Severe hepatotoxicity and acute renal failure caused by diniconazole

Some evidence supporting the use of optically pure R-(-)-diniconazole: Toxicokinetics and configuration conversion on chiral diniconazole

Diniconazole is a chiral pesticide that exists in two enantiomers, R-(-)-diniconazole and S-(+)-diniconazole, with the R-enantiomer being much more active than the S-enantiomer. Previous enantioselective toxicology studies of diniconazole focused mostly on simple environmental model organisms. In this study, we evaluated the toxicokinetics of the two diniconazole enantiomers in rats and mice to provide a more comprehensive risk assessment. The two enantiomers displayed clear differences in their stereoselective contents in vivo. The t1/2 of R-(-)-diniconazole was 7.06 ± 3.35 h, whereas that of S-(+)-diniconazole was 9.14 ± 4.60 h, indicating that R-(-)-diniconazole was eliminated faster in vivo. The excretion rates of R-(-)-diniconazole and S-(+)-diniconazole were 4.08 ± 0.50 % and 2.68 ± 0.58 %, respectively, indicating more excretion of R-(-)-diniconazole. S-(+)-diniconazole had a higher bioavailability than R-(-)-diniconazole (52.19 % vs. 42.44 %). S-(+)-Diniconazole was also found in relatively high abundance in tissues such as the stomach, large intestine, small intestine, cecum, liver, kidney, brain, and testes, with the abundance being 1.71-2.48-fold that of R-(-)-diniconazole. The selective degradation of both enantiomers in the tissues and their mutual conversion in vivo were not observed, and this could indicate that configuration conversion did not contribute to the differences in the content of enantiomers in the tissues. Instead, such differences were mainly caused by the differences in affinity of each enantiomer for the tissues. Furthermore, investigation of the interconversion between optically pure R-(-)-diniconazole and S-(+)-diniconazole monomers in soil revealed no interconversion. All of the above results indicated no interconversion between R-(-)-diniconazole and S-(+)-diniconazole in vivo and in the soil, and that S-(+)-diniconazole tends to have a greater potential to accumulate in vivo. Thus, if only R-(-)-diniconazole is used as a pesticide, the negative impact on mammals and the environment will be reduced, suggesting that in agriculture, the application of optically pure R-(-)-diniconazole may be a better strategy.

Comparative cytotoxic effects of five commonly used triazole alcohol fungicides on human cells of different tissue types

The widespread application of triazole fungicides makes people attach great concern over its adverse effects in mammalian. In this paper, cytotoxic effects of triazole alcohol fungicides (TAFs) were assessed on human HeLa, A549, HCT116 and K562 cells, and the potential mechanism of TAFs cytotoxicity was studied preliminarily. Results showed that TAFs had cytotoxicity on human cells with different level and cytotoxic selectivity. TAFs cytotoxicity was resonated with a typical hormetic biphasic dose action that produced a complex pattern of stimulatory or inhibitory effects on cell viability. Among the five TAFs, diniconazole revealed a widest range of cytotoxicity to inhibit the viability of the adherent and the suspension cells, causing HeLa cells shrinkage, A549 cells shrunken, and K562 cells collapse, and showed stronger cytotoxicity than hexaconazole. Moreover, the involvement of ROS generation in the cytotoxicity of TAFs on human cells was observed, and the apoptosis of HeLa cells and the formation of apoptotic body in K562 cells induced by diniconazole were characterized. The results indicated the cytotoxicity of TAFs with different structures on human cells was depended on their own property and cell specificity, K562 cells were the most susceptible to TAFs and diniconazole was the strongest toxic.

1H NMR-based metabolomics analysis of adult zebrafish (Danio rerio) after exposure to diniconazole as well as its bioaccumulation behavior

As a systemic triazole fungicide, limited information is known about diniconazole. In this study, toxicological effects and bioaccumulation behavior of diniconazole in zebrafish were both evaluated to perform an overall assessment of its environmental risk towards aquatic organisms. The ¹H NMR-based metabolomics analysis revealed that 70 μg L^-1 diniconazole exposure increased valine, leucine, isoleucine, alanine, lactate and choline, accompanied by decreased glucose, creatine and taurine, in comparison to the control. In the exposure group of 300 μg L^-1 diniconazole, only down-regulated glucose and creatine were observed. The above results indicated that diniconazole disturbed energy metabolism, amino acid metabolism and lipid metabolism. Histological examination showed that the swell and vacuolization in the liver, as well as the reduction of spermatids in the diniconazole exposure groups. No enantioselectivity was observed in the bioaccumulation process of both 70 and 300 μg L^-1 diniconazole exposure groups. The above results play a vital role for a comprehensive environmental assessment of diniconazole.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: focus on the cancer hallmark of tumor angiogenesis

One of the important 'hallmarks' of cancer is angiogenesis, which is the process of formation of new blood vessels that are necessary for tumor expansion, invasion and metastasis. Under normal physiological conditions, angiogenesis is well balanced and controlled by endogenous proangiogenic factors and antiangiogenic factors. However, factors produced by cancer cells, cancer stem cells and other cell types in the tumor stroma can disrupt the balance so that the tumor microenvironment favors tumor angiogenesis. These factors include vascular endothelial growth factor, endothelial tissue factor and other membrane bound receptors that mediate multiple intracellular signaling pathways that contribute to tumor angiogenesis. Though environmental exposures to certain chemicals have been found to initiate and promote tumor development, the role of these exposures (particularly to low doses of multiple substances), is largely unknown in relation to tumor angiogenesis. This review summarizes the evidence of the role of environmental chemical bioactivity and exposure in tumor angiogenesis and carcinogenesis. We identify a number of ubiquitous (prototypical) chemicals with disruptive potential that may warrant further investigation given their selectivity for high-throughput screening assay targets associated with proangiogenic pathways. We also consider the cross-hallmark relationships of a number of important angiogenic pathway targets with other cancer hallmarks and we make recommendations for future research. Understanding of the role of low-dose exposure of chemicals with disruptive potential could help us refine our approach to cancer risk assessment, and may ultimately aid in preventing cancer by reducing or eliminating exposures to synergistic mixtures of chemicals with carcinogenic potential.

Enantioseletive bioaccumulation and metabolization of diniconazole in earthworms (Eiseniafetida) in an artificial soil

Degradation and enantioselective bioaccumulation of diniconazole in earthworms (Eiseniafetida) in artificial soil was investigated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) method under laboratory condition. Three exposure concentrations (1 mg/kg, 10 mg/kg and 25 mg/kg) of diniconazole in soil (dry weight) to earthworms were used. The uptake kinetics fitted the first-order kinetics well. The bioaccumulation factors (BAF) of R, S isomers were 6.6046 and 8.5115 in 25 mg/kg dose exposure, 2.6409 and 2.9835 in 10mg/kg dose exposure, 1.7784 and 2.0437 in 1 mg/kg dose exposure, respectively. Bioaccumulation of diniconazole in earthworm tissues was enantioselective with a preferential accumulation of S-diniconazole and the enantiomer fractions were about 0.45-0.50 in all three level dose exposures. In addition, it was obvious that both R-diniconazole and S-diniconazole had bioaccumulation effect in earthworm. Diniconazole was metabolized to 1,2,4-triazole, (E)-3-(1H-1,2,4-triazol-1-yl) acrylaldehyde, (E, S)-4-(2, 4-dichlorophenyl)-2, 2-dimethyl-5-(1H-1,2,4-triazol-1-yl)pent-4-ene-1,3-diol, and (E)-4-(2, 4-dichlorophenyl)-3-hydroxy-2,2-dimethyl-5-(1H-1,2,4-triazol-1-yl) pent-4-enoic acid in earthworms; the metabolites of 1,2,4-triazole and (E)-3-(1H-1,2,4-triazol-1-yl)acrylaldehyde could be detected in soil as well.