neurotoxicity in zebrafish by interfering with the cholinergic system, dopamine and 5-hydroxytryptamine signaling, HPI axis function as well as neuronal development. This study provides an important theoretical basis for the mixed exposure of heavy metals and their toxicity to aquatic organisms.

Design, Synthesis and Evaluation of 8‐(Piperazin‐1‐yl) Imidazo[1,2‐a]Pyrazine Derivatives as Acetylcholinesterase Inhibitors and Antioxidants

AbstractA series of 8‐(piperazin‐1‐yl) imidazo [1,2‐a] pyrazine derivatives were designed and synthesized as acetylcholinesterase inhibitors (AChEIs) and antioxidants for the treatment of Alzheimer's disease (AD). Moreover, the biological evaluation results demonstrated that these synthesized compounds exhibited moderate inhibitory activities toward acetylcholinesterase (AChE) and radical scavenging activities. Among them, the compound with the strongest inhibitory activity against AChE had an IC50 value of 0.55 μM, which was higher than that of galantamine as the reference compound (IC50 value=5.01 μM). The compound with the strongest antioxidant activity had an IC50 value of 57.94 μM, which was lower than that of the ascorbic acid (IC50 value=25.70 μM) as the control drug. Furthermore, the results of molecular docking studies indicated that the compound could simultaneously bind to both catalytic active site (CAS) and peripheral anionic site (PAS) of AChE, which was consistent with the mixed inhibition pattern shown by enzyme kinetic studies. The interaction's stability was also assessed using a conventional atomistic 100 ns dynamics simulation study, which revealed the conformational stability of representative compound in the cavity of the AChE. In addition, the molecular properties of all compounds were predicted online through the SwissADME, and most compounds matched the properties of most orally administered drugs. Based on the biological activity and molecular properties, 8‐(piperazin‐1‐yl) imidazo[1,2‐a] pyrazine derivatives as AChEI were valuable for further development.

Effects of Green and Gold Kiwifruit Varieties on Antioxidant Neuroprotective Potential in Pigs as a Model for Human Adults

Kiwifruit (KF) has shown neuroprotective potential in cell-based and rodent models by augmenting the capacity of endogenous antioxidant systems. This study aimed to determine whether KF consumption modulates the antioxidant capacity of plasma and brain tissue in growing pigs. Eighteen male pigs were divided equally into three groups: (1) bread, (2) bread + Actinidia deliciosa cv. ‘Hayward’ (green-fleshed), and (3) bread + A. chinensis cv. ‘Hort16A’ (yellow-fleshed). Following consumption of the diets for eight days, plasma and brain tissue (brain stem, corpus striatum, hippocampus, and prefrontal cortex) were collected and measured for biomarkers of antioxidant capacity, enzyme activity, and protein expression assessments. Green KF significantly increased ferric-reducing antioxidant potential (FRAP) in plasma and all brain regions compared with the bread-only diet. Gold KF increased plasma ascorbate concentration and trended towards reducing acetylcholinesterase activity in the brain compared with the bread-only diet. Pearson correlation analysis revealed a significant positive correlation between FRAP in the brain stem, prefrontal cortex, and hippocampus with the total polyphenol concentration of dietary interventions. These findings provide exploratory evidence for the benefits of KF constituents in augmenting the brain’s antioxidant capacity that may support neurological homeostasis during oxidative stress.

Trace Amount of Bi-Doped Core-Shell Pd@Pt Mesoporous Nanospheres with Specifically Enhanced Peroxidase-Like Activity Enable Sensitive and Accurate Detection of Acetylcholinesterase and Organophosphorus Nerve Agents.

The urgent need for sensitive and accurate assays to monitor acetylcholinesterase (AChE) activity and organophosphorus pesticides (OPs) arises from the imperative to safeguard human health and protect the ecosystem. Due to its cost-effectiveness, ease of operation, and rapid response, nanozyme-based colorimetry has been widely utilized in the determination of AChE activity and OPs. However, the rational design of nanozymes with high activity and specificity remains a great challenge. Herein, trace amount of Bi-doped core-shell Pd@Pt mesoporous nanospheres (Pd@PtBi2) have been successfully synthesized, exhibiting good peroxidase-like activity and specificity. With the incorporation of trace bismuth, there is a more than 4-fold enhancement in the peroxidase-like performance of Pd@PtBi2 compared to that of Pd@Pt. Besides, no significant improvement of oxidase-like and catalase-like activities of Pd@PtBi2 was found, which prevents interference from O2 and undesirable consumption of substrate H2O2. Based on the blocking impact of thiocholine, a colorimetric detection platform utilizing Pd@PtBi2 was constructed to monitor AChE activity with sensitivity and selectivity. Given the inhibition of OPs on AChE activity, a biosensor was further developed by integrating Pd@PtBi2 with AChE to detect OPs, capitalizing on the cascade amplification strategy. The OP biosensor achieved a detection limit as low as 0.06 ng mL-1, exhibiting high sensitivity and anti-interference ability. This work is promising for the construction of nanozymes with high activity and specificity, as well as the development of nanozyme-based colorimetric biosensors.

Protective effect of Ganoderma lucidum-fermented crop extracts against hydrogen peroxide- or β-amyloid-induced damage in human neuronal SH-SY5Y cells

BackgroundAlzheimer's disease (AD) is a neurodegenerative disorder characterized by the accumulation of stacked β-amyloid peptides in the brain and associated with the generation of oxidative stress. So far, there is no cure for AD or a way to stop its progression. Although the neuroprotective effects of Ganoderma lucidum aqueous extract and G. lucidum-derived triterpenoids and polysaccharides have been reported, the influence of G. lucidum-fermented crops on AD still lacks clarity.MethodsThis study aimed to investigate the protective effect of G. lucidum-fermented crop extracts against hydrogen peroxide- or β-amyloid peptide (Aβ25-35)-induced damage in human neuroblastoma SH-SY5Y cells.ResultsVarious extracts of G. lucidum-fermented crops, including extract A: 10% ethanol extraction using microwave, extract B: 70˚C water extraction, and extract C: 100˚C water extraction followed by ethanol precipitation, were prepared and analyzed. Extract B had the highest triterpenoid content. Extract C had the highest total glucan content, while extract A had the highest gamma-aminobutyric acid (GABA) content. The median inhibitory concentration (IC50, mg/g) for DPPH and ABTS scavenging activity of the fermented crop extracts was significantly lower than that of the unfermented extract. Pretreatment with these extracts significantly increased the cell viability of SH-SY5Y cells damaged by H2O2 or Aβ25-35, possibly by reducing cellular reactive oxygen species (ROS) and malondialdehyde (MDA) levels and increasing superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) activities. Moreover, extract B markedly alleviated the activity of acetylcholinesterase (AChE), which is crucial in the pathogenesis of AD.ConclusionThese results clearly confirmed the effects of G. lucidum-fermented crop extracts on preventing against H2O2- or Aβ25-35-induced neuronal cell death and inhibiting AChE activity, revealing their potential in management of AD.

The role of the cholinergic system in the memory-protecting effects of metformin in a model of scopolamine-induced memory impairment in aged rats

PurposeAs the elderly population grows, the prevalence of dementia is also rapidly increasing worldwide. Metformin, an antidiabetic drug, has been shown to have ameliorative effects on impaired cognitive functions in experimental models. However, studies have generally used young animals. Additionally, although it has a major role in Alzheimer's disease (AD) and memory, literature information about the effects of metformin on the cholinergic system is limited. In this study, we investigated the effects of metformin on memory in a model of scopolamine-induced memory impairment in aged rats. We also examined the effects of metformin on the cholinergic system, which is very important in cognitive functions. MethodsMetformin was administered orally to male Wistar rats (20-22 months old) at 100mg/kg/day for three weeks. Morris water maze (MWM) tests were performed to assess spatial memory. Before the probe test of the MWM test, scopolamine was injected intraperitoneally at a dose of 1mg/kg. After testing, animals were sacrificed, whole brains were removed, and hippocampus samples were separated for biochemical analysis. ResultsImpaired memory associated with scopolamine administration was reversed by metformin. In addition, metformin administration ameliorated scopolamine-induced changes in acetylcholine (ACh) levels, acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), and choline acetyltransferase (ChAT) activity. ConclusionOur results show that metformin may have protective effects in a scopolamine-induced memory impairment model in aged animals by improving cholinergic function. Metformin shows promise in preventing dementia with its dual cholinesterase inhibition and ChAT activation effect.

Flavonoid-Rich Trianthema decandra Ameliorates Cognitive Dysfunction in the Hyperglycemic Rats.

The present study was aimed at the evaluation of neuroprotective ability of methanolic extract of Trianthema decandra (METD) against hyperglycemia-related cognitive impairment in rats. The extract of T. decandra was standardized by TLC and HPTLC methods. To verify the identity and purity of isolated compounds, they were segregated and characterized using various techniques, including UV-visible spectrophotometry, FT-IR, H-NMR, and Mass spectroscopy. α-Amylase and α-glucosidase inhibition property of the extracts were assessed in-vitro. The screening of the neuroprotective effects of METD in hyperglycemic rats was done utilizing Morri's water (MWM) and elevated plus maze (EPM) model, as well as acetylcholinesterase (AChE) activity. The extracts of Trianthema decandra and its chemical constituents, namely quercetin and phytol, demonstrated a significant protective effect on enzymes like α-amylase and α-glucosidase. Methanol and hydroalcoholic extracts have shown the strongest inhibitory activity followed by chloroform extract. Quercetin and phytol were associated with the methanolic and chloroform extracts which were identified using TLC and HPTLC techniques. During the thirty days of the study, the induction of diabetes in the rats exhibited persistent hyperglycemia, hyperlipidemia, higher escape latency during training trials and reduced time spent in target quadrant in probe trial in Morris water maze test, and increased escape latency in EPM task. Regimen of METD (200 and 400 mg/kg) in the diabetic rats reduced the glucose levels in blood, lipid, and liver profile and showed positive results on Morri's water and elevated plus maze tasks. During the investigation, it was determined that Trianthema decandra extracts and the chemical constituent's quercetin and phytol in it had anti-diabetic and neuroprotective activities.

Antinociceptive Analysis of Natural Monoterpenes Eugenol, Menthol, Carvacrol and Thymol in a Zebrafish Larval Model

In the last decade, a considerable number of studies have broadened our knowledge of the nociceptive mechanisms of pain, a global health problem in both humans and animals. The use of herbal compounds such as eugenol, menthol, thymol, and carvacrol as analgesic agents has accompanied the growing interest in this area, offering a possible solution for this complex problem. Here, we aimed to explore how these natural substances—at three different concentrations (2, 5 and 10 mg/L)—affect the pain responses in zebrafish (Danio rerio) larvae exposed to 0.05% acetic acid (AA) for 1 min. By analysing the activity of acetylcholinesterase (AChE), 5′-ectonucleotidase and NTPDases, as well as aversion and exploratory behaviours, it was observed that that although all substances were effective in counteracting the pain stimulus, the concentration range within which they do so might be very limited. Eugenol, despite its acknowledged properties in fish anaesthesia, failed to alleviate the pain stimulus at low concentrations. Contrastingly, menthol exhibited the most promising results at the lowest concentrations tested. Overall, it is concluded that menthol might be a good analgesic for this species, qualifying it as a substance of interest for prospective studies.

Sensitivity of cholinesterases and carboxylesterases to pharmaceutical products in Tinca tinca.

Discharges to the aquatic environment of pharmaceuticals represent a hazard to the aquatic organisms. Subchronic assay with 17-alpha-ethinylestradiol (EE2) and in vitro essays with pharmaceuticals of environmental concern were conducted to examine the sensitivity of tissue acetylcholinesterase (AChE) and carboxylesterase (CbE) activities of Tinca tinca to them. Subchronic exposure to 17-alpha-EE2 caused significant effects on brain, liver, and muscle CbE, but no on AChE activities. Most of the pharmaceuticals tested in vitro were considered as weak inhibitors of tissular AChE activity. Depending on the tissues, some compounds were classified as moderate inhibitors of CbE activity while other were categorized as weak enzymatic inhibitors. An opposite trend was observed depending on the tissue, while brain and liver CbE activities were inhibited, the muscle CbE activity was induced. Changes experienced on enzymatic activities after exposure to pharmaceuticals might affect the physiological functions in which these enzymes are involved. In vitro exposure to 17-alpha-EE2 in tench could be an informative, but not a surrogate model to know the effect of this synthetic estrogen on AChE and CbE activities.

Enrofloxacin exposure undermines gut health and disrupts neurotransmitters along the microbiota-gut-brain axis in zebrafish

Enrofloxacin exposure undermines gut health and disrupts neurotransmitters along the microbiota-gut-brain axis in zebrafish

Insecticidal efficacy of some apiaceae plant metabolites against glyphodes pyloalis walker (lepidoptera: pyralidae)

Botanical based-insecticides are presently recognized to interfere behavioral and physiological performances of herbivorous insects. In the current study, the insecticidal properties of Pimpinella anisum, Foeniculum vulgare and Heracleum persicum essential oils (EOs), and their main component, trans-anethole, were studied on a destructive pest of mulberry leaves, Glyphodes pyloalis Walker. The effect of essential oils (EOs) on the larval feeding was evaluated by the leaf-dipping method and demonstrated the highest insecticidal and antifeedant activities of F. vulgare and H. persicum. Apart from negative effects on feeding indices, feeding treatment with the EOs significantly inhibited the activities of digestive enzymes and acetylcholinesterase (AChE). At nearly, all the tested compounds increased the activities of detoxifying and antioxidant enzymes. Thus, these EOs demonstrate potential as new control products to combat G. pyloalis, and they may function as an insecticide, antifeedant, or inhibitor of physiological performance.

Synthesis, biological activity, X-ray crystallographic, DFT calculations and molecular dynamics simulation studies of 2-phenylthiazole-1,3,5-triazine derivatives as potential cholinesterase inhibitors

Seven 2-phenylthiazole-1,3,5-triazine derivatives were synthesized and estimated for cholinesterase inhibitory activity. All target compounds were characterized by 1H NMR, 13C NMR, FT-IR, and HRMS, and their purity was tested by HPLC to be above 99 %. The in vitro enzyme inhibitory activity assays determined that the majority of compounds exhibited moderate to good inhibitory effects on acetylcholinesterase or butyrylcholinesterase and compound 6g displayed the best acetylcholinesterase (IC50 = 0.26 μM) and butyrylcholinesterase inhibitory activity (IC50 = 0.78 μM). The structures of compounds 6a and 6g was further investigated by single-crystal X-ray diffraction, and the Hirshfeld surfaces, crystal voids, and molecular energy framework analysis were further discussed to study the molecular conformations, crystal packing modes, intermolecular interactions, and their energies. What's more, the density functional theory calculations including frontier molecular orbitals, global reactivity descriptors, and molecular electrostatic potential were carried out to reveal the chemical reactivity and stability of 6a and 6g molecules. Molecular docking study indicated that compound 6g could not only interact with acetylcholinesterase but also with butyrylcholinesterase. Molecular dynamics simulations study showed that compound 6g could bind to acetylcholinesterase stably. In addition, ADMET properties prediction implied the drug-like properties and safety of seven compounds. Considering these results, several of the target compounds could work as novel cholinesterase inhibitors, and compound 6g may possess the potential to become a lead compound to develop novel anti-Alzheimer drugs.

Enzymatic synthesis of Artemisia capillaris-derived prebiotic oligosaccharide using Leuconostoc mesenteroides MKSR dextransucrase and its potential health functional effects

This study focuses on the enzymatic synthesis of prebiotic oligosaccharide from Artemisia capillaris (AC) using Leuconostoc mesenteroides MKSR dextransucrase and explores their antidiabetic, antidementia, and antioxidant effects through in vitro experiments. A Box-Behnken design was used to optimize transglycosylation conditions to produce Artemisia capillaris-derived oligosaccharide (ACOD) containing isomaltooligosaccahrides (IMO), dextran, and A. capillaris-derived substances with high α-glucosidase inhibition (AGI). The optimized conditions were 3.62 brix of AC, 182.54 mM sucrose, and 11.304 mM maltose. ACOD completely inhibited α-glucosidase activity, with 1.52-fold increase compared to other samples, such as OD (IMO and dextran, transglycosylated by dextransucrase without AC) and AC + OD (a simple mixture of AC and OD). Additionally, ACOD showed noteworthy acetylcholinesterase (103.91%) and butyrylcholinesterase (103.30%) inhibitory activity and potent antioxidant properties in terms of DPPH radical scavenging activity (70.04%), reducing power (100%), and ferric reducing antioxidant power (FRAP). ACOD (3.60) showed a higher prebiotic index compared with AC (-23.11), OD (-2.27), and AC + OD (-9.12). In conclusion, ACOD offers enhanced multi-biological activities as a potential health-functional prebiotic. These findings hold promise for applications in functional foods and pharmaceuticals, expanding our understanding of prebiotic functionality.

Myclobutanil induces neurotoxicity by activating autophagy and apoptosis in zebrafish larvae (Danio rerio)

Myclobutanil (MYC), a typical broad-spectrum triazole fungicide, is often detected in surface water. This study aimed to explore the neurotoxicity of MYC and the underlying mechanisms in zebrafish and in PC12 cells. In this study, zebrafish embryos were exposed to 0, 0.5 and 1 mg/L of MYC from 4 to 96 hours post fertilization (hpf) and neurobehavior was evaluated. Our data showed that MYC decreased the survival rate, hatching rate and heart rate, but increased the malformation rate and spontaneous movement. MYC caused abnormal neurobehaviors characterized by decreased swimming distance and movement time. MYC impaired cerebral histopathological morphology and inhibited neurogenesis in HuC:egfp transgenic zebrafish. MYC also reduced the activities of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and downregulated neurodevelopment related genes (gfap, syn2a, gap43 and mbp) in zebrafish and PC12 cells. Besides, MYC activated autophagy through enhanced expression of the LC3-II protein and suppressed expression of the p62 protein and autophagosome formation, subsequently triggering apoptosis by upregulating apoptotic genes (p53, bax, bcl-2 and caspase 3) and the cleaved caspase-3 protein in zebrafish and PC12 cells. These processes were restored by the autophagy inhibitor 3-methyladenine (3-MA) both in vivo and in vitro, indicating that MYC induces neurotoxicity by activating autophagy and apoptosis. Overall, this study revealed the potential autophagy and apoptosis mechanisms of MYC-induced neurotoxicity and provided novel strategies to counteract its toxicity.

Assessing the water quality in a World Heritage Site using biomarkers in top fish predators

The use of biomarkers in fish for biomonitoring is a valuable approach to reveal effects of human impacts on biota health. Top predator fish are effective models for monitoring human activities' impacts on aquatic ecosystems. The Guaraguaçu River is the largest river-system on coastal region of South Brazil and a World Heritage site. The river receives contaminants from disorderly urban growth, including discharges of domestic sewage and small fishery boats, particularly during the tourist season. Our study aimed to assess impact of anthropogenic activities on water quality in the Guaraguaçu River by analyzing environmental contamination biomarkers in the top fish predator Hoplias malabaricus. Fish were collected using a fyke net trap across sectors representing a gradient of anthropic impact: sector 1 - pristine; sector 2 – impacted; and sector 3 - less impacted. Water samples were collected to analyze the presence of trace elements and pesticide. Biomarkers of the antioxidant system, histopathology, genotoxicity, neurotoxicity, and concentration of trace elements were analyzed in fish tissues. In water samples Al, Fe and Mn were detected, but no pesticides were found. In fish muscle, zinc and iron were detected. Brain acetylcholinesterase activity decreased in impacted sectors, indicating neurotoxic effects. The antioxidant system increased activity in gills and liver, and damage from lipoperoxidation was observed, particularly in sector 2 when compared to sector 1, suggesting oxidative stress. Histopathological biomarkers revealed lesions in the liver and gills of fish in impacted sectors. Micronuclei, a genotoxicity biomarker, were observed in organisms from all sectors. Our results demonstrate detrimental effects of poor water quality on biota health, even when contaminants are not detected in water.

Treatment of Organophosphorus Poisoning with 6-Alkoxypyridin-3-ol Quinone Methide Precursors: Resurrection of Methylphosphonate-Aged Acetylcholinesterase.

Organophosphorus (OP) nerve agents inhibit acetylcholinesterase (AChE), creating a cholinergic crisis in which death can occur. The phosphylated serine residue spontaneously dealkylates to the OP-aged form, which current therapeutics cannot reverse. Soman's aging half-life is 4.2 min, so immediate recovery (resurrection) of OP-aged AChE is needed. In 2018, we showed pyridin-3-ol-based quinone methide precursors (QMPs) can resurrect OP-aged electric eel AChE in vitro, achieving 2% resurrection after 24 h of incubation (pH 7, 4 mM). We prepared 50 unique 6-alkoxypyridin-3-ol QMPs with 10 alkoxy groups and five amine leaving groups to improve AChE resurrection. These compounds are predicted in silico to cross the blood-brain barrier and treat AChE in the central nervous system. This library resurrected 7.9% activity of OP-aged recombinant human AChE after 24 h at 250 μM, a 4-fold increase from our 2018 report. The best QMP (1b), with a 6-methoxypyridin-3-ol core and a diethylamine leaving group, recovered 20.8% (1 mM), 34% (4 mM), and 42.5% (predicted maximum) of methylphosphonate-aged AChE activity over 24 h. Seven QMPs recovered activity from AChE aged with Soman and a VX degradation product (EA-2192). We hypothesize that QMPs form the quinone methide (QM) to realkylate the phosphylated serine residue as the first step of resurrection. We calculated thermodynamic energetics for QM formation, but there was no trend with the experimental biochemical data. Molecular docking studies revealed that QMP binding to OP-aged AChE is not the determining factor for the observed biochemical trends; thus, QM formation may be enzyme-mediated.

Pathogenicity, infection process, physiological and biochemical effects of Metarhizium rileyi against Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) larvae

BackgroundMetarhizium rileyi is an important entomopathogenic fungus which has a wide range of host pests. In this work, the virulence of M. rileyi EFNL-08 against 3rd instar larvae of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), was quantified. Additionally, the infection process and aspects of the host immunological response were described in the laboratory.ResultsBioassay results proved that M. rileyi was highly virulent to 3rd instar S. frugiperda larvae with 98.33% mortality at 1 × 108 conidia/ml. Scanning electron microscopy was used to monitor morphological aspects of the infection process. When hyphal bodies (Hbs) of M. rileyi were injected into the hemocoel of host, they were not recognized by the host’s immune system as invaders. There were nonsignificant differences in the hemocytes and phenoloxidase activity between the infected and control larvae at the initial 30 h, indicating that fungus successfully avoids the attack from the immune system. However, it inhibited the enzyme activity at the latest stage when Hbs reached a high density. After infection with M. rileyi, the activity of glutathione-S-transferase (GST) of S. frugiperda larvae presented a significant upward trend, while the activity of acetylcholinesterase (AchE) initially increased, followed by a decrease, and eventually stabilized. However, the activity of both detoxification enzymes in the control group showed slight fluctuations in the initial stage, and then stabilized at a low level.ConclusionObtained results provided new insights into the virulence and potential physiological responses of M. rileyi. This provides ideas for further development of novel and efficient entomopathogenic fungi (EPF) for pest control.

Ameliorative potential of Astaxanthin on glyphosate-induced neurocognitive functional changes in adult zebrafish via acid phosphatase and annexin A2 dysfunction

Glyphosate (GYP) is a phosphonate type of herbicide and potentially causes neurodegenerations. Astaxanthin (AST) is a red pigment and it is a group of carotenoids. It possesses the potential antioxidants and neuroprotective actions. However, the ameliorative role of AST in GYP- induced neurocognitive dysfunction has not been studied yet. Hence, the present study is designed to investigate the ameliorative potential of AST in GYP-induced cognitive dysfunction via regulations of acid phosphatase (AP) and annexin A2 (AXA2) actions in the zebrafish model. The cognitive dysfunction was induced by exposure to GYP (0.5 mg/L for 30 minutes/day) for 14 consecutive days. The AST (50, 75, and 100 mg/L for 30 minutes/day) and reference drug i.e., donepezil (DP; 1 µg/mL for 30 minutes/day) were exposed for 14 consecutive days before GYP exposure. On the 14th day, cognitive changes i.e., three horizontal compartment test,optokinetic motor response (OMR), startle response (SR), and T-maze tests were assessed. The changes of biomarkers i.e., acetylcholinesterase (AChE) activity, thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), AP, and AXA2 levels were estimated in brain tissue. The administration of AST ameliorates the GYP-induced neurocognitive dysfunctions via the antioxidant, regulation of AP and AXA2 actions. Hence, it can be used for neurocognitive disorders against the phosphonate type of herbicide (GYP) toxicity.

Assessment ofdeltamethrin-induced DNA damage, neurotoxic and neuroimmune effects inthe brain tissue ofbrown trout (Salmo trutta fario).

This study investigated the impact ofdeltamethrin (DM) toxicity onbrown trout (Salmo trutta fario), examining its effects onthe immune system, including the white blood cell (WBC), lymphocyte (Lym), total immunoglobulin (T.Ig), and lysozyme levels, aswell asits neurotoxic consequences onthe brain tissue. Theneurotoxic effects encompassed oxidative stress, the activity ofthe antioxidant enzymes, such asthe superoxide dismutase (SOD) and catalase (CAT), acetylcholinesterase (AChE) activity, and DNA damage using 8-hydroxy-2-deoxyguanosine (8-OHdG). The DM exposure led toelevated levels ofmalondialdehyde (MDA), and 8-OHdG, while concurrently causing areduction inthe AChE activity, protein and lipid content, WBC count, Lym, lysozyme activity, T.Ig levels, aswell asthe SOD and CAT levels inthe brain tissues ofgroups2 and 3 when compared tothose ingroup1. Insummary, the findings ofthis study strongly indicate that DM induces DNA damage, immunotoxicity, and neurotoxicity inthe brain tissue ofbrown trout, primarily due tothe excessive production ofreactive oxygen species (ROS). Moreover, the observed dose-dependent responses ofDM tothe environmental concentrations onall theinvestigated parameters suggest its potential utility inaquaculture risk assessment.