Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.889
Filtrar
1.
Chemosphere ; 263: 127979, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32841877

RESUMO

Glyphosate (PMG) has been the most widely used herbicide in the world, and its environmental mobility and fate are mainly controlled by interactions with mineral surfaces. In soil systems, kaolinite is typically associated with humic acids (HAs) in the form of mineral-HA complexes, and hence it is crucial to characterize the molecular-scale interactions that occur between PMG and kaolinite and kaolinite-HA complexes. Batch experiments, Fourier transform infrared spectrum (FTIR) and X-ray photoelectron spectroscopy (XPS), isothermal titration calorimetry (ITC), and molecular dynamics (MD) simulations were performed to decipher the molecular interactions between PMG and kaolinite and kaolinite-HA composites. Our results reveal that kaolinite-HA composites adsorb higher concentrations of PMG than does kaolinite alone, likely due to more adsorption sites existed on kaolinite-HA than on kaolinite. FTIR and XPS analysis reveal that the carboxyl, phosphonyl and amino groups of PMG interacted with kaolinite and kaolinite-humic acid via Hydrogen bonds. The ITC results and interaction energy calculations indicate that the adsorption of PMG onto the kaolinite-HA is more energetically favorable relative to that onto kaolinite. MD simulations suggest that the PMG molecule adsorbs parallel to the surface of kaolinite and the composites through hydrogen bonding. Humic acid increases the adsorption of PMG through the creation of H-bond networks between PMG, the kaolinite surface, and humic acid. The results from this study improve our molecular-level understanding of the interactions between PMG and two important components of soil systems, and hence yield valuable information for characterizing the fate and behavior of PMG in soil environments.


Assuntos
Glicina/análogos & derivados , Herbicidas/química , Substâncias Húmicas , Caulim/química , Adsorção , Calorimetria , Glicina/química , Concentração de Íons de Hidrogênio , Minerais/química , Simulação de Dinâmica Molecular , Espectroscopia Fotoeletrônica , Solo , Espectroscopia de Infravermelho com Transformada de Fourier
2.
Chem Biol Interact ; 330: 109247, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32866466

RESUMO

This study investigated the enantioselective metabolism of benoxacor, an ingredient of herbicide formulations, in microsomes or cytosol prepared from female or male rat livers. Benoxacor was incubated for ≤30 min with microsomes or cytosol, and its enantioselective depletion was measured using gas chromatographic methods. Benoxacor was depleted in incubations with active microsomes in the presence and absence of NADPH, suggesting its metabolism by hepatic cytochrome P450 enzymes (CYPs) and microsomal carboxylesterases (CESs). Benoxacor was depleted in cytosolic incubations in the presence of glutathione, consistent with its metabolism by glutathione S-transferases (GSTs). The depletion of benoxacor was faster in incubations with cytosol from male than female rats, whereas no statistically significant sex differences were observed in microsomal incubations. The consumption of benoxacor was inhibited by the CYP inhibitor 1-aminobenzotriazole, the CES inhibitor benzil, and the GST inhibitor ethacrynic acid. Estimates of the intrinsic clearance of benoxacor suggest that CYPs are the primary metabolic enzyme responsible for benoxacor metabolism in rats. Microsomal incubations showed an enrichment of the first eluting benoxacor enantiomer (E1-benoxacor). A greater enrichment occurred in incubations with microsomes from female (EF = 0.67 ± 0.01) than male rats (EF = 0.60 ± 0.01). Cytosolic incubations from female rats resulted in enrichment of E1-benoxacor (EF = 0.54 ± 0.01), while cytosolic incubations from male rats displayed enrichment of the second eluting enantiomer (E2-benoxacor; EF = 0.43 ± 0.01). Sex-dependent differences in the metabolism of benoxacor in rats could significantly impact ecological risks and mammalian toxicity. Moreover, changes in the enantiomeric enrichment of benoxacor may be a powerful tool for environmental fate and transport studies.


Assuntos
Fígado/metabolismo , Oxazinas/metabolismo , Frações Subcelulares/metabolismo , Animais , Sistema Enzimático do Citocromo P-450/metabolismo , Citosol/enzimologia , Citosol/metabolismo , Feminino , Herbicidas/química , Masculino , Microssomos Hepáticos/enzimologia , Microssomos Hepáticos/metabolismo , Ratos , Fatores Sexuais , Estereoisomerismo
3.
PLoS One ; 15(9): e0238092, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32931491

RESUMO

New and facile one-pot three component approach for the synthesis of substituted dihydropyrimidinones derivatives (4a-4h) from reaction of equimolar substituted aldehydes (1a-1h), methyl acetoacetate (2a) and urea (3a) in presence of nature derived catalyst viz. Cocos nucifera L. juice, Solanum lycopersicum L. juice and Citrus limetta juice, commonly known as coconut juice, tomato juice and musambi juice respectively, at room temperature has been carried out. All synthesized compounds were evaluated for in vitro herbicidal activity against Raphanus sativus L. (Radish seeds). The compounds (4a-4h) were also screened for their antifungal activity against Rhizoctonia solani and Colletotrichum gloeosporioides by poisoned food techniques method. Antibacterial activity was also studied against Erwinia cartovora and Xanthomonas citri by inhibition zone method. From activity data, it was found that compounds 4g and 4d were most active against Raphanus sativus L. (root) and Raphanus sativus L. (shoot) respectively. Compounds 4f and 4c was found most active against Rhizoctonia solani and Colletotrichum gloeosporioides fungus respectively at highest concentration. Compound 4g has shown maximum inhibition zone i.e. 1.00-5.50 mm against Erwinia cartovora at 2000 µg/mL concentration. Maximum Xanthomonas citrii growth was inhibited by compounds 4f showing inhibition zone 4.00-12.00 mm at highest concentration. Short reaction time, high yields, mild reaction condition and simple work-up are some merits of present methodology.


Assuntos
Antifúngicos/química , Antifúngicos/farmacologia , Biocatálise , Sucos de Frutas e Vegetais , Pirimidinonas/química , Pirimidinonas/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/síntese química , Técnicas de Química Sintética , Herbicidas/síntese química , Herbicidas/química , Herbicidas/farmacologia , Pirimidinonas/síntese química
4.
Ecotoxicol Environ Saf ; 203: 111046, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888614

RESUMO

Agricultural pesticides serve as effective controls of unwanted weeds and pests. However, these same chemicals can exert toxic effects in non-target organisms. To determine chemical modes of action, the toxicity ratio (TR) and critical body residues (CBRs) of 57 pesticides were calculated for Daphnia magna. Results showed that the CBR values of inert compounds were close to a constant while the CBR values of pesticides varied over a wider range. Although herbicides are categorized as specifically-acting compounds to plants, herbicides did not exhibit excess toxicity to Daphnia magna and were categorized as inert compounds with an average logTR = 0.41, which was less than a threshold of one. Conversely, fungicides and insecticides exhibited strong potential for toxic effects to Daphnia magna with an average logTR >2. Many of these chemicals act via disruption of the nervous, respiratory, or reproductive system, with high ligand-receptor binding activity which leads to higher toxicity for Daphnia magna. Molecular docking using acetylcholinesterase revealed that fungicides and insecticides bind more easily with the biological macromolecule when compared with inert compounds. Quantitative structure-activity relationship (QSAR) analysis revealed that the toxicity of fungicides was mainly dependent upon the heat of formation and polar surface area, while the toxicity of insecticides was more related to hydrogen-bond properties. This comprehensive analysis reveals that there are specific differences in toxic mechanisms between fungicides and insecticides. These results are useful for determining relative risk associated with pesticide exposure to aquatic crustaceans, such as Daphnia magna.


Assuntos
Daphnia/efeitos dos fármacos , Modelos Biológicos , Praguicidas/química , Praguicidas/toxicidade , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade , Acetilcolinesterase/metabolismo , Animais , Daphnia/metabolismo , Relação Dose-Resposta a Droga , Fungicidas Industriais/química , Fungicidas Industriais/toxicidade , Herbicidas/química , Herbicidas/toxicidade , Ligação de Hidrogênio , Inseticidas/química , Inseticidas/toxicidade , Simulação de Acoplamento Molecular , Resíduos de Praguicidas/metabolismo , Relação Quantitativa Estrutura-Atividade
5.
J Environ Sci Health B ; 55(11): 1009-1019, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32816605

RESUMO

The present study addresses the herbicidal activity and biological effects of the metribuzin (MET) and tribenuron-methyl (TBM) herbicides used to control various weed species (Amaranthus retroflexus, Sinapis arvensis, and Leucanthemum maximum). The effects of the free herbicides and the herbicides embedded in granules of degradable polymer poly-3-hydroxybutyrate [P(3HB)] blended with birch wood flour were compared. Metribuzin, regardless of the form, caused 100% mortality of the three weeds by day 21. The herbicidal activity of tribenuron-methyl was lower than that of metribuzin, but the embedded TBM was superior to the free herbicide in the length and strength of its action on the weeds. Both metribuzin forms dramatically decreased the main parameters of fluorescence: maximum quantum yield of photosystem-II [Y(II)max], maximum quantum yield of non-photochemical quenching [Y(NPQ)max], and maximum rate of non-cyclic electron transport [ETRmax] and concentrations of chlorophyll a and b. The effect of the embedded TBM on the photosynthetic activity of the weeds was lower in the first two weeks of the growth of herbicide-treated plants but lasted longer than the effect of the free TBM and increased over time. Embedding of metribuzin in the matrix of degradable blend did not decrease its herbicidal activity.


Assuntos
Sulfonatos de Arila/farmacologia , Herbicidas/farmacologia , Plantas Daninhas/efeitos dos fármacos , Triazinas/farmacologia , Amaranthus/efeitos dos fármacos , Sulfonatos de Arila/química , Betula/química , Clorofila A/metabolismo , Preparações de Ação Retardada , Herbicidas/química , Hidroxibutiratos/química , Leucanthemum/efeitos dos fármacos , Fotossíntese/efeitos dos fármacos , Plantas Daninhas/metabolismo , Plantas Daninhas/fisiologia , Poliésteres/química , Sinapis/efeitos dos fármacos , Triazinas/química , Madeira/química
6.
Plant Physiol Biochem ; 155: 444-454, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32818792

RESUMO

Two Fabaceae exhibiting rapid osmocontractile pulvinar movements were used in this study because this activity is modified by natural auxin and dramatically by 2,4D. A short chain with a carboxylic group being required for auxinic properties, a critical point to analyze is whether the recently synthesized proherbicide ε-(2,4-dichlorophenoxyacetyl)-L-Lys (2-4D-L-Lys) maintains some biological activity despite the increase in length of the chain and the substitution of the carboxyl group by an α-amino acid function. No trace of 2,4D could be detected in the pulvinar tissues treated for 1 h with 2,4D-L-Lys. Complementary approaches (electrophysiology, pH measurements, use of plasma membrane vesicles) suggest that it was less efficient than 2,4D to activate the plasma membrane H+-ATPase (PM-H+-ATPase). However, it modified the various ion-driven reactions of Mimosa pudica and Cassia fasciculata pulvini in a similar way as 2,4D. Additionally, it was much more effective than fusicoccin to inhibit seismonastic movements of M. pudica leaves and, at low concentrations, to promote leaflet opening in dark, indicating that its mode of action is more complex than the only activation of the PM-H+-ATPase. Various substitutions on 2,4D-L-Lys affected its activity in correlation with the molecular descriptor "halogen ratio" of these derivatives. Conjugation with D-Lys also led to a decrease of pulvinar reaction, suggesting that 2,4D-Lys maintains the main signaling properties of 2,4D involved in pulvinar movements providing that the terminal zwitterion is in a suitable orientation. Our data guide future investigations on the effect of 2,4D and 2,4D-L-Lys on the vacuolar pump activity of motor cells.


Assuntos
Cassia/efeitos dos fármacos , Herbicidas/química , Mimosa/efeitos dos fármacos , Células Vegetais/efeitos dos fármacos , Ácido 2,4-Diclorofenoxiacético/química , Membrana Celular/metabolismo , Lisina/análogos & derivados , Lisina/química , ATPases Translocadoras de Prótons/metabolismo
7.
Ecotoxicol Environ Saf ; 205: 111141, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32846294

RESUMO

Lactofen is a chiral herbicide and widely used against broadleaf weeds in agriculture. As a pesticide, it is directly released to the environment, and easily caused contamination in soil and aquatic ecosystem. The enantioselective degradation of lactofen in the environment has been reported, but the molecular biological mechanism of this phenomenon is still unclear. In this study, strain Edaphocola flava HME-24 could degrade 96.7% of 50 mg L-1 lactofen within 72 h. Lactofen was initially hydrolyzed to desethyl lactofen and subsequently acifluorfen by strain HME-24. A novel gene lanE, involved in lactofen transformation, was obtained from Edaphocola flava HME-24. Gene lanE encoded a protein of 471 amino acids that contained the conserved GXSXG esterase motif and clustered into esterase subfamily V. LanE shared the highest identity with esterase EstD (Q9WYH1) from Thermotoga maritima MSB8 (29.14%). This esterase was also able to transform p-nitrophenyl esters (C4-C8), and the activity decreased when the carbon chain length increased. LanE showed enantioselectivity during the degradation of lactofen, diclofop-methyl, and quizalofop-ethyl, with a higher degradation efficiency of (S)-enantiomers than (R)-enantiomers. The three-dimensional structure of LanE was simulated, and molecular docking revealed that when the (S)-enantiomers of lactofen occupied the active sites, the distance between the ligand molecule and the coordination atom was shorter than that when the (R)-enantiomers occupied the active sites, which facilitated the formation of the transition state complex. The results in this study enhanced our understanding of the preferential catabolism of the (S)-enantiomers of lactofen on the molecular level and could illustrate the reported enantioselective degradation of lactofen in the environment.


Assuntos
Esterases/metabolismo , Éteres Difenil Halogenados/química , Herbicidas/química , Bacteroidetes/enzimologia , Biodegradação Ambiental , Ecossistema , Simulação de Acoplamento Molecular , Nitrobenzoatos , Praguicidas , Estereoisomerismo
8.
Ecotoxicol Environ Saf ; 202: 110915, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800250

RESUMO

Benzobicyclon is a systemic herbicide that was officially registered in China in 2018. The environmental behaviors of benzobicyclon hydrolysate (BH), the main metabolite and active product of benzobicyclon, remain poorly understood in paddy fields. Here, agricultural soil samples were collected from paddy fields in Jiangxi (Ferralsols), Shandong (Alisols), Hebei (Luvisols), Heilongjiang (Phaeozems), Zhejiang (Anthrosols), Sichuan (Gleysols), Hainan (Plinthosols), and Hubei (Lixisols) across China. The equilibrium oscillation method was used to study the adsorption-desorption behaviors of BH in the eight soils. The relationships between BH adsorption and soil physicochemical properties, environmental factors (temperature and initial solution pH), and other external conditions (addition of humic acid, biochar, and metal ions) were quantified. The adsorption-desorption parameters of BH in all soils were well fitted by the Freundlich model. The adsorption constant of BH varied between 0.066 and 4.728. The BH adsorption capacity decreased in the following order: Phaeozems > Alisols > Ferralsols > Lixisols > Plinthosols > Anthrosols > Luvisols > Gleysols. The Freundlich adsorption and desorption constants of BH were linearly positively correlated with soil clay content (R2 = 0.711 and 0.709; P = 0.009 and 0.009, respectively), organic carbon content (R2 = 0.684 and 0.672; P = 0.011 and 0.013, respectively), and organic matter content (R2 = 0.698 and 0.683; P = 0.010 and 0.011, respectively); however, their linear relationships with soil cation exchange capacity were not significant (R2 = 0.192 and 0.192; P = 0.278 and 0.278, respectively). The adsorption and desorption constants of BH had negative, albeit not significant, correlations with soil pH (R2 = 0.104 and 0.100; P = 0.437 and 0.445, respectively). The adsorption of BH by soil occurred spontaneously and was mainly based on physical adsorption. Either low or high temperature reduced the ability of the soil to adsorb BH. The addition of humic acid to the soil increased BH adsorption, while the addition of biochar increased the solution pH, resulting in decreased BH adsorption. Cation type and ionic strength also had strong effects on BH adsorption. With the exception of Phaeozems, BH exhibited intermediate or high mobility in the agricultural soils and thus poses risks to surface water and groundwater.


Assuntos
Compostos Bicíclicos com Pontes/química , Herbicidas/química , Poluentes do Solo/química , Sulfonas/química , Adsorção , Agricultura , China , Argila , Água Subterrânea , Herbicidas/análise , Solo/química , Poluentes do Solo/análise
9.
Food Chem ; 333: 127540, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32682226

RESUMO

A novel of magnetic dummy-template molecularly imprinted polymers (mag-MWCNTs-DMIPs) were prepared by surface molecular imprinting technique. The structure of polymers were characterized and the binding properties were assessed by adsorption experiments. The synthetic mag-MWCNTs-DMIPs exhibit satisfying adsorption capacity, excellent selectivity and fast adsorption rate toward phenoxy carboxylic acid (PCA) herbicides. Afterwards, a reliable analytical method for selective separation and determination of trace PCA herbicides in cereals was established by using magnetic solid-phase extraction (mag-MWCNTs-DMIPs as magnetic adsorbent) and UPLC-MS/MS detection. A series of requisite factors were optimized in detail to achieve expected extraction performance. Under the optimum MSPE parameters, the mean spiked recoveries for analytes in different cereals ranged from 86.7% to 95.2% with intra- and inter-day precision not greater than 8.5% and 10.6%, respectively. At last, the developed method was successfully utilized for determination the four PCA herbicides in actual cereals.


Assuntos
Ácidos Carboxílicos/análise , Ácidos Carboxílicos/isolamento & purificação , Grão Comestível/química , Herbicidas/química , Impressão Molecular , Nanotubos de Carbono/química , Extração em Fase Sólida/métodos , Adsorção , Ácidos Carboxílicos/química , Contaminação de Alimentos/análise , Imãs/química , Polímeros/síntese química , Polímeros/química , Fatores de Tempo
10.
Ecotoxicol Environ Saf ; 201: 110764, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32480162

RESUMO

Phenoxy herbicides are widely applied in agricultural weeding. The determination of herbicides is important in environmental protection, agricultural production, food safety, and public health. In this study, a facile and efficient analytical method was proposed for the trace detection of phenoxy herbicides in soil, cucumber, and tap water samples by coupling pipette tip solid phase extraction (PT-SPE) with high performance liquid chromatography. UiO-66-funtionalized cotton (Cotton@UiO-66) was packed into pipette-tip as sorbent to fabricate extraction device. The modification of UiO-66 on cotton fiber was confirmed using scanning electron microscope, Fourier transform infrared spectroscopy, and X-ray diffraction. The main factors affecting the adsorption of Cotton@UiO-66 for four phenoxy herbicides were evaluated by response surface methodology in detail. Under optimized conditions, Cotton@UiO-66 displayed excellent properties in the extraction of phenoxy herbicides with good peak shape. Linear ranges of 4-chlorophenoxyacetic acid, dicamba, 2,4-dichlorophenoxyacetic acid, and 2-(2,4-dichlorophenoxy) propionic acid were 1.4-72 µg/L, 5.6-280 µg/L, 2.8-140 µg/L and 3.2-160 µg/L (RSDs < 6.3%), respectively. The recoveries were between 83.3 and 106.8% with RSDs <6.7%, with detection limits ranging from 0.1 µg/L to 0.3 µg/L. The results show that Cotton@UiO-66 in PT-SPE is an effective method for monitoring phenoxy herbicides in complex samples.


Assuntos
Herbicidas/química , Extração em Fase Sólida/métodos , Ácido 2,4-Diclorofenoxiacético/análogos & derivados , Adsorção , Cromatografia Líquida de Alta Pressão , Fibra de Algodão , Herbicidas/análise
11.
Chemosphere ; 258: 127217, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535437

RESUMO

The widespread use of pesticides has received increasing attention in regulatory agencies because their extensive overuse and various adverse effects on all living organisms. Organizations such as EPA and ECHA have published laws that pesticides should be fully evaluated before bring them to market. In the present study, we evaluated the pesticides toxicity using the Quantitative Structural-Activity Relationship (QSAR) method. The models for the single class pesticides (herbicides, insecticides and fungicides) as well as the general class pesticides (the combined dataset plus some microbicides, molluscicides, etc.) were developed using the Genetic Algorithm and Multiple Linear Regression method. The internal and external validation results suggested that all the obtained models were stable and predictive. According to the modeling descriptors, the lipophilic descriptors contributed positively while all the electrotopological state descriptors showed a negative contribution, their presences in every model verified the conspicuous influence of molecular lipophilicity and hydrophilicity on the pesticides toxicity. However, the influence of topological structure descriptors was different and varies with the physiochemical information they encode. Finally, the models presented in this paper would help assess the pesticides toxicity against Americamysis bahia, shorten test time, and reduce the cost of pesticides risk assessment.


Assuntos
Crustáceos/efeitos dos fármacos , Modelos Teóricos , Praguicidas/química , Praguicidas/toxicidade , Animais , Bases de Dados Factuais , Fungicidas Industriais/química , Fungicidas Industriais/toxicidade , Herbicidas/química , Herbicidas/toxicidade , Interações Hidrofóbicas e Hidrofílicas , Inseticidas/química , Inseticidas/toxicidade , Modelos Lineares , Relação Quantitativa Estrutura-Atividade
12.
Food Chem ; 330: 127205, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32521397

RESUMO

The incidence of endocrine disruptors, both possible (glyphosate and glufosinate), and demonstrated (perchlorate and chlorate), was estimated in baby food commodities (meat, fish, cheese, vegetable and fruit). Ion-chromatography coupled to high resolution mass spectrometry analysis of the 105 samples did not show traces of glyphosate, glufosinate or their metabolites, while in 10.5% of the samples a quantifiable amount of perchlorate was found. Some samples based on fruit and vegetables revealed a substantial amount of chlorate, especially the preparations that contained carrots and potatoes: five samples were in a concentration range of 40-120 µg kg-1, while one homogenized pear sample reached 372.2 µg kg-1. The pure meat samples revealed occasional chlorate appearance, with less than 10 µg kg-1. This is the first report of chlorate evaluated in various types of baby food and may serve as symptomatic data regarding its occurrence in infant/toddler diets. Therefore, effective monitoring programs and subsequent strict regulations are strongly required.


Assuntos
Cloratos/análise , Contaminação de Alimentos/análise , Herbicidas/análise , Alimentos Infantis/análise , Percloratos/análise , Animais , Cloratos/química , Produtos Pesqueiros/análise , Frutas/química , Herbicidas/química , Carne/análise , Percloratos/química , Verduras/química
13.
J Environ Sci Health B ; 55(9): 767-782, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32586186

RESUMO

Activated biocarbons were prepared using biomass wastes: sugarcane bagasse, coconut shell and endocarp of babassu coconut; as a renewable source of low-cost raw materials and without prior treatments. These activated biocarbons were characterized by textural analysis, solid-state 13C nuclear magnetic resonance spectroscopy, X-ray diffraction and scanning electronic microscopy. Textural analysis results revealed that those activated biocarbons were microporous, with specific surface area values of 547, 991 and 1,068 m2 g-1 from sugarcane bagasse, coconut shell and endocarp of babassu coconut, respectively. The innovation of this work was to evaluate which biomass residue was able to offer the best performance in removing 2,4-dichlorophenoxyacetic acid herbicide (2,4-D) from water by adsorption. Adsorption process of 2,4-D was investigated and the Langmuir and Redlich-Peterson models described best the adsorption process, with R2 values within 0.96-0.99. The 2,4-D removal performance were 97% and 99% for the coconut and babassu biocarbons, respectively. qM parameter values obtained from Langmuir model were 153.9, 233.0 and 235.5 mg g-1 using sugarcane bagasse, coconut shell and endocarp of babassu, respectively. In addition, the adsorption kinetics were described nicely by the second-order model and the Gibbs free energy parameter values were negative, pointing to a spontaneous adsorption, as well.


Assuntos
Ácido 2,4-Diclorofenoxiacético/isolamento & purificação , Resíduos Industriais , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Ácido 2,4-Diclorofenoxiacético/química , Adsorção , Agricultura , Biomassa , Celulose/química , Cocos/química , Herbicidas/química , Herbicidas/isolamento & purificação , Concentração de Íons de Hidrogênio , Cinética , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Varredura , Saccharum/química , Termodinâmica , Poluentes Químicos da Água/química , Difração de Raios X
14.
J Environ Sci Health B ; 55(7): 646-654, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32432942

RESUMO

The aim of this work was to know the differential composition of the dissolved fraction of a glyphosate-based herbicide (GBH), commercialized as GLIFOPAC, when reaches different aquatic environments and its ecotoxicological effects on crustaceans species living in them. Daphnia magna, Tisbe longicornis, and Emerita analoga were exposed to glyphosate herbicide called GLIFOPAC (480 g L-1 of active ingredient or a.i.) at concentrations between 0.5 and 4.8 g a.i. L-1. Acute toxicity in D. magna (48 h-LC50), E. analoga (48 h-LC50), and T. longicornis (96 h-LC50) was studied. Chromatographic analysis of the GBH composition used and water (freshwater/sea water) polluted with GLIFOPAC were evaluated. Results reported acute toxicity (48-96 h-LC50) values for D. magna, E. analoga and T. longicornis of 27.4 mg L-1, 806.4 mg L-1, and 19.4 mg L-1, respectively. Chromatographic evaluation described around 45 substances of the GLIFOPAC composition, such as from the surfactant structures (aliphatic chain with esther/ether group), metabolites (AMPA), and other substances (glucofuranose, glucopyranoside, galactopyranose). This study evidenced differences in the GLIFOPAC composition in freshwater and marine water, which may differentiate the toxic response at the crustacean-level in each aquatic environment.


Assuntos
Crustáceos/efeitos dos fármacos , Daphnia/efeitos dos fármacos , Glicina/análogos & derivados , Herbicidas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Braquiúros/efeitos dos fármacos , Ecotoxicologia/métodos , Biomarcadores Ambientais/efeitos dos fármacos , Água Doce , Glicina/química , Glicina/toxicidade , Herbicidas/química , Dose Letal Mediana , Testes de Toxicidade Aguda , Poluentes Químicos da Água/química
15.
J Agric Food Chem ; 68(22): 6048-6057, 2020 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-32392059

RESUMO

In this work, 12 novel herbicidal ionic liquids (HILs) based on acifluorfen were prepared by pairing with the fluorescent hydrazides or different alkyl chains for increasing activities and reducing negative impacts on the aquatic environment. The results showed that the fluorescence of coumarin hydrazide in the HILs was applied as the internal and supplementary light source to meet the requirement of light wavelength range of acifluorfen, which improved the phytotoxicity of acifluorfen to weeds by enhancing singlet oxygen generation with increased sunlight utilization. The herbicidal activities of HILs were related positively with the length of chain of cation under high light intensity and depended mainly on the fluorescence characteristic of the cation under low light intensity, and the double salt IL forms of acifluorfen containing coumarin hydrazide and n-hexadecyltrimethylammonium had enhanced efficacies against broadleaf weeds in the field. Compared with acifluorfen sodium, HILs had lower water solubility, better surface activity, weaker mobility in soils, and higher decomposition temperature. These results demonstrated that HILs containing different cations provided a wider scope for fine-tuning of the physicochemical and biological properties of herbicides and established a promising way for the development of environmentally friendly herbicidal formulations.


Assuntos
Herbicidas/química , Herbicidas/farmacologia , Líquidos Iônicos/química , Nitrobenzoatos/química , Nitrobenzoatos/farmacologia , Composição de Medicamentos , Fluorescência , Líquidos Iônicos/farmacologia , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/metabolismo , Plantas Daninhas/efeitos da radiação , Oxigênio Singlete/metabolismo , Solubilidade/efeitos da radiação , Luz Solar
16.
Sci Rep ; 10(1): 8713, 2020 05 26.
Artigo em Inglês | MEDLINE | ID: mdl-32457385

RESUMO

Natural tolerance in hexaploid bread wheat (Triticum aestivum L.) to synthetic auxin herbicides is primarily due to rapid metabolic detoxification, but genes encoding these herbicide-detoxifying enzymes have yet to be identified. Herbicide safeners are commonly applied in wheat to achieve herbicide tolerance by inducing the expression and activity of herbicide-detoxifying enzymes. While safeners have been utilized for decades, knowledge of mechanisms that induce gene expression is limited. Our objective was to identify wheat chromosomes possessing genes that endow natural or safener-induced tolerance to halauxifen-methyl (HM), a postemergence (POST) wheat-selective synthetic auxin herbicide, using alien substitution (the S genome of Aegilops searsii) and aneuploid lines. Two POST rates of HM were applied to seedlings with 1-2 leaves (Zadoks stages 11-12), and the highest HM rate was also applied with the safener cloquintocet-mexyl (CM). Wheat chromosomes possessing genes associated only with natural HM tolerance were identified because Ae. searsii is HM-sensitive but CM-responsive. Lines with substitutions for 5A and 5B displayed sensitivity to HM, and experiments with nullisomic-tetrasomic (NT) lines further indicated major genes associated with HM tolerance are present on 5A and 5B chromosomes. However, the genes on 5A appear to play a larger role because lines lacking 5A chromosomes displayed more sensitivity than lines lacking 5B. Overall, these results can be utilized to guide future transcriptome analyses to identify candidate genes that confer HM tolerance in wheat.


Assuntos
Cromossomos de Plantas/genética , Tolerância a Medicamentos , Locos de Características Quantitativas , Triticum/crescimento & desenvolvimento , Mapeamento Cromossômico , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Herbicidas/efeitos adversos , Herbicidas/química , Ácidos Indolacéticos/efeitos adversos , Ácidos Indolacéticos/química , Proteínas de Plantas/genética , Poliploidia , Locos de Características Quantitativas/efeitos dos fármacos , Quinolinas/efeitos adversos , Triticum/efeitos adversos , Triticum/genética
17.
J Environ Sci Health B ; 55(7): 630-645, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32338140

RESUMO

Effect of the wheat straw ash (WSA) on pretilachlor and the rice straw ash (RSA) on sulfosulfuron kinetics and adsorption behavior was studied. Kinetics study suggested that adsorption of herbicides in soil/soil + 0.2% ash mixture was best explained by the pseudo second order model. Ashes at 0.1%-0.5% levels increased adsorption of respective herbicide; but, effect varied with ash content and soil type. Effect of ash (0.2%) on herbicide's adsorption was more in the sandy loam soil (144%-188%) than in the clay loam soil (112%-122%) suggesting masking of ash particles. The Freundlich adsorption isotherm explained the adsorption of herbicides in the soils/soil + ash mixtures and sorption was highly nonlinear as 1/n (slope) values varied between 0.57 and 1.25 for pretilachlor and 0.32 and 0.77 for sulfosulfuron. Adsorption increased with increase in temperature. High surface area unburnt carbon in ashes was responsible for increase in adsorption and decrease in desorption of herbicides in ash mixed soils. The pH of soil/soil + ash mixtures affected herbicide adsorption, but effect was significant for pretilachlor. The negative free energy change (ΔG) values suggested that the sorption process was exothermic and spontaneous in nature. This study has implications in identifying the role of crop residue burning on fate of herbicides applied in succeeding crop.


Assuntos
Produtos Agrícolas/química , Herbicidas/química , Poluentes do Solo/química , Acetanilidas/química , Adsorção , Carbono , Argila , Índia , Cinética , Oryza/química , Pirimidinas/química , Solo/química , Sulfonamidas/química , Triticum/química
18.
J Agric Food Chem ; 68(17): 4851-4864, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32259440

RESUMO

Herbicides are a key element in agriculture but they do cause environmental problems and natural alternatives are being sought. In this context, invasive plants could provide an as yet unexplored source for the development of future herbicides. Urochloa humidicola has great invasive potential in Brazilian environments as it hampers the establishment of other plants. The phytotoxicity of U. humidicola root extracts has been evaluated, and the major components have been identified. The phytotoxicity of the extract was assessed in the wheat coleoptile assay on seeds of troublesome weeds and on Anadenanthera colubrina, a tree species used in ecological restoration programs. The ethyl acetate extract showed the highest activity, and the most affected weeds were E. crus-galli, M. maximus, and A. viridis with the latter weed more affected by the extract than by the herbicide Logran. Microscopic ultrastructural analysis of A. colubrina roots indicated possible signals of cell death. Seven compounds were identified in the ethyl acetate extract of which one diterpene and four saponins are new. Six of these compounds were tested in the wheat coleoptile bioassay. The most active were diterpene 1 and saponins 2, 3, and 6. The phytotoxic activity of U. humidicola explains the issues observed in ecological restoration with A. colubrina in the presence of Urochloa species, and its effect on weeds reinforces its potential use in agriculture.


Assuntos
Brachiaria/química , Herbicidas/farmacologia , Extratos Vegetais/farmacologia , Raízes de Plantas/química , Bioensaio , Brasil , Herbicidas/química , Estrutura Molecular , Extratos Vegetais/química , Plantas Daninhas/efeitos dos fármacos , Poaceae/efeitos dos fármacos
19.
J Agric Food Chem ; 68(16): 4588-4594, 2020 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-32243143

RESUMO

Dicamba is a widely applied herbicide for crop protection and has potential for volatility. New formulations containing dicamba with greatly reduced volatility, introduced to the market in 2017, still caused foliar injury to crops and other plants in Arkansas and neighboring states in the United States. In response, we proposed the transformation of dicamba into protic as well as aprotic dicamba-based organic salts called herbicidal ionic liquids (HILs). All of the HILs were characterized by high stability, whereas the biological activity of the most effective products, evaluated during greenhouse studies, was found to be greater than that of currently used commercial analogues. Furthermore, the possibility of introducing an alkyl chain of a specific length allows one to obtain plant protection products with the desired physicochemical properties while maintaining herbicidal effectiveness. These studies are expected to aid in the design and development of new herbicidal formulations, which, depending on the weed species, could increase the efficacy of the applied active ingredient. Simultaneously, the volatility of the synthesized compounds, particularly those containing quaternary ammonium cations, was multiple times lower than that of the free acid of dicamba. This strategy minimizes the risk of off-site movement via volatilization, which may cause significant damage to neighboring broadleaf crops and pose a threat to existing ecosystems.


Assuntos
Dicamba/química , Herbicidas/química , Líquidos Iônicos/química , Composição de Medicamentos , Herbicidas/síntese química , Solubilidade , Volatilização
20.
J Agric Food Chem ; 68(18): 5059-5067, 2020 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-32286826

RESUMO

4-Hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) has been identified as one of the most significant targets in herbicide discovery for resistant weed control. In a continuing effort to discover potent novel HPPD inhibitors, we adopted a ring-expansion strategy to design a series of novel pyrazole-quinazoline-2,4-dione hybrids based on the previously discovered pyrazole-isoindoline-1,3-dione scaffold. One compound, 3-(2-chlorophenyl)-6-(5-hydroxy-1,3-dimethyl-1H-pyrazole-4-carbonyl)-1,5-dimethylquinazoline-2,4(1H,3H)-dione (9bj), displayed excellent potency against AtHPPD, with an IC50 value of 84 nM, which is approximately 16-fold more potent than pyrasulfotole (IC50 = 1359 nM) and 2.7-fold more potent than mesotrione (IC50 = 226 nM). Furthermore, the co-crystal structure of the AtHPPD-9bj complex (PDB ID 6LGT) was determined at a resolution of 1.75 Å. Similar to the existing HPPD inhibitors, compound 9bj formed a bidentate chelating interaction with the metal ion and a π-π stacking interaction with Phe381 and Phe424. In contrast, o-chlorophenyl at the N3 position of quinazoline-2,4-dione with a double conformation was surrounded by hydrophobic residues (Met335, Leu368, Leu427, Phe424, Phe392, and Phe381). Remarkably, the greenhouse assay indicated that most compounds displayed excellent herbicidal activity (complete inhibition) against at least one of the tested weeds at the application rate of 150 g of active ingredient (ai)/ha. Most promisingly, compounds 9aj and 9bi not only exhibited prominent weed control effects with a broad spectrum but also showed very good crop safety to cotton, peanuts, and corn at the dose of 150 g of ai/ha.


Assuntos
4-Hidroxifenilpiruvato Dioxigenase/antagonistas & inibidores , Inibidores Enzimáticos/química , Proteínas de Plantas/antagonistas & inibidores , Plantas Daninhas/enzimologia , Pirazóis/química , Quinazolinas/química , 4-Hidroxifenilpiruvato Dioxigenase/química , 4-Hidroxifenilpiruvato Dioxigenase/metabolismo , Inibidores Enzimáticos/farmacologia , Herbicidas/química , Herbicidas/farmacologia , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Daninhas/química , Plantas Daninhas/efeitos dos fármacos , Pirazóis/farmacologia , Quinazolinas/farmacologia , Relação Estrutura-Atividade , Controle de Plantas Daninhas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA