RESUMO

Concerned about weed infestation, a major threat to food production and herbicide resistance that interferes in the mechanism of action of the main herbicides, we have synthesized eight isatin derivatives using the "Click Chemistry" approach through copper-catalyzed azide-alkyne cycloadditions (CuAAC). Sixteen isatin derivatives were evaluated for their phytotoxic activity against the seed culture of the model plants, Lactuca sativa and Allium cepa. Six of them showed phytotoxic activity similar to the positive control, trifluralin. Hypocotyl length measurement analysis in L. sativa revealed that triazole derivative 8 is more active than trifluralin. For A. cepa, root length measurement analyses revealed that 3, 10, 14, 16, and 17 were similar to the positive control trifluralin. Three-dimensional quantitative structure-activity relationship (3D-QSAR) comparative molecular field analysis (CoMFA) model construction using the acetolactate synthase (ALS) crystallographic structure displayed pki values of predicted inhibitory activity and contour maps revealing sterically bulky groups for 11, the CF3 group in ortho, and for 17, Br in ortho, favoring the inhibitory ALS activity.

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Pesticides, which are associated with endocrine dysfunction, immunological dysregulation, and cancer, are widespread sources of drinking water contamination. The state of Paraná has a population of 11 million, is the second largest grain producer in Brazil and is a leading consumer of pesticides. In this study, we analyzed the extent of drinking water contamination from 11 proven, probable, or potentially carcinogenic pesticides (alachlor, aldrin-dieldrin, atrazine, chlordane, DDT-DDD-DDE, diuron, glyphosate-AMPA, lindane-γ-HCH, mancozeb-ETU, molinate, and trifluralin) in 127 grain-producing municipalities in the state of Paraná. Extensive contamination of drinking water was found, including legacy pesticides such as aldrin-dieldrin (mean 0.047 ppb), DDT-DDD-DDE (mean: 0.07), chlordane (mean: 0.181), and lindane-HCH (mean: 2.17). Most of the municipalities were significantly above the maximum limits for each one of the currently allowed pesticides (67% for alachlor, 9.44% for atrazine, 96.85% for diuron, 100% for glyphosate-AMPA, 80.31% for mancozeb-ETU, 91.33% for molinate, and 12.6% for trifluralin). Ninety-seven percent of municipalities presented a sum of all pesticides at levels significantly above (189.84 ppb) the European Union preconized limits (<0.5 ppb). Using the mean pesticide concentration in water (ppb), the exposed population for each municipality, and the benchmark cancer risk for pesticides, we estimated the minimum number of cancer cases attributable to pesticide-contaminated drinking water during the period (total of 542 cases). More than 80% were attributed to mancozeb-ETU and diuron. Glyphosate-AMPA and diuron-attributable cases strongly correlated with the total cancer cases in the same period (R = 0.8117 and 0.8138, respectively) as well as with breast cancer cases (R = 0.7695 and 0.7551, respectively). Water contamination was significantly correlated with the sum of the estimated cancer cases for all 11 pesticides detected in each city (R = 0.58 and p < 0.0001). These findings reveal extensive contamination of drinking water in the state of Paraná and suggest that contamination may increase the risk of cancer in this region.

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Emerging contaminants, such as the herbicides trifluralin and tebuthiuron, comprise a class of compounds for which toxicological data are lacking, especially data regarding their harmful effects and biomarkers of exposure. Their potential damage to the environment and non-target organisms makes understanding their toxic mechanisms an urgent matter. Mitochondria, which exert an energy production function, play a vital role in maintaining many cellular activities and therefore are reliable predictors of substance toxicity. This study evaluates whether the herbicides trifluralin and tebuthiuron (at concentrations ranging from 1 to 100 µM) affect isolated rat liver mitochondria. The herbicides were analyzed according to their ability to interact with the mitochondrial membrane and induce swelling, lipoperoxidation, ROS formation, and NAD(P)H oxidation; dissipate the membrane potential; dysregulate calcium homeostasis; and alter ATP and GSH/GSSG levels. Tebuthiuron does not disrupt the mitochondrial biochemistry at any of the tested concentrations. In contrast, trifluralin can disturb the mitochondrial respiration, especially at the highest concentration, but it cannot induce oxidative stress. These results suggest that the aforementioned effects can occur as toxic mechanisms of trifluralin in non-target organisms, as well.

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RESUMO

Trifluralin, a pre-emergent herbicide, is widely used in Brazil in the weed grass management in restoration areas. The objective was to evaluate the tolerance of Piptadenia gonoacantha to trifluralin. The treatments had three trifluralin doses (445, 890, and 1335 g a.i. ha-1), applied in pre-sowing, as well as the control, without herbicide. Visual intoxication, seed germination, survival rate, emergence speed index (EMI), mean germination period, seedling height, and diameter, micromorphometric parameters of plant roots collected at 60 d after sowing, root length (RL) and volume, leaf area (LA), leaf numbers, root and shoot dry matter, and fluorescence of chlorophyll a at 30, 45, and 60 d after sowing were analyzed. Visual intoxication values above 50% were observed only with 1335 g a.i. ha-1. The herbicide did not affect seed germination, EMI, average germination period, seedling height, and diameter, root micromorphometric parameters, length, dry matter or root volume, and chlorophyll a fluorescence. The dose 1335 g a.i. ha-1 caused a reduction of 41.5% in survival, 50.3% in the LA, 36.7% in the number of leaves (LN), and 59.8% in the aerial dry mass of seedlings. The trifluralin presents potential for restoration programs of degraded areas with this forest species.

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This study investigates the oxidation of trifluralin residues during ozonation in aqueous and food matrices (tomato). Domestic ozonation equipment with average production of 23.9 mg O3 L-1 h-1 was used in the tests. Modern chromatographic systems (SPME-GC-IT/MS/MS and QuEChERS-GC-IT/MS/MS) were applied for extraction and detection of trifluralin residue in fortified samples of ultrapure water, tap water, superficial water and tomato fruit. The samples were submitted to the ozonation process during 0, 5, 10 and 20 min. Treatment at 5 min was able to degrade 71.5% of herbicide trifluralin in surface water. The removal (%) in ultrapure water reached 83.4% after 20 min of ozonation. The degradation of trifluralin in fortified tomato samples (0.025-0.1 mg kg-1) were conducted with ozonation at 20 min, and it ranged from 84.4 to 92.7%. After treatment, levels of trifluralin in tomato remained within the established MRLs to EU, USEPA and ANVISA (Brazil). The data provided evidence that ozone is effective for removing trace trifluralin from water and foods.

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RESUMO

In this study, the quality of surface water in the headwaters of São Lourenço River in Mato Grosso, Brazil, was evaluated in relation to contamination by pesticides. For this purpose, samples were collected between December 2015 and June 2016 by grab sampling and by passive sampling using an integrative polar organic compound sampler installed in the field during four 14-day cycles between March and June 2016. The analyses were performed by gas chromatography (CG/MS) and by liquid chromatography (UPLC-MS/MS). The results showed the detection of two pesticides (atrazine and pyraclostrobin) of the five analyzed by passive sampling and eight active principles among the 20 analyzed (malathion, diuron, carbofuran, carbendazim, trifluralin, imidacloprid, metolachlor, and acetamiprid) by grab sampling. The detection of 10 pesticides, even almost a decade after the beginning of a recovery process of the ciliary forest, confirms the headwaters' vulnerability to these contaminants and passive sampling proved to be an important tool in capturing small concentrations of pesticides constituting an interesting complement to grab sampling.

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Objetivou-se, neste trabalho, avaliar a seletividade de fomesafen, isolado ou associado com outros herbicidas, aplicado em pré-emergência de cultivares de algodoeiro. Foram conduzidos, simultaneamente, seis experimentos em casa de vegetação em Latossolo Vermelho distrófico, com pH em água de 5,9; 2,94% de MO e 320 g kg-1 de argila. O delineamento utilizado foi inteiramente casualizado, com cinco repetições. Os tratamentos resultaram do arranjo fatorial (2 x 4) + 1, representado por duas doses de fomesafen (375 e 500 g ha-1 de ingrediente ativo i.a.) e associações com os herbicidas diuron (1,25 kg ha-1 de i.a.), trifluralin (1,80 kg ha-1 de i.a.) e prometryn (1,25 kg ha-1 de i.a.). O tratamento adicional foi uma testemunha sem herbicida. Aos 30 dias após a aplicação dos tratamentos, coletou-se a parte aérea do algodoeiro para posterior quantificação da massa seca. Observou-se que a aplicação de fomesafen, isolado ou em associação com diuron, trifluralin e prometryn, afetou o acúmulo de massa seca das seis cultivares. De modo geral, a associação de fomesafen com trifluralin foi o tratamento mais seletivo. Existe resposta diferencial de cultivares à aplicação de fomesafen. A cultivar IMA CD 6001 LL foi a mais tolerante e a IMA 8221, a mais sensível à aplicação de fomesafen e suas associações.(AU)

The objective of this work was to evaluate the selectivity of fomesafen, in single application or in association with other herbicides, in pre-emergence of six cotton cultivars. Six experiments were conducted simultaneously in greenhouse conditions, in Red Oxisoil in water with pH of 5,9; 2,94% of OM and 320g kg-1 of clay. The experimental design was completely randomized with five replicates. Treatments were arranged in a factorial scheme (2 x 4) + 1, represented by two doses of fomesafen (375 and 500 g ha-1 - active ingredient) and association with diuron (1,25 kg ha-1 a.i.), trifluralin (1,80 kg ha-1 a.i.) and prometryn (1,25 kg ha-1 a.i.). A herbicide-free treatment was also added. At 30 days after the application of treatments, the cotton shoot was collected to quantify the dry mass accumulation. It was observed that the single fomesafen application or its association with diuron, trifluralin and prometryn affected the dry mass accumulation of the six cultivars. In general, the association of fomesafen with trifluralin was the most selective treatment. There is a differential response of cotton cultivars to fomesafen. The cultivar IMA CD 6001 LL was the most tolerant and IMA 8221 was the most sensible to fomesafen and its associations.(AU)

Assuntos

RESUMO

Objetivou-se, neste trabalho, avaliar a seletividade de fomesafen, isolado ou associado com outros herbicidas, aplicado em pré-emergência de cultivares de algodoeiro. Foram conduzidos, simultaneamente, seis experimentos em casa de vegetação em Latossolo Vermelho distrófico, com pH em água de 5,9; 2,94% de MO e 320 g kg-1 de argila. O delineamento utilizado foi inteiramente casualizado, com cinco repetições. Os tratamentos resultaram do arranjo fatorial (2 x 4) + 1, representado por duas doses de fomesafen (375 e 500 g ha-1 de ingrediente ativo – i.a.) e associações com os herbicidas diuron (1,25 kg ha-1 de i.a.), trifluralin (1,80 kg ha-1 de i.a.) e prometryn (1,25 kg ha-1 de i.a.). O tratamento adicional foi uma testemunha sem herbicida. Aos 30 dias após a aplicação dos tratamentos, coletou-se a parte aérea do algodoeiro para posterior quantificação da massa seca. Observou-se que a aplicação de fomesafen, isolado ou em associação com diuron, trifluralin e prometryn, afetou o acúmulo de massa seca das seis cultivares. De modo geral, a associação de fomesafen com trifluralin foi o tratamento mais seletivo. Existe resposta diferencial de cultivares à aplicação de fomesafen. A cultivar IMA CD 6001 LL foi a mais tolerante e a IMA 8221, a mais sensível à aplicação de fomesafen e suas associações.

The objective of this work was to evaluate the selectivity of fomesafen, in single application or in association with other herbicides, in pre-emergence of six cotton cultivars. Six experiments were conducted simultaneously in greenhouse conditions, in Red Oxisoil in water with pH of 5,9; 2,94% of OM and 320g kg-1 of clay. The experimental design was completely randomized with five replicates. Treatments were arranged in a factorial scheme (2 x 4) + 1, represented by two doses of fomesafen (375 and 500 g ha-1 - active ingredient) and association with diuron (1,25 kg ha-1 a.i.), trifluralin (1,80 kg ha-1 a.i.) and prometryn (1,25 kg ha-1 a.i.). A herbicide-free treatment was also added. At 30 days after the application of treatments, the cotton shoot was collected to quantify the dry mass accumulation. It was observed that the single fomesafen application or its association with diuron, trifluralin and prometryn affected the dry mass accumulation of the six cultivars. In general, the association of fomesafen with trifluralin was the most selective treatment. There is a differential response of cotton cultivars to fomesafen. The cultivar IMA CD 6001 LL was the most tolerant and IMA 8221 was the most sensible to fomesafen and its associations.

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RESUMO

This study describes a novel electrochemical method to determine the herbicide trifluralin in samples of water, fruit juice, and vegetable extracts in the presence of surfactants, using a glassy carbon electrode (GCE). In acidic media, trifluralin was irreversible on the glassy carbon electrode surface at -0.5 V vs. Ag/AgCl. Surfactant presence on the electrode-solution interface modified current intensities and shifted the reduction peak potential of trifluralin. Different types of surfactant and their concentrations were investigated. The anionic surfactant significantly enhanced the peak current intensity of trifluralin. Under optimal analytical conditions, an analytical curve was obtained in the concentration range of 0.48-32.20 µM. The limits of detection and quantification were estimated at 0.031 and 0.104 µM, respectively. The method was successfully applied to quantify trifluralin in samples of water, orange and tomato juice, and green pepper, carrot, and onion extracts, with recovery rates of 97.9-102.1%. The results were in good agreement with those obtained using high-performance liquid chromatography, indicating that the proposed electrochemical method can be employed to quantify trifluralin in various types foods, with sensitivity, specificity, selectivity and reproducibility.

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RESUMO

Brazil has been the largest world consumer of pesticides since 2008, followed by the USA. The herbicides trifluralin and tebuthiuron have been widely applied in agriculture. These herbicides are selective for some plant species, and their use brings various benefits. However, the genotoxic and mutagenic effects of tebuthiuron on non-target organisms are poorly known, and in addition, the effects of trifluralin must be better investigated. Therefore, this study employed genetic tests including the comet assay and micronucleus test to evaluate the genotoxic effects of trifluralin and tebuthiuron on HepG2 cells. In addition, we have used the Ames test to assess the mutagenic effects of the herbicides on the TA97a, TA98, TA100, and TA1535 strains of Salmonella typhimurium. On the basis of the comet assay and the micronucleus test, trifluralin did not cause genetic damage to HepG2 cells. In addition, trifluralin did not impact the tested S. typhimurium strains. Regarding tebuthiuron, literature has shown that this herbicide damaged DNA in Oreochromis niloticus. Nevertheless, we have found that tebuthiuron was not genotoxic to either HepG2 cells or the S. typhimurium strains. Therefore, neither trifluralin nor tebuthiuron exerted genotoxic or mutagenic potential at the tested conditions.

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