Inhibition Of Brain Acetylcholinesterase Research Articles

The mechanistic basis for the toxicity difference between juvenile rats and mice following exposure to the agricultural insecticide chlorpyrifos

At high exposure levels, organophosphorus insecticides (OPs) exert their toxicity in mammals through the inhibition of brain acetylcholinesterase (AChE) leading to the accumulation of acetylcholine in cholinergic synapses and hyperactivity of the nervous system. Currently, there is a concern that low-level exposure to OPs induces negative impacts in developing children and the chemical most linked to these issues is chlorpyrifos (CPF). Our laboratory has observed that a difference in the susceptibility to repeated exposure to CPF exists between juvenile mice and rats with respect to the inhibition of brain AChE. The basis for this difference is unknown but differences in the levels of the detoxification mechanisms could play a role. To investigate this, 10-day old rat and mice pups were exposed daily for 7 days to either corn oil or a range of dosages of CPF via oral gavage. Four hours following the last administration of CPF on day 16, brain, blood, and liver were collected. The inhibition of brain AChE activity was higher in juvenile rats as compared to juvenile mice. The levels of activity of the detoxification enzymes and the impact of CPF exposure on their activity were determined in the two species at this age. In blood and liver, the enzyme paraoxonase-1 (PON1) hydrolyzes the active metabolite of CPF (CPF-oxon), and the enzymes carboxylesterase (CES) and cholinesterase (ChE) act as alternative binding sites for CPF-oxon removing it from circulation and providing protection. Both species had similar levels of PON1 activity in the liver and serum. Mice had higher ChE activity in liver and serum than rats but, following CPF exposure, the percentage inhibition was similar between species at an equivalent dosage. Even though rats had slightly higher liver CES activity than mice, the level of inhibition following exposure was higher in rats. In serum, juvenile mice had an 8-fold higher CES activity than rats, and exposure to a CPF dosage that almost eliminated CES activity in rats only resulted in 22% inhibition in mice suggesting that the high serum CES activity in mice as compared to rats is a key component in this species difference. In addition, there was a species difference in the sensitivity of CES to inhibition by CPF-oxon with rats having a lower IC50 in both liver and serum as compared to mice. This greater enzyme sensitivity suggests that saturation of CES would occur more rapidly in juvenile rats than in mice, resulting in more CPF reaching the brain to inhibit AChE in rats.

Inhibition of Serum Esterases in Juvenile Rats Repeatedly Exposed to Low Levels of Chlorpyrifos.

Chlorpyrifos (CPF) is an organophosphorus insecticide that has gained significant attention cue to the reported toxicity associated with developmental exposure. While the canonical mechanism of toxicity of CPF involves the inhibition of brain acetylcholinesterase (AChE), we have reported that exposure of juvenile rats to levels of CPF that do not yield any inhibition of brain AChE results in neurobehavioral alterations at later ages. However, it is unclear what effect exposure to these low levels of CPF has on blood esterase activities which are frequently used not only as biomarkers of exposure but also to set exposure levels in risk assessment. To determine this, male and female rat pups were exposed orally from postnatal day 10 to 16 to either corn oil (vehicle) or 0.5, 0.75, or 1.0 mg/kg CPF. At 12 h after the final exposure, serum cholinesterase (ChE), butyrylcholinesterase (BChE), and carboxylesterase (CES), and red blood cell (RBC) and brain AChE activities were determined. There were no differences between sexes in either the controls or individual treatments for all enzymes. Only the highest dosage of 1.0 mg/kg CPF yielded significant brain AChE inhibition (22-24%) but all dosages significantly inhibited the blood esterases with inhibition being highest with serum CES (65-85%) followed by serum BChE (57-76%), RBC AChE (35-65%), and then serum ChE (16-32%). Our data verify that blood esterases are inhibited at dosages of CPF that alter neurobehavioral performance in the absence of effects on brain AChE activity.

Emetine and Indirubin- 3- monoxime interaction with human brain acetylcholinesterase: A computational and statistical analysis.

Alzheimer's disease is a chronic neurodegenerative ailment and the most familiar type of dementia in the older population with no effective cure to date. It is characterized by a decrease in memory, associated with the mutilation of cholinergic neurotransmission. Presently, acetylcholinesterase inhibitors have emerged as the most endorsed pharmacological medications for the symptomatic treatment of mild to moderate Alzheimer's disease. This study aimed to research the molecular enzymatic inhibition of human brain acetylcholinesterase by a natural compound emetine and I3M. Molecular docking studies were used to identify superior interaction between enzyme acetylcholinesterase and ligands. Furthermore, the docked acetylcholinesterase-emetine complex was validated statistically using an analysis of variance in all tested conformers. In this interaction, H-bond, hydrophobic interaction, pi-pi, and Cation-pi interactions played a vital function in predicting the accurate conformation of the ligand that binds with the active site of acetylcholinesterase. The conformer with the lowest free energy of binding was further analyzed. The binding energy for acetylcholinesterase complex with emetine and I3M was -9.72kcal/mol and -7.09kcal/mol, respectively. In the current study, the prediction was studied to establish a relationship between binding energy and intermolecular energy (coefficient of determination [R2 linear = 0.999), and intermolecular energy and Van der wall forces (R2 linear = 0.994). These results would be useful in gaining structural insight for designing novel lead compounds against acetylcholinesterase for the effective management of Alzheimer's disease.

Anti-Amnesic Effect of Curculigo orchioides Plant Extract and Its Function on Acetylcholinesterase Enzyme

Background: Alzheimer’s disease (AD) is a progressive neurodegenerative disorder, and one of the most predominant causes of dementia in older people. Preventing acetylcholine from breakdown by an excess amount of acetylcholinesterase is a proven therapy for AD. Traditionally Curculigo orchioides is known for its antioxidant activity, enzyme inhibition activity, and other medicinal uses. In this study, in vitro acetylcholinesterase, inhibitory activity was investigated, and methanolic extract of the plant showed significant activity. This study aims to investigate cholinesterase inhibitory activity, learning, and memory-enhancing activity of Curculigo orchioides.
 Materials and Methods: The crude methanol extract of the dried powder was prepared by the cold extraction method. In-vitro acetylcholinesterase (AChE) inhibitory activities were determined by the modified Ellman’s method. To confirm learning and memory-enhancing effects, the scopolamine-induced memory impairment Swiss-albino mice were used, and to find the anti-amnesic effect of the extract, a passive shock avoidance task was applied.
 Results: Results proved that scopolamine-induced cognitive dysfunction decreased significantly by administration of the plant extract solution in the passive avoidance task, and inhibited brain acetylcholinesterase activity. While running an in-vitro AChE inhibitory test the IC50 was 0.782±0.067μg/ml.
 Conclusion: The results suggested that methanolic extract of Curculigo orchioides can inhibit AChE in-vitro. Besides this, it provides data that proves its ability to improve whole brain AChE activity and enhance memory.

Inhibition of rat brain and human red cell acetylcholinesterase by thiocarbamate herbicides.

Thiocarbamates are a major class of herbicides that were used extensively in the agricultural industry. Toxicological evaluation showed molinate caused reproductive impairment in male rats, whilst others produced behavioural effects at high doses. Rats dosed with molinate either as a single large oral dose of 100mg/kg or as multiple doses of 50mg/kg for 7 days produced inhibition of brain acetylcholinesterase (AChE). Molinate and other thiocarbamate herbicides undergo metabolism to form sulphoxides that can carbamoylate thiol's such as glutathione and proteins. We have chemically synthesised the sulphoxide and sulphone metabolites of six thiocarbamate herbicides and examined their ability to inhibit rat brain and human red cell AChE in vitro. Parent thiocarbamates were inactive, whilst the sulphoxides produced inhibition with IC50's in the 1-10mM range, the sulphone metabolites were the most active with IC50's for molinate, pebulate, EPTC and vernolate in the μM range. Inhibition was both time- and dose-dependent with biomolecular rate constants for the inhibition of the human red cell enzyme of 0.3×102 and 2.0×102M-1min-1 for molinate sulphoxide and sulphone, respectively. No recovery of enzyme activity, with either enzyme, was seen following dilution of the inhibitor to a concentration that does not inhibit the enzyme for up to 24h at 25°C at pH7.4. The metabolites of these thiocarbamate herbicides are rather poor inhibitors of AChE when compared to the organophosphorus ester, paraoxon or the monomethylcarbamate, eserine. Unlike eserine the inhibition produced by the thiocarbamates is irreversible.

Ex-vivo Acetylcholinesterase and Butyrylcholinesterase Inhibitory Activities Assay of G. asiatica and G. tiliaefolia (Tiliaceae) Leaves

Aims: Our study was carried out to appraise acetylcholinestrase (AChE) and butyrylcholinestrase (BChE) inhibitory activities of Grewia asiatica and Grewia tiliaefolia leaves extracts.
 Study Design: For the purpose of these experiments the extracts were subjected to an ex-vivo study.
 Place and Duration of Study: The study was carried out between June 2018 to December 2018 in the Department of Pharmacy, Southeast University, Dhaka, Bangladesh.
 Methodology: In this study, cholinesterase inhibitory activities of different fractions of crude ethanol extract of both plants were examined using swiss albino mice at 300 mg/kg b.w. dose. We determined anti-acetylcholinestrase (AChE) and anti-butyrylcholinestrase (BChE) activities using slightly modified Elman coupled enzyme assay.
 Results: The highest inhibition of bovine brain acetylcholinesterase and human blood butyrylcholinesterase were exhibited by PEF and CLF of G. asiatica with the IC50 values were found to be 55.88 μg/ml and 26.14 μg/ml respectively whereas the highest inhibition of bovine brain acetylcholinesterase and human blood butyrylcholinesterase were exhibited by CLF of G. tiliaefolia. 
 Conclusion: The result of the present study on various fractions of these plants has a considerable anti-acetylcholinesterase and anti-butyrylcholinesterase activities which suggest its effectiveness against various neurodegenerative disorders.

New cyclooctathienopyridine derivatives in the aim of discovering better Anti-Alzheimer's agents

The cure from Alzheimer's disease is a challenging mission. Acetylcholinesterase enzyme (AChE) inhibitors, including tacrine, are considered the most important line for Alzheimer's therapy. In the current study, we aimed at designing and synthesizing new thienopyridine-tacrine analogues. The molecular structures of the synthesized compounds were illustrated by spectroscopic and elemental analysis. These compounds have been screened for their in vivo brain acetyl cholinesterase inhibition activities. The majority of the tested compounds exhibited inhibitory activity towards AChE. The IC50 for the most promising members was determined in vitro. Interestingly, compound 11a displayed the best profile with IC50 of about 172 nM.

Protective role of hydroalcoholic extract of Cajanus cajan Linn leaves against memory impairment in sleep deprived experimental rats

BackgroundThe plant Cajanus cajan had earlier shown protective effect against hypoxic-ischemic brain damage in rats. ObjectiveHence, hydroalcoholic extract of C. cajan Linn leaves (HECC) was evaluated for its protective role against memory impairment in sleep-deprived Sprague Dawley rats. Materials and methodsAdult rats were divided into five groups each consisting of 5 rats (n = 5). Groups I, II, III, IV and V received 1 mL/kg 1% CMC, 1 mL/kg 1% CMC, 200 mg/kg HECC, 400 mg/kg HECC and 200 mg/kg piracetam respectively as per b.wt. orally everyday for 14 days. Animals of every groups except group-I were subjected to sleep-deprivation from 15th to 19th day for induction of memory impairment. Behavioral activities i.e., elevated plus maze test and locomotor activity were evaluated. Afterwards, brain was isolated from the sacrificed animals for biochemical investigation of acetylcholinesterase (AChE); antioxidant activities i.e., catalase (CAT), superoxide dismutase (SOD), lipid peroxide; and histopathological changes. ResultsThe percent number of entries, number of entries in open arm, AChE activity, lipid peroxide activity of HECC-treated group-III and group-IV were significantly (p < 0.01) decreased while, their CAT and SOD activities were significantly (p < 0.01) increased in dose-dependent manner as compared to sleep-deprived group-II. The activities of group-IV were almost significantly equivalent to that of piracetam-treated group-V. Protective effect of HECC was well supported with brain's histopathology. ConclusionHECC possesses a protective effect against memory impairment indicating its therapeutic efficacy against memory loss as in Alzheimer's disease. Probable underlying mechanisms may be brain's AChE inhibition and increased antioxidant potential by HECC.

Transcriptional effects of dietary chlorpyrifos‑methyl exposure in Atlantic salmon (Salmo salar) brain and liver

Elevated levels of chlorpyrifos‑methyl have been detected in plant-based Atlantic salmon feeds. To evaluate the potential negative effects of long-term and continuous dietary exposure to chlorpyrifos‑methyl in fish, we fed juvenile Atlantic salmon three concentrations (0.1, 1.0 and 8.0 mg/kg) of the pesticide for about two months. Brain and liver tissues were collected after 30 and 67 days of exposure. Homogenized brain tissue was examined for effects on acetylcholinesterase, and brain and liver tissue from fish exposed to 8.0 mg/kg were used for transcriptional analysis (RNA-seq). The results showed a transient accumulation of chlorpyrifos‑methyl in the brain with lower levels after 67 days of exposure compared to after 30 days of exposure. In contrast, the liver showed a time-dependent accumulation pattern. No effect on acetylcholinesterase activity, the primary target of chlorpyrifos‑methyl, was seen in the brain. However, after 30 days of exposure, 98 significantly differentially expressed genes (DEGs) were found in brain tissue and 239 DEGs in liver tissue. After 67 days of exposure, two and 258 DEGs were found in brain and liver tissue, respectively. Continuous dietary exposure of chlorpyrifos‑methyl most profoundly affected mechanisms associated with protein degradation and lipid metabolism in both brain and liver. Specific for the brain, many of the significant DEGs encode proteins involved in neuron function. In conclusion, this study shows that chlorpyrifos‑methyl affects the transcription of genes involved in neurological function in Atlantic salmon brain, even at exposure concentrations below the threshold for systemic toxicity as seen from brain acetylcholinesterase inhibition.

Neuroprotective Potentials of Ayurvedic Rasayana Desmodium triquetrum on Brain Aging and Chemically Induced Amnesia in Animal Models Relevant to Dementia

Cognitive impairments in dementia is a common feature which disrupts life style of the patients suffering neurodegenerative disorders. Management of cognitive dysfunctions such as dementia and Alzheimer’s disease is very challenging as there is proper medicine with proved effect is available at present. In the current study, neuroprotective potentials of methanol extract of dried roots of Desmodium triquetrum (DT) was investigated in the mouse models relevant to dementia. Exteroceptive behavioral models like Elevated plus maze and Morris water maze were used to assess learning and memory in mice. Scopolamine (0.4 mg/kg, i.p.) induced amnesia and diazepam (1 mg/kg, i.p.) amnesia were the interoceptive behavioral models. DT (50 and 100 mg/kg, p.o.) significantly attenuated amnesic deficits in scopolamine, diazepam and natural aging amnesic models. DT was also useful in reversing aging induced amnesia. DT increased whole brain acetyl cholinesterase inhibition activity in mice. Hence, DT might be used as memory enhancing agent and possibly may be employed in treatment of dementia and other neurodegenerative disorders. The mechanism of action may be due to its potential neuroprotective and acetyl cholinesterase inhibitory properties.

Ameliorative Effects of Roots of &lt;I&gt;Asparagus adscendens&lt;/I&gt; Roxb. on Cognitive Impairments and Brain Aging Induced by Scopolamine and Diazepam in Animal Models Relevant to Alzheimer's Disease

Memory loss in dementia is often the most disabling feature of many disorders, impairing the normal daily activities of the patients and profoundly affecting their families. Treatment of cognitive disorders like dementia and Alzheimer's disease has been challenging since no potential drug is available at present with proved efficacy. In the present study, nootropic activity of methanolic extract of roots of Asparagus adscendens Roxb.(AR) was studied in mice. Elevated plus maze and passive avoidance paradigm were employed to evaluate learning and memory. Scopolamine (0.4 mg/kg, i.p.) and diazepam (1 mg/kg, i.p.) were used to induce amnesia in mice. AR (50 and 100 mg/kg, p.o.) significantly attenuated amnesic deficits induced by scopolamine, diazepam and natural aging. Furthermore, it also reversed aging induced amnesia due to natural aging of mice. AR profoundly increased whole brain acetyl cholinesterase inhibition activity. Hence, AR might prove to be a useful memory restorative agent in the treatment of dementia seen in the elderly. The underlying mechanism of its action may be attributed to its antioxidant and acetyl cholinesterase inhibition properties.

Neuroprotective effect of Cubebin: A dibenzylbutyrolactone lignan on scopolamine-induced amnesia in mice.

Background & objectives:Acetylcholinesterase (AChE) inhibitors represent a major class of drugs which provide symptomatic relief and improvement in cognitive function in Alzheimer's disease (AD). In this study, cubebin, a dibenzylbutyrolactone lignan, was isolated from Piper cubeba and investigated for its AChE inhibitory activity in an attempt to explore its potential for memory-enhancing activities in mice.Methods:Molecular docking of cubebin was carried out followed by in vitro AChE activity. Mice were treated with cubebin (25 & 50 mg/kg; i.p.), for three days and memory impairment was induced by scopolamine (3 mg/kg; i.p.). Memory function was evaluated by Morris water maze (MWM) test. Biochemical parameters of oxidative stress and cholinergic function were estimated in brain.Results:Molecular docking study revealed that cubebin was well bound within the binding site of the AChE enzyme showing interactions such as π-π stacking and hydrogen bonding with residues present therein. Cubebin inhibited AChE enzyme in an in vitro assay with IC50 value of 992 μM. Scopolamine administration caused a significant impairment of learning and memory in mice, as indicated by a marked decrease in MWM performance. Scopolamine administration also produced a significant enhancement of brain AChE activity and oxidative stress in mice brain. Pre-treatment of cubebin (25 and 50 mg/kg; i.p.) significantly prevented scopolamine-induced learning and memory deficits along with attenuation of scopolamine-induced rise in brain AChE activity and oxidative stress level.Interpretation & conclusions:Cubebin showed promising protective activity in scopolamine-induced spatial memory impairment in mice. This could be attributed to its brain AChE inhibition and antioxidant activity.

Two cholinesterase inhibitors trigger dissimilar effects on behavior and body weight in C57BL/6 mice: The case of chlorpyrifos and rivastigmine

Cholinesterases (ChE) are common targets of organophosphate (OP) pesticides and play a critical role in the pathology of some dementias. While chlorpyrifos (CPF) remains one of the most commonly used OPs in the world, numerous investigations have reported its neurotoxic potential and highlighted behavioral disturbances upon its administration. Rivastigmine currently serves to treat Alzheimer’s disease, but it may induce cholinergic overstimulation in non-demented individuals. The present investigation aimed to compare the acute and delayed effects caused by both ChE inhibitors in adult C57BL/6 male mice. The animals were daily fed either a standard, a CPF- (5mg/kg body weight) or a rivastigmine-supplemented diet (1 or 2mg/kg body weight) for 8 weeks. After the treatment, we established an 8-week washout period to assess recovery. ChE enzyme activity, biomarkers, physical effects, and behavioral alterations were evaluated at different time points during the exposure and after the washout period. Both rivastigmine doses induced a time-dependent weight increase. CPF and rivastigmine inhibited brain acetylcholinesterase following an isoform-specific pattern. As for behavioral assessment, CPF negatively modulated learning strategies and impaired memory in a Barnes maze task at the end of the exposure. On the other hand, the low dose of rivastigmine improved memory recall at the end of the washout period in a Morris water maze. Indeed, our results endorse the positive effects of low doses of rivastigmine following a drug-free period in young mice. Therefore, doses and periodicity of treatment to improve cognition in elderly people upon rivastigmine administration should be revised.

Evaluation of a Brain Acetylcholinesterase Extraction Method and Kinetic Constants after Methyl-Paraoxon Inhibition in Three Brazilian Fish Species.

Acetylcholinesterase (AChE) is an important enzyme in the control of the neuronal action potential and sensitive to organophosphate inhibition. Brain fish AChE is less sensitive to organophosphate inhibition than AChE from terrestrial animals, although this sensitivity is variable among species and has not yet been fully evaluated in fish species. In this setting, inhibition kinetic constants for progressive irreversible inhibition of brain acetylcholinesterase due to methyl-paraoxon exposure were determined in three fish species (Mugil liza, Genidens genidens and Lagocephalus laevigatus) and hen (Gallus domesticus). Enzyme extraction using a detergent was shown to be adequate, and samples presented activity inhibition in high substrate concentrations and suppression of inhibition by methyl-paraoxon in the presence of the substrate, similar to kinetic patterns from purified enzyme preparations. Catfish (G. genidens) AChE presented the highest sensitivity among the evaluated fish species (IC50 = 1031.20 nM ± 63.17) in comparison to M. liza and L. laevigatus (IC50: 2878.83 ± 421.94 and 2842.5 ± 144.63 nM respectively). The lower dissociation constant (Kd = 20.3 ± 2.95 μM) of catfish AChE showed greater enzyme affinity for methyl-paraoxon, explaining this species higher sensitivity to organophosphates. Hen AChE presented higher ki (900.57 ± 65.3 mM-1min-1) and, consequently, greater sensitivity to methyl-paraoxon, explained by a lower Kd (0.6 ± 0.13 μM). Furthermore, hen AChE did not differentiate between the propionylthiocholine and acetylthiocholine substrates, indicating easier access of methyl-paraoxon to the hen enzyme activity site. The results obtained herein indicate a suitable extraction of AChE and, despite different inhibition kinetic constants, demonstrate that fish AChE is less sensitive to methyl-paraoxon, probably due to reduced access to the catalytic center which provides greater enzyme substrate selectivity.

Effect of diphenyl diselenide diet supplementation on oxidative stress biomarkers in two species of freshwater fish exposed to the insecticide fipronil

The ability of diphenyl diselenide [(PhSe)2] to attenuate oxidative damage was evaluated in the liver, gills, brain, and muscle of carp (Cyprinus carpio) and silver catfish (Rhamdia quelen) experimentally exposed to fipronil (FPN). Initially, the fish were fed a diet without (PhSe)2 or a diet containing 3.0mg/kg of (PhSe)2 for 60days. After the 60-day period, the fish were exposed to 0.65µg/L of FPN for 192h. The results showed that carp exposed to FPN and not fed with (PhSe)2 exhibited acetylcholinesterase (AChE) inhibition in brain and muscle, and increased thiobarbituric acid-reactive substance (TBARS) in liver, gills, and brain. Furthermore, FPN decreased nonprotein thiols (NPSH) and δ-aminolevulinate dehydratase (δ-ALA-D) in carp liver and gills, and increased plasma glucose and protein levels. In silver catfish, FPN inhibited AChE and increased TBARS levels in muscle. In addition, glutathione S-transferase (GST) decreased in liver and muscle, and plasma glucose was increased. (PhSe)2 reversed some of these effects. It prevented the increase in TBARS levels in liver, gills, and brain in carp and in silver catfish muscle, and reversed the increase in plasma glucose levels in both species. Additionally, (PhSe)2 increased the NPSH levels in carp and silver catfish that had decreased in response to FPN exposure. However, (PhSe)2 was not effective in reversing the AChE inhibition in brain and muscle or the δ-ALA-D decrease in carp liver. Thus, (PhSe)2 protects tissues of both species of fish, mainly by preventing or counteracting the effects of FPN, on TBARS levels, antioxidants, and present anti-hyperglycemic property.

6-Methyluracil derivatives as acetylcholinesterase inhibitors for treatment of Alzheimer's disease.

6-Methyluracil derivatives as acetylcholinesterase inhibitors for treatment of Alzheimer's disease.

In vitro antioxidant and cholinesterase inhibitory activities of methanolic fruit extract of Phyllanthus acidus.

BackgroundAlzheimer’s disease (AD) is a progressive neurodegenerative disorder clinically characterized by loss of memory and cognition. Cholinergic deficit and oxidative stress have been implicated in the pathogenesis of AD. Therefore, inhibition of acetylcholinesterase and oxidation are the two promising strategies in the development of drug for AD. Phyllanthus acidus, belonging to the family Euphorbiaceae, is a tree and has been used in traditional medicine to treat several pain, inflammatory and oxidative stress related disorders such as rheumatism, bronchitis, asthma, respiratory disorder, also important to promote intellect and enhance memory, thus supporting its possible anti-Alzheimer’s properties. In this study, P. acidus was evaluated for its cholinesterase inhibitory and antioxidant activities.MethodsIn this study, we evaluated the antioxidant potential and neuroprotective activity of P. acidus by assessing total phenol content (FCR assay), total flavonoid content, total antioxidant capacity, Fe3+ reducing power capacity, DPPH (2, 2-diphenyl-1-picrylhydrazyl) and hydroxyl radical scavenging capacity, lipid peroxidation inhibition activity & metal chelating activity. In addition acetylcholinestrase (AChE) and butyrylcholinestrase (BChE) inhibitory activities were performed using Ellman’s method.ResultsTotal phenolic content and total flavonoid content of the extract were 116.98 mg of gallic acid equivalent and 168.24 mg of quercetin equivalent per gm of dried extract. The methanolic extract of P. acidus (MEPA) showed considerable total antioxidant activity and reducing capacity. In DPPH scavenging assay and hydroxyl radical scavenging assay, the MEPA showed 84.33 % and 77.21 % scavenging having IC50 of 15.62 and 59.74 μg/ml respectively. In lipid peroxidation inhibition activity MEPA showed moderate inhibition of peroxidation at all concentrations with IC50 value of 471.63 μg/ml and exhibited metal chelating activity with IC50 value 308.67 μg/ml. The MEPA exhibited inhibition of rat brain acetylcholinesterase and human blood butyrylcholinesterase in a dose dependent manner and the IC50 value was found to be 1009.87 μg/ml and 449.51 μg/ml respectively.ConclusionThese results of the present study reveal that MEPA has considerable amount of antioxidant activity as well as anti-acetylcholinesterase and anti-butyrylcholinesterase activity which suggest its effectiveness against Alzheimer's disease and other neurodegenerative disorders.

Single and cartel effect of pesticides on biochemical and haematological status of Clarias batrachus: A long-term monitoring.

Pesticide mixtures are common in the streams of agricultural or urban catchments. Individual and cartel toxicity of four different pesticides, namely Endosulfan, Carbofuran, Methyl parathion and Cypermethrin were studied. Sub acute exposure (1/10th of LC50) for 1, 7, 15, 30 and 60 days in Clarias batrachus active tissues such as brain, gills, blood and liver were evaluated. Growth, hepatosomatic index and survival performance were decreased, inhibition of brain acetylcholinesterase, gills Na(+)/K(+) ATPase activities, and abnormal behavior are noticed. The characteristics of the blood respiratory burst activity, erythrocyte count, contents of hematocrit and hemoglobin are dwindled. Plasma total proteins and liver glycogen decreased whereas blood glucose and serum creatinine, triglycerides are elevated. The immunological attributes such as white blood cell count was elevated, whereas albumin, globulins and lysozyme activity significantly decreased. Hepatic superoxide dismutase, catalase and glutathione S-transferase activities and lipid peroxidation levels are elevated, whereas glutathione peroxidase and glutathione are reduced. Toxicity effect of pesticides reached to a crest on 30th day and showed a descent thereafter except in endosulfan which mounted its detrimental effect throughout the experimental period. Toxicity trends of the present study are determined to be highest in Mix group followed by cypermethrin, methyl parathion and carbofuran. Indiscriminate application of these chemicals pose a toxic threat to non-target organisms, damage the ecosystems and jeopardizes human health.

The effect of PON1 enhancers on reducing acetylcholinesterase inhibition following organophosphate anticholinesterase exposure in rats.

Novel nucleophiles, a series of substituted phenoxyalkyl pyridinium oximes, have been previously shown by our laboratories to enhance in vitro paraoxonase 1 (PON1)-mediated degradation of a sarin surrogate (nitrophenyl isopropyl methylphosphonate, NIMP) and a VX surrogate (nitrophenyl ethyl methylphosphonate, NEMP). Five of the most efficacious of these nucleophiles were tested in rats for their ability to reduce the level of acetylcholinesterase (AChE) inhibition in brain and peripheral tissues following exposure to NIMP or NEMP. Following simultaneous administration of a nucleophile plus surrogate (at 3 dosages yielding about 10-50% AChE inhibition in the brain at 15 min), all five nucleophiles reduced the AChE inhibition in the brain at all 3 dosages, and reduced peripheral AChE inhibition at the lowest dosage. Protective effects were seen for only a short period of time, i.e., 15 min. Even though these nucleophiles are oximes, they are not effective AChE reactivators so it is unlikely that the resultant decreases in AChE inhibition are from appreciable AChE reactivation. It is likely that the protective effects seen are, at least in part, the result of enhancement of PON1-mediated surrogate degradation, an unprecedented mechanism of therapy that has the potential to be developed into a nerve agent countermeasure.

Assessing joint toxicity of four organophosphate and carbamate insecticides in common carp (Cyprinus carpio) using acetylcholinesterase activity as an endpoint

Mixtures of organophosphate (OP) and carbamate (CB) pesticides are commonly detected in freshwater ecosystems. These pesticides inhibit the activity of acetylcholinesterase (AChE) and have potential to interfere with behaviors that may be essential for the survival of species. Although the effects of individual anticholinesterase insecticides on aquatic species have been studied for decades, the neurotoxicity of mixtures is still poorly understood. In the present study, brain AChE inhibition in carp (Cyprinus carpio) exposed to a series of concentrations of the organophosphates (malathion and triazophos) as well as the carbamates (fenobucarb and carbosulfan) was measured. In equitoxic mixtures, the observed AChE activity inhibition of the malathion plus triazophos, and triazophos plus carbosulfan mixtures, was synergism. In equivalent concentration mixtures, the combination of malathion plus fenobucarb mixture conformed to synergism, while the observed AChE activity inhibition of the remaining pairings was less than additive. Single pesticide risk assessments are likely to underestimate the impacts of these insecticides on carps in aquatic environment where mixtures occur. Moreover, mixtures of pesticides that have been commonly reported in aquatic ecosystems may pose a more important challenge than previously anticipated.