Facilitation of acetylcholine signaling by the dithiocarbamate fungicide propineb

Catalyst/Metal/Solvent-Free Markovnikov Hydrothiolation of Unactivated Alkenes with Dithiocarbamic Acids

Catalyst-free Markovnikov-selective hydrothiolation of unactivated alkenes still remains a great challenge. Herein, we develop a catalyst/metal/solvent-free methodology for the Markovnikov hydrothiolation of unactivated alkenes with in situ prepared dithiocarbamic acids, providing a wide array of alkyl dithiocarbamates. A variety of terminal, internal, cyclic, and acyclic unactivated alkenes were applied successfully in this protocol. This three-component thiol-ene reaction can be considered as a new family of click reactions.

Acute health symptoms related to perception and practice of pesticides use among farmers from all regions of Thailand

Introduction

Occupational exposure to pesticides may cause acute health effects for farmers and agricultural workers. Therefore, this study aims to investigate the prevalence of poisoning symptoms related pesticide exposure among farmers from all regions of Thailand, as well as factors linked to poisoning symptoms of neurological and neuromuscular systems, the respiratory system, and eye and skin disorders.

Methods

A cross sectional study was conducted in 4,035 farmers who lived in four regions of Thailand. The samples were chosen using stratified random sampling, with 746 for the Central region, 2,065 for the North-East, 586 for the North, and 638 for the South.

Results

The results found that the highest prevalence of poisoning symptoms was found in association with neurological and neuromuscular systems (75%), followed by the respiratory system (60.4%), the eyes (41.2%), and skin (14.8%). The most prevalent symptoms were muscle pain (49%) for neurological and neuromuscular symptoms, burning nose (37.6%) for respiratory symptoms, itchy eyes (26.3%) for eye symptoms, and rashes (14.4%) for skin symptoms. The remarkable findings were that types of pesticide use, task on the farm, types of pesticide sprayers, and perception are the crucial factors affecting all poisoning symptoms.

Discussion

The findings are also beneficial to the Thai government and other relevant organizations for launching measures, campaigns, or interventions to lower modifiable risk factors, resulting in reducing health risks associated with pesticide exposure.

Ecotoxicity of pesticide formulations and their mixtures: the case of potato crops in Costa Rica

Despite their environmental implications, ecotoxicological information regarding pesticide mixtures is relatively scarce. This study aimed to determine the ecotoxicity of individual pesticide formulations and their mixtures (insecticides and fungicides), which are applied during the production cycle of potato, according to agricultural practices from a Latin American region in Costa Rica. Two benchmark organisms were employed: Daphnia magna and Lactuca sativa. First, the evaluation of individual formulations (chlorothalonil, propineb, deltamethrin+imidacloprid, ziram, thiocyclam and chlorpyrifos) revealed differences between available EC₅₀ for active ingredients (a.i.) and their respective formulations toward D. magna; on the contrary, no information could be retrieved from scientific literature for comparison in the case of L. sativa. In general, acute toxicity was higher toward D. magna than L. sativa. Moreover, interactions could not be determined on L. sativa, as the chlorothalonil formulation was not toxic at high levels and the concentration-response to propineb could not be fitted to obtain an IC₅₀ value. The commercial formulation composed of deltamethrin+imidacloprid followed the concentration addition model (when compared with parameters retrieved from individual a.i.) and the other three mixtures evaluated (I: chlorothalonil-propineb-deltamethrin+imidacloprid; II: chlorothalonil-propineb-ziram-thiocyclam; III: chlorothalonil-propineb-chlorpyrifos) produced an antagonistic effect on D. magna, thus suggesting less acute toxicity than their individual components. Subsequent chronic studies showed that one of the most toxic mixtures (II) negatively affected D. magna reproduction at sublethal concentrations indicating that this mixture poses a risk to this species if these pesticides co-exist in freshwater systems. These findings provide useful data to better estimate the impact of real agricultural practices related to the use of agrochemicals.

Prevalence of pesticide related occupational diseases among Indonesian vegetable farmers - A collaborative work

Objective

This study was done to understand the prevalence of various occupational diseases including dry eyes, nail dystrophy, and neuropathy related to pesticide exposure in Indonesian local vegetable farmers.

Methods

The data were collected through questionnaires and physical examination involving dermatology, neurology, and ophthalmology domains at Ngablak District, Magelang, Central Java directed to local vegetable farmers. Ocular Surface Disease Index (OSDI) questionnaire and the Schirmer test were used. Analysis was done using descriptive statistics using the Statistical Package for the Social Sciences (SPSS 21.0) and presented in tables.

Results

Inadequate spraying equipment and improper storage of pesticides were found. Out of 105 farmers, 41.9 % experienced occupational skin diseases (OSD). Definite cognitive impairments were found in 3.4 % of subjects but probable in 28.3 % of subjects. Neuropathies were found in 61.7 % of subjects, and dry-eyes syndrome were found in 28.78 % of subjects.

Conclusion

There was a high prevalence of peripheral neuropathy and tremor, dry eyes syndrome in one-third of the population, and the most common skin problem was nail discoloration, with a low incidence of contact dermatitis.

Metal-free visible-light-induced multi-component reactions of α-diazoesters leading to S-alkyl dithiocarbamates

A metal-free and visible-light-promoted strategy has been developed for the synthesis of S-alkyl dithiocarbamates through multicomponent reactions of α-diazoesters, amines and CS2.

An insight into medicinal attributes of dithiocarbamates: Bird's eye view

Dithiocarbamates are considered as an important motif owing to its extensive biological applications in medicinal chemistry. The synthesis of this framework can easily be achieved via a one-pot reaction of primary/secondary amines, CS₂, and alkyl halides under catalyst-free conditions or sometimes in the presence of a base. By virtue of its colossal pharmacological scope, it has been an evolving subject of interest for many researchers around the world. The present review aims to highlight various synthetic approaches for dithiocarbamates with the major emphasis on medicinal attributes of these architectures as leads in the drug discovery of small molecules such as HDAC inhibitor, lysine-specific demethylase 1 (LSD1) down-regulator, kinase inhibitor (focal adhesion kinase, pyruvate kinase, Bruton's tyrosine kinase), carbonic anhydrase inhibitor, DNA intercalators, and apoptosis-inducing agents. Moreover, recent medicinal advancements in the synthesis of dithiocarbamate derivatives as anticancer, antifungal, antibacterial, anti-Alzheimer, antitubercular, anti-glaucoma, anti-cholinergic, antihyperglycemic, anti-inflammatory activities have been elaborated with notable examples.

A new Mumm-type rearrangement with dithiocarbamates via isocyanide-based multicomponent reaction under ultrasound irradiation: synthesis of polysubstituted pyrrolidine compounds

Through a domino reaction, five new bonds were formed, carbon–sulfur, two carbon–nitrogen, and two carbon–carbon bonds.

Determination of propineb and its metabolites propylenethiourea and propylenediamine in banana and soil using gas chromatography with flame photometric detection and LC-MS/MS analysis

A sensitive and specific method for the determination of propineb and its metabolites, propylenethiourea (PTU) and propylenediamine (PDA), using gas chromatography with flame photometric detection (GC-FPD) and LC-MS/MS was developed and validated. Propineb and its metabolite residue dynamics in supervised field trials under Good Agricultural Practice (GAP) conditions in banana and soil were studied. Recovery of propineb (as CS₂), PDA and PTU ranged from 75.3 to 115.4% with RSD (n = 5) of 1.3-11.1%. The limit of quantification (LOQ) of CS₂, PDA and PTU ranged from 0.005 to 0.01 mg kg^-1, and the limit of detection (LOD) ranged from 0.0015 to 0.0033 mg kg^-1. Dissipation experiments showed that the half-life of propineb in banana and soil ranged from 4.4 to 13.3 days. PTU was found in banana with a half-life of 31.5-69.3 days, while levels of PDA were less than 0.01 mg kg^-1 in banana and soil. It has been suggested that PTU is the major metabolite of propineb in banana. The method was demonstrated to be reliable and sensitive for the routine monitoring of propineb and its metabolites in banana and soil. It also serves as a reference for the detection and monitoring of dithiocarbamates (DTCs) residues and the evaluation of their metabolic pathway.

Synthesis of N,S-Heterocycles and Dithiocarbamates by the Reaction of Dithiocarbamic Acids and S-Alkyl Dithiocarbamates with Nitroepoxides

A facile and efficient procedure for the synthesis of substituted thiazole-2(3H)-thiones and thiazolidine-2-thiones by the reaction of primary amines, carbon disulfide, and nitroepoxides is described. By using secondary amines in this protocol, the corresponding dithiocarbamate-substituted phenyl-2-propanones were prepared in excellent yields. In addition, substituted thiazoles and 1-(alkylthio)-1-phenylpropan-2-ones were prepared in reactions of S-alkyl dithiocarbamates and nitroepoxides.

One-pot three-component route for the synthesis of S-trifluoromethyl dithiocarbamates using Togni's reagent

A one-pot three-component route for the synthesis of S-trifluoromethyl dithiocarbamates by the reaction of secondary amines, carbon disulfide and Togni’s reagent is described. The reactions proceed in moderate to good yields. A similar reaction using a primary aliphatic amine afforded the corresponding isothiocyanate in high yield. A variable temperature NMR study revealed a rotational barrier of 14.6, 18.8, and 15.9 kcal/mol for the C–N bond in the dithiocarbamate moiety of piperidine, pyrrolidine, and diethylamine adducts, respectively. In addition, the calculated barriers of rotation are in reasonable agreement with the experiments.

Pesticide residue screening using a novel artificial neural network combined with a bioelectric cellular biosensor

We developed a novel artificial neural network (ANN) system able to detect and classify pesticide residues. The novel ANN is coupled, in a customized way, to a cellular biosensor operation based on the bioelectric recognition assay (BERA) and able to simultaneously assay eight samples in three minutes. The novel system was developed using the data (time series) of the electrophysiological responses of three different cultured cell lines against three different pesticide groups (carbamates, pyrethroids, and organophosphates). Using the novel system, we were able to classify correctly the presence of the investigated pesticide groups with an overall success rate of 83.6%. Considering that only 70,000–80,000 samples are annually tested in Europe with current conventional technologies (an extremely minor fraction of the actual screening needs), the system reported in the present study could contribute to a screening system milestone for the future landscape in food safety control.

Development and validation of a cellular biosensor detecting pesticide residues in tomatoes

Two of the most important categories of pesticides used in agricultural practice are organophosphates and dithiocarbamates. Their extensive and inappropriate use has rendered their reliable monitoring at trace levels more and more necessary. This study presents the construction of a rapid and sensitive cellular biosensor test based on the measurement of changes of the cell membrane potential of immobilized cells, according to the working principle of the Bioelectric Recognition Assay (BERA). The cells were immobilized by entrapment in a sodium alginate bead and directly applied in different pesticide dilutions and agricultural samples. The pesticides used were the organophosphate insecticide diazinon and the dithiocarbamate fungicide propineb. Two different cell types, N2a (neuroblastoma) and Vero (fibroblast) were used as the biosensory elements in order to investigate their differential response against the pesticides. In this way, we hoped to increase the selectivity of the assay. Based on the observed patterns of response, we demonstrate that the sensor can be used for the qualitative and, in some concentrations, quantitative detection of the pesticides with a high degree of reproducibility. The lowest detected concentration was 3nM. Finally, for the investigation of the effects of different pesticides on the accumulation of cytosolic Ca(2+), we conducted a fluorescent assay on N2a cells treated with tomato sample extracts, which were replicates of the E.U. proficiency test sample. The tomato samples were either organically grown or contained 14 different pesticides. The experimental results showed a higher increase of the intracellular Ca(2+) concentration in cells treated with non-organic samples compared to the cells treated with organic samples.

Reactive oxygen species in in vitro pesticide-induced neuronal cell (SH-SY5Y) cytotoxicity: role of NFkappaB and caspase-3

Oxidative stress has been implicated in pesticide-induced neurotoxicity, based on its role in the cascade of biochemical changes that lead to dopaminergic neuronal cell death. We have, therefore, examined the role of oxidative stress caused by the pesticides endosulfan and zineb in human neuroblastoma cells (SH-SY5Y) in culture. Upon treatment with 50-200 microM concentrations of either of these pesticides, SH-SY5Y cells generated both superoxide anion and hydrogen peroxide in a dose-and time-dependent manner. Mixtures of the pesticides significantly enhanced the production of these reactive oxygen species compared to individual pesticide exposures. Pesticide treatment decreased superoxide dismutase, glutathione peroxidase, and catalase activities in SH-SY5Y cells. Additionally, these pesticides induced lipid peroxide (thiobarbituric acid reactive products) formation in these cells. While both pesticides individually (at 100 microM) increased caspase-3 activity, cells exposed to a mixture of the pesticides exhibited significantly low levels of this enzyme, probably due to excessive necrotic cell death. Furthermore, exposure to these pesticides increased nuclear NFkappaB activity. Taken together, these findings suggest that the cytotoxicity of endosulfan and zineb, both individually and in mixtures may, at least in part, be associated with the generation of reactive oxygen species with concomitant increased expression of NFkappaB.

Selective effects of carbamate pesticides on rat neuronal nicotinic acetylcholine receptors and rat brain acetylcholinesterase

Effects of commonly used carbamate pesticides on rat neuronal nicotinic acetylcholine receptors expressed in Xenopus laevis oocytes have been investigated using the two-electrode voltage clamp technique. The potencies of these effects have been compared to the potencies of the carbamates to inhibit rat brain acetylcholinesterase. The potency order of six carbamates to inhibit alpha4beta4 nicotinic receptors is fenoxycarb > EPTC > carbaryl, bendiocarb > propoxur > aldicarb with IC50 values ranging from 3 microM for fenoxycarb to 165 microM for propoxur and >1 mM for aldicarb. Conversely, the potency order of these carbamates to inhibit rat brain acetylcholinesterase is bendiocarb > propoxur, aldicarb > carbaryl > EPTC, fenoxycarb with IC50 values ranging from 1 microM for bendiocarb to 17 microM for carbaryl and > mM for EPTC and fenoxycarb. The alpha4beta2, alpha3beta4, and alpha3beta2 nicotinic acetylcholine receptors are inhibited by fenoxycarb, EPTC, and carbaryl with potency orders similar to that for alpha4beta4 receptors. Comparing the potencies of inhibition of the distinct subtypes of nicotinic acetylcholine receptors shows that the alpha3beta2 receptor is less sensitive to inhibition by fenoxycarb and EPTC. The potency of inhibition depends on the carbamate as well as on a combination of alpha and beta subunit properties. It is concluded that carbamate pesticides affect different subtypes of neuronal nicotinic receptors independently of acetylcholinesterase inhibition. This implicates that neuronal nicotinic receptors are additional targets for some carbamate pesticides and that these receptors may contribute to carbamate pesticide toxicology, especially after long-term exposure.

Significance of changes of gastrointestinal peptides in blood and ileum of experimental spleen deficiency rats

AIM: To explore the mechanism of spleen deficiency (SD) by studying the relationship of gastro-intestinal peptides level and ileal electro-mechanical activity of SD rats and cold restrain rats.

METHODS: (1) spleen deficiency (SD) model was established by feeding Houpou:Zhishi: Dahuang in the ratio of 3:3:2, 3 ml/time, for 42 days. (2) The cold restrain stress model: Animals were restrained on grille and placed in a cool water at 18 °C for 3 h. (3) Substance P (SP) and vasoactive intestinal peptide (VIP) levels in all layers of initial part of ileum and blood in rats were measured by radioimmunoassays (RIA) while changes of electric activity and motility in ileum of rats were recorded with electrode and strain gauge.

RESULTS: SP levels in ileum and blood of experimental SD rats were significantly higher than that of the control groups (9.89 ± 5.65 vs 1.22 ± 1.18, P < 0.005, in ileum; 22.7 ± 3.95 vs 6.60 ± 1.47, P < 0.001, in blood) while the VIP levels of the SD rats were significantly lower than that of the controls (3.50 ± 2.01 vs 9.10 ± 4.91, P < 0.05, in ileum; 229.8 ± 62.4 vs 560.4 ± 151.3, P < 0.001, in blood). As compared with the controls, the average frequency of slow electric waves (21.3 ± 0.96 vs 18.2 ± 2.28, P < 0.05) and motility (21.5 ± 0.58 vs 18 ± 2.65, P < 0.005) of SD rats increased obviously and the frequency of fast waves of SD rat also increased. In spontaneous recovery cases, SP levels recovered significantly (compared with the SD groups, 2.99 ± 0.62 vs 9.89 ± 5.65, P < 0.001, in ileum; 14.4 ± 4.22 vs 22.7 ± 3.95, P < 0.001, in blood) but did not drop to normal. After the SD rats treated with Chinese herbs (Jiawei Sijun zi Tang), SP improved (compared with SD cases, 2.20 ± 1.25 vs 9.89 ± 5.65, (P < 0.001), in ileum; 10.7 ± 1.88 vs 22.7 ± 3.95, (P < 0.001), in blood) and VIP in blood also improved (compared with SD rats, 485.7 ± 229.0 vs 229.8 ± 62.4, P < 0.01) while the amplitude of motility decreased apparently (compared with the SD rats, 0.64 ± 0.096 vs 0.89 ± 0.15, P < 0.01). The ileal SP levels of cool stress didn’t change while the ileal VIP levels of cool stress became significantly lower than that of the control groups (2.87 ± 0.87 vs 9.10 ± 4.91, P < 0.01). The blood SP levels of cool stress were significantly higher (15.60 ± 1.83 vs 6.60 ± 1.47, P < 0.001) whereas the blood VIP levels of cool stress were significantly lower than that of the control group (153.4 ± 70.46 vs 560.4 ± 151.30, P < 0.001).

CONCLUSION: Changes of SP and VIP levels in initial part of ileum and blood of SD rats and cool stress rats may be closely related to the gastrointestinal motility disorders presented in SD and cool stress rats. the Chinese herbs (Jiawei Sijun zi Tang) currently used have partially therapeutic effect.