Carbamate Insecticides Target Human Melatonin Receptors

Melatonin receptor structure and signaling

Melatonin (5-methoxy-N-acetyltryptamine) binds with high affinity and specificity to membrane receptors. Several receptor subtypes exist in different species, of which the mammalian MT1 and MT2 receptors are the best-characterized. They are members of the G protein-coupled receptor superfamily, preferentially coupling to Gi/o proteins but also to other G proteins in a cell-context-depending manner. In this review, experts on melatonin receptors will summarize the current state of the field. We briefly report on the discovery and classification of melatonin receptors, then focus on the molecular structure of human MT1 and MT2 receptors and highlight the importance of molecular simulations to identify new ligands and to understand the structural dynamics of these receptors. We then describe the state-of-the-art of the intracellular signaling pathways activated by melatonin receptors and their complexes. Brief statements on the molecular toolbox available for melatonin receptor studies and future perspectives will round-up this review.

Beyond the Nucleus: Plastic Chemicals Activate G Protein-Coupled Receptors

G protein-coupled receptors (GPCRs) are central mediators of cell signaling and physiological function. Despite their biological significance, GPCRs have not been widely studied in the field of toxicology. Herein, we investigated these receptors as novel targets of plastic chemicals using a high-throughput drug screening assay with 126 human non-olfactory GPCRs. In a first-pass screen, we tested the activity of triphenol phosphate, bisphenol A, and diethyl phthalate, as well as three real-world mixtures of chemicals extracted from plastic food packaging covering all major polymer types. We found 11 GPCR-chemical interactions, of which the chemical mixtures exhibited the most robust activity at adenosine receptor 1 (ADORA1) and melatonin receptor 1 (MTNR1A). We further confirm that polyvinyl chloride and polyurethane products contain ADORA1 or MTNRA1 agonists using a confirmatory secondary screen and pharmacological knockdown experiments. Finally, an analysis of the associated gene ontology terms suggests that ADORA1 and MTNR1A activation may be linked to downstream effects on circadian and metabolic processes. This work highlights that signaling disruption caused by plastic chemicals is broader than that previously believed and demonstrates the relevance of nongenomic pathways, which have, thus far, remained unexplored.

Pesticides: An alarming detrimental to health and environment

Pesticides are chemical substances of natural or synthetic origin that are used to eradicate pests and insects. These are indispensable in the agricultural processes for better crop production. Pesticide use aims to promote crop yield and protect the crops from diseases and damage. Pesticides must be handled carefully and disposed of appropriately because they are dangerous to people and other species by default. Environmental pollution occurs when pesticide contamination spreads away from the intended plants. Older pesticides such as lindane and dichlorodiphenyltrichloroethane (DDT) may remain in water and soil for a longer time. These accumulate in various parts of the food chain and cause damage to the ecosystem. Biological techniques in the management of pest control such as importation, augmentation, and conservation, and the accompanying procedures are more efficient, less expensive, and ecologically sound than other ways. This review mainly focuses on the consequences on the targeted and non-targeted organisms including the health and well-being of humans by the use of pesticides and their toxicity. The side effects that occur when a pesticide's LD50 exceeds the accepted limit through oral or skin penetration due to their binding to various receptors such as estrogen receptors, GABA, EGFR, and others. These pesticide classes include carbamates, pyrethroids, organochlorides, organophosphorus, and others. The current study seeks to highlight the urgent requirement for a novel agricultural concept that includes a major reduction in the use of chemical pesticides.

Organophosphorus and carbamate pesticides: Molecular toxicology and laboratory testing

Population and food requirements are increasing daily throughout the world. To fulfil these requirements application of pesticides is also increasing. Organophosphorous (OP) and Organocarbamate (OC) compounds are widely used pesticides. These pesticides are used for suicidal purposes too. Both inhibit Acetylcholinesterase (AChE) and cholinergic symptoms are mainly used for the diagnosis of pesticide poisoning. Although the symptoms of the intoxication of OP and OC are similar, recent research has described different targets for OP and OC pesticides. Researchers believe the distinction of OP/OC poisoning will be beneficial for the management of pesticide exposure. OP compounds produce adducts with several proteins. There is a new generation of OP compounds like glyphosate that do not inhibit AChE. Therefore, it's high time to develop biomarkers that can distinguish OP poisoning from OC poisoning.

Is exposure to chemical pollutants associated with sleep outcomes? A systematic review

Environmental exposures may influence sleep; however, the contributions of environmental chemical pollutants to sleep health have not been systematically investigated. We conducted a systematic review to identify, evaluate, summarize, and synthesize the existing evidence between chemical pollutants (air pollution, exposures related to the Gulf War and other conflicts, endocrine disruptors, metals, pesticides, solvents) and dimensions of sleep health (architecture, duration, quality, timing) and disorders (sleeping pill use, insomnia, sleep-disordered breathing)). Of the 204 included studies, results were mixed; however, the synthesized evidence suggested associations between particulate matter, exposures related to the Gulf War, dioxin and dioxin-like compounds, and pesticide exposure with worse sleep quality; exposures related to the Gulf War, aluminum, and mercury with insomnia and impaired sleep maintenance; and associations between tobacco smoke exposure with insomnia and sleep-disordered breathing, particularly in pediatric populations. Possible mechanisms relate to cholinergic signaling, neurotransmission, and inflammation. Chemical pollutants are likely key determinants of sleep health and disorders. Future studies should aim to evaluate environmental exposures on sleep across the lifespan, with a particular focus on developmental windows and biological mechanisms, as well as in historically marginalized or excluded populations.

Amelioration of Hepatotoxic and Neurotoxic Effect of Cartap by Aloe vera in Wistar Rats

Pesticide exposure can pose a serious risk to nontarget animals. Cartap is being broadly used in agricultural fields. The toxic effects of cartap on the levels of hepatotoxicity and neurotoxicity have not been properly studied in mammalian systems. Therefore, the present work focused on the effect of cartap on the liver and brain of Wistar rats and made an assessment of the ameliorating potential of A. vera. The experimental animals were divided into 4 groups, comprising six rats in each: Group 1-Control; Group 2-A. vera; Group 3-Cartap; and Group 4-A. vera + Cartap. The animals orally given cartap and A. vera were sacrificed after 24 h of the final treatment and histological and biochemical investigations were conducted in liver and brain of Wistar rats. Cartap at sublethal concentrations caused substantial decreases in CAT, SOD, and GST levels in the experimental rats. The activity levels of transaminases and phosphatases in cartap group were also found to be substantially altered. The AChE activity was recorded as decreasing in RBC membrane and brain of the cartap-treated animals. The TNF-α and IL-6 level in serum were increased expressively in the cartap challenged groups. Histological investigation of liver showed disorganized hepatic cords and severely congested central veins due to cartap. However, the A. vera extract was observed to significantly protect against the effects of cartap toxicity. The protective impact of A. vera against cartap toxicity may be due to the existence of antioxidants in it. These findings suggest that A. vera may be developed as a potential supplement to the appropriate medication in the treatment of cartap toxicity.

Discovery and structure-activity relationship of Morita-Baylis-Hillman adducts as larvicides against dengue mosquito vector, Aedes aegypti (Diptera: Culicidae)

Neglected tropical diseases (NTDs) have become a significant public health problem worldwide, notably the life-threatening dengue hemorrhagic fever borne by the Aedes aegypti mosquito. Thus, mosquito vector control measures remain essential in public health vector surveillance and control to combat Aedes-borne infections. Therefore, a series of MBH adducts were synthesized and assessed towards the fourth instar mosquito larvae, Aedes aegypti, along with the preliminary structure-activity relationship (SAR). Noteworthy, this compound class might be synthetized by an efficient eco-friendly synthesismethod and a rapid route for the synthesis of commercial larvicide through a single synthetic step. The bioassays showed that this compound class is a promising larvicide to control Aedes aegypti mosquito larvae, mainly 3g, with an LC₅₀ of 41.35 µg/mL, which was higher than evaluated positive controls. Nevertheless, it is a viable larvicidalhit candidate for further hit-to-leadproperties optimization of its biphenyl backbone scaffold with enhanced insecticidalbioactivity. Moreover, scanning electron microscopy analysis suggested a disruption of the osmoregulatory/ionoregulatory functions by the complete deterioration of the terminal exoskeleton hindgut and anal papillae. Therefore, this new study shows the larvicidal efficacy of the tested compounds against the Aedes aegypti larvae.

Degradation of malathion and carbosulfan by ozone water and analysis of their by-products

BACKGROUND

Treatment by ozone water is an emerging technology for the degradation of pesticide residues in vegetables. The ozone dissolved in water generates hydroxyl radicals (^· OH), which are highly effective in decomposing organic substances, such as malathion and carbosulfan.

RESULTS

We found that washing pak choi with 2.0 mg L^-1 ozone water for 30 min resulted in 58.3% and 38.2% degradation of the malathion and carbosulfan contents respectively, and the degradation rates of these pure pesticides were 83.0% and 66.3% respectively. In addition, the 'first + first'-order reaction kinetic model was found to predict the trend in the pesticide content during ozone water treatment. Based on investigations by gas chromatography-mass spectrometry combined with the structures of the pesticides, the by-products generated were identified. More specifically, the ozonation-based degradation of carbosulfan generated carbofuran and benzofuranol, whereas malathion produced succinic acid and phosphoric acid. Although some new harmful compounds were formed during degradation of the parent pesticides, these were only present in trace quantities and were transient intermediates that eventually disappeared during the reaction.

CONCLUSION

Our results, therefore, indicate that ozone water treatment technology for pesticide residue degradation is worthy of popularization and application. © 2022 Society of Chemical Industry.

Melatonin Receptors: A Key Mediator in Animal Reproduction

Melatonin, a hormone produced by the mammalian pineal gland, influences various physiological activities, many of which are related to animal reproduction, including neuroendocrine function, rhythm regulation, seasonal behavior, gonadogenesis, gamete development and maturation, sexual maturation, and thermoregulation. Melatonin exerts beneficial actions mainly via binding with G-protein-coupled receptors (GPCR), termed MT1 and MT2. Melatonin receptors are crucial for mediating animal reproduction. This paper reviews the characteristics of melatonin receptors including MT1 and MT2, as well as their roles in mediating signal transduction and biological effects, with a focus on their function in animal reproduction. In addition, we briefly summarize the developments in pharmacological research regarding melatonin receptors as drug targets. It is expected that this review will provide a reference for further exploration and unveiling of melatonin receptor function in reproductive regulation.

Prenatal maternal pesticide exposure in relation to sleep health of offspring during adolescence

STUDY OBJECTIVES

The neurobiological processes involved in establishing sleep regulation are vulnerable to environmental exposures as early as seven weeks of gestation. Studies have linked in utero pesticide exposure to childhood sleep-disordered breathing. However, the impact of in utero pesticide exposure on the sleep health of adolescents remains unexplored.

MATERIALS AND METHODS

Data from 137 mother-adolescent pairs from a Mexico City cohort were analyzed. We used maternal urinary 3-phenoxybenzoic acid (3-PBA, pyrethroid metabolite) and 3, 5, 6-trichloro-2-pyridinol (TCPy, chlorpyrifos metabolite) from trimester three to estimate in utero pesticide exposure. Among adolescents, we obtained repeated measures of objectively assessed sleep duration, midpoint, and fragmentation using wrist-actigraphy devices for 7 consecutive days in 2015 and 2017. Unstratified and sex-stratified associations between maternal urinary 3-PBA and TCPy and adolescent sleep measures were examined using generalized linear mixed models (GLMMs). We also examined the interactive effects of maternal pesticide exposure and offspring sex on sleep outcomes.

RESULTS

3-PBA and TCPy were detected in 44.4% and 93% of urine samples, respectively. Adjusted findings demonstrated that higher exposure to maternal TCPy was associated with longer sleep duration and later sleep timing. Findings from interaction tests between maternal pesticide exposure and offspring sex were not statistically significant, although adjusted sex-stratified findings showed that the association between TCPy with duration and midpoint was evident only among female offspring. To illustrate, those in the highest tertile of exposure had a 59 minute (95% CI: 12.2, 104.8) (p, trend = 0.004) longer sleep duration and a 0.6 hour (95% CI: 0.01, 1.3) (p, trend = 0.01) later sleep midpoint. We found no significant associations between 3-PBA and sleep outcomes.

CONCLUSION

Within a cohort of mother-adolescent pairs, we found associations between maternal prenatal pesticide exposure and longer sleep duration and later sleep timing among adolescent offspring. Further, this association may be female-specific.

Specificity of time- and dose-dependent morphological endpoints in the fish embryo acute toxicity (FET) test for substances with diverse modes of action: the search for a "fingerprint"

The fish embryo acute toxicity (FET) test with the zebrafish (Danio rerio) embryo according to OECD TG 236 was originally developed as an alternative test method for acute fish toxicity testing according to, e.g., OECD TG 203. Given the versatility of the protocol, however, the FET test has found application beyond acute toxicity testing as a common tool in environmental hazard and risk assessment. Whereas the standard OECD guideline is restricted to four core endpoints (coagulation as well as lack of somite formation, heartbeat, and tail detachment) for simple, rapid assessment of acute toxicity, further endpoints can easily be integrated into the FET test protocol. This has led to the hypothesis that an extended FET test might allow for the identification of different classes of toxicants via a "fingerprint" of morphological observations. To test this hypothesis, the present study investigated a set of 18 compounds with highly diverse modes of action with respect to acute and sublethal endpoints. Especially at higher concentrations, most observations proved toxicant-unspecific. With decreasing concentrations, however, observations declined in number, but gained in specificity. Specific observations may at best be made at test concentrations ≤ EC₁₀. The existence of a "fingerprint" based on morphological observations in the FET is, therefore, highly unlikely in the range of acute toxicity, but cannot be excluded for experiments at sublethal concentrations.

Ameliorative Impact of Aloe vera on Cartap Mediated Toxicity in the Brain of Wistar Rats

Exposure to pesticides can pose a greater threat to multiple organs of nontarget animals. Cartap is a thiocarbamate pesticide, broadly used in agricultural fields. The assessment of neurotoxicity of cartap has not been properly studied in the mammalian systems. The present investigation unveils the toxic effects of cartap in the brain of Wistar rats its amelioration by using aqueous extract of Aloe vera leaves. We have used 4 groups of animals comprising six in each: Group 1- control, Group 2- control with Aloe vera, Group 3- cartap, Group 4- cartap with Aloe vera treated. After 15 days of treatment, biochemical investigations were conducted. Wistar rats orally exposed to sublethal doses of cartap, showed significant variations in the levels of prooxidants i.e. MDA and GSH (an oxidative stress marker) and enzymatic antioxidants i.e. SOD, CAT, GST, GPx. The decreased levels of CAT, SOD, GST and increased levels of GPx were detected in the experimental rats treated with cartap. The significant alterations were recorded with the declined activities of LDH and AChE, considered as the biomarker of energy metabolism and altered cholinergic function, respectively. However, the pre-administration of aqueous extract of Aloe vera leaves was found to markedly ameliorate the toxic effects of cartap by shielding the levels of aforesaid oxidative markers near to the control. The ameliorative impact of Aloe vera, might be due to the presence of several antioxidant molecules in it which were able to counter the oxidative stress generated by cartap stress. These results suggested that Aloe vera could be utilized as a possible supplement with the relevant therapeutics in the suitable management of cartap toxicity in association.

Insecticide Resistance in the West Nile Encephalitis, Japanese Encephalitis, Avian Malaria and Lymphatic Elephantiasis Vector, Culex pipiens complex (Diptera: Culicidae) in Iran

Background

Culex pipiens complex is considered as a vector of some important diseases such as West Nile fever, equine encephalitis, Rift valley fever, St. Louis encephalitis, Elephanthiasis and avian malaria in the world. The main measure for vector control is using insecticides. High use of insecticides caused resistance in the populations. The aim of this study was to review the status of insecticide resistance in the vector.

Methods

Insecticide resistance in this species was found by the available papers and map of the data for carbamates, organochlorine, organophosphates, pyrethroids, microbial and insect growth regulator insecticides were done. An intensive search of scientific literature was done in "PubMed", "Web of Knowledge", "Scopus", "Google Scholar", "SID", and related resources.

Results

Results showed that a wide variety of resistance to different insecticides in the country. Due to importance of this species in transmission of diseases.

Discussion

resistance management strategies should be further considered to prevent from in secticide resistance and replacement of novel approach for vector control.

Association between pesticide exposure and sleep health among a representative sample of US adults: evidence from NHANES 2009-2014

BACKGROUND

Data suggest that pesticides interact with the melatonin receptor, which may influence sleep. However, the link between pesticides and sleep remains unexplored among the general adult population. This study evaluated unstratified and sex-stratified associations between urinary pesticide exposure (N = 4,478) and self-reported acute household pesticide exposure (N = 14,956), with sleep health outcomes within a nationally representative sample of US adults.

METHODS

Data from the National Health and Nutrition Examination Surveys (NHANES) 2009-2014 were combined for analysis of aim 1 and aim 2. Urinary pesticide metabolite concentrations served as biomarkers of pesticide exposure. Acute household pesticide exposure (if any chemical products were used in the home in the past seven days to control pests) was self-reported (yes/no). Insufficient sleep duration (< 7 h/night) and trouble sleeping (yes/no) were self-reported. Log-binomial regression models that accounted for complex survey weights and adjusted for confounders were used to compute prevalence ratios and 95% CI.

RESULTS

Log urinary 3-phenoxybenzoic acid (3-PBA) was related to a higher probability of insufficient sleep [1.09 (95% CI: 1.00, 1.20), p = 0.04] and trouble sleeping [1.14 (95% CI: 1.02, 1.27), p = 0.02] among males. Self-reported acute household pesticide exposure was associated with a higher probability of insufficient sleep duration [1.16 (95% CI: 1.02, 1.32), p = 0.03] and trouble sleeping [1.20 (95% CI: 1.01, 1.44), p = 0.04] in the unstratified sample. Sex-stratified findings showed that associations between acute household pesticide exposure and trouble sleeping only persisted  among males [1.69 (95% CI: 1.27, 2.24), p < .001].

CONCLUSIONS

In summary, acute pesticide exposure may be detrimental to adult sleep health, particularly among US males.

Pharmacological Actions of Carbamate Insecticides at Mammalian Melatonin Receptors

Integrated in silico chemical clustering and melatonin receptor molecular modeling combined with in vitro 2-[125I]-iodomelatonin competition binding were used to identify carbamate insecticides with affinity for human melatonin receptor 1 (hMT1) and human melatonin receptor 2 (hMT2). Saturation and kinetic binding studies with 2-[125I]-iodomelatonin revealed lead carbamates (carbaryl, fenobucarb, bendiocarb, carbofuran) to be orthosteric ligands with antagonist apparent efficacy at hMT1 and agonist apparent efficacy at hMT2 Furthermore, using quantitative receptor autoradiography in coronal brain slices from C3H/HeN mice, carbaryl, fenobucarb, and bendiocarb competed for 2-[125I]-iodomelatonin binding in the suprachiasmatic nucleus (SCN), paraventricular nucleus of the thalamus (PVT), and pars tuberalis (PT) with affinities similar to those determined for the hMT1 receptor. Carbaryl (10 mg/kg i.p.) administered in vivo also competed ex vivo for 2-[125I]-iodomelatonin binding to the SCN, PVT, and PT, demonstrating the ability to reach brain melatonin receptors in C3H/HeN mice. Furthermore, the same dose of carbaryl given to C3H/HeN mice in constant dark for three consecutive days at subjective dusk (circadian time 10) phase-advanced circadian activity rhythms (mean = 0.91 hours) similar to melatonin (mean = 1.12 hours) when compared with vehicle (mean = 0.04 hours). Carbaryl-mediated phase shift of overt circadian activity rhythm onset is likely mediated via interactions with SCN melatonin receptors. Based on the pharmacological actions of carbaryl and other carbamate insecticides at melatonin receptors, exposure may modulate time-of-day information conveyed to the master biologic clock relevant to adverse health outcomes. SIGNIFICANCE STATEMENT: In silico chemical clustering and molecular modeling in conjunction with in vitro bioassays identified several carbamate insecticides (i.e., carbaryl, carbofuran, fenobucarb, bendiocarb) as pharmacologically active orthosteric melatonin receptor 1 and 2 ligands. This work further demonstrated that carbaryl competes for melatonin receptor binding in the master biological clock (suprachiasmatic nucleus) and phase-advances overt circadian activity rhythms in C3H/HeN mice, supporting the relevance of circadian effects when interpreting toxicological findings related to carbamate insecticide exposure.

Occurrence, statutory guideline values and removal of contaminants of emerging concern by Electrochemical Advanced Oxidation Processes: A review

A wide variety of chemical compounds are used in human activities; however, part of these compounds reach surface water, groundwater and even water considered for potable uses. Due to the limited efficiency of water treatment by the Water and Wastewater Treatment Plants, the presence of these compounds in natural and human consumption waters can be very harmful due to their high persistence and adverse effects; these characteristics define the contaminants of emerging concern (CECs). Water treatment by Electrochemical Advanced Oxidation Processes (EAOPs) has been evaluated as a promising process for the removal of persistent and recalcitrant organic contaminants. With this background, the present review aims to gather studies and information published between 2015 and 2020 regarding the occurrence of CECs in surface, potable and groundwater, its treatment by EAOPs, the main operating conditions and by-product generation of EAOPs, contaminant toxicity assessments and international statutory guideline values concerning CEC standards and allowable concentrations in the environment and treated drinking water. Therefore, in this review it was found that the compounds bisphenol A (BPA), diethyltoluamide (DEET), 17α-ethinyl estradiol (EE2), perfluorobutanoic acid (PFBA), carbamazepine, caffeine and atrazine were the most frequently detected in water sources, with concentrations ranging from 35.54-4800, 1.21-98, 0.005-38.5, 5-742.904, 0.0071-586, 0.89-1040, and 100-323 (ng L-1), respectively. Among the operational conditions of EAOPs, current density, pH and oxidant concentration are the main operational parameters that have an influence on these treatment technologies, besides the by-products generated, which might be removed by the integration of EAOPs with biological digestion treatments. Regarding the values of water quality standards, many CECs do not have established standard allowable concentration values, which represents a concern toward the possible toxic effects of these compounds on non-target organisms.

Ozone treatment pak choi for the removal of malathion and carbosulfan pesticide residues

Since the beginning of the widespread use of pesticides, their removal from food has become a serious concern. In this study, the removal of residual pesticides (malathion and carbosulfan) from pak choi via treatment with ozonated water was investigated. Under the optimal treatment conditions, i.e., 2.0 mg/L ozonated water and a treatment duration of 15 min, malathion and carbosulfan were degraded by 53.0 and 33.0%, respectively, without any significant changes in color. Even though there was a slight decrease in vitamin C content (~7.9 mg/100 g) following the treatments, a significant decrease in the microbial colonies on the vegetables was observed. Additionally, the pesticide degradation mechanism showed good fitting with a "first + first"-order kinetic model (R² > 0.9), and the slope (k) indicated that ozone had a more prominent degradation effect on malathion than on carbosulfan. Therefore, this study provides a theoretical basis for controlling agricultural pesticide residues in household applications.

Anti-Inflammatory and Antioxidative Potential of Aloe vera on the Cartap and Malathion Mediated Toxicity in Wistar Rats

Aloe vera has been the most useful medicinal herb in the world since ancient times due to its vast biological effects. The presence of high content of bioactive compounds make Aloe vera a promising complementary and alternative agent in disease prevention. The effectiveness of A. vera-based medicines against pesticide toxicity has never been evaluated. It was therefore envisaged to develop an A. vera-based strategy to protect the non-target animals from adverse effects of the pesticides. This article illustrates the ameliorating effect of aqueous extract (AE) of A. vera leaves against the cartap and malathion toxicity. To evaluate the protective impact of A. vera against cartap (Ctp), malathion (Mtn) and a mixture of both pesticides, the animals were divided in eight groups, each containing six rats: Group 1- C (control), Group 2- AE + C, Group 3- Ctp, Group 4- Mtn, Group 5- Ctp + Mtn, Group 6- AE + Ctp, Group 7- AE + Mtn, Group 8- AE + Ctp + Mtn. Wistar rats exposed to Ctp, Mtn and Ctp + Mtn, displayed significant change in body weight. It was observed that the WBC level increased significantly in Mtn and Ctp + Mtn challenged groups. The contents of TNF-α and IL-6 in serum increased expressively in the Ctp, Mtn and Ctp + Mtn challenged groups. Rats treated with Ctp, Mtn and Ctp + Mtn displayed significant alterations in the levels of antioxidative indices (MDA, GSH, GST, GPx, SOD and CAT). Significant alterations were recorded in the activities of AST, ALT, ACP and ALP in Ctp, Mtn and Ctp + Mtn challenged groups. The histopathological results of liver supported the biochemical data. The pre-treatment of rats with the aqueous extract of A. vera leaves significantly protected them from the toxicity of pesticides. These results suggested that A. vera extract may be used as a promising natural agent for the management of pesticide induced toxicity.

Determination and Extraction of Carbofuran Pesticide in Different Matrices using Cloud Point Extraction Method

Background:

Pesticides are increasingly used in agriculture and households, but they are also considered a major pollutant to the environment. Carbofuran (CAR; 2,3-dihydro-2,2- dimethylbenzofuran-7-yl methylcarbamate) is a widely used pesticide due to its effectiveness on soybean aphids.

Objectives:

A simple and green method was suggested for the extraction and determination of CAR in different matrices.

Methods:

A diazotization reaction involving the use of the drug compound metoclopramide was utilized in this study. A red dye product, which was formed from the diazotization coupling between CAR and diazotized metoclopramide (DMCP), was extracted using cloud point extraction with the nonionic surfactant Triton X-114 and measured at a wavelength of 515 nm.

Results:

The linearity of the extracted method was over a concentration range of 0.1-0.5 µg/mL (r2 = 0.996) for CAR with a detection limit of 0.064 µg/mL and enrichment factors of about 148 folds for CAR. The mean recovery percentage was in the range of 99-102% for water and soil samples with precision (RSD%) of less than 0.4%.

Conclusion:

The described method was effectively utilized in the simultaneous extraction of CAR from water and soil samples.

Pesticides, cognitive functions and dementia: A review

Pesticides are widely-used chemicals commonly applied in agriculture for the protection of crops from pests. Depending on the class of pesticides, the specific substances may have a specific set of adverse effects on humans, especially in cases of acute poisoning. In past years, evidence regarding sequelae of chronic, low-level exposure has been accumulating. Cognitive impairment and dementia heavily affect a person's quality of life and scientific data has been hinting towards an association between them and antecedent chronic pesticide exposure. Here, we reviewed animal and human studies exploring the association between pesticide exposure, cognition and dementia. Additionally, we present potential mechanisms through which pesticides may act neurotoxically and lead to neurodegeneration. Study designs rarely presented homogeneity and the estimation of the exposure to pesticides has been most frequently performed without measuring the synergic effects and the possible interactions between the toxicants within mixtures, and also overlooking low exposures to environmental toxicants. It is possible that a Real-Life Risk Simulation approach would represent a robust alternative for future studies, so that the safe exposure limits and the net risk that pesticides confer to impaired cognitive function can be examined. Previous studies that evaluated the effect of low dose chronic exposure to mixtures of pesticides and other chemicals intending to simulate real life exposure scenarios showed that hormetic neurobehavioral effects can appear after mixture exposure at doses considered safe for individual compounds and these effects can be exacerbated by a coexistence with specific conditions such as vitamin deficiency. However, there is an overall indication, derived from both epidemiologic and laboratory evidence, supporting an association between exposure to neurotoxic pesticides and cognitive dysfunction, dementia and Alzheimer's disease.

Identification of Psychoactive Metabolites from Cannabis sativa, Its Smoke, and Other Phytocannabinoids Using Machine Learning and Multivariate Methods

Cannabis sativa is a medicinal plant having a very complex matrix composed of mainly cannabinoids and terpenoids. The literature has numerous reports, which indicate that tetrahydrocannabinol (THC) is the only major psychoactive metabolite in C. sativa. It is important to explore other metabolites having the possibility of exhibiting the psychoactive character of various degrees and also to identify metabolites targeting other receptors such as opioid, γ amino butyric acid (GABA), glycine, serotonin, and nicotine present in C. sativa, the smoke of C. sativa, and other phytocannabinoid matrices. This article aims to achieve this goal by application of batteries of computational tools such as machine learning tools and multivariate methods on physiochemical and absorption, distribution, metabolism, excretion, and toxicity (ADMET) descriptors of 468 metabolites from C. sativa, its smoke and, other phytocannabinoids. The structure-activity relationship (SAR) showed that 54 metabolites from C. sativa have high scaffold homology with THC. Its implications on the route of administration and factors affecting the SAR are discussed. C. sativa smoke has metabolites that have possibility of interacting with GABA, and glycine receptors.

Binding of iodinated contrast media (ICM) and their transformation products with hormone receptors: Are ICM the new EDCs?

Iodinated contrast media (ICM) have been detected at high concentrations (as high as about 3 μg/L) in surface water systems, and recently in fish brains and gonad. The mismatch between the polarity of ICM and the high lipid content of brain raises questions on whether their bioaccumulation is receptor-mediated. Furthermore, the structural similarity of ICM to the natural thyroid hormones thyroxine and triiodothyronine suggest potential binding of ICM to nuclear receptors in the endocrine system. Therefore, an in silico approach based on Surflex-Dock module of SYBYL was used to investigate the molecular docking of selected ICM (diatrizoic acid, iohexol, iopamidol, and iopromide). These ICM showed interaction with nuclear receptors that play key roles in endocrine regulation, including the androgen and estrogen receptors. Furthermore, the results indicate peroxisome proliferator-activated receptor gamma (PPARg) as one of the viable targets in the endocrine disrupting potential of ICM with higher Cscores for the ICM and iopromide transformation products than the reference ligand for the receptor. The data obtained from in silico calculations showed stronger binding of iohexol to the transthyretin-binding pocket compared to the natural hormones, thyroxine and triiodothyronine, suggesting the potential of ICM to act as endocrine disrupting chemicals (EDCs) in the environment.

Methylselenol release as a cytotoxic tool: a study of the mechanism of the activity achieved by two series of methylselenocarbamate derivatives

A molecular modeling study has been carried out on two previously reported series of methylselenocarbamate derivatives that show remarkable antiproliferative and cytotoxic in vitro activity, against a panel of human cancer cell lines. These derivatives can be considered as having been constructed by a selenomethyl fragment located over a carbon atom which is decorated with two carbamate moieties, both aliphatic and aromatic, one of them attached by a single bond to the central carbon atom, while the second is connected by a double bond. According to the data obtained, these derivatives can undergo a water-mediated nucleophilic attack on the carbons with marked electrophilic character, which leads to the rupture of C-Se and carbamate C-O bonds. The aliphatic derivatives, series 1, show an early release of methylselenol and a further release of hydroxyl derivatives (alcohols), whereas the aromatic carbamates, series 2, show an early release of phenols followed by the subsequent release of methylselenol. Thus, the activity of the compounds can be related to the progressive release of active fragments. The data that support this connection are related to the overall molecular topology, volume and surface area as well as to quantum parameters such as the relative electrophilic character of the target carbon atoms (measured in terms of positive charge values) or the bond order values, especially concerning the central C-SeCH3 bond and the carbamate ones. Moreover, the data obtained regarding the chromatographic behavior of some representative compounds confirm this proposal.

Development of an immunoassay for the detection of carbaryl in cereals based on a camelid variable heavy-chain antibody domain

BACKGROUND

The variable domain of camelid heavy-chain antibodies (VHH) is increasingly being adapted to detect small molecules in various matrices. The insecticide carbaryl is widely used in agriculture while its residues have posed a threat to food safety and human health.

RESULTS

VHHs specific for carbaryl were generated from an alpaca immunized with the hapten CBR1 coupled to keyhole limpet hemocyanin. An enzyme-linked immunosorbent assay (ELISA) based on the VHH C1 and the coating antigen CBR2-BSA was developed for the detection of carbaryl in cereals. This assay, using an optimized assay buffer (pH 6.5) containing 10% methanol and 0.8% NaCl, has a half-maximum signal inhibition concentration of 5.4 ng mL^-1 and a limit of detection (LOD) of 0.3 ng mL^-1 for carbaryl, and shows low cross reactivity (≤0.8%) with other tested carbamates. The LOD of carbaryl using the VHH-based ELISA was 36 ng g^-1 in rice and maize and 72 ng g^-1 in wheat. Recoveries of carbaryl in spiked rice, maize and wheat samples were in the range of 81-106%, 96-106% and 83-113%, respectively. Relative standard deviations of repeatability and intra-laboratory reproducibility were in the range of 0.8-9.2% and 2.9-9.7%, respectively.

CONCLUSION

The VHH-based ELISA was highly effective in detecting carbaryl in cereal samples after simple sample extraction and dilution. © 2019 Society of Chemical Industry.

Quantification and Confirmation of Fifteen Carbamate Pesticide Residues by Multiple Reaction Monitoring and Enhanced Product Ion Scan Modes via LC-MS/MS QTRAP System

In this research, fifteen carbamate pesticide residues were systematically analyzed by ultra-high performance liquid chromatography⁻quadrupole-linear ion trap mass spectrometry on a QTRAP 5500 system in both multiple reaction monitoring (MRM) and enhanced product ion (EPI) scan modes. The carbamate pesticide residues were extracted from a variety of samples by QuEChERS method and separated by a popular reverse phase column (Waters BEH C18). Except for the current conformation criteria including selected ion pairs, retention time and relative intensities from MRM scan mode, the presence of carbamate pesticide residues in diverse samples, especially some doubtful cases, could also be confirmed by the matching of carbamate pesticide spectra via EPI scan mode. Moreover, the fragmentation routes of fifteen carbamates were firstly explained based on the mass spectra obtained by a QTRAP system; the characteristic fragment ion from a neutral loss of CH₃NCO (-57 Da) could be observed. The limits of detection and quantification for fifteen carbamates were 0.2⁻2.0 μg kg-1 and 0.5⁻5.0 μg kg-1, respectively. For the intra- (n = 3) and inter-day (n = 15) precisions, the recoveries of fifteen carbamates from spiked samples ranged from 88.1% to 118.4%, and the coefficients of variation (CVs) were all below 10%. The method was applied to pesticide residues detection in fruit, vegetable and green tea samples taken from local markets, in which carbamates were extensively detected but all below the standard of maximum residue limit.

Melatonin receptors: molecular pharmacology and signalling in the context of system bias

Melatonin, N-acetyl-5-methoxytryptamine, an evolutionally old molecule, is produced by the pineal gland in vertebrates, and it binds with high affinity to melatonin receptors, which are members of the GPCR family. Among the multiple effects attributed to melatonin, we will focus here on those that are dependent on the activation of the two mammalian MT1 and MT2 melatonin receptors. We briefly summarize the latest developments on synthetic melatonin receptor ligands, including multi-target-directed ligands, and the characterization of signalling-biased ligands. We discuss signalling pathways activated by melatonin receptors that appear to be highly cell- and tissue-dependent, emphasizing the impact of system bias on the functional outcome. Different proteins have been demonstrated to interact with melatonin receptors, and thus, we postulate that part of this system bias has its molecular basis in differences of the expression of receptor-associated proteins including heterodimerization partners. Finally, bias at the level of the receptor, by the expression of genetic receptor variants, will be discussed to show how a modified receptor function can have an effect on the risk for common diseases like type 2 diabetes in humans. LINKED ARTICLES: This article is part of a themed section on Recent Developments in Research of Melatonin and its Potential Therapeutic Applications. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.16/issuetoc.

Effects of Commonly Used Pesticides in China on the Mitochondria and Ubiquitin-Proteasome System in Parkinson's Disease

Evidence continues to accumulate that pesticides are the leading candidates of environmental toxins that may contribute to the pathogenesis of Parkinson’s disease. The mechanisms, however, remain largely unclear. According to epidemiological studies, we selected nine representative pesticides (paraquat, rotenone, chlorpyrifos, pendimethalin, endosulfan, fenpyroximate, tebufenpyrad, trichlorphon and carbaryl) which are commonly used in China and detected the effects of the pesticides on mitochondria and ubiquitin-proteasome system (UPS) function. Our results reveal that all the nine studied pesticides induce morphological changes of mitochondria at low concentrations. Paraquat, rotenone, chlorpyrifos, pendimethalin, endosulfan, fenpyroximate and tebufenpyrad induced mitochondria fragmentation. Furthermore, some of them (paraquat, rotenone, chlorpyrifos, fenpyroximate and tebufenpyrad) caused a significant dose-dependent decrease of intracellular ATP. Interestingly, these pesticides which induce mitochondria dysfunction also inhibit 26S and 20S proteasome activity. However, two out of the nine pesticides, namely trichlorphon and carbaryl, were found not to cause mitochondrial fragmentation or functional damage, nor inhibit the activity of the proteasome, which provides significant guidance for selection of pesticides in China. Moreover, our results demonstrate a potential link between inhibition of mitochondria and the UPS, and pesticide-induced Parkinsonism.

Sleep apnea and pesticide exposure in a study of US farmers

INTRODUCTION

Carbamate and organophosphate pesticides inhibit acetylcholinesterase, and poisoning leads to respiratory depression. Thus, involvement in sleep apnea is plausible, but no data exist at lower levels of exposure. Other pesticides could impact sleep apnea by different mechanisms but have not been studied. Our study examines the associations between pesticide exposure and sleep apnea among pesticide applicators from a US farming population.

PARTICIPANTS AND METHODS

We analyzed data from 1569 male pesticide applicators, mostly farmers, from an asthma case-control study nested within the prospective Agricultural Health Study. On questionnaires, participants reported use of specific pesticides and physician diagnosis plus prescribed treatments for sleep apnea. We used multivariable logistic regression to estimate associations between ever use of 63 pesticides and sleep apnea (234 cases, 1335 noncases).

RESULTS

The most notable association was for carbofuran, a carbamate (100 exposed cases, odds ratio 1.83, 95% confidence interval 1.34-2.51, P=.0002). Carbofuran use began before reported onset of sleep apnea in all cases.

DISCUSSION

This study adds to the known adverse health outcomes of exposure to carbofuran, a pesticide canceled in the United States in 2009 for most agricultural purposes but persists in the environment and remains in use in some other countries.

CONCLUSIONS

We conducted the first epidemiological study investigating the association of pesticide exposure and sleep apnea. Our results in a male agricultural population suggests that exposure to carbofuran is positively associated with sleep apnea.