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1.
J Agric Food Chem ; 68(1): 17-32, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31809036

RESUMO

Weeds had caused significant loss for crop production in the process of agriculture. Herbicides have played an important role in securing crop production. However, the high reliance on herbicides has led to environmental issues as well as the evolution of herbicide resistance. Thus, there is an urgent need for new herbicides with safer toxicological profiles and novel modes of action. Actinomycetes produce very diverse bioactive compounds, of which some show potent biopesticidal activity. The herbicidal secondary metabolites from actinomycetes can be classified into several groups, such as amino acids, peptides, nucleosides, macrolides, lactones, amide, amines, etc., some of which have been successfully developed as commercial herbicides. The structure diversity and evolved biological activity of secondary metabolites from actinomycetes can offer opportunities for the development of both directly used bioherbicides and synthetic herbicides with new target sites, and thus, this review focuses on the structure, herbicidal activity, and modes of action of secondary metabolites from actinomycetes.


Assuntos
Actinobacteria/química , Herbicidas/química , Herbicidas/farmacologia , Actinobacteria/metabolismo , Descoberta de Drogas , Herbicidas/metabolismo , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/crescimento & desenvolvimento , Metabolismo Secundário , Controle de Plantas Daninhas
2.
J Sci Food Agric ; 100(3): 1185-1194, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31680262

RESUMO

BACKGROUND: Ludwigia hyssopifolia (G. Don) Exell, one of the problem weeds in some rice-producing countries, was studied to determine its allelopathic potential based on the effects of aqueous extracts of its tissues (leaves, roots and stem) on seedling growth of selected weeds and rice. The major phenolic compound of its leaves was also isolated and characterized. RESULTS: L. hyssopifolia aqueous leaf extract showed significant inhibition of shoot growth and biomass accumulation of weeds (Amaranthus spinosus L., Dactyloctenium aegyptium L., Cyperus iria L.) while maintaining less adverse effects on rice (crop) compared to other aqueous extracts of roots and stem. Phytochemical screening showed that phenols, tannins, flavonoids, terpenoids, saponins and coumarins are found in its leaf aqueous extract. The Folin-Ciocalteu method revealed that its leaves contain 26.66 ± 0.30 mg GAE g-1 leaf. The extract was then acid-hydrolyzed to liberate the phenolics (25 mg phenolics g-1 leaf). The major compound was isolated via preparative thin-layer chromatography using formic acid-ethyl acetate-n-hexane (0.05:4:6) solvent system. It had maximum UV absorption at 272 nm while its Fourier transform infrared spectrum revealed phenol, carboxylic acid and ether functionalities. This also had similar chromatographic mobility when run together with syringic acid in two-dimensional paper chromatography and thin-layer chromatography. CONCLUSIONS: L. hyssopifolia has potential allelopathic activity and its leaf aqueous extract showed the highest phytotoxic activity (P ≤ 0.05) indicating its potential as a bioherbicide. The most probable identity of the major phenolic compound is syringic acid. © 2019 Society of Chemical Industry.


Assuntos
Herbicidas/química , Onagraceae/química , Extratos Vegetais/química , Amaranthus/efeitos dos fármacos , Amaranthus/crescimento & desenvolvimento , Flavonoides/química , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Herbicidas/isolamento & purificação , Herbicidas/farmacologia , Fenóis/química , Fenóis/isolamento & purificação , Fenóis/farmacologia , Compostos Fitoquímicos/química , Compostos Fitoquímicos/isolamento & purificação , Compostos Fitoquímicos/farmacologia , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/farmacologia , Folhas de Planta/química , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/crescimento & desenvolvimento , Taninos/química , Taninos/farmacologia
3.
J Agric Food Chem ; 67(45): 12382-12392, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31635461

RESUMO

Protoporphyrinogen oxidase (PPO, EC 1.3.3.4) is a promising target for herbicide discovery. Search for new compounds with novel chemotypes is a key objective for agrochemists. Here, we describe the discovery and systematic SAR-based structure optimization of novel N-isoxazolinylphenyltriazinones 5-9 as PPO inhibitors. The in vivo herbicidal activity and in vitro Nicotiana tabacum PPO (NtPPO) inhibitory activity were explored in detail. A number of the new synthetic compounds displayed strong PPO inhibitory activity with Ki values in the nanomolar range. Some compounds exhibited excellent and broad-spectrum weed control at the rate of 9.375-37.5 g ai/ha by postemergence application and showed improved monocotyledonous weed control compared to saflufenacil. Most promisingly, ethyl 3-(2-chloro-5-(3,5-dimethyl-2,6-dioxo-4-thioxo-1,3,5-triazinan-1-yl)-4-fluorophenyl)-5-methyl-4,5-dihydroisoxazole-5-carboxylate, 5a, with a Ki value of 4.9 nM, displayed over 2- and 6-fold higher potency than saflufenacil (Ki = 10 nM) and trifludimoxazin (Ki = 31 nM), respectively. Moreover, 5a showed excellent and broad-spectrum weed control against 32 kinds of weeds at 37.5-75 g ai/ha. Rice exhibited relative tolerance to 5a at 150 g ai/ha by postemergence application, indicating that 5a could be a potential herbicide candidate for weed control in paddy fields.


Assuntos
Inibidores Enzimáticos/farmacologia , Herbicidas/química , Herbicidas/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Protoporfirinogênio Oxidase/antagonistas & inibidores , Descoberta de Drogas , Inibidores Enzimáticos/química , Cinética , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Daninhas/química , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/enzimologia , Protoporfirinogênio Oxidase/química , Protoporfirinogênio Oxidase/metabolismo , Relação Quantitativa Estrutura-Atividade , Tabaco/química , Tabaco/efeitos dos fármacos , Tabaco/enzimologia , Controle de Plantas Daninhas
4.
J Agric Food Chem ; 67(43): 11839-11847, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31589436

RESUMO

4-Hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) is an important target site for discovering new bleaching herbicides. To explore novel HPPD inhibitors with excellent herbicidal activity, a series of novel N-aroyl diketone/triketone derivatives were rationally designed by splicing active groups and bioisosterism. Bioassays revealed that most of these derivatives displayed preferable herbicidal activity against Echinochloa crus-galli (EC) at 0.045 mmol/m2 and Abutilon juncea (AJ) at 0.090 mmol/m2. In particular, compound I-f was more potent compared to the commercialized compound mesotrione. Molecular docking indicated that the corresponding active molecules of target compounds and mesotrione shared similar interplay with surrounding residues, which led to a perfect interaction with the active site of Arabidopsis thaliana HPPD.


Assuntos
4-Hidroxifenilpiruvato Dioxigenase/antagonistas & inibidores , Inibidores Enzimáticos/química , Herbicidas/química , Cetonas/química , Proteínas de Plantas/antagonistas & inibidores , 4-Hidroxifenilpiruvato Dioxigenase/química , 4-Hidroxifenilpiruvato Dioxigenase/metabolismo , Domínio Catalítico , Echinochloa/efeitos dos fármacos , Echinochloa/enzimologia , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/farmacologia , Herbicidas/síntese química , Herbicidas/farmacologia , Cetonas/farmacologia , Malvaceae/efeitos dos fármacos , Malvaceae/enzimologia , Simulação de Acoplamento Molecular , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/enzimologia , Relação Estrutura-Atividade
5.
J Agric Food Chem ; 67(39): 10844-10852, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31525997

RESUMO

The discovery of 4-hydroxyphenylpyruvate dioxygenase (HPPD, EC 1.13.11.27) inhibitors has been an active area of research due to their great potential as herbicides for weed control. Starting from the binding mode of known inhibitors of HPPD, a series of HPPD inhibitors with new molecular scaffolds were designed and synthesized by hybridizing 2-benzoylethen-1-ol and isoindoline-1,3-dione fragments. The results of the in vitro tests indicated that the newly synthesized compounds showed good HPPD inhibitory activity with IC50 values against the recombinant Arabidopsis thaliana HPPD (AtHPPD) ranging from 0.0039 µM to over 1 µM. Most promisingly, compound 4ae, 2-benzyl-5-(5-hydroxy-1,3-dimethyl-1H-pyrazole-4- carbonyl)isoindoline-1,3-dione, showed the highest AtHPPD inhibitory activity with a Ki value of 3.92 nM, making it approximately 10 times more potent than pyrasulfotole (Ki = 44 nM) and slightly more potent than mesotrione (Ki = 4.56 nM). In addition, the cocrystal structure of the AtHPPD-4ae complex was successfully resolved at a resolution of 1.8 Å. The X-ray diffraction analysis indicated that the two carbonyl groups of 2-benzoylethen-1-ol formed a bidentate chelating interaction with the metal ion, while the isoindoline-1,3-dione moiety formed pronounced π-π stacking interactions with Phe381 and Phe424. Moreover, water-mediated hydrogen bonding interactions were observed between Asn282 and the nitrogen atoms of the pyrazole ring of 4ae. The above results showed that the pyrazole-isoindoline-1,3-dione hybrid is a promising scaffold for developing HPPD inhibitors.


Assuntos
4-Hidroxifenilpiruvato Dioxigenase/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Herbicidas/farmacologia , Isoindóis/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Pirazóis/farmacologia , 4-Hidroxifenilpiruvato Dioxigenase/química , 4-Hidroxifenilpiruvato Dioxigenase/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Herbicidas/síntese química , Herbicidas/química , Isoindóis/química , Cinética , Estrutura Molecular , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/crescimento & desenvolvimento , Pirazóis/química , Relação Estrutura-Atividade
6.
J Environ Sci Health B ; 54(8): 681-692, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31403392

RESUMO

Although there are many reports on the dangers posed by glyphosate, this herbicide is still one of the most popular and widely used total weed killers. Therefore, great effort should be made to minimize exposure to this herbicide and limit its losses into the environment. The aim of this study was to prepare a new formulation consisted of various molecular weight chitosans with glyphosate and their evaluation toward active substance release, phytotoxicity, and preliminary herbicidal efficiency. The phytotoxicity study of the obtained chitosan/glyphosate formulations was determined based on the Organisation for Economic Co-operation and Development 208 guideline. Among all tested formulations evaluated for phytotoxicity, that containing the highest molecular weight of chitosan was found to be the least toxic, showing simultaneously the most effective herbicidal activity against selected weeds. The release rate of glyphosate from the obtained formulations was dependent on the molecular weight and viscosity of chitosan.


Assuntos
Quitosana/química , Glicina/análogos & derivados , Herbicidas/química , Herbicidas/farmacologia , Quitosana/farmacologia , Glicina/química , Glicina/farmacocinética , Glicina/farmacologia , Herbicidas/farmacocinética , Peso Molecular , Plantas Daninhas/efeitos dos fármacos
7.
Molecules ; 24(15)2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31370299

RESUMO

Radicinin (1), is a fungal dihydropyranopyran-4,5-dione isolated together with some analogues, namely 3-epi-radicinin, radicinol, 3-epi-radicinol, and cochliotoxin (2-5), from the culture filtrates of the fungus Cochliobolus australiensis, a foliar pathogen of buffelgrass (Cenchrus ciliaris), an invasive weed in North America. Among the different metabolites 1 showed target-specific activity against the host plant and no toxicity on zebrafish embryos, promoting its potential use to develop a natural bioherbicide formulation to manage buffelgrass. These data and the peculiar structural feature of 1 suggested to carry out a structure-activity relationship study, preparing some key hemisynthetic derivatives and to test their phytotoxicity. In particular, p-bromobenzoyl, 5-azidopentanoyl, stearoyl, mesyl and acetyl esters of radicinin were semisynthesized as well as the monoacetyl ester of 3-epi-radicinin, the diacetyl esters of radicinol and its 3 epimer, and two hexa-hydro derivatives of radicinin. The spectroscopic characterization and the activity by leaf puncture bioassay against buffelgrass of all the derivatives is reported. Most of the compounds showed phytotoxicity but none of them had comparable or higher activity than radicinin. Thus, the presence of an α,ß unsaturated carbonyl group at C-4, as well as, the presence of a free secondary hydroxyl group at C-3 and the stereochemistry of the same carbon proved to be the essential feature for activity.


Assuntos
Cenchrus/efeitos dos fármacos , Plantas Daninhas/efeitos dos fármacos , Pironas/química , Relação Estrutura-Atividade , Alcaloides/química , Alcaloides/farmacologia , Ascomicetos/química , Cenchrus/crescimento & desenvolvimento , Fungos Mitospóricos/química , Estrutura Molecular , América do Norte , Plantas Daninhas/crescimento & desenvolvimento , Pironas/farmacologia , Toxinas Biológicas/química , Toxinas Biológicas/farmacologia
8.
Molecules ; 24(16)2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31426281

RESUMO

Fungal phytotoxins used as ecofriendly bioherbicides are becoming efficient alternatives to chemical herbicides for sustainable weed management. Previous study found that cultures of the pathogenic fungus Colletotrichum gloeosporioides BWH-1 showed phytotoxic activity. This study further isolated the major phytotoxin from cultures of the strain BWH-1 using bioactivity-guided isolation, by puncturing its host plant for an activity test and analyzing on the HPLC-DAD-3D mode for a purity check. Then, the active and pure phytotoxin was characterized as a dirhamnolipid (Rha-Rha-C10-C10) using the NMR, ESIMS, IR and UV methods. The herbicidal activity of dirhamnolipid was evaluated by the inhibition rate on the primary root length and the fresh plant weight of nine test plants, and the synergistic effect when combining with commercial herbicides. Dirhamnolipid exhibited broad herbicidal activity against eight weed species with IC50 values ranging from 28.91 to 217.71 mg L-1 and no toxicity on Oryza sativa, and the herbicidal activity could be synergistically improved combining dirhamnolipid with commercial herbicides. Thus, dirhamnolipid that originated from C. gloeosporioides BWH-1 displayed the potential to be used as a bioherbicide alone, or as an adjuvant added into commercial herbicides, leading to a decrease in herbicides concentration and increased control efficiency.


Assuntos
Colletotrichum/metabolismo , Glicolipídeos/farmacologia , Herbicidas/farmacologia , Micotoxinas/farmacologia , Plantas Daninhas/efeitos dos fármacos , Agricultura , Glicolipídeos/isolamento & purificação , Humanos , Concentração Inibidora 50 , Estrutura Molecular , Micotoxinas/isolamento & purificação , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/crescimento & desenvolvimento , Plantas Daninhas/crescimento & desenvolvimento , Metabolismo Secundário , Controle de Plantas Daninhas/métodos
9.
J Agric Food Chem ; 67(37): 10489-10497, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31452371

RESUMO

In order to develop a novel herbicide containing the ß-triketone motif, a series of 4-hydroxyl-3-(2-phenoxyacetyl)-pyran-2-one derivatives were designed and synthesized. The bioassay results showed that compound II15 had good pre-emergent herbicidal activity even at a dosage of 187.5 g ha-1. Moreover, compound II15 showed a broader spectrum of weed control when compared with a commercial herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), and displayed good crop safety to Triticum aestivum L. and Zea mays Linn. when applied at 375 g ha-1 under pre-emergence conditions, which indicated its great potential as a herbicide. More importantly, studying the molecular mode of action of compound II15 revealed that the novel triketone structure is a proherbicide of its corresponding phenoxyacetic acid auxin herbicide, which has a herbicidal mechanism similar to that of 2,4-D. The present work indicates that the 4-hydroxyl-3-(2-phenoxyacetyl)-pyran-2-one motif may be a potential lead structure for further development of novel auxin-type herbicides.


Assuntos
Herbicidas/síntese química , Herbicidas/farmacologia , Plantas Daninhas/efeitos dos fármacos , Arabidopsis/efeitos dos fármacos , Desenho de Drogas , Herbicidas/química , Estrutura Molecular , Plantas Daninhas/crescimento & desenvolvimento , Relação Estrutura-Atividade , Controle de Plantas Daninhas , Zea mays/efeitos dos fármacos
10.
Molecules ; 24(15)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31374997

RESUMO

In recent years, heavy metals (HMs) levels in soil and vegetation have increased considerably due to traffic pollution. These pollutants can be taken up from the soil through the root system. The ability of plants to accumulate HMs into their tissues can therefore be used to monitor soil pollution. The aim of this study was to test the ruderal species Senecio vulgaris L., Polygonum aviculare L., and Poa annua L., as possible candidates for biomonitoring Cu, Zn, Cd, Cr, Ni and Pb in multiple environments. The soils analyzed in this work came from three different environments (urban, woodland, and ultramafic), and therefore deeply differed for their metal content, texture, pH, and organic matter (OM) content. All urban soils were characterized by high OM content and presence of anthropogenic metals like Pb, Zn, Cd, and Cu. Woodland soils were sandy and characterized by low metal content and low OM content, and ultramafic soils had high Ni and Cr content. This soil variability affected the bioindication properties of the three studied species, leading to the exclusion of most metals (Zn, Cu, Cr, Cd, and Pb) and one species (P. aviculare) due to the lack of linear relations between metal in soil and metal in plants. Senecio vulgaris and Poa annua, conversely, appeared to be good indicators of Ni in all the soils tested. A high linear correlation between total Ni in soil and Ni concentration in P. annua shoots (R2 = 0.78) was found and similar results were achieved for S. vulgaris (R2 = 0.88).


Assuntos
Monitoramento Ambiental , Metais Pesados/química , Plantas Daninhas/química , Poluentes do Solo/química , China , Metais Pesados/toxicidade , Plantas Daninhas/efeitos dos fármacos , Poa/química , Polygonum/química , Senécio/química , Solo/química , Poluentes do Solo/toxicidade
11.
Molecules ; 24(15)2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31387317

RESUMO

BACKGROUND: essential oils are well known for their pharmacological effectiveness as well as their repellent, insecticide, and herbicide activities. The emergence of resistant weeds, due to the overuse of synthetic herbicides, makes it necessary to find natural alternatives for weed control. The aim of this study was to evaluate the phytotoxic effects of Eucalyptus citriodora, Lavandula angustifolia, and Pinus sylvestris, three common commercial essential oils, on weeds (Portulaca oleracea, Lolium multiflorum, and Echinochloa crus-galli), food crops (tomato and cucumber), and the invasive species Nicotiana glauca. Methods: to determine herbicidal effects, essential oils were tested at different concentrations (0.125-1µL/mL). The index of germination and seedling length data were recorded over 14 days. RESULTS: the in vitro assays showed that L. angustifolia with linalool (38.7 ± 0.1%), 1,8-cineole (26.5 ± 0.1%), and camphor (14.2 ± 0.1%) as the main compounds showed the most phytotoxic effects affecting seed germination in weeds and tomato, and the aforementioned invasive species. L. multiflorum was the most sensitive weed, particularly to lavender essential oil, which decreased the growth of its hypocotyl and radicle by 87.8% and 76.7%, respectively, at a dose of 1 µL/mL. Cucumber was the most resistant food crop, with no significant reduction observed in seed germination and hypocotyl growth with E. citriodora and L. angustifolia essential oils. CONCLUSIONS: lavender essential oil represents a promising candidate for the development of effective and safe herbicides in the management of L. multiflorum affecting cucumber crops.


Assuntos
Eucalyptus/química , Lavandula/química , Óleos Voláteis/farmacologia , Pinus sylvestris/química , Produtos Agrícolas/efeitos dos fármacos , Cromatografia Gasosa-Espectrometria de Massas , Germinação/efeitos dos fármacos , Herbicidas/farmacologia , Espécies Introduzidas , Óleos Voláteis/química , Plantas Daninhas/efeitos dos fármacos , Plântula/efeitos dos fármacos , Controle de Plantas Daninhas
12.
Pest Manag Sci ; 75(11): 3113-3121, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31317630

RESUMO

BACKGROUND: Strigolactones (SLs) have a vast number of ecological implications because of the broad spectrum of their biological activities. Unfortunately, the limited availability of SLs restricts their applicability for the benefit of humanity and renders synthesis the only option for their production. However, the structural complexity of SLs impedes their economical synthesis, which is unfeasible on a large scale. Synthesis of SL analogues and mimics with a simpler structure, but with retention of bioactivity, is the solution to this problem. RESULTS: Here, we present eight new hybrid-type SL analogues derived from auxin, synthesized via coupling of auxin ester [ethyl 2-(1H-indol-3-yl)acetate] and of ethyl 2-phenylacetate with four D-rings (mono-, two di- and trimethylated). The new hybrid-type SL analogues were bioassayed to assess the germination activity of seeds of the parasitic weeds Striga hermonthica, Orobanche minor and Phelipanche ramosa using the classical method of counting germinated seeds and a colorimetric method. The bioassays revealed that analogues with a natural monomethylated D-ring had appreciable to good activity towards the three species and were the most active derivatives. By contrast, derivatives with the trimethylated D-ring showed no activity. The dimethylated derivatives (2,4-dimethyl and 3,4-dimethyl) were slightly active, especially towards P. ramosa. CONCLUSIONS: New hybrid-type analogues derived from auxins have been prepared. These analogues may be attractive as potential suicidal germination agents for parasitic weed control because of their ease of preparation and relevant bioactivity. © 2019 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Germinação/efeitos dos fármacos , Ácidos Indolacéticos/química , Lactonas/síntese química , Orobanchaceae/efeitos dos fármacos , Plantas Daninhas/efeitos dos fármacos , Controle de Plantas Daninhas/métodos , Orobanchaceae/fisiologia , Orobanche/efeitos dos fármacos , Orobanche/fisiologia , Plantas Daninhas/fisiologia , Sementes/efeitos dos fármacos , Sementes/fisiologia , Striga/efeitos dos fármacos , Striga/fisiologia
13.
J Agric Food Chem ; 67(33): 9254-9264, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31356740

RESUMO

In continuation of our search for potent protoporphyrinogen IX oxidase (PPO, EC 1.3.3.4) inhibitors, we designed and synthesized a series of novel herbicidal cycloalka[d]quinazoline-2,4-dione-benzoxazinones. The bioassay results of these synthesized compounds indicated that most of the compounds exhibited very strong Nicotiana tabacum PPO (NtPPO) inhibition activity. More than half of the 37 synthesized compounds displayed over 80% control of all three tested broadleaf weeds at 37.5-150 g ai/ha by postemergent application, and a majority of them showed no phytotoxicity toward at least one kind of crop at 150 g ai/ha. Promisingly, 17i (Ki = 6.7 nM) was 6 and 4 times more potent than flumioxazin (Ki = 46 nM) and trifludimoxazin (Ki = 31 nM), respectively. Moreover, 17i displayed excellent, broad-spectrum herbicidal activity, even at levels as low as 37.5 g ai/ha, and it was determined to be safe for wheat at 150 g ai/ha in postemergent application, indicating the great potential for 17i development as a herbicide for weed control in wheat fields.


Assuntos
Benzoxazinas/química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Herbicidas/química , Herbicidas/farmacologia , Proteínas de Plantas/antagonistas & inibidores , Protoporfirinogênio Oxidase/antagonistas & inibidores , Quinazolinas/química , Benzoxazinas/farmacologia , Desenho de Drogas , Cinética , Proteínas de Plantas/química , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/enzimologia , Protoporfirinogênio Oxidase/química , Relação Quantitativa Estrutura-Atividade , Quinazolinas/farmacologia , Tabaco/efeitos dos fármacos , Tabaco/enzimologia , Controle de Plantas Daninhas
14.
Molecules ; 24(9)2019 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-31072064

RESUMO

Safranal, the main volatile chemical of Saffron (Crocus sativus) was studied to estimate its allelopathic effects on the photosynthetic pigment chlorophyll, leaf electrolyte leakage, fresh weight, catalase (CAT), and peroxidase (POX) activity of the test plant Lettuce (Lactuca sativa). In this study, the effective concentration (EC50) of safranal on CAT was estimated to be 6.12 µg/cm3. CAT activity was inhibited in a dose-dependent manner by the increase in the safranal concentration while POX activity was increased. Moreover, Safranal caused significant physiological changes in chlorophyll content, leaf electrolyte leakage, and fresh weight of several weed species with Lolium multiflorum being the most sensitive. Furthermore, 5 µM Safranal showed significant inhibitory activity against dicotyledonous in comparison to the monocotyledons under greenhouse conditions. The inhibition of the CAT by safranal was similar to those of uncompetitive inhibitors, and therefore the decline in carbon fixation by plants might be the mechanism behind the inhibitory activity of safranal.


Assuntos
Crocus/química , Cicloexenos/farmacologia , Alface/fisiologia , Feromônios/farmacologia , Plantas Daninhas/fisiologia , Terpenos/farmacologia , Catalase/metabolismo , Domínio Catalítico , Cicloexenos/química , Glutationa Peroxidase/metabolismo , Alface/efeitos dos fármacos , Pigmentação/efeitos dos fármacos , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/crescimento & desenvolvimento , Espécies Reativas de Oxigênio/metabolismo , Terpenos/química , Compostos Orgânicos Voláteis/farmacologia
15.
Int J Mol Sci ; 20(10)2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31096560

RESUMO

The introduction of glyphosate-resistant (GR) crops revolutionized weed management; however, the improper use of this technology has selected for a wide range of weeds resistant to glyphosate, referred to as superweeds. We characterized the high glyphosate resistance level of an Amaranthus hybridus population (GRH)-a superweed collected in a GR-soybean field from Cordoba, Argentina-as well as the resistance mechanisms that govern it in comparison to a susceptible population (GSH). The GRH population was 100.6 times more resistant than the GSH population. Reduced absorption and metabolism of glyphosate, as well as gene duplication of 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) or its overexpression did not contribute to this resistance. However, GSH plants translocated at least 10% more 14C-glyphosate to the rest of the plant and roots than GRH plants at 9 h after treatment. In addition, a novel triple amino acid substitution from TAP (wild type, GSH) to IVS (triple mutant, GRH) was identified in the EPSPS gene of the GRH. The nucleotide substitutions consisted of ATA102, GTC103 and TCA106 instead of ACA102, GCG103, and CCA106, respectively. The hydrogen bond distances between Gly-101 and Arg-105 positions increased from 2.89 Å (wild type) to 2.93 Å (triple-mutant) according to the EPSPS structural modeling. These results support that the high level of glyphosate resistance of the GRH A. hybridus population was mainly governed by the triple mutation TAP-IVS found of the EPSPS target site, but the impaired translocation of herbicide also contributed in this resistance.


Assuntos
3-Fosfoshikimato 1-Carboxiviniltransferase/genética , Amaranthus/efeitos dos fármacos , Amaranthus/genética , Substituição de Aminoácidos , Glicina/análogos & derivados , Resistência a Herbicidas/genética , Herbicidas/farmacologia , Argentina , Relação Dose-Resposta a Droga , Duplicação Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Glicina/metabolismo , Glicina/farmacologia , Mutação/efeitos dos fármacos , Fosfatos/metabolismo , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/genética , Alinhamento de Sequência , Análise de Sequência de Proteína , Ácido Chiquímico/metabolismo , Soja
16.
J Environ Sci Health B ; 54(7): 615-621, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31116075

RESUMO

The application of minimal doses of herbicides is very popular due to concerns about the negative impacts of herbicides on the environment and public health. Studies were conducted to estimate the possibility of using quick and non- destructive methods to investigate Chenopodium album L. and Abutilon theophrasti Medik. response to mesotrione. The studies were conducted in a controlled environment to determine the response of C. album and A. theophrasti to mesotrione using dose-response curves created based on plant dry weight, chlorophyll fluorescence parameters and chlorophyll content. The obtained effective dose values showed that the studied weeds were susceptible to reduced doses of mesotrione. ED95 values estimated for both species for dry weight and chlorophyll fluorescence parameters were lower than the recommended dose rate (120 g a.i. ha-1), with less than 85 g a.i. ha-1 needed to achieve a reduction of 95%, compared with untreated plants, while ED95 value (A. theophrasti: 182 g a.i. ha-1 and C. album: 180 g a.i. ha-1) for chlorophyll content for both species was above the recommended dose rates. Consequently, dry weight and the chlorophyll fluorescence parameters are suitable for estimating the plant response to mesotrione, while chlorophyll content is not.


Assuntos
Chenopodium album/efeitos dos fármacos , Cicloexanonas/farmacologia , Herbicidas/farmacologia , Malvaceae/efeitos dos fármacos , Chenopodium album/metabolismo , Clorofila/metabolismo , Cicloexanonas/administração & dosagem , Relação Dose-Resposta a Droga , Herbicidas/administração & dosagem , Malvaceae/metabolismo , Plantas Daninhas/efeitos dos fármacos
17.
J Agric Food Chem ; 67(16): 4453-4462, 2019 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-30933503

RESUMO

Atrazine is one of the most used herbicides and has been associated with persistent surface and groundwater contamination, and novel formulations derived from nanotechnology can be a potential solution. We used poly(ε-caprolactone) nanoencapsulation of atrazine (NC+ATZ) to develop a highly effective herbicidal formulation. Detailed structural study of interaction between the formulation and Brassica juncea plants was carried out with evaluation of the foliar uptake of nanoatrazine and structural alterations induced in the leaves. Following postemergent treatment, NC+ATZ adhered to the leaf and penetrated mesophyll tissue mainly through the hydathode regions. NC+ATZ was transported directly through the vascular tissue of the leaves and into the cells where it degraded the chloroplasts resulting in herbicidal activity. Nanocarrier systems, such as the one used in this study, have great potential for agricultural applications in terms of maintenance of herbicidal activity at low concentrations and a substantial increase in the herbicidal efficacy.


Assuntos
Atrazina/química , Herbicidas/química , Mostardeira/efeitos dos fármacos , Nanopartículas/química , Atrazina/metabolismo , Atrazina/farmacologia , Composição de Medicamentos , Herbicidas/metabolismo , Herbicidas/farmacologia , Mostardeira/metabolismo , Nanopartículas/metabolismo , Nanotecnologia , Tamanho da Partícula , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/crescimento & desenvolvimento
18.
Pestic Biochem Physiol ; 156: 9-28, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31027586

RESUMO

4-Hydroxyphenylpyruvate dioxgenase (HPPD) enzymes from rat and from several plants contained only about a single inhibitor-binding active site per dimer which matched the content of iron in the purified Arabidopsis thaliana and Avena sativa enzymes. The dimeric HPPDs were about 10 fold more catalytically active than the tetrameric P. fluorescens enzyme with kcat/KmHPP values ranging from 0.8 to 2.5 s-1 µM-1. Most were also highly sensitive to herbicides with, for example, Ki values for mesotrione ranging from 25 to 100 pM. Curiously HPPDs from cool climate grasses were much less herbicide-sensitive. When likewise expressed in Nicotinia tabacum, Avena sativa HPPD, Ki value of 11 nM for mesotrione, conferred far greater tolerance to mesotrione (CallistoTM) than did any of the more sensitive HPPDs. Targeted mutagenesis of the Avena HPPD led to the discovery of 4 mutations imparting improved inherent tolerance, defined as the ratio of Ki to KmHPP, by about 16 fold without any loss of catalytic activity. The Nicotinia line with the highest expression of this quadruple mutant exhibited substantial resistance even up to a 3 kg/ha post-emergence application of mesotrione. The maximum observed expression level of heterologous plant HPPDs in tobacco was ca. 0.35% of the total soluble protein whereas the endogenous tobacco HPPD constituted only ca. 0.00075%. At such high expression even HPPDs with impaired catalytic activity could be effective. A quintuple mutant Avena sativa HPPD conferred substantial tolerance across a broad range of HPPD herbicide chemistries despite being only ca. 5 % as catalytically active as the wild type enzyme. Testing various wild type and mutant HPPDs in tobacco revealed that tolerance to field rates of herbicide generally requires about two order of magnitude increases in both inherent herbicide tolerance and expression relative to endogenous levels. This double hurdle may explain why target-site based resistance to HPPD-inhibiting herbicides has been slow to evolve in weeds.


Assuntos
4-Hidroxifenilpiruvato Dioxigenase/metabolismo , Produtos Agrícolas/efeitos dos fármacos , Produtos Agrícolas/enzimologia , Cicloexanonas/farmacologia , Herbicidas/farmacologia , 4-Hidroxifenilpiruvato Dioxigenase/antagonistas & inibidores , Sequência de Aminoácidos , Animais , Arabidopsis/genética , Arabidopsis/metabolismo , Dados de Sequência Molecular , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/metabolismo , Ratos , Homologia de Sequência de Aminoácidos
19.
Pest Manag Sci ; 75(9): 2517-2529, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30972945

RESUMO

BACKGROUND: Allelopathy and bioassays constitute fundamental tools in the search for new herbicide templates. The work described here is a continuation of a previous study focused on the structure-activity relationships between transport phenomena and phytotoxic activity. Different modifications were made to the naphthoquinone backbone and two key factors were identified as being responsible for changes in activity: lipophilicity and the nature of the functional group. The study of other naturally occurring and semi-synthetic naphthoquinones was also proposed. RESULTS: A total of 12 5-O-acyl plumbagins and 18 analogs with unsaturated and aromatic substituents at positions 2 and 5 were synthesized. These compounds were evaluated in the wheat coleoptile bioassay and against Standard Target Species (STS) and three weeds, namely Echinochloa crus-galli L., Lolium rigidum Gaud. and Lolium perenne L. A strong structure-function relationship was observed for the different naphthoquinones and root and shoot length were the parameters that were most affected. CONCLUSION: Strong inhibitory effects were observed for the isomeric forms 23 and 33 and the derivatives with a free hydroxyl group, i.e. 24 and 30, gave values higher than 70% inhibition for root length in barnyardgrass and perennial ryegrass. These results highlight the potential of these compounds as models in the development of herbicides based on natural products. © 2019 Society of Chemical Industry.


Assuntos
Agentes de Controle Biológico/farmacologia , Herbicidas/farmacologia , Naftoquinonas/farmacologia , Plantas Daninhas/efeitos dos fármacos , Echinochloa/efeitos dos fármacos , Lolium/efeitos dos fármacos , Relação Estrutura-Atividade
20.
Sensors (Basel) ; 19(7)2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30939774

RESUMO

Effective control of the parasitic weed sunflower broomrape (Orobanche cumana Wallr.) can be achieved by herbicides application in early parasitism stages. However, the growing environmental concerns associated with herbicide treatments have motivated the adoption of precise chemical control approaches that detect and treat infested areas exclusively. The main challenge in developing such control practices for O. cumana lies in the fact that most of its life-cycle occurs in the soil sub-surface and by the time shoots emerge and become observable, the damage to the crop is irreversible. This paper approaches early O. cumana detection by hypothesizing that its parasitism already impacts the host plant morphology at the sub-soil surface developmental stage. To validate this hypothesis, O. cumana- infested sunflower and non-infested control plants were grown in pots and imaged weekly over 45-day period. Three-dimensional plant models were reconstructed using image-based multi-view stereo followed by derivation of their morphological parameters, down to the organ-level. Among the parameters estimated, height and first internode length were the earliest definitive indicators of infection. Furthermore, the detection timing of both parameters was early enough for herbicide post-emergence application. Considering the fact that 3-D morphological modeling is nondestructive, is based on commercially available RGB sensors and can be used under natural illumination; this approach holds potential contribution for site specific pre-emergence managements of parasitic weeds and as a phenotyping tool in O. cumana resistant sunflower breeding projects.


Assuntos
Helianthus/fisiologia , Orobanche/crescimento & desenvolvimento , Algoritmos , Produtos Agrícolas , Helianthus/crescimento & desenvolvimento , Herbicidas/farmacologia , Modelos Lineares , Modelos Teóricos , Orobanche/efeitos dos fármacos , Fotografação/instrumentação , Fotografação/métodos , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/fisiologia , Plantas Daninhas/efeitos dos fármacos , Plantas Daninhas/crescimento & desenvolvimento
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