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1.
Ecotoxicol Environ Saf ; 203: 110983, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678760

RESUMO

Chelating agents have been considered as an important phytoremediation strategy to enhance heavy metal extraction from contaminated soil. A pot experiment was conducted to explore the effects of low molecular weight organic acids (LMWOAs) on the phytoremediation efficiency of copper (Cu) by castor bean, and soil enzyme activities. Results indicated that the addition of all the three kinds of LMWOAs (citric, tartaric, oxalic acids) did not decrease the biomass of castor bean, despite the fact they reduced the concentration of chlorophyll-a in leaves compared to the control. The Cu concentrations in the roots and shoots significantly increased by 6-106% and 5-148%, respectively, in the LMWOAs treatments so that the total accumulation of Cu by whole plants in all the LMWOAs treatments increased by 21-189% in comparison with the control. The values of the translocation factor (TF) and bio-concentration factor (BCF) of Cu in castor bean also rose following the addition of LMWOAs, indicating that the LMWOAs enhanced the uptake and transportation of Cu. Moreover, the application of LMWOAs did not significantly change the soil pH but significantly increased the activity of soil enzymes (urease, catalase, and alkaline phosphatase). The addition of exogenous LMWOAs increased the available Cu significantly in the soil, thus promoted the phytoextraction efficiency of Cu by castor bean. These results will provide some new insights into the practical use of LMWOAs for the phytoremediation of heavy-metal-contaminated soil employing castor bean.


Assuntos
Bioacumulação , Semente de Rícino/metabolismo , Quelantes/química , Cobre/metabolismo , Compostos Orgânicos/química , Poluentes do Solo/metabolismo , Solo/química , Ácidos/administração & dosagem , Ácidos/química , Biodegradação Ambiental , Semente de Rícino/efeitos dos fármacos , Quelantes/administração & dosagem , Peso Molecular , Compostos Orgânicos/administração & dosagem
2.
Food Chem ; 332: 127440, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32652411

RESUMO

Rehydration in an alkaline solution has been shown to improve the rehydration behaviour of milk protein isolate (MPI). In this study, the focus is on citric acid neutralization of MPI powder dissolved in alkaline solution. The results showed that alkalization induced more negative zeta-potential compared to MPI control, reducing it from -22.4 mV to -32.6 mV. Neutralization had a relatively similar zeta-potential value as alkalized sample. Sodium carbonate addition increased pH and caused a consequential reduction of ionic calcium in aqueous phase and, neutralization caused a small increase in ionic calcium. Soluble aggregate of κ-casein protein and whey protein was suggested in alkalization and neutralization process by non-reducing SDS-PAGE. In addition, neutralization kept a stable colloidal particle size for pHs decreased to pH 9,8 and 7; however, alkalization and neutralization created casein aggregates of larger colloidal particle size than primary casein micelle in control MPI.


Assuntos
Cálcio/química , Caseínas/química , Quelantes/química , Animais , Bovinos , Ácido Cítrico/química , Concentração de Íons de Hidrogênio , Micelas , Tamanho da Partícula , Proteínas do Soro do Leite/química
3.
Chemosphere ; 258: 127227, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554003

RESUMO

Eight different types of complexing agents were employed for the development of new biodegradable decontamination solutions that are able to form strippable coatings after they are dispersed and allowed to dry on a variety of surfaces contaminated with 60Co, 133Ba, 137Cs and 241Am radioactive isotopes. The new generation of eco-friendly chelators with superior biodegradability, utilized for the first time in such applications, can easily replace the non-biodegradable and carcinogenic complexing agents that are still in use today, due to their decontamination performances. Furthermore, besides the complexing action over the radionuclides, the solutions contain two types of clays, Bentonite (BT) and Saponite (SP), which have the capacity to adsorb specific ions, improving the decontamination efficiency of the solutions. Our research revealed that it is preferable to replace BT with SP, due to its better dispersibility, thermal stability, next to superior ability to gel and better thermal stability (Miles, 2011). The solutions showed a decontamination factor superior to 95% for 137Cs (on all surfaces), over 90% for 60Co and 133Ba, and more than 72% 241Am (on all surfaces), except for galvanized metal plates, where lower decontamination factors were obtained: over 70% for 133Ba, maximum 41.87% for 241Am and 43.19% for 60Co.


Assuntos
Quelantes/química , Descontaminação/métodos , Substâncias Perigosas/análise , Nanoestruturas/química , Radioisótopos/análise , Adsorção , Silicatos de Alumínio/química , Bentonita/química , Biodegradação Ambiental , Álcool de Polivinil/química , Radioatividade , Soluções , Propriedades de Superfície
4.
SAR QSAR Environ Res ; 31(5): 347-371, 2020 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-32460542

RESUMO

Two simple and reliable correlations are introduced for the prediction of emission and absorption of porphyrins and their derivatives, i.e. metalloporphyrins and ligand coordinated metalloporphyrins. They can be used to sense the extracted precious metals. The proposed models require only simple structural parameters such as the number of carbon, metal and metal-free molecular fragments of desirable porphyrins or their derivatives. Since the proposed models depend on molecular structures of the desired compounds, they can be easily applied for complex molecular structures. Experimental data of 272 porphyrin derivatives were used to derive and test the novel models for the assessment of their emission (Em.) and absorption (Abs.) values in three solvents namely dichloromethane, toluene and chloroform. The values of the coefficients of determination (r 2) for the training set (183 compounds) in dichloromethane and three different test sets, corresponding to the three mentioned solvents, for the emission and absorption correlations were greater than 0.70. The calculated values of the root-mean-square error (RMSE) for the training sets of Em. and Abs. correlations were equal to 7.56 and 4.86 nm, respectively. Further statistical parameters also confirm the high reliability of the new models.


Assuntos
Quelantes/química , Porfirinas/química , Relação Quantitativa Estrutura-Atividade , Solventes/química , Clorofórmio/química , Hidroquinonas/química , Ligantes , Substâncias Macromoleculares/química , Metais Pesados/química , Cloreto de Metileno/química
5.
Chemistry ; 26(31): 7131-7139, 2020 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-32255539

RESUMO

Protein-protein interactions (PPIs) of 14-3-3 proteins are a model system for studying PPI stabilization. The complex natural product Fusicoccin A stabilizes many 14-3-3 PPIs but is not amenable for use in SAR studies, motivating the search for more drug-like chemical matter. However, drug-like 14-3-3 PPI stabilizers enabling such studies have remained elusive. An X-ray crystal structure of a PPI in complex with an extremely low potency stabilizer uncovered an unexpected non-protein interacting, ligand-chelated Mg2+ leading to the discovery of metal-ion-dependent 14-3-3 PPI stabilization potency. This originates from a novel chelation-controlled bioactive conformation stabilization effect. Metal chelation has been associated with pan-assay interference compounds (PAINS) and frequent hitter behavior, but chelation can evidently also lead to true potency gains and find use as a medicinal chemistry strategy to guide compound optimization. To demonstrate this, we exploited the effect to design the first potent, selective, and drug-like 14-3-3 PPI stabilizers.


Assuntos
Proteínas 14-3-3/química , Produtos Biológicos/química , Quelantes/química , Metais/química , Descoberta de Drogas , Glicosídeos , Humanos , Conformação Molecular , Ligação Proteica
6.
PLoS One ; 15(3): e0230022, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32143211

RESUMO

The objective of this study was to regulate the cytotoxicity of cisplatin (cisPt) minimizing its adverse effects. For this purpose, the lowest cisPt concentration needed to obtain a significant positive response in cutaneous squamous cell carcinoma (cSCC) was explored. Two adjuvant agents as gold nanoparticles (AuNP) and chelating tricine were tested as enhancers in cisPt treatment. Effectiveness of all treatments was assessed by means of biochemical techniques, which offer quantitative data, as well as two microscopy-based techniques that provided qualitative cell imaging. The present work confirms the effectiveness of free cisplatin at very low concentrations. In order to enhance its effectiveness while the side effects were probably diminished, cisPt 3.5 µM was administered with AuNP 2.5 mM, showing an effectiveness practically equal to that observed with free cisPt. However, the second treatment investigated, based on cisPt 3.5 µM combined with tricine 50 mM, enhanced drug effectiveness, increasing the percentage of cells dying by apoptosis. This treatment was even better in terms of cell damage than free cisPt at 15 µM. Images obtained by TEM and cryo-SXT confirmed these results, since a notable number of apoptotic bodies were detected when cisPt was combined with tricine. Thus, tricine was clearly a better adjuvant for cisPt treatments.


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Cisplatino/química , Portadores de Fármacos/química , Antineoplásicos/química , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas/patologia , Linhagem Celular Tumoral , Tamanho Celular/efeitos dos fármacos , Quelantes/química , Cisplatino/farmacologia , Glicina/análogos & derivados , Glicina/química , Glicina/toxicidade , Ouro/química , Humanos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/toxicidade , Microscopia Eletrônica de Transmissão , Transdução de Sinais/efeitos dos fármacos , Neoplasias Cutâneas/metabolismo , Neoplasias Cutâneas/patologia
7.
Artigo em Inglês | MEDLINE | ID: mdl-32109747

RESUMO

Cd(II) is toxic to many species, including humans, because it inactivates a number of enzymes and induces cytopathic effects in the liver, kidney, and skeletal tissues in humans. Metallothionein and glutathione (GSH) play a major role in the protection against Cd(II)-induced toxicity in mammalian cells. In this study, a relatively simple method for detecting trace amounts of Cd(II) chelators was developed by using 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid (TPPS). The TPPS-Cd(II) complex was added to the elutions of high-performance liquid chromatography. The Cd(II) chelators separated by column chromatography were mixed with Cd(II)-bound TPPS (TPPS-Cd(II)). Cd(II) from TPPS-Cd(II) was chelated by the eluted Cd(II) chelators, resulting in the formation of free TPPS. The absorbance of TPPS shifted from 434 nm (TPPS-Cd(II)) to 414 nm (TPPS), and this characteristic shift was used to estimate the quantity and affinity of the Cd(II) chelators. This new method was compared with the bathocuproine disulfonate (BCS) method developed in our previous study. Instead of BCS-Cu(I), TPPS-Cd(II) was used as the colorimetric reagent. The experimental setup of the TPPS-based method is more general, and the preparation of the colorimetric solution is also much simpler than the BCS method. To verify the efficacy of this new method, we determined the actual Cd(II)-chelating ability of GSH in horse blood; the obtained concentration was in good agreement with the previously reported value.


Assuntos
Aporfinas/química , Cádmio/química , Quelantes/análise , Quelantes/química , Cromatografia Líquida de Alta Pressão/métodos , Animais , Glutationa , Cavalos , Limite de Detecção , Estresse Oxidativo
8.
Chem Commun (Camb) ; 56(17): 2642-2645, 2020 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-32021998

RESUMO

A nickel-catalyzed tandem reaction of N-vinylamides with arylboronic acids and bromodifluoroacetate has been developed. The use of amide carbonyl as a chelating group efficiently furnishes a series of protected α,α-difluoro-γ-amino acid esters. The reaction can also extend to bromoacetate and 2-bromomalonate. The advantages of this protocol are high functional group tolerance and a broad substrate scope, including a variety of N-vinylamides. In particular, the use of removable amide carbonyl groups provides potential opportunities for applications in peptide chemistry and protein engineering.


Assuntos
Amidas/química , Aminoácidos/química , Níquel/química , Catálise , Quelantes/química
9.
Int J Nanomedicine ; 15: 31-47, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32021163

RESUMO

Purpose: Using our chelate-free, heat-induced radiolabeling (HIR) method, we show that a wide range of metals, including those with radioactive isotopologues used for diagnostic imaging and radionuclide therapy, bind to the Feraheme (FH) nanoparticle (NP), a drug approved for the treatment of iron anemia. Material and methods: FH NPs were heated (120°C) with nonradioactive metals, the resulting metal-FH NPs were characterized by inductively coupled plasma mass spectrometry (ICP-MS), dynamic light scattering (DLS), and r1 and r2 relaxivities obtained by nuclear magnetic relaxation spectrometry (NMRS). In addition, the HIR method was performed with [90Y]Y3+, [177Lu]Lu3+, and [64Cu]Cu2+, the latter with an HIR technique optimized for this isotope. Optimization included modifying reaction time, temperature, and vortex technique. Radiochemical yield (RCY) and purity (RCP) were measured using size exclusion chromatography (SEC) and thin-layer chromatography (TLC). Results: With ICP-MS, metals incorporated into FH at high efficiency were bismuth, indium, yttrium, lutetium, samarium, terbium and europium (>75% @ 120 oC). Incorporation occurred with a small (less than 20%) but statistically significant increases in size and the r2 relaxivity. An improved HIR technique (faster heating rate and improved vortexing) was developed specifically for copper and used with the HIR technique and [64Cu]Cu2+. Using SEC and TLC analyses with [90Y]Y3+, [177Lu]Lu3+ and [64Cu]Cu2+, RCYs were greater than 85% and RCPs were greater than 95% in all cases. Conclusion: The chelate-free HIR technique for binding metals to FH NPs has been extended to a range of metals with radioisotopes used in therapeutic and diagnostic applications. Cations with f-orbital electrons, more empty d-orbitals, larger radii, and higher positive charges achieved higher values of RCY and RCP in the HIR reaction. The ability to use a simple heating step to bind a wide range of metals to the FH NP, a widely available approved drug, may allow this NP to become a platform for obtaining radiolabeled nanoparticles in many settings.


Assuntos
Óxido Ferroso-Férrico/química , Marcação por Isótopo/métodos , Nanopartículas/química , Radioisótopos/química , Quelantes/química , Cromatografia em Gel , Radioisótopos de Cobre/química , Difusão Dinâmica da Luz , Lutécio/química , Espectroscopia de Ressonância Magnética , Compostos Radiofarmacêuticos/química
10.
Chemosphere ; 248: 126060, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32032879

RESUMO

Naturally occurring and synthetic chelating ligands can act as suppressants for fungal pathogens, nematodes and weeds, based on their ability to alter micronutrient bioavailability in soil, particularly iron. Chelators are also used as detergents, for remediation of heavy metal contamination and for supplying metals as fertiliser. The aim of this work was to test the ability of chelators to solubilise metals, in particular iron, in tropical soils over an environmentally relevant pH range. Six topsoils from farms in North Queensland, Australia were adjusted to pH 5, 6 and 7 and then extracted with CaCl2, EDTA, DTPA, EDDHA and mimosine. The extracts were analysed for concentrations of aluminium, copper, iron, magnesium, manganese, potassium, strontium and zinc. EDDHA solubilised iron effectively under all of the conditions tested, indicating its likely suitability for pest suppression. The concentration of aluminium in EDDHA extracts was positively correlated with pH, and at pH 7 the concentration of aluminium was far greater than that of iron. An increase in the mobility of aluminium from EDDHA application to soil may lead to aluminium toxicity in plants, which should be considered further in any practical application of EDDHA. Mimosine, which is also a strong chelator, was a poor extractor of all metals, possibly due to adsorption to the soil.


Assuntos
Quelantes/química , Recuperação e Remediação Ambiental/métodos , Metais Pesados/análise , Poluentes do Solo/análise , Adsorção , Disponibilidade Biológica , Cobre/análise , Etilenodiaminas , Fertilizantes/análise , Ferro/análise , Ligantes , Manganês/análise , Solo , Oligoelementos/análise , Zinco/análise
11.
Int J Pharm Compd ; 24(1): 38-43, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32023215

RESUMO

Pharmaceutical formulation involves patient acceptability and compliance, ease of preparation, microbiological considerations, and chemical and physical factors affecting compatibility of all ingredients and stability. Physical factors such as light, heat, and humidity can trigger or accelerate undesirable chemical reactions such as oxidation, hydrolysis, decarboxylation, racemization, and photolysis, compromising drug stability. Many drug products and preparations are subject to oxidation, which can often be catalyzed by light, temperature, hydrogen ion concentration, presence of trace metals, or peroxides. Oxidation of a product may be manifested as an unpleasant odor or taste, discoloration or other change in appearance, precipitation, or even a slight loss of activity. Antioxidants are often introduced to improve the shelf life of pharmaceuticals along with suggested procedures to minimize oxidation. Often, chelating agents are added with antioxidants to bind with any trace metals present and enhance the stability of the formulation.


Assuntos
Antioxidantes , Composição de Medicamentos/métodos , Excipientes , Quelantes/química , Estabilidade de Medicamentos , Humanos
12.
Chem Soc Rev ; 49(4): 1090-1108, 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-32016270

RESUMO

Inorganic phosphate has numerous biomedical functions. Regulated primarily by the kidneys, phosphate reaches abnormally high blood levels in patients with advanced renal diseases. Since phosphate cannot be efficiently removed by dialysis, the resulting hyperphosphatemia leads to increased mortality. Phosphate is also an important component of the environmental chemistry of surface water. Although required to secure our food supply, inorganic phosphate is also linked to eutrophication and the spread of algal blooms with an increasing economic and environmental burden. Key to resolving both of these issues is the development of accurate probes and molecular receptors for inorganic phosphate. Yet, quantifying phosphate in complex aqueous media remains challenging, as is the development of supramolecular receptors that have adequate sensitivity and selectivity for use in either blood or surface waters. Metal-based receptors are particularly well-suited for these applications as they can overcome the high hydration enthalpy of phosphate that limits the effectiveness of many organic receptors in water. Three different strategies are most commonly employed with inorganic receptors for anions: metal extrusion assays, responsive molecular receptors, and indicator displacement assays. In this review, the requirements for molecular receptors and probes for environmental applications are outlined. The different strategies deployed to recognize and sense phosphate with metal ions will be detailed, and their advantages and shortfalls will be delineated with key examples from the literature.


Assuntos
Metais/química , Fosfatos/química , Quelantes/química , Complexos de Coordenação/química , Elementos da Série dos Lantanídeos/química , Metais/metabolismo , Fosfatos/metabolismo , Elementos de Transição/química , Água/química
13.
Biomater Sci ; 8(7): 1923-1933, 2020 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-32031543

RESUMO

Unwanted formation of bacterial biofilms can cause problems in both the medical sector and industrial settings. However, removing them from surfaces remains an ongoing challenge since biofilm bacteria efficiently protect themselves from external influences such as mechanical shear forces by embedding themselves into a matrix of extracellular polymeric substances. Here, we discuss microscopic principles, which are responsible for alterations in the viscoelastic properties of biofilms upon contact with metal ions. We suggest that it is a combination of mainly two parameters, that decides if biofilm stiffening occurs or not: the ion size and the detailed configuration of polyanionic macromolecules from the biofilm matrix. Our results provide new insights in the molecular mechanisms that govern the mechanical properties of biofilms. Also, they indicate that hydrogels comprising purified biopolymers can serve as suitable model systems to reproduce certain aspects of biofilm mechanics - provided that the correct biopolymer is chosen.


Assuntos
Antibacterianos/química , Azotobacter vinelandii/efeitos dos fármacos , Bacillus subtilis/efeitos dos fármacos , Biofilmes , Quelantes/química , Alginatos/química , Antibacterianos/farmacologia , Azotobacter vinelandii/fisiologia , Bacillus subtilis/fisiologia , Quelantes/farmacologia , Elasticidade , Hidrogéis/química , Metais/química , Polímeros/química , Viscosidade
14.
Chemistry ; 26(34): 7602-7608, 2020 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-32068310

RESUMO

In this study a bispidine ligand has been applied to the complexation of gallium(III) and radiolabelled with gallium-68 for the first time. Despite its 5-coordinate nature, the resulting complex is stable in serum for over two hours, demonstrating a ligand system well matched to the imaging window of gallium-68 positron emission tomography (PET). To show the versatility of the bispidine ligand and its potential use in PET, the bifunctional chelator was conjugated to a porphyrin, producing a PET/PDT-theranostic, which showed the same level of stability to serum as the non-conjugated gallium-68 complex. The PET/PDT complex killed >90 % of HT-29 cells upon light irradiation at 50 µm. This study shows bispidines have the versatility to be used as a ligand system for gallium-68 in PET.


Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/química , Quelantes/química , Gálio/química , Porfirinas/química , Compostos Bicíclicos Heterocíclicos com Pontes/análise , Radioisótopos de Gálio , Humanos , Ligantes , Tomografia por Emissão de Pósitrons/métodos , Nanomedicina Teranóstica/métodos
15.
Inorg Chem ; 59(3): 2070-2082, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31940188

RESUMO

The thermodynamic stability of a metal-ligand complex, as measured by the formation constant (log ß), is one of the most important parameters that determines metal ion selectivity and potential applications in, for example, radiopharmaceutical science. The stable coordination chemistry of radioactive 89Zr4+ in an aqueous environment is of paramount importance when developing positron-emitting radiotracers based on proteins (usually antibodies) for use with positron emission tomography. Desferrioxamine B (DFO) remains the chelate of choice for clinical applications of 89Zr-labeled proteins, but the coordination of DFO to Zr4+ ions is suboptimal. Many alternative ligands have been reported, but the challenges in measuring very high log ß values with metal ions such as Zr4+ that tend to hydrolyze mean that accurate thermodynamic data are scarce. In this work, density functional theory (DFT) calculations were used to predict the reaction energetics for metal ion complexation. Computed values of pseudoformation constants (log ß') are correlated with experimental data and showed an excellent linear relationship (R2 = 0.97). The model was then used to estimate the absolute and relative formation constants of 23 different Zr4+ complexes using a total of 17 different ligands, including many of the alternative bifunctional chelates that have been reported recently for use in 89Zr4+ radiochemistry. In addition, detailed computational studies were performed on the geometric isomerism and hydration state of Zr-desferrioxamine. Collectively, the results offer new insights into Zr4+ coordination chemistry that will help guide the synthesis of future ligands. The computational model developed here is straightforward and reproducible and can be readily applied in the design of other metal coordination compounds.


Assuntos
Quelantes/química , Complexos de Coordenação/química , Desferroxamina/química , Termodinâmica , Zircônio/química , Quelantes/síntese química , Complexos de Coordenação/síntese química , Teoria da Densidade Funcional , Ligantes , Modelos Moleculares , Tomografia por Emissão de Pósitrons , Traçadores Radioativos
16.
Inorg Chem ; 59(3): 2051-2061, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31967459

RESUMO

Dioxygen O-O bond activation is a process for oxygenases and oxidases to perform biological functions and synthetic biomimetic catalysts to carry out oxygenation reactions using molecular O2 as an oxidant. Inspired by the experimental development of a CoIII-peroxo complex (i.e., [CoIII(TBDAP)(O2)]+, TBDAP = N,N-ditert-butyl-2,11-diaza[3.3](2,6)-pyridinophane) that exhibits dioxygenase-like reactivity to activate nitriles, a density functional theory (DFT) mechanistic study has been carried out to understand how the peroxo ligand is broken to activate nitriles. The study unveils that the O-O bond cleavage takes place via conversion to a CoII-superoxo complex aided by nitrile coordination, followed by formation of a five-membered intermediate via superoxo O2 radical nucleophilic attack at the nitrile carbon. Finally, a [1,3]-sigmatropic rearrangement-like process breaks the dioxygen bond. The otherwise difficult [1,3]-sigmatropic rearrangement is enabled by the mediation of CoIII(TBDAP) which alters a concerted rearrangement to a sequential process of O-O bond cleavage and N-O bond formation. Expectedly, the unveiling of the O-O bond cleavage mechanism could offer a clue for the development of biomimetic metal oxygenation catalysts.


Assuntos
Quelantes/química , Cobalto/química , Complexos de Coordenação/química , Teoria da Densidade Funcional , Dioxigenases/química , Peróxidos/química , Quelantes/síntese química , Quelantes/metabolismo , Cobalto/metabolismo , Complexos de Coordenação/síntese química , Complexos de Coordenação/metabolismo , Dioxigenases/metabolismo , Modelos Moleculares , Estrutura Molecular , Oxigênio/química , Oxigênio/metabolismo , Peróxidos/metabolismo
17.
J Agric Food Chem ; 68(7): 2091-2098, 2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-31927882

RESUMO

In this study, we used reversed-phase high performance liquid chromatography (LC) to isolate three novel peptides with calcium-chelating capacity from tilapia bone collagen hydrolysate. Using LC-tandem mass spectrometry, we determined the amino acid sequences to be GPAGPHGPVG, FDHIVY, and YQEPVIAPKL. We then synthesized the three peptides and verified their calcium-chelating activity. Results showed that the calcium-chelating activity of GPAGPHGPVG, FDHIVY, and YQEPVIAPKL reached 18.80 ± 0.49, 35.73 ± 0.74, and 28.4 ± 0.94 mg/g, respectively. We next investigated how each peptide enhanced intestinal calcium absorption using Caco-2 cell monolayers. Compared with the control group, GPAGPHGPVG, FDHIVY, and YQEPVIAPKL potently enhanced calcium transport within 30 min by 89 ± 9, 202 ± 12, and 130 ± 7%, respectively. Results suggest that these peptides isolated from tilapia bone hydrolysate can be used as dietary supplements to increase calcium absorption.


Assuntos
Osso e Ossos/química , Cálcio/química , Cálcio/metabolismo , Quelantes/química , Colágeno/química , Proteínas de Peixes/química , Mucosa Intestinal/metabolismo , Peptídeos/química , Sequência de Aminoácidos , Animais , Transporte Biológico/efeitos dos fármacos , Células CACO-2 , Humanos , Mapeamento de Peptídeos , Hidrolisados de Proteína/química , Tilápia
18.
J Agric Food Chem ; 68(7): 2164-2173, 2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-31985224

RESUMO

Reactive extrusion of bio-derived active packaging offers a new approach to address converging concerns over environmental contamination and food waste. Herein, metal-chelating nitrilotriacetic acid (NTA) ligands were grafted onto poly(lactic acid) (PLA) by reactive extrusion to produce metal-chelating PLA (PLA-g-NTA). Radical grafting was confirmed by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy with the introduction of secondary alkyl stretches (2919 and 2860 cm-1) and by X-ray photoelectron spectroscopy (XPS) with an increase in the atomic percentage of nitrogen. Compared to films prepared from native, granular PLA (gPLA), PLA-g-NTA films had lower contact angles and hysteresis values (86.35° ± 2.49 and 31.89° ± 2.27 to 79.91° ± 1.58 and 21.79° ± 1.72, respectively), supporting the surface orientation of the NTA ligands. The PLA-g-NTA films exhibited a significant antioxidant character with a radical scavenging capacity of 0.675 ± 0.026 nmol Trolox(eq)/cm2 and an iron chelation capacity of 54.09 ± 9.36 nmol/cm2. PLA-g-NTA films delayed ascorbic acid degradation, retaining ∼45% ascorbic acid over the 9-day study compared to <20% for control PLA. This research makes significant advances in translating active packaging technologies to bio-derived materials using scalable, commercially translatable synthesis methods.


Assuntos
Antioxidantes/química , Embalagem de Alimentos/instrumentação , Poliésteres/química , Quelantes/química , Ácido Nitrilotriacético/química , Polimerização , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Chemosphere ; 246: 125810, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31927379

RESUMO

Chelate-assisted phytoextraction is proposed to be an effective approach for the removal of metals from contaminated soil. Organic chelators can improve this biological technique by increasing metal solubility. The aim of this study was to investigate the possibility of improving the phytoextraction of lead (Pb) and zinc (Zn) by the application of panchakavya, a traditional Indian organic formulation. Panchakavya was prepared by fermentation process in open environment using cow dunk, cow ghee, cow urine, cow milk, cow curd, tender coconut water, crude jaggery, and mashed bananas. Soil metal fraction studies indicate that the panchakavya treatment decreased (73%) water-soluble fraction of Pb. Plant growth analysis indicated the application of panchakavya to increase Zea mays fresh root weight, shoot biomass and superoxide dismutase level in Zn contaminated soil. Similarly, a significant increase in the Zn accumulation (12% in shoots and 9% in roots) was observed in panchakavya treated plants. However, when compared to control plants, panchakavya treatment significantly decreased (32% in shoots and 37% in roots) Pb accumulation in Z. mays. Obtained results point out that panchakavya could potentially increase the phytoremediation of Zn in Z. mays.


Assuntos
Biodegradação Ambiental , Chumbo/metabolismo , Poluentes do Solo/metabolismo , Zea mays/metabolismo , Zinco/metabolismo , Biomassa , Quelantes/química , Fertilizantes/análise , Chumbo/análise , Compostos Orgânicos/química , Desenvolvimento Vegetal , Raízes de Plantas/química , Solo , Poluentes do Solo/análise , Zea mays/crescimento & desenvolvimento , Zinco/análise
20.
Artigo em Inglês | MEDLINE | ID: mdl-31941097

RESUMO

Adding chelating agents is a critical technique of heavy metal activation for enhancing phytoextraction through the formation of soluble metal complexes which will be more readily available for extraction. The preliminary, dynamic, equilibrium activation experiments and speciation analysis of Pb, Cd and Tl in contaminated red soils were used to select six chelates with relatively good activation performance from nine chelates, and the effects of dosage and pH on the heavy metals activation were studied systematically. Results showed that the activation of Pb, Cd and Tl by chelates reached equilibrium within 2 h, and the activation process showed three stages. Under neutral conditions, chelates had better activation performance on Pb- and Cd-contaminated soils. Except for S,S-ethylenediamine disuccinic acid (S,S-EDDS) and citric acid (CA), the maximum equilibrium activation effect (MEAE) of ethylenediaminetetraacetic acid (EDTA), N,N-bis (carboxymethyl) glutamic acid (GLDA), diethylenetriaminepentaacetic acid (DTPA) and aminotriacetic acid (NTA) was over 81%. The MEAE of Tl-contaminated soil was less than 15%. The decreasing order of the dosage of chelating agents corresponding to MEAE for three types of contaminated soils was Pb-, Cd- and Tl-contaminated soil, relating to the forms of heavy metals, the stability constants of metal-chelates and the activation of non-target elements Fe in red soil. Under acidic conditions, the activation efficiencies of chelates decreased to differing degrees in Pb- and Cd-contaminated soils, whereas the activation efficiencies of chelating agents in Tl-contaminated soils were slightly enhanced.


Assuntos
Cádmio/química , Quelantes/química , Chumbo/química , Poluentes do Solo/química , Tálio/química , Biodegradação Ambiental , Ácido Cítrico/química , Ácido Edético/química , Etilenodiaminas/química , Glutamatos/química , Glicina/análogos & derivados , Glicina/química , Ácido Pentético/química , Solo/química , Succinatos/química
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