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1.
Food Chem ; 333: 127532, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32668396

RESUMO

Poly(melamine) (PMel) was synthesized via the electropolymerization of melamine monomer, which was then characterized by field-emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The possible polymerization mechanisms of melamine were also revealed by FT-IR spectroscopy and UV-Vis spectroscopy. Next, the PMel modified GCE (PMel/GCE) was used for the simultaneous determination of nitrite (NO2-) and tartrazine, and the parameters were optimized. The kinetic study showed that the electrochemical oxidation of nitrite and tartrazine at the surface of PMel/GCE is a typical surface-controlled electrode process. Under the optimun conditions, the developed sensor outperformed those previously reported, and it also exhibited high selectivity and reproducibility. Finally, the PMel/GCE was used for the simultaneous determination of nitrite and tartrazine in foodstuffs, and the results indicated that the proposed sensor could be a promising candidate for accurate determination of nitrite and tartrazine in real food samples.


Assuntos
Nitritos/análise , Polimerização , Tartrazina/análise , Triazinas/química , Espectroscopia Dielétrica , Eletroquímica , Eletrodos , Microscopia Eletrônica de Varredura , Nitritos/química , Oxirredução , Reprodutibilidade dos Testes , Tartrazina/química , Fatores de Tempo
2.
Food Chem ; 332: 127395, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32615385

RESUMO

This paper describes a simple, efficient and rapid analytical method for extraction and determination of nitrite in meat and chicken products by vortex-assisted supramolecular solvent-based liquid phase microextraction (VA-SUPRAS-LPME) prior to spectrophotometric detection. The SUPRAS was rapidly formed by the addition of a colloidal decanoic acid suspension to tetrahydrofuran (THF). The validation studies were carried out in terms of linearity, limit of detection (LOD), limit of quantitation (LOQ), matrix effects, robustness, uncertainty measurement, precision, accuracy, and certified reference material (CRM) analysis using optimized experimental conditions. The LOD, LOQ, linearity and matrix effect were 0.035 ng mL-1, 0.1 ng mL-1, 0.1-300 ng mL-1, and 9.6% respectively, with high preconcentration factor (200). The method was successfully applied for the determination of nitrite in processed products. Moreover, the results obtained by the proposed method were compared to the standard Griess method, and showed no significant differences in term of Student's t-test.


Assuntos
Galinhas , Análise de Alimentos/métodos , Microextração em Fase Líquida/métodos , Carne/análise , Nitritos/análise , Nitritos/isolamento & purificação , Solventes/química , Animais , Contaminação de Alimentos/análise , Manipulação de Alimentos , Química Verde , Humanos , Limite de Detecção , Espectrofotometria Ultravioleta
3.
Exp Parasitol ; 217: 107934, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32698075

RESUMO

The inadequacy of available treatments for leishmaniasis has presented up to 40% therapeutic failure. This fact suggests an urgency in the discovery of new drugs or alternative approaches for treating this disease. The objective of this study was to evaluate the antileishmanial activity of combined therapy between crotamine (CTA) from Crotalus durissus terrificus and the pentavalent antimonial Glucantime® (GLU). The assays were in vitro performed measuring the inhibition of Leishmania amazonensis amastigotes, followed by the evaluation of cellular production of cytokines and nitrites. After that, analytical methods were performed in order to characterize the molecules involved in the study by Mass Spectrometry, molecular affinity through an in silico assay and Surface Plasmon Resonance. In vivo experiments with BALB/c mice were performed by analyzing parasitemia, lesion size and immunological mediators. In the in vitro experiments, the pharmacological association improved the inhibition of the amastigotes, modulated the production of cytokines and nitric oxide. The therapy improved the effectiveness of the GLU, demonstrating a decreased parasitemia in the infected tissues. Altogether, the results suggest that the combined approach with CTA and GLU may be a promising alternative for the treatment of cutaneous leishmaniasis.


Assuntos
Antiprotozoários/uso terapêutico , Venenos de Crotalídeos/uso terapêutico , Crotalus , Leishmania mexicana/efeitos dos fármacos , Leishmaniose Cutânea/tratamento farmacológico , Antimoniato de Meglumina/uso terapêutico , Animais , Antiprotozoários/farmacologia , Venenos de Crotalídeos/farmacologia , Combinação de Medicamentos , Interleucina-12/sangue , Interleucina-12/metabolismo , Leishmania mexicana/isolamento & purificação , Linfonodos/parasitologia , Macrófagos Peritoneais , Espectrometria de Massas , Antimoniato de Meglumina/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Simulação de Acoplamento Molecular , Óxido Nítrico/metabolismo , Nitritos/análise , Fator de Necrose Tumoral alfa/sangue , Fator de Necrose Tumoral alfa/metabolismo
4.
Chem Biol Interact ; 329: 109210, 2020 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-32726580

RESUMO

Cigarette smoke is a complex mixture capable of triggering inflammation and oxidative damage in animals at pulmonary and systemic levels. Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) reduces tissue injury associated with inflammation in vivo by mechanisms that are not completely understood. Here we evaluated the effect of tempol on inflammation and oxidative damage induced by acute exposure to cigarette smoke in vivo. Male C57BL/6 mice (n = 32) were divided into 4 groups (n = 8 each): 1) control group exposed to ambient air (GC), 2) animals exposed to cigarette smoke for 5 days (CSG), mice treated 3) prior or 4) concomitantly with tempol (50 mg/kg/day) and exposed to cigarette smoke for 5 days. The results showed that the total number of leukocytes and neutrophils increased in the respiratory tract and lung parenchyma of mice exposed to cigarette smoke. Likewise, MPO levels and activity as well as lipid peroxidation and lung protein nitration and carbonylation also increased. Administration of tempol before or during exposure to cigarette smoke inhibited all the above parameters. Tempol also reduced the pulmonary expression of the inflammatory cytokines Il-6, Il-1ß and Il-17 to basal levels and of Tnf-α by approximately 50%. In contrast, tempol restored Il-10 and Tgf-ß levels and enhanced the expression of Nrf2-associated genes, such as Ho-1 and Gpx2. Accordingly, total GPx activity increased in lung homogenates of tempol-treated animals. Taken together, our results show that tempol protects mouse lungs from inflammation and oxidative damage resulting from exposure to cigarette smoke, likely through reduction of leukocyte infiltration and increased transcription of some of the Nrf2-controlled genes.


Assuntos
Óxidos N-Cíclicos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Fator 2 Relacionado a NF-E2/metabolismo , Infiltração de Neutrófilos/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Fumar/efeitos adversos , Animais , Líquido da Lavagem Broncoalveolar/química , Interleucina-10/genética , Interleucina-10/metabolismo , Peroxidação de Lipídeos/efeitos dos fármacos , Pulmão/efeitos dos fármacos , Pulmão/metabolismo , Pulmão/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fator 2 Relacionado a NF-E2/genética , Nitritos/análise , Peroxidase/metabolismo , Carbonilação Proteica/efeitos dos fármacos , Marcadores de Spin , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/metabolismo
5.
Chemosphere ; 258: 127228, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535438

RESUMO

Urea hydrolysis in partial nitritation process forming nitrite and ammonia is advantageous to subsequent treatment with ANAMMOX for total nitrogen removal. In this study, stable partial nitritation for urea wastewater with urea increasing from 250 to 2000 mg L-1 were achieved in an aerobic SBR. Urea removal efficiency and nitrite accumulation percentage both kept above 98%, with nitrite production rate about 0.985 kg N·m-3·d-1. Urea hydrolysis mechanism in this aerobic system was described as, (1) massive urea in the bulk was absorbed into cell, (2) urea was hydrolyzed by intracellular urease inside cell, (3) produced ammonia then slowly diffused into the bulk through membrane, which is later converted by ammonia-oxidizing bacteria (AOB) into nitrite. Due to this mechanism, the activity of AOB could not be inhibited by high FA (free ammonia) value under high urea concentration condition while nitrite-oxidizing bacteria (NOB) remained to be inhibited. An uncultured genus belonging to poorly characterized phylum Gemmatimonadetes was found enriched in this process and became dominant genus. This genus was speculated to have same energy pathway like ureaplasma, by absorbing excessive urea from environment and utilize urea hydrolysis to generate energy. So it was believed to be responsible for urea hydrolysis mechanism mentioned above. This SBR showed stable partial nitritation and high urea removal efficiency for treating urea wastewater, which was obviously feasible as the pretreatment process for subsequent ANAMMOX.


Assuntos
Amônia/análise , Reatores Biológicos/microbiologia , Nitritos/análise , Ureia/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Aerobiose , Amônia/metabolismo , Bactérias/metabolismo , Hidrólise , Nitritos/metabolismo , Nitrogênio/análise , Nitrogênio/metabolismo , Oxirredução , Ureia/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/metabolismo
6.
Food Chem ; 330: 127151, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32521395

RESUMO

The research developed a diazo-coupling carbon-dots (CDs) method for determining nitrite and optimized variables of sodium sulfanilate, CDs synthesis, characteristic wavelength, reaction time and temperature. The method can assay 0.025-2.0 mg/L NO2- and has a detection limit of 9.6 µg/L and 95-105% recovery. Subsequently, it was applied in detecting NO2- changes in some Chinese home cooking, the gotten results indicated that if the sautéed vegetables (cabbage, Chinese cabbage, spinach and lettuce) and stir-fry pork, fried peas and pickled vegetable are stored at 4 °C for 72 h, nitrite contents are far lower than the recommended value, but if stored at room temperature for 24 h, the content in pure vegetables and shredded pork with green pepper will exceed the recommended value. Therefore, the staying fresher for the sautéed vegetables at room temperature is 24 h, if stored in a refrigerator at 4 °C, their staying fresher can be extended to 72 h.


Assuntos
Culinária , Nitritos/análise , Verduras/química , Carbono/análise , Dicroísmo Circular , Temperatura Alta
7.
Chemosphere ; 255: 126833, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32387724

RESUMO

Understanding the transformation pattern of nitrogen (N) pollutants and its pathways in the prechlorinated raw water distribution system (PRWDS) is vital for controlling the stablitiy and safety of raw water qulity. This study investigated the N transformation, N functional genes and their correlations to find the N transformation pathways along the PRWDS. Results suggested that simultaneous nitrification, anaerobic ammonium oxidation and denitrification (SNAD) contribute to the N transformationin the PRWDS. Along the pipeline, anammox 16S rRNA (9.18 × 107-8.41 × 108 copies/g), limited by prechlorination, was the most abundant N functional genes and anammox process was the main pathway of ammonia nitrogen (NH4+-N). The decreasing NH4+-N was connected with Planctomycetes, Nitrospira and abundance of nxrA attributing to the joint effort of anammox and declined nitrification. The concentration of nitrate (NO3--N) increasing at first and then decreasing, was correlated positively with Sphingomonas. because of the declined nitritication and increased denitrification. Besides, the NO3--N→NO2--N process was considered to be primary NO3--N transformation pathways. Increases in the concentration of dissolved organic nitrogen (DON) and nitrite (NO2--N) observed in the PRWDS had positive correlation with relative abundance of Pseudomonas. We believe that prechlorination shaped the particular bacterialcharacteristics in biofilms and influenced the N transformation pathways indirectly, resulting in the varying N transformation rules in PRWDSs. Moreover, systematic and extended research is particularly vital for determining the effects of changes in source water quality and environmental conditions on bacterial community structure and N conversion along PRWDSs.


Assuntos
Nitrogênio/análise , Poluentes da Água/análise , Abastecimento de Água/estatística & dados numéricos , Amônia/metabolismo , Bactérias/metabolismo , Biofilmes , Reatores Biológicos/microbiologia , Desnitrificação , Poluentes Ambientais/metabolismo , Nitratos/metabolismo , Nitrificação , Nitritos/análise , Oxirredução , RNA Ribossômico 16S/metabolismo
8.
J Food Sci ; 85(4): 1027-1036, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32180223

RESUMO

Variations in the taste quality of no-added-nitrite Chinese bacon (unsmoked) during processing were investigated using 1 H-NMR and multivariate data analysis. The results showed that 21 metabolites were dominant during processing, which involved marinating, air-drying, fermentation, and baking, including amino acids, sugars, organic acids, nucleic acids and their derivatives, and alkaloids. The contents of isoleucine, leucine, valine, alanine, acetate, glutamate, succinate, glycine, sucrose, tyrosine, and phenylalanine increased continuously throughout the process. The lactate, creatine, carnosine, betaine, taurine, hypoxanthine, and AMP contents all significantly increased after baking; the inosine content significantly increased after fermentation and then decreased; the histamine content significantly increased after air-drying and then decreased; and the histidine content decreased. Each processing treatment promoted taste formation in no-added-nitrite Chinese bacon (unsmoked), especially baking. The baking point owned relatively higher levels of metabolites and sensory evaluation compared to other treatments. Sensory evaluation revealed that the ultimate taste of Chinese bacon (unsmoked) at the end of baking tended toward umami (glutamate), sweetness (AMP), and sourness (lactate). The first and second principal components explained 74.0% and 13.4% of the variables, respectively. These findings indicated the potential of NMR-based metabolomics for assessing the taste quality of no-added-nitrite Chinese bacon (unsmoked), which could contribute to a better understanding of taste compound changes in meat products. PRACTICAL APPLICATION: Nitrite is commonly used in Chinese bacon (unsmoked), but excessive intake is not good for human health. Nitrite has been replaced with nitrite substitutes to prepare no-added-nitrite Chinese bacon (unsmoked). The metabolites of no-added-nitrite Chinese bacon (unsmoked) were detected to determine the key treatment that contributes to the formation of taste during processing. This study determined the main taste components of no-added-nitrite Chinese bacon (unsmoked) and its formation process, which provides new insight into the production and characteristics of flavor in Chinese bacon (unsmoked).


Assuntos
Metabolômica/métodos , Nitritos/análise , Carne de Porco/análise , Aminoácidos/química , Animais , China , Manipulação de Alimentos , Conservantes de Alimentos/análise , Humanos , Espectroscopia de Ressonância Magnética/métodos , Produtos da Carne/análise , Análise Multivariada , Açúcares/química , Paladar
9.
Am J Clin Nutr ; 111(4): 749-756, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32091599

RESUMO

BACKGROUND: A diet rich in fruits and vegetables is associated with lowering of blood pressure (BP), but the nutrient(s) responsible for these effects remain unclear. Research suggests that inorganic nitrate present in leafy green vegetables is converted into NO in vivo to improve cardiovascular function. OBJECTIVE: In this study, we evaluated the effect of leafy green vegetables on BP in subjects with elevated BP, with the aim of elucidating if any such effect is related to their high nitrate content. DESIGN: We enrolled 243 subjects, 50-70 y old, with a clinic systolic BP (SBP) of 130-159 mm Hg. After a 2-wk run-in period on a nitrate-restricted diet the subjects were randomly assigned to receive 1 of the following 3 interventions daily for 5 wk: low-nitrate vegetables + placebo pills, low-nitrate vegetables + nitrate pills (300 mg nitrate), or leafy green vegetables containing 300 mg nitrate + placebo pills. The primary end point measure was the difference in change in 24 h ambulatory SBP between the groups. RESULTS: A total of 231 subjects (95%) completed the study. The insignificant change in ambulatory SBP (mean ± standard deviation) was -0.6 ± 6.2 mm Hg in the placebo group, -1.2 ± 6.8 mm Hg in the potassium nitrate group, and -0.5 ± 6.6 mm Hg in the leafy green vegetable group. There was no significant difference in change between the 3 groups. CONCLUSIONS: A 5-wk dietary supplementation with leafy green vegetables or pills containing the same amount of inorganic nitrate does not decrease ambulatory SBP in subjects with elevated BP. This trial was registered at clinicaltrials.gov as NCT02916615.


Assuntos
Pressão Sanguínea , Hipertensão/dietoterapia , Hipertensão/fisiopatologia , Nitritos/metabolismo , Verduras/metabolismo , Idoso , Dieta , Feminino , Humanos , Hipertensão/metabolismo , Masculino , Pessoa de Meia-Idade , Nitritos/análise , Folhas de Planta/química , Folhas de Planta/metabolismo , Verduras/química
10.
Life Sci ; 246: 117423, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32057902

RESUMO

Bleomycin (BLM) is one of the most common anti-cancer drugs used to treat numerous types of tumors. However, pulmonary toxicity is considered the most dramatic effect of BLM. Therefore, BLM has been frequently used for induction of pulmonary fibrosis. This study aimed to evaluate the effect of nicorandil on BLM-induced pulmonary fibrosis and explore the possible mechanisms. BLM was instilled intratracheally into male Sprague-Dawley rats as a single dose (5 mg/kg) and oral nicorandil was given (30 mg/kg/day) for 6 weeks after BLM challenge. At the end of experimental period, rats were sacrificed, and lung histopathology and biochemical parameters were evaluated. Nicorandil therapy attenuated lung inflammation and fibrosis elicited by BLM. Nicorandil significantly reduced total protein content, lactate dehydrogenase (LDH) activity and total and differential cell counts. Moreover, nicorandil diminished lung levels of malondialdehyde and total nitrite/nitrate, in addition to increasing lung contents of reduced glutathione and superoxide dismutase activity. Nicorandil reduced lung and bronchoalveolar lavage fluid contents of hypoxia inducible factor-1α (HIF-1α) and lung content of thioredoxin-interacting protein (TXNIP). Besides, nicorandil significantly improved histological lesions and reduced collagen deposition as well as hydroxyproline content. Immunohistochemical examination revealed that nicorandil-treated rats exhibited significant diminutions in protein expression levels of transforming growth factor beta-1(TGF-ß1) and inducible nitric oxide synthase (iNOS) and enhanced pulmonary protein expression of endothelial NOS (eNOS). In conclusion, these results illustrate the possible potential effects of nicorandil for managing pulmonary fibrosis caused by BLM.


Assuntos
Antibióticos Antineoplásicos/toxicidade , Bleomicina/toxicidade , Proteínas de Ciclo Celular/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Nicorandil/farmacologia , Óxido Nítrico Sintase Tipo III/antagonistas & inibidores , Óxido Nítrico Sintase Tipo II/antagonistas & inibidores , Óxido Nítrico/metabolismo , Fibrose Pulmonar/induzido quimicamente , Animais , Líquido da Lavagem Broncoalveolar/química , Proteínas de Ciclo Celular/análise , Subunidade alfa do Fator 1 Induzível por Hipóxia/análise , L-Lactato Desidrogenase/metabolismo , Pulmão/efeitos dos fármacos , Pulmão/patologia , Masculino , Nicorandil/uso terapêutico , Nitratos/análise , Óxido Nítrico/análise , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Nitritos/análise , Fibrose Pulmonar/tratamento farmacológico , Ratos , Ratos Sprague-Dawley
11.
Food Chem ; 317: 126361, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32070846

RESUMO

A rapid, sensitive, and highly selective method for determining nitrite in food has been developed. This method is based on the reaction of nitrite with the amino group of 3,3,5,5-tetramethylbenzidine (TMB) to form a diazonium salt, and then the diazonium salt and glucosamine hydrochloride are coupled to each other to form an orange compound. The optimal conditions for maximum color and other analytical parameters were studied. A colorimetric method for nitrite detection has been developed with an outstanding correlation coefficient (R2 = 0.9944), a wide linear range (1-75 µM) and 0.73 µM limit of detection (at S/N = 3) for nitrite ions. This method was successfully applied to the determination of nitrite in a variety of foods and gave recoveries in the range between 100.16% and 103.07%, demonstrating that the accuracy, reliability and potential application of this assay for monitoring nitrite in foods.


Assuntos
Benzidinas/química , Análise de Alimentos/métodos , Nitritos/análise , Colorimetria/métodos , Glucosamina/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Nitritos/química , Reprodutibilidade dos Testes
12.
Food Chem ; 316: 126396, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32066068

RESUMO

This study employed the use of a microfluidic paper-based analytical device (µPAD) to determine the concentration of nitrite in pork and enhanced the limit of detection by analyzing the coffee-ring effect. The µPAD was fabricated by designing and embedding wax channels onto the cellulose-based filter paper through printing and subjecting the paper to heat treatment to allow wax penetration. Nitrite concentration was determined by monitoring the colorimetric reaction that occurred between nitrite and the added Griess reagent. The limit of detection of this device for nitrite in pork was determined to be 19.2 mg kg-1 by analyzing the inner-chamber reaction, while it could be as low as 1.1 mg kg-1 if the coffee-ring region was analyzed. The overall analysis could be completed within 15 min. This µPAD-based method has potential applications to routinely screen the nitrite concentration of meat products and ensure food safety and consumer health.


Assuntos
Nitritos/análise , Carne Vermelha/análise , Animais , Colorimetria , Etilenodiaminas/análise , Filtração , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/instrumentação , Papel , Sulfanilamidas/análise , Suínos
13.
Food Chem ; 317: 126456, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32109661

RESUMO

In recent years, gold nanoclusters (AuNCs) have received considerable attention as optical transducers in chemo/biosensors. Herein, a facile and efficient assay for NO2- has been successfully developed based on the fluorescence quenching of AuNCs co-modified by bovine serum albumin and 3-mercaptopropionic acid (BSA/MPA-AuNCs). In the presence of NO2- under acidic conditions, Fe2+ can be readily oxidized and transformed to Fe3+, which can significantly suppress the fluorescence of BSA/MPA-AuNCs via non-radiative electron-transfer mechanism. The linear range and detection limit for this system were found to be 5-30 µM (r = 0.9975) and 0.7 µM, respectively. Other common anions and cations showed only very minor interference with the NO2- detection. Furthermore, the effectiveness of the proposed sensing strategy was validated by the demonstration of good performance in the determination of the amount of NO2- in ham samples, rendering it a powerful tool for the assessment of food security and water quality.


Assuntos
Análise de Alimentos/métodos , Ferro/química , Nanoestruturas/química , Nitritos/análise , Ácido 3-Mercaptopropiônico/química , Técnicas Biossensoriais , Fluorescência , Corantes Fluorescentes/química , Análise de Alimentos/instrumentação , Ouro/química , Limite de Detecção , Nitritos/química , Oxirredução , Carne de Porco/análise , Sensibilidade e Especificidade , Soroalbumina Bovina/química , Espectrometria de Fluorescência
14.
Talanta ; 209: 120577, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31892035

RESUMO

Human Exhaled Breath Condensate (EBC) contains markers of several inflammatory diseases. Its analysis is of interest to a number of researchers. Nitrite ions (NO2-), which are widely used in our daily lives, are nevertheless among these indicators. In this study, a simple, fast, portable, non-invasive and cheap electrochemical sensor is developed for the analysis of the nitrite profile in EBC. In this regard, sodium nitrite (NaNO2) was first immobilized on self-assembled 2-aminothiophenol (2-ATP) on a screen-printed gold electrode (Au-SPE). Then, a polymer matrix composed of polyvinyl alcohol (PVA) crosslinked with glutaraldehyde (GA) was combined with gold nanoparticles (Au-NPs) to cover the modified Au-SPE and complete the fabrication of the Ion Imprinted Polymer (IIP) sensor. The electrochemical behaviour of the sensor was monitored using Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and Differential Pulse Voltammetry (DPV) methods, while the morphology and chemical composition of its layers were observed by infrared Fourier transform (FTIR), Atomic Force Microscopy (AFM) and Scanning Electron Microscopy coupled with energy dispersion X-Ray spectroscopy (SEM-EDS) techniques. In addition, after a successful control test using a Non-Imprinted Ion Polymer (NIIP) sensor, the obtained results demonstrated satisfactory sensitivity and selectivity to nitrite compared to co-existing interfering substances in EBC, such as nitrate, acetate and ammonium nitrate. Under improved experimental conditions, the nitrite IIP sensor exhibits responses proportional to nitrite concentrations (R2 = 0.96) over a concentration range of 0.5-50 µg mL-1 with a detection limit (LOD) of 4 µmol L-1 (signal-to-noise ratio S/N = 3). The proposed approach was well applied for the nitrite determination in EBC samples with a relative standard deviation (RSD = 4%) and could open clinical applications in respiratory medicine.


Assuntos
Testes Respiratórios/instrumentação , Técnicas Eletroquímicas/instrumentação , Ouro/química , Nanoestruturas/química , Nitritos/análise , Polímeros/química , Compostos de Anilina/química , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Testes Respiratórios/métodos , Técnicas Eletroquímicas/métodos , Desenho de Equipamento , Humanos , Limite de Detecção , Impressão Molecular/instrumentação , Impressão Molecular/métodos , Nanoestruturas/ultraestrutura , Álcool de Polivinil/química
15.
Artigo em Inglês | MEDLINE | ID: mdl-31944907

RESUMO

Dietary exposure to nitrate and nitrite occurs via three main sources; occurrence in (vegetable) foods, food additives in certain processed foods and contaminants in drinking water. While nitrate can be converted to nitrite in the human body, their risk assessment is usually based on single substance exposure in different regulatory frameworks. Here, we assessed the long-term combined exposure to nitrate and nitrite from food and drinking water. Dutch monitoring data (2012-2018) and EFSA data from 2017 were used for concentration data. These were combined with data from the Dutch food consumption survey (2012-2016) to assess exposure. A conversion factor (median 0.023; range 0.008-0.07) was used to express the nitrate exposure in nitrite equivalents which was added to the nitrite exposure. The uncertainty around the conversion factor was taken into account by using conversion factors randomly sampled from the abovementioned range. The combined dietary exposure was calculated for the Dutch population (1-79 years) with different exposure scenarios to address regional differences in nitrate and nitrite concentrations in drinking water. All scenarios resulted in a combined exposure above the acceptable daily intake for nitrite ion (70 µg/kg bw), with the mean exposure varying between 95-114 µg nitrite/kg bw/day in the different scenarios. Of all ages, the combined exposure was highest in children aged 1 year with an average of 250 µg nitrite/kg bw/day. Vegetables contributed most to the combined exposure in food in all scenarios, varying from 34%-41%. Food additive use contributed 8%-9% to the exposure and drinking water contributed 3%-19%. Our study is the first to perform a combined dietary exposure assessment of nitrate and nitrite while accounting for the uncertain conversion factor. Such a combined exposure assessment overarching different regulatory frameworks and using different scenarios for drinking water is a better instrument for protecting human health than single substance exposure.


Assuntos
Água Potável/análise , Aditivos Alimentares/análise , Análise de Alimentos , Contaminação de Alimentos/análise , Nitratos/análise , Nitritos/análise , Incerteza
16.
Phytochemistry ; 171: 112233, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31911267

RESUMO

Eight previously undescribed and 15 known components, including six neolignans, two monolignan, three sesquineolignans, three dineolignans, eight phenylpropanoids, and one steroid were identified from the seed testa of Vernicia fordii. Their structures were established based on the comprehensive analysis of NMR and ECD data. The anti-neuroinflammatory effects of the isolates were evaluated through nitrite assays in LPS-induced BV2 cells. As a result, isodiverniciasin A, diverniciasin B, diverniciasin C, isoprincepin, princepin, 3, 3'-bisdemethylpinoresinol, (+)-7-epi-sesamin-dicatechol, isoamericanin A, americanin B, 7S, 8R-americanin D, 4-hydroxyl cinnamic aldehyde, 3-hydroxyl-4-methoxyl cinnamic aldehyde and 24R-6ß-hydroxy-24- ethylcholest-4-en-3-one exhibited significant inhibitory effects on nitric oxide (NO) production and isoprincepin, princepin, americanin B, and 4-hydroxyl cinnamic aldehyde suppressed the overexpression of inflammatory cytokines TNF-α, IL-1ß, and IL-6 in over-activated microglia. The results suggested that bioactive ingredients from the seed testa of V. fordii can serve as potential therapeutic agents for neurodegenerative diseases.


Assuntos
Anti-Inflamatórios/farmacologia , Euphorbiaceae/química , Inflamação/tratamento farmacológico , Fármacos Neuroprotetores/farmacologia , Compostos Fitoquímicos/farmacologia , Animais , Anti-Inflamatórios/química , Anti-Inflamatórios/isolamento & purificação , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Lipopolissacarídeos/antagonistas & inibidores , Lipopolissacarídeos/farmacologia , Camundongos , Conformação Molecular , Fármacos Neuroprotetores/química , Fármacos Neuroprotetores/isolamento & purificação , Nitritos/análise , Nitritos/antagonistas & inibidores , Nitritos/metabolismo , Compostos Fitoquímicos/química , Compostos Fitoquímicos/isolamento & purificação
18.
J Agric Food Chem ; 68(6): 1725-1730, 2020 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-31967806

RESUMO

Milk powders in the United States (US) may contain nitrates and nitrites from several potential sources. These sources include the ingestion of nitrates and nitrites by dairy cows during grazing and drinking, nitric acid used during the sanitization of dairy equipment, and the production of nitrous oxides in directly heated spray dryers. Recently, milk powders manufactured in the US have been rejected during import to other countries because nitrite concentrations were greater than 2 mg/kg (ppm). To date, the concentrations of nitrates and nitrites in milk and plant-based powders in the US are unknown. In this study the nitrate and nitrite concentrations present in diverse milk powders were investigated including 81 milk powders from local and online retailers from 2015 to 2018. In addition, 71 commercial milk powders were obtained from blinded production facilities. Nitrate and nitrite concentrations were determined using ion chromatography with conductivity and UV detection. A subset of samples was analyzed for N-nitrosodimethylamine using gas chromatography-mass spectrometry. Carbon and nitrogen bulk isotope ratios analyzed using isotope ratio mass spectrometry were used to obtain some insights into the production method (organic vs conventional) and geographic source of the milk powder samples. Background nitrate concentrations in US-produced milk powder samples averaged 17 ± 12 mg/kg. Nitrite was detected at concentrations greater than 2 mg/kg in 5 out of 39 different brands of retail milk and plant-based powders. Of these brands, two were plant-based (soy and coconut) powders and the other three had consistently high nitrites. The analysis of milk powders using stable isotope analysis revealed further information about the cow's diet.


Assuntos
Leite/química , Nitratos/análise , Nitritos/análise , Plantas/química , Ração Animal/análise , Animais , Bovinos/metabolismo , Leite/economia , Leite/metabolismo , Nitratos/metabolismo , Nitritos/metabolismo , Plantas/metabolismo , Pós/química , Pós/economia
19.
Sci Total Environ ; 704: 135260, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31780159

RESUMO

How to achieve stable nitrite accumulation was still a huge challenge for low-carbon and energy-saving biological nitrogen removal of low-strength ammonium wastewater. This study proposed a new way to solve this problem with zeolite biological fixed bed (ZBFB) by cycle operation of adsorption and biological desorption. In order to evaluate nitritation performance of this reactor, the influence of operational temperature on nitrite accumulation stability was investigated by 126 cycles operation in four parallel ZBFB reactors for low-strength ammonium wastewater (50 mg/L NH4+-N). It was found that higher operational temperature (i.e., 36.0 °C), rather than other temperature (i.e., 27.0 °C, 30.0 °C, 33.0 °C), could maintain stable nitrite accumulation with nitrite production rate of 0.312 kg NO2--N·m-3 zeolite·day-1 and nitrite accumulation ratio higher than 95.0% after biological desorption. High-throughput sequencing analysis results showed that bacterial structure significantly changed in ZBFB under different operational temperature, and obvious enrichment of genus Nitrosomonas (AOB) and gradually enhanced free ammonia (FA) inhibition on genus Nitrospira and Nitrobacter (NOB) were found by elevation of operational temperature, leading to different nitrite accumulation performance in ZBFB reactors. The mechanism for stable nitrite accumulation performance by ZBFB might be attributed to overwhelming growth rate of AOB than NOB, faster ammonium desorption and enhanced FA inhibition on NOB under operational temperature (i.e., 36.0 °C). All in all, keeping high temperature for biological desorption step should be extremely crucial for stable nitrite accumulation by ZBFB, which could facilitate further low-carbon and energy-saving biological nitrogen removal for low-strength ammonium wastewater treatment.


Assuntos
Compostos de Amônio/análise , Nitritos/análise , Eliminação de Resíduos Líquidos/métodos , Adsorção , Amônia , Bactérias , Biofilmes , Reatores Biológicos , Nitrobacter , Nitrogênio , Temperatura , Águas Residuárias/química , Zeolitas/química
20.
Chemosphere ; 241: 125089, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31629234

RESUMO

The Pantanal (Brazil) is a wetland region characterized by seasonal flooding. Hydrological cycles influence the water physicochemical parameters, causing seasonal variations in pH and nitrites. Thus, the objective of this study was to evaluate the effects of varying pH and nitrite concentrations on the toxicity of the cypermethrin-based pesticide Barrage®, considering both lethal (mortality) and sublethal endpoints (growth and development). Larvae of the endemic shrimp Macrobrachium pantanalense and of the estuarine Amazonian congener Macrobrachium amazonicum were exposed to cypermethrin (through Barrage®) under several pH levels (6.5, 7.5 and 8.5) or nitrite concentrations (0.1, 0.2 and 0.4 mg/L). The pH had direct effects on all the tested endpoints for both species. For M. pantanalense, the lethal effects of the cypermethrin formulation were more pronounced at low pH (96-h LC50 = 0.004 µg/L at pH 6.5, and 0.146 µg/L at pH 8.5). For M. amazonicum, an opposite response was observed, with increased toxicity of the formulation at high pH (96-h LC50 = 0.110 µg/L at pH 6.5 and 0.044 µg/L at pH 8.5). Variations in pH also seemed to modify the sublethal effects of the formulation on larval growth and development of M. pantanalense. Nitrite concentrations affected larval growth of both species, modifying also the effects of the cypermethrin formulation on the larval development of M. amazonicum. This work shows the importance of considering abiotic factors for risk assessment either due to possible direct effects on the physiology of organisms and/or due to interactions with other stressors, particularly in fragile biomes such as Pantanal.


Assuntos
Água Doce/química , Palaemonidae/efeitos dos fármacos , Praguicidas/toxicidade , Piretrinas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Brasil , Ecotoxicologia , Feminino , Água Doce/análise , Concentração de Íons de Hidrogênio , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Dose Letal Mediana , Mortalidade , Nitritos/análise , Nitritos/química , Palaemonidae/crescimento & desenvolvimento , Praguicidas/química , Piretrinas/química , Especificidade da Espécie , Testes de Toxicidade Aguda , Áreas Alagadas
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