Exposure to dithiocarbamate fungicide maneb in vitro and in vivo: Neuronal apoptosis and underlying mechanisms

The mechanism of SiJunZi decoction in the treatment of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease, but treatment options for PD are limited, and drug development has reached a bottleneck. With the progress of the aging population, the number of PD patients in China is increasing day by day, imposing a heavy burden on patients and society. Therefore, it is urgent to explore targeted medicine based on the pathogenesis of PD and disease targets. Ancient physicians have used the traditional Chinese medicine formula SiJunZi decoction (SJZD) to treat PD. However, it is less commonly used clinically now, and its pharmacological mechanism still needs to be further elucidated. In this study, based on network pharmacology research and molecular docking technology, the mechanism of SJZD in treating PD was revealed, showing that the extract of SJZD acts on cell microdomain membranes and lipid rafts, affecting ubiquitin-protein ligase binding and ubiquitin-like protein ligase binding processes, and plays a role in neurogenesis. Molecular docking results showed that Ellipticine and Hederagenin in SJZD exhibited significant effects on targets: CASP3, BCL2, and PTGS2. The effect of SJZD reversing MPP+-induced SH-SY5Y cells injury was verified by experiments, concentrations ranging from 5ug/mL to 0.1ug/mL showed significant cell protection at 24 h.

Solid-State Fluorescent Organic Polymers for Visual Detection and Elimination of Heavy Metals in Water

Selective sensing and removal of toxic heavy metals from water are highly essential since their presence poses significant health and environmental hazards. Herein, we designed and synthesized a novel fluorescent nonconjugated organic polymer by strategically incorporating two key functional groups, namely, a dansyl fluorophore and dithiocarbamate (DTC). Different characterization techniques, including 1H nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR), and fluorescence spectroscopy, were performed to understand its structure and material properties. The quantum yield of 4.72% and its solid-state fluorescence indicate that it has potential for various applications in several technological and scientific domains. In this study, we investigated a specific application involving the detection and elimination of heavy metals from water. Interestingly, the presence of dansyl and DTC moieties demonstrated remarkable selectivity toward Cu2+, Co2+, Ni2+, Fe3+, and Fe2+ sensing, displaying distinct color changes specific to each metal. Cu2+ resulted in a yellow color, Co2+ showed a green color, Ni2+ displayed a pale yellowish-green color, and Fe2+/Fe3+ exhibited a brown color. The LOD (limit of detection) for each metal was obtained in the nanomolar range by using a fluorescence spectrometer and the micromolar range from UV-visible spectra: 13.27 nM and 0.518 μM for Cu2+, 8.27 nM and 0.581 μM for Co2+, 14.36 nM and 0.140 μM for Ni2+, 14.95 nM and 0.174 μM for Fe2+, and 15.54 nM and 0.33 μM for Fe3+. Moreover, the DTC functionality on its backbone facilitates effective interaction with the aforementioned heavy metals, subsequently removing them from water (except Fe2+ and Fe3+), validating its dual functionality as both an indicator and a purifier for heavy metals in water. The polymer exhibited a maximum adsorption capacity of 192.30 mg/g for Cu2+, 159.74 mg/g for Co2+, and 181.81 mg/g for Ni2+. Furthermore, this approach exhibits versatility in crafting fluorescent polymers with adjustable attributes that are suitable for a wide range of applications.

Natural pyrethrins induce cytotoxicity in SH-SY5Y cells and neurotoxicity in zebrafish embryos (Danio rerio)

Natural pyrethrins are widely used in agriculture because of their good insecticidal activity. Meanwhile, natural pyrethrins play an important role in the safety evaluation of pyrethroids as precursors for structural development of pyrethroid insecticides. However, there are fewer studies evaluating the neurological safety of natural pyrethrins on non-target organisms. In this study, we used SH-SY5Y cells and zebrafish embryos to explore the neurotoxicity of natural pyrethrins. Natural pyrethrins were able to induce SH-SY5Y cells damage, as evidenced by decreased viability, cycle block, apoptosis and DNA damage. The apoptotic pathway may be related to the involvement of mitochondria and the results showed that natural pyrethrins induced a rise in Capase-3 viability, Ca2+ overload, a decrease in adenosine triphosphate (ATP) and a collapse of mitochondrial membrane potential in SH-SY5Y cells. Natural pyrethrins may mediate DNA damage in SH-SY5Y cells through oxidative stress. The results showed that natural pyrethrins induced an increase in reactive oxygen species (ROS) levels, superoxide dismutase (SOD) activity, malondialdehyde (MDA) content and catalase (CAT) activity, and induced a decrease in glutathione peroxidase (GPx) activity in SH-SY5Y cells. In vivo, natural pyrethrins induced developmental malformations in zebrafish embryos, which were mainly characterized by pericardial edema and yolk sac edema. Meanwhile, the results showed that natural pyrethrins induced damage to the Huc-GFP axis and disturbed lipid metabolism in the head of zebrafish embryos. Further results showed elevated ROS levels and apoptosis in the head of zebrafish embryos, which corroborated with the results of the cell model. Finally, the results of mRNA expression assay of neurodevelopment-related genes indicated that natural pyrethrins exposure interfered with their expression and led to neurodevelopmental damage in zebrafish embryos. Our study may raise concerns about the neurological safety of natural pyrethrins on non-target organisms.

Direct detection of dithiocarbamate fungicides by SALDI/MS using porous TiC ceramic powder as a substrate

Dithiocarbamate fungicides (DTCs) have been widely used all over the world. Some of them show toxicities, such as growth toxicity and teratogenicity. Therefore, the analysis of DTCs in environments or crops is very significant. However, their direct and individual analysis was difficult, because most of them are metal complex compounds and have macromolecular properties and a low solubility in water or organic solvents. In the conventional analytical methods for DTCs, the total amount of DTCs was obtained by the quantification of the derivatives of the ligand or by measuring the carbon disulfide formed by the decomposition of the fungicides. Surface assisted laser desorption (SALDI)/MS can detect various compounds, such as metal complexes and macromolecules, present in a nanostructured substrate. The porous titanium carbide (TiC) ceramic powder shows adsorptive properties to various substances and can be used as a substrate for SALDI/MS. In this study, a method for the individual and direct detection of dithiocarbamate pesticides by SALDI/MS using porous TiC ceramics as a substrate has been developed. The dithiocarbamate fungicide was mixed with the porous TiC powder in a mortar, and the mixture was analyzed by SALDI/MS. The deprotonated ion of the ethylene-bis-dithiocarbamate complex, mancozeb or zineb, was detected in the negative ion mode. For the dimethyldithiocarbamate complexes, ferbam and ziram, the ion of the eliminated dithiocarbamate ligand was detected in the positive ion mode. Calibration curves by the present method for Manzeb showed good linearity by using an internal standard material. Based on these results, we concluded that this method is useful for the analysis of DTCs.

Mechanism of the adverse outcome of Chlorella vulgaris exposure to diethyl phthalate: Water environmental health reflected by primary producer toxicity

As a ubiquitous contaminant in aquatic environments, diethyl phthalate (DEP) is a major threat to ecosystems because of its increasing utilization. However, the ecological responses to and toxicity mechanisms of DEP in aquatic organisms remain poorly understood. To address this environmental concern, we selected Chlorella vulgaris (C. vulgaris) as a model organism and investigated the toxicological effects of environmentally relevant DEP concentrations at the individual, physiological, biochemical, and molecular levels. Results showed that the incorporation of DEP significantly inhibited the growth of C. vulgaris, with inhibition rates ranging from 10.3 % to 83.47 %, and disrupted intracellular chloroplast structure at the individual level, while the decrease in photosynthetic pigments, with inhibition rates ranging from 8.95 % to 73.27 %, and the imbalance of redox homeostasis implied an adverse effect of DEP at the physio-biochemical level. Furthermore, DEP significantly reduced the metabolic activity of algal cells and negatively altered the cell membrane integrity and mitochondrial membrane potential. In addition, the apoptosis rate of algal cells presented a significant dose-effect relationship, which was mainly attributed to the fact that DEP pollutants regulated Ca2+ homeostasis and further increased the expression of Caspase-8, Caspase-9, and Caspase-3, which are associated with internal and external pathways. The gene transcriptional expression profile further revealed that DEP-mediated toxicity in C. vulgaris was mainly related to the destruction of the photosynthetic system, terpenoid backbone biosynthesis, and DNA replication. Overall, this study offers constructive understandings for a comprehensive assessment of the toxicity risks posed by DEP to C. vulgaris.

Exposure to the environmentally relevant fungicide Maneb: Studying toxicity in the soil nematode Caenorhabditis elegans

Maneb is a manganese-containing ethylene bisdithiocarbamate fungicide and is still commonly used as no cases of resistance have been documented. However, studies have shown that Maneb exposure has neurodegenerative potential in mammals, resulting in symptoms affecting the motor system. Despite its extensive use, structural elucidation of Maneb has only recently been accomplished by our group. This study aimed to examine the bioavailability of Maneb, the quantification of oxidative stress-related endpoints and neurotransmitters employing pure Maneb, its metabolites and structural analogues, in the model organism Caenorhabditis elegans. Exposure to Maneb did not increase the bioavailability of Mn compared to manganese chloride, although Maneb was about 8 times more toxic with regard to lethality. Maneb generated not significantly reactive oxygen and nitrogen species (RONS) but decreased the ATP level while increasing the amount of glutathione and its oxidized form in a dose-dependent manner. Nevertheless, an alteration in the neurotransmitter homeostasis of dopamine, acetylcholine, and gamma-butyric acid (GABA) was observed as well as morphological changes in the dopaminergic neurons upon Maneb exposure, which underlines the assumption of the neurotoxic potential of Maneb. This study showed that Maneb exhibits effects based on a combined interaction of the ligand and manganese.

The Structure of Maneb, An Important Manganese-Containing Bis(dithiocarbamate) Fungicide

Maneb is a manganese(II)-containing fungicide with a multi-site effect and no resistance, therefore it is widely applied in many parts of the world. There is, however, mounting evidence for neurotoxic effects with Parkinson-like symptoms (manganism) related to usage of Maneb. Due to its insolubility in most solvents and its paramagnetism, structural elucidation is not trivial, and thus its exact molecular structure remains unknown. We report herein a synthesis procedure to prepare Maneb reproducibly in pure form and the use of various analytical techniques including X-ray diffraction, X-ray absorption spectroscopy and electron diffraction to determine the molecular structure of Maneb in the solid state and also in solution.