Stability Constants of Copper(II), Zinc, Manganese(II), Calcium, and Magnesium Complexes of N-(Phosphonomethyl)glycine (Glyphosate).

Madsen, Henrik Breuning; Christensen, Hans Henrik; Gottlieb-Petersen, C.; Andresen, Arne F.; Smidsrød, Olav; Pontchour, Cha-On; Phavanantha, Pathana; Pramatus, Supanich; Cyvin, Bjørg N.; Cyvín, S. J.

doi:10.3891/acta.chem.scand.32a-0079

Cited by 117 publications

(74 citation statements)

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“…The data presented here, showed that younger plants (V4 growth stage) are more sensitive to glyphosate effects than plants receiving glyphosate at a later growth stage (V7). Because a single application contains the total dose, it differs from sequential application in which the same dose is fragmented (50%-50%), thus, using a single application, the plant has less time to recover from the likely chelating effects of the higher glyphosate rate (Jaworski, 1972;Kabachnik et al, 1974;Madsen et al, 1978;Glass, 1984;Bromilow et al, 1993;Coutinho and Mazo, 2005;Eker et al, 2006;Zobiole et al, 2010). Since glyphosate forms insoluble metal complexes (Madsen et al, 1978;Glass, 1984;Coutinho and Mazo, 2005), the decrease in micronutrient accumulation could also affect the main function of chloroplast, i.e.…”

Section: Nutrient Accumulationmentioning

confidence: 99%

Nutrient Accumulation and Photosynthesis in Glyphosate-Resistant Soybeans Is Reduced Under Glyphosate Use

Zobiole

Oliveira

Kremer

et al. 2010

Journal of Plant Nutrition

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Section: Nutrient Accumulationmentioning

confidence: 99%

Nutrient Accumulation and Photosynthesis in Glyphosate-Resistant Soybeans Is Reduced Under Glyphosate Use

Zobiole

Oliveira

Kremer

et al. 2010

Journal of Plant Nutrition

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“…As constantes de estabilidade determinadas por Madsen e colaboradores 16 estão na Tabela 2. Em 2000, Kobylecka e colaboradores 33 estudaram o complexo de zinco(II) com glifosato, através de análise térmica, espectroscopia de IR e difração de Raios-X.…”

Section: Sintetizaram Os Complexos De Zinco(ii) E De Manganês(ii) unclassified

“…A constante de estabilidade do composto foi determinada pelo método descrito na literatura 34 e obteve-se o valor de log K igual a 7,61. O valor encontrado pelos autores foi menor que o encontrado por Madsen e colaboradores 16 (log K = 8,4). A solubilidade do complexo em água foi determinada e o valor encontrado foi 8,81x10…”

Section: Sintetizaram Os Complexos De Zinco(ii) E De Manganês(ii) unclassified

Complexos metálicos com o herbicida glifosato: revisão

Coutinho¹,

Mazo²

2005

Quím. Nova

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Recebido em 27/9/04; aceito em 22/3/05; publicado na web em 24/8/05 METALLIC COMPLEXES WITH GLYPHOSATE: A REVIEW. We present studies involving metallic ions and the herbicide glyphosate. The metallic complexes of Cu(II), Zn(II), Mn(II), Ni(II), Cd(II), Pb(II), Cr(III), Fe(III), Co(III), ammonium, sodium, Ag(I), alkaline earth metals and of some lanthanides ions are described. The complexes are discussed in terms of their synthesis, identification, stability and structural properties, based on data from the current literature.Keywords: metallic complexes; glyphosate; transition metal ions. INTRODUÇÃOO glifosato [N-(fosfonometil)glicina] é um herbicida sistêmico, pós-emergente e não seletivo largamente utilizado na agricultura 1 . O glifosato pertence ao grupo químico dos aminoácidos fosfonados e tal como seu precursor, a glicina, apresenta comportamento zwiteriônico, com separação de duas cargas em pH neutro, uma positiva no grupo amino e uma negativa no grupo fosfonato. A fór-mula estrutural do glifosato é mostrada na Figura 1.O modo de ação do glifosato consiste na alteração de diferentes processos bioquímicos vitais nas plantas, como a biosíntese de aminoácidos, proteínas e ácidos nucléicos 2 . O herbicida é absorvido pelo tecido vivo e translocado, via floema, através da planta para raízes e rizomas, e sua ação inibe enzimas específicas como a enolpiruvil shikimato-3-fosfato sintase (EPSP) suspendendo a sín-tese de aminoácidos aromáticos 1,3 . As plantas tratadas com glifosato morrem lentamente, em poucos dias ou semanas, e devido ao transporte por todo o sistema, nenhuma parte da planta sobrevive.Em condições normais, a enzima EPSP catalisa, na planta, a reação que envolve a transferência do enolpiruvil do fosfoenolpiruvato (PEP) para o shikimato-3-fosfato (S3P), formando 5-enolpiruvil shikimato-3-fosfato (EPSP) e fosfato inorgânico (P i ). Esta reação está representada na Figura 2. Numerosos estudos usando NMR, fluorescência e calorimetria de varredura diferencial demonstraram que o glifosato forma preferencialmente um complexo ternário estável com a enzima EPSP sintase e S3P (EPSP-S3P-glifosato). Esse provável complexo ternário representa a forma atualmente aceita como responsável pela atividade do herbicida 4 . Na maioria dos casos, o glifosato não é metabolizado pela planta, razão pela qual não apresenta seletividade. Quando aplicado diretamente no solo apresenta baixa atividade, devido à degradação microbiológica para produtos não fitotóxicos 5 (CO 2 , PO 4 -3 e NH 3 ) e à grande adsorção pelos constituintes do solo 6 .O grupo fosfonato R-PO(OH) 2 do composto tem a habilidade de formar complexos fortes com metais. Todos os processos de adsorção, fotodegradação e biodegradação dos fosfonatos são modificados pela presença de íons metálicos, devido à formação de complexos solúveis e não solúveis 7 . Além do grupo fosfonato, o herbicida possui outros dois grupos funcionais (amino e carboxilato) que podem se coordenar fortemente com íons metálicos, especialmente com os de transição em pH próximo de neutro on...

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“…In 1978, Madsen et al, in their report on the chemical properties of glyphosate, noted its propensity to form stable chelates with metal cations [16]. From kinetics characterized in figure 2 in their paper, one can predict that, at the physiologic pH range of approximately 7.4, in an idealized liquid medium with adequate glyphosate, up to half of the manganese cations could be bound in stable chelate with glyphosate, thus reducing their bio-availability.…”

Section: Metal Chelation By Glyphosate/gfhmentioning

confidence: 99%

“…Studies have documented that glyphosate also chelates zinc [16,22,23]. Because zinc is required for the synthesis of thyroid hormones, it is possible that lack of bioavailable zinc is a contributory factor in hypothyroidism [24].…”

Section: Metal Chelation By Glyphosate/gfhmentioning

confidence: 99%

Is there a link between autism and glyphosate-formulated herbicides?

Beecham¹,

Seneff²

2016

J Autism

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Glyphosate is the most widely used herbicide on the planet, and its increasing use over time in the United States aligns well with the increasing rates of autism determined by the Centers for Disease Control. Based on the known mechanism of glyphosate toxicity, we hypothesize that a pregnant woman's exposure at midpregnancy to glyphosate-formulated herbicides (GFH) may produce, in her unborn child's brain, anatomic alterations of cortical neuron layering remarkably similar to those found in the brains of humans with autism. Glyphosate's known ability to chelate manganese ions combined with evidence of severely depleted serum manganese in cows exposed to glyphosate makes it likely that glyphosate would induce manganese deficiency in humans, interfering with the function of manganese-dependent enzymes. In particular, this would affect the maternal pituitary's manganese-dependent Protein Phosphatase 1 (PP1) enzyme, resulting in a significant reduction in maternal serum levels of Thyroid-Stimulating Hormone (TSH). A study of mid-pregnancy maternal TSH serum levels in human mothers has found a statistical correlation of reduced TSH to increased risk of autism in offspring. Since insufficient thyroid stimulation by TSH or by iodine deficiency would both induce hypothyroidism, effects of iodine deficiency can be expected to emulate effects of TSH deficiency. Cortical neuron disarrangements have been produced in the brains of offspring of rat dams fed an iodine-deficient diet, and such foci of disordered cortical neurons are characteristically found in human autistic brains. While the research literature on glyphosate's endocrine disrupting effects is limited, diverse evidence from animal studies reveals effects that suggest impaired thyroid function. If our hypothesis can be substantiated by a focused research effort, it would provide further justification for reducing or, ideally, eliminating glyphosate-formulated herbicide exposures in pregnant women.

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Stability Constants of Copper(II), Zinc, Manganese(II), Calcium, and Magnesium Complexes of N-(Phosphonomethyl)glycine (Glyphosate).

Cited by 117 publications

References 0 publications

Nutrient Accumulation and Photosynthesis in Glyphosate-Resistant Soybeans Is Reduced Under Glyphosate Use

Nutrient Accumulation and Photosynthesis in Glyphosate-Resistant Soybeans Is Reduced Under Glyphosate Use

Complexos metálicos com o herbicida glifosato: revisão

Is there a link between autism and glyphosate-formulated herbicides?

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