Complementary biological and computational approaches identify distinct mechanisms of chlorpyrifos versus chlorpyrifos-oxon-induced dopaminergic neurotoxicity.

Organophosphate (OP) pesticides are widely used in agriculture. While acute cholinergic toxicity has been extensively studied, chronic effects on other neurons are less understood. Here, we demonstrated that the OP pesticide chlorpyrifos (CPF) and its oxon metabolite are dopaminergic neurotoxicants in Caenorhabditis elegans. CPF treatment led to inhibition of mitochondrial complex II, II + III, and V in rat liver mitochondria, while CPF-oxon did not (complex II + III and IV inhibition observed only at high doses). While the effect on C. elegans cholinergic behavior was mostly reversible with toxicant washout, dopamine-associated deficits persisted, suggesting dopaminergic neurotoxicity was irreversible. CPF reduced the mitochondrial content in a dose-dependent manner and the fat modulatory genes cyp-35A2 and cyp-35A3 were found to have a key role in CPF neurotoxicity. These findings were consistent with in vitro effects of CPF and CPF-oxon on nuclear receptor signaling and fatty acid/steroid metabolism observed in ToxCast assays. Two-way hierarchical analysis revealed in vitro effects on estrogen receptor, pregnane X receptor, and peroxisome proliferator-activated receptor gamma pathways as well as neurotoxicity of CPF, malathion, and diazinon, whereas these effects were not detected in malaoxon and diazoxon. Taken together, our study suggests that mitochondrial toxicity and metabolic effects of CPF, but not CPF-oxon, have a key role of CPF neurotoxicity in the low-dose, chronic exposure. Further mechanistic studies are needed to examine mitochondria as a common target for all OP pesticide parent compounds, because this has important implications on cumulative pesticide risk assessment.

Caenorhabditis elegans Neurotoxicity Testing: Novel Applications in the Adverse Outcome Pathway Framework.

Neurological hazard assessment of industrial and pesticidal chemicals demands a substantial amount of time and resources. Caenorhabditis elegans is an established model organism in developmental biology and neuroscience. It presents an ideal test system with relatively fewer neurons (302 in hermaphrodites) versus higher-order species, a transparent body, short lifespan, making it easier to perform neurotoxic assessment in a time and cost-effective manner. Yet, no regulatory testing guidelines have been developed for C. elegans in the field of developmental and adult neurotoxicity. Here, we describe a set of morphological and behavioral assessment protocols to examine neurotoxicity in C. elegans with relevance to cholinergic and dopaminergic systems. We discuss the homology of human genes and associated proteins in these two signaling pathways and evaluate the morphological and behavioral endpoints of C. elegans in the context of published adverse outcome pathways of neurodegenerative diseases. We conclude that C. elegans neurotoxicity testing will not only be instrumental to eliminating mammalian testing in neurological hazard assessment but also lead to new knowledge and mechanistic validation in the adverse outcome pathway framework.

Bacterial degradation of distillery wastewater pollutants and their metabolites characterization and its toxicity evaluation by using Caenorhabditis elegans as terrestrial test models.

Distillery wastewater has significant amount of coloring compounds and organic substances even after the secondary treatment process, which poses many severe environmental and health threats. However, the recalcitrant coloured compounds have not yet been clearly identified. In this study, two bacterial strains DS3 and DS5 capable to decolorize distillery wastewater (DWW) pollutants were isolated and characterized as Staphylococcus saprophyticus (MF182113) and Alcaligenaceae sp. (MF182114), respectively. Results showed that mixed bacterial culture was found more effective decolorizing 71.83% DWW compared to axenic culture DS3 and DS5 resulting only 47.94% and 50.67% decolorization, respectively. The FT-IR and LC-MS/MS analysis of untreated DWW showed the presence of many recalcitrant compounds having different functional groups, but after bacterial treatment, most of compounds get diminished and the toxicity of DWW was reduced significantly. Further, the Nile red staining of Caenorhabditis elegans exposed to untreated and bacteria treated DWW for evaluation of toxicity assay and results revealed that the worms exposed to untreated DWW showed sharp reduction in total fat content having more profound effects, suggesting the diminished nAchR signaling as compare to bacterial treated DWW. Hence, this study revealed that inadequate disposal of untreated DWW may cause transfer of toxic substances into the environment and receiving water bodies.

Swertiamarin, a secoiridoid glycoside modulates nAChR and AChE activity.

The ailments related to a malfunction in cholinergic functioning currently employ the use of inhibitors for acetylcholinesterase (AChE) and N-methyl-d-aspartate (NMDA) receptors. The present study was designed to elucidate the potential of swertiamarin (SW), a secoiridoidal glycoside isolated from Enicostemma littorale in curtailing the cholinergic dysfunction. Using Caenorhabditis elegans as a model, SW was found to enhance neurotransmission by modulating AChE and nicotinic acetylcholine receptor (nAChR) activity; being orchestrated through up-regulation of unc-17 and unc-50. SW exhibited AChE inhibition both in vivo and cell-free system. The in silico molecular docking of SW and human AChE (hAChE) displayed good binding energy of -6.02. Interestingly, the increase in aldicarb and levamisole sensitivity post SW treatment was curtailed to a significant level in daf-16 and skn-1 mutants. SW raised the level of the endogenous antioxidant enzymes through up-regulation of sod-3 and gst-4 that act downstream to DAF-16 and SKN-1, imparting protection against neurodegeneration. The outcome of our study displays SW as a potential natural molecule for the amelioration of cholinergic dysfunction. Moreover, the study also indicates that SW elicits antioxidant response via up-modulation of daf-16 possibly through unc-17 upregulation. Further research on SW pertaining to the underlying mechanism and potential is expected to significantly advance the current understanding and design of possible ameliorative or near ameliorative regimens for cholinergic dysfunction.

Perfluorooctane Sulfonate (PFOS) Produces Dopaminergic Neuropathology in Caenorhabditis elegans.

Perfluorooctane sulfonate (PFOS) has been widely utilized in numerous industries. Due to long environmental and biological half-lives, PFOS is a major public health concern. Although the literature suggests that PFOS may induce neurotoxicity, neurotoxic mechanisms, and neuropathology are poorly understood. Thus, the primary goal of this study was to determine if PFOS is selectively neurotoxic and potentially relevant to specific neurological diseases. Nematodes (Caenorhabditis elegans) were exposed to PFOS or related per- and polyfluoroalkyl substances (PFAS) for 72 h and tested for evidence of neuropathology through examination of cholinergic, dopaminergic, gamma-amino butyric acid (GABA)ergic, and serotoninergic neuronal morphologies. Dopaminergic and cholinergic functional analyses were assessed through 1-nonanol and Aldicarb assay. Mechanistic studies assessed total reactive oxygen species, superoxide ions, and mitochondrial content. Finally, therapeutic approaches were utilized to further examine pathogenic mechanisms. Dopaminergic neuropathology occurred at lower exposure levels (25 ppm, approximately 50 µM) than required to produce neuropathology in GABAergic, serotonergic, and cholinergic neurons (100 ppm, approximately 200 µM). Further, PFOS exposure led to dopamine-dependent functional deficits, without altering acetylcholine-dependent paralysis. Mitochondrial content was affected by PFOS at far lower exposure level than required to induce pathology (≥1 ppm, approximately 2 µM). Perfluorooctane sulfonate exposure also enhanced oxidative stress. Further, mutation in mitochondrial superoxide dismutase rendered animals more vulnerable. Neuroprotective approaches such as antioxidants, PFAS-protein dissociation, and targeted (mitochondrial) radical and electron scavenging were neuroprotective, suggesting specific mechanisms of action. In general, other tested PFAS were less neurotoxic. The primary impact is to prompt research into potential adverse outcomes related to PFAS-induced dopaminergic neurotoxicity in humans.

Anti-ageing and anti-Parkinsonian effects of natural flavonol, tambulin from Zanthoxyllum aramatum promotes longevity in Caenorhabditis elegans.

Ageing is a progressive deterioration in functional and structural well-being of the body, accompanied with age-associated neurological disorders such as Parkinson's disease (PD), Alzheimer's disease and Huntington's disease. PD is marked with motor function decline, progressive neurodegeneration due to aggregation of insoluble α-synuclein in the dopaminergic neuron. Here we investigated the effect of tambulin (3,5-dihydroxy-7,8-dimethoxy-2-(4-methoxyphenyl) chromen-4-one), a hydroxy substituted flavanol isolated from fruits of Zanthoxyllum armatum DC (Family-Rutaceae) for its longevity promoting and neuromodulatory activities using Caenorhabditis elegans model system. Our results show that tambulin treatment significantly enhance lifespan and stress tolerance in worms, along with mitigation of ageing biomarkers like lipofuscin and protein carbonyl. In line with the alleviated ROS levels, tambulin treatment led to upregulated mRNA expression of ROS scavenging genes viz., sod-1, sod-3, and ctl-2. Upregulation in daf-16 gene indicates the involvement of insulin signaling pathway in tambulin mediated longevity. Tambulin treatment exhibited curtailed PD manifestations in terms of reduced α-synuclein levels, lipid accumulation, improved locomotary behavior and dopamine levels. Altogether, our data suggest that tambulin mediated alleviation of PD manifestations possibly involved PD counter protective machinery as evident through upregulated mRNA expression of lagr-1, ymel-1, pdr-1, ubc-12, and lrk-1. Our studies present tambulin as a potential molecule for its properties against ageing and Parkinson's disease. Further studies are speculated to realize the mechanistic and pharmacological aspects of tambulin.

ALA-mediated biphasic downregulation of α-7nAchR/HIF-1α along with mitochondrial stress modulation strategy in mammary gland chemoprevention.

The study elucidates the effect of ɑ-linolenic acid (ALA) on mitochondrial stress, hypoxic cancer microenvironment, and intervention of cholinergic anti-inflammatory pathway using N-methyl-N-nitrosourea (MNU) induced estrogen receptor (ER+) mammary gland carcinoma and Caenorhabditis elegans model, respectively. The efficacy of ALA was scrutinized in vivo and in vitro using various experiments like hemodynamic studies, morphological analysis, antioxidants parameters, immunoblotting, and quantitative reverse transcription polymerase chain reaction. The effect of ALA was also validated using C. elegans worms. ALA administration had a positive effect on tissue architecture of the malignancy when scrutinized through the whole mount carmine staining, hematoxylin and eosin staining, and scanning electron microscopy. The proteomic and genomic checkpoint revealed the participation of mitochondrial dysfunction, alteration of hypoxic microenvironment, and involvement of cholinergic anti-inflammatory response after treatment with ALA. ALA treatment has also increased the level of synaptic acetylcholine and acetylcholine esterase with a significant decrease in lipid content. It was concluded that ALA persuaded the mitochondrial stress, activation of downstream cholinergic anti-inflammatory markers, and favorable regulation of hypoxia microenvironment through inhibition of fatty acid synthase and sterol regulatory element-binding protein.

From the Cover: Harmane-Induced Selective Dopaminergic Neurotoxicity in Caenorhabditis elegans.

Parkinson's disease (PD) is a debilitating neurodegenerative disease. Although numerous exposures have been linked to PD etiology, causative factors for most cases remain largely unknown. Emerging data on the neurotoxicity of heterocyclic amines suggest that this class of compounds should be examined for relevance to PD. Here, using Caenorhabditis elegans as a model system, we tested whether harmane exposure produced selective toxicity to dopamine neurons that is potentially relevant to PD. Harmane is a known tremorigenic ß-carboline (a type of heterocyclic amine) found in cooked meat, roasted coffee beans, and tobacco. Thus, this compound represents a potentially important exposure. In the nematode model, we observed dopaminergic neurons to be selectively vulnerable, showing significant loss in terms of structure and function at lower doses than other neuronal populations. In examining mechanisms of toxicity, we observed significant harmane-induced decreases in mitochondrial viability and increased reactive oxygen species levels. Blocking transport through the dopamine transporter (DAT) was not neuroprotective, suggesting that harmane is unlikely to enter the cell through DAT. However, a mitochondrial complex I activator did partially ameliorate neurodegeneration. Further, mitochondrial complex I activator treatment reduced harmane-induced dopamine depletion, measured by the 1-nonanol assay. In summary, we have shown that harmane exposure in C. elegans produces selective dopaminergic neurotoxicity that may bear relevance to PD, and that neurotoxicity may be mediated through mitochondrial mechanisms.

Galantamine attenuates N,N-dimethyl hydrazine induced neoplastic colon damage by inhibiting acetylcholinesterase and bimodal regulation of nicotinic cholinergic neurotransmission.

The present study reveals the effect of galantamine (GAL) against 1, 2-dimethylhydrazine (DMH) induced colon cancer. Wistar albino rats were arbitrarily divided into four groups (n = 8). Group 1 served as normal control (normal saline, 3ml/kg/day, p.o.); group 2, 3 and 4 received DMH (20mg/kg/week, s.c.), for 6 weeks; groups 3 and 4 also received GAL (2 and 4mg/kg/day, p.o) for 6 weeks. DMH treated rats showed decreased heart rate variability (HRV) factors, increased incidence of aberrant crypt foci (ACF), increased thiobarbituric acid reactive substances (TBARs) along with the decrease in the enzymatic activity of superoxide dismutase (SOD) and catalase. Increased levels of inflammatory marker cyclooxygenase (COX) and lipoxygenase (LOX) was also evident in DMH treated animals. The colonic surface architecture was studied using scanning electron microscopy revealed aberrant crypts(X500) and neoplastic nodules (X2000). GAL treatment helped to minimize the ACF count, restored oxidative stress and inflammatory markers favorably. To further validate our results, our study was directed to define the effect of GAL on acetylcholine neurotransmission using a simple model organism, Caenorhabditis elegans (C. elegans). Increased synaptic cholinergic transmission by GAL (32µM) was evident in the worms when studied through aldicarb assay. However, GAL (32µM) treatment negatively modulated α7 nicotinic acetylcholine receptor (α7nAch receptor), when evaluated using the levamisole assay. GAL (32µM) treatment down regulated the genomic expression of ace-1, ace-2 along with unc-29, unc-38, and unc-50 (essential components of α7 nAch receptor). GAL by inhibiting AchE and regulating Alpha7nACh activity can improve cholinergic neurotransmission.

Alpha-linolenic acid stabilizes HIF-1 α and downregulates FASN to promote mitochondrial apoptosis for mammary gland chemoprevention.

Alpha linolenic acid is an essential polyunsaturated fatty acid and is reported to have the anti-cancer potential with no defined hypothesis or mechanism/s. Henceforth present study was in-quested to validate the effect of alpha linolenic acid on mitochondrial apoptosis, hypoxic microenvironment and de novo fatty acid synthesis using in-vitro and in-vivo studies. The IC50 value of alpha linolenic acid was recorded to be 17.55µM against ER+MCF-7 cells. Treatment with alpha linolenic acid was evident for the presence of early and late apoptotic signals along with mitochondrial depolarization, when studied through acridine orange/ethidium bromide and JC-1 staining. Alpha linolenic acid arrested the cell cycle in G2/M phase. Subsequently, the in-vivo efficacy was examined against 7, 12-dimethylbenz anthracene induced carcinogenesis. Treatment with alpha linolenic acid demarcated significant effect upon the cellular proliferation as evidenced through decreased in alveolar bud count, restoration of the histopathological architecture and loss of tumor micro vessels. Alpha linolenic acid restored the metabolic changes to normal when scrutinized through 1H NMR studies. The immunoblotting and qRT-PCR studies revealed participation of mitochondrial mediated death apoptosis pathway and curtailment of hypoxic microenvironment after treatment with alpha linolenic acid. With all above, it was concluded that alpha linolenic acid mediates mitochondrial apoptosis, curtails hypoxic microenvironment along with inhibition of de novo fatty acid synthesis to impart anticancer effects.

5-Desmethylnobiletin augments synaptic ACh levels and nicotinic ACh receptor activity: A potential candidate for alleviation of cholinergic dysfunction.

Cholinergic function is compromised in plethora of neurodegenerative disorders especially Alzheimer's disease. Increasing acetylcholine (ACh) levels has been the mainstay in majority of the therapeutic regimens, accepted for management of disease. The present study investigates the efficacy of 5-Desmethylnobiletin (DN), a polymethoxyflavone in augmenting cholinergic function using Caenorhabditis elegans as a model organism. The studies revealed significant elevation in cholinergic transmission mediated through increased levels of ACh and activity of nicotinic acetylcholine receptors (nAChR). Further investigation into the mechanistic aspects indicated that DN enhanced cholinergic function through down modulation of acetylcholinesterase activity at enzyme and transcript level along with upregulation of non alpha subunit, unc-29 which could be linked with enhanced nAChR activity as evident from levamisole assay. Additionally, studies on antioxidant properties, implicated significant potential of DN in curtailing ROS, both in vivo and in vitro. Our studies present DN as a phytomolecule with novel biological activities which could be exploited and researched upon for therapeutic avenues in terms of cholinergic function and antioxidant potential.

1-Methyl-4-propan-2-ylbenzene from Thymus vulgaris Attenuates Cholinergic Dysfunction.

Cholinergic dysfunction is manifested in a plethora of neurodegenerative and psychiatric disorders such as Alzheimer's, Parkinson's, and Huntington's diseases. The extent of cholinergic affliction is maximum in Alzheimer's disease which is a progressive neurodegenerative disorder involving death of cholinergic neurons. To this date, the therapeutic management of cholinergic dysfunction is limited to provide symptomatic relief through the use of acetylcholinesterase (Ache) inhibitors only. The present study elaborates the potential of thyme oil and its individual components in curtailing cholinergic deficits. We found that thyme oil augments neurotransmission by modulating synaptic acetylcholine (Ach) levels and nicotinic acetylcholine receptor activity, being orchestrated through upregulation of genes cho-1, unc-17 and unc-50. Studies on individual components revealed para-cymene (1-methyl-4-propan-2-ylbenzene) as the active component of thyme oil, contributing its effects through upregulation of cho-1, cha-1, unc-17 and unc-50, while downregulating ace-1 and ace-2. Interestingly, thymol and gamma-terpinene which although were devoid of any activity individually, exhibited significantly enhanced synaptic Ach levels and nicotinic acetylcholine receptor (nAchR) responsiveness, when administered in combination. Our findings advocate thyme oil and its constituents as potential candidates for amelioration of cholinergic dysfunction. The study is speculated to make a way for a new line of "phytomolecules-based drugs" from the diverse pool of natural compounds.

RNAi of cat-2, a putative tyrosine hydroxylase, increases alpha synuclein aggregation and associated effects in transgenic C. elegans.

Neurodegenerative Parkinson's disease (PD) is a multifactorial disorder; effects like alpha synuclein aggregation, low dopamine levels and dopaminergic neurodegeneration are considered to be hallmarks of the disease. Several recent studies have pointed towards an important role of enzyme tyrosine hydroxylase (TH) in the pathophysiology of PD. We embarked on the present studies to explore the mechanistic role of C. elegans gene cat-2, a putative tyrosine hydroxylase, in PD. Utilizing the powerful genetic model system C. elegans, which has previously provided critical understanding of several human diseases, we employed a reverse genetics approach via RNAi mediated gene silencing of cat-2, to study various disease related effects in three different transgenic strains of the nematode. Knocking-down of cat-2 led to increase in aggregation of alpha synuclein, as was studied via expression of YFP. Similarly the silencing of cat-2 had significant effects on associated endpoints including oxidative stress, lipid content and neurotransmission; exemplifying the role of cat-2, the putative tyrosine hydroxylase, in Parkinsonism of the nematode model. The findings are significant as this model could further be used to study the entire associated pathway in greater detail and with the advantages that the model system C. elegans presents, the knockdown of cat-2 in the alpha synuclein expressing strain, could be employed for screening potential pharmacological agents targeted at TH which could lead to designing of possible therapeutic interventions for the disease.

Anti-Parkinsonian effects of Bacopa monnieri: insights from transgenic and pharmacological Caenorhabditis elegans models of Parkinson's disease.

Neurodegenerative Parkinson's disease (PD) is associated with aggregation of protein alpha synuclein and selective death of dopaminergic neurons, thereby leading to cognitive and motor impairment in patients. The disease has no complete cure yet; the current therapeutic strategies involve prescription of dopamine agonist drugs which turn ineffective after prolonged use. The present study utilized the powerful genetics of model system Caenorhabditis elegans towards exploring the anti-Parkinsonian effects of a neuro-protective botanical Bacopa monnieri. Two different strains of C. elegans; a transgenic model expressing "human" alpha synuclein [NL5901 (P(unc-54)::alphasynuclein::YFP+unc-119)], and a pharmacological model expressing green fluorescent protein (GFP) specifically in the dopaminergic neurons [BZ555 (P(dat-1)::GFP)] treated with selective catecholaminergic neurotoxin 6-hydroxy dopamine (6-OHDA), were employed for the study. B. monnieri was chosen for its known neuroprotective and cognition enhancing effects. The study examined the effect of the botanical, on aggregation of alpha synuclein, degeneration of dopaminergic neurons, content of lipids and longevity of the nematodes. Our studies show that B. monnieri reduces alpha synuclein aggregation, prevents dopaminergic neurodegeneration and restores the lipid content in nematodes, thereby proving its potential as a possible anti-Parkinsonian agent. These findings encourage further investigations on the botanical, and its active constituent compounds, as possible therapeutic intervention against Parkinson's disease.

Sir-2.1 modulates 'calorie-restriction-mediated' prevention of neurodegeneration in Caenorhabditis elegans: implications for Parkinson's disease.

The phenomenon of aging is known to modulate many disease conditions including neurodegenerative ailments like Parkinson's disease (PD) which is characterized by selective loss of dopaminergic neurons. Recent studies have reported on such effects, as calorie restriction, in modulating aging in living systems. We reason that PD, being an age-associated neurodegenerative disease might be modulated by interventions like calorie restriction. In the present study we employed the transgenic Caenorhabditis elegans model (P(dat-1)::GFP) expressing green fluorescence protein (GFP) specifically in eight dopaminergic (DA) neurons. Selective degeneration of dopaminergic neurons was induced by treatment of worms with 6-hydroxy dopamine (6-OHDA), a selective catecholaminergic neurotoxin, followed by studies on effect of calorie restriction on the neurodegeneration. Employing confocal microscopy of the dopaminergic neurons and HPLC analysis of dopamine levels in the nematodes, we found that calorie restriction has a preventive effect on dopaminergic neurodegeneration in the worm model. We further studied the role of sirtuin, sir-2.1, in modulating such an effect. Studies employing RNAi induced gene silencing of nematode sir-2.1, revealed that presence of Sir-2.1 is necessary for achieving the protective effect of calorie restriction on dopaminergic neurodegeneration. Our studies provide evidence that calorie restriction affords, an sir-2.1 mediated, protection against the dopaminergic neurodegeneration, that might have implications for neurodegenerative Parkinson's disease.

Trans-cellular introduction of HIV-1 protein Nef induces pathogenic response in Caenorhabditis elegans.

BACKGROUND: Caenorhabditis elegans has emerged as a very powerful model for studying the host pathogen interactions. Despite the absence of a naturally occurring viral infection for C. elegans, the model is now being exploited experimentally to study the basic aspects of virus-host interplay. The data generated from recent studies suggests that the virus that infects mammalian cells does infect, replicate and accumulate in C. elegans. METHODOLOGY/PRINCIPAL FINDINGS: We took advantage of the easy-to-achieve protein introduction in C. elegans and employing the methodology, we administered HIV-1 protein Nef into live worms. Nef is known to be an important protein for exacerbating HIV-1 pathogenesis in host by enhancing viral replication. The deletion of nef from the viral genome has been reported to inhibit its replication in the host, thereby leading to delayed pathogenesis. Our studies, employing Nef introduction into C. elegans, led to creation of an in-vivo model that allowed us to study, whether or not, the protein induces effect in the whole organism. We observed a marked lipodystrophy, effect on neuromuscular function, impaired fertility and reduced longevity in the worms exposed to Nef. The observed effects resemble to those observed in Nef transgenic mice and most interestingly the effects also relate to some of the pathogenic aspects exhibited by human AIDS patients. CONCLUSIONS/SIGNIFICANCE: Our studies underline the importance of this in vivo model for studying the interactions of Nef with host proteins, which could further be used for identifying possible inhibitors of such interactions.

Novel carbamates as orally active acetylcholinesterase inhibitors found to improve scopolamine-induced cognition impairment: pharmacophore-based virtual screening, synthesis, and pharmacology.

A systematic virtual screening (VS) experiment, consisting of the development of 3D-pharmacophore, screening of virtual library, synthesis, and pharmacology, is reported. The predictive pharmacophore model (correlation = 0.955) with one H-bond donor and three hydrophobic features was developed using HypoGen on a training set of 24 carbamates as AChE inhibitors. The model was validated on a test set of 40 carbamates (correlation = 0.844). The pharmacophore-based VS of virtual library led to the identification of novel carbamates as potent AChE inhibitors. The synthesis and pharmacological evaluation of nine carbamates against three diverse assay systems, namely (i) in vitro Ellman method, (ii) in vivo passive avoidance test, and (iii) aldicarb-sensitivity assay, led to the discovery of orally active novel AChE inhibitors which improved scopolamine-induce cognition impairment in Swiss male mice. Finally, two novel lead compounds 85 and 86 are selected as candidate molecules for further optimization.