RESUMO
Folin-Ciocalteu and the more recent Fast Blue BB (FBBB) reactions are used for the quantification of total phenolics in food matrices. Despite its known interferences, Folin-Ciocalteu is still widely employed, considering Solid Phase Extraction (SPE) as clean-up step only in a few cases. Meanwhile, FBBB has shown no interferences for the determination of total phenolics in fruits and cereals, although its utilization in other popular matrices containing potential interferences, such as legumes, remains unexplored. In this study, the total phenolic content of 24 flours from legumes, cereals, fruits, nuts and plant seeds was evaluated by Folin-Ciocalteu and FBBB, with and without SPE. Folin-Ciocalteu showed interferences for 75% of the flours (attributed to reducing sugars and enediols), whereas FBBB only for legumes and nuts (attributed to the presence of tyrosine), both methods in those matrices requiring SPE. Although both SPE-FBBB and SPE-Folin-Ciocalteu presented excellent reproducibility, SPE-FBBB displayed 1.5 times higher sensitivity.
Assuntos
Compostos de Diazônio/química , Fabaceae/química , Fenóis/análise , Extratos Vegetais/análise , Nozes/química , Extratos Vegetais/química , Sementes/químicaRESUMO
Biofilm formation is a main challenge in treatment of bone-implant-associated infections, resulting in tolerance to immune system and antibiotics. However, smart non-surgical or non-invasive treatment methods of combating established biofilm on an implant have been less reported. Herein, a therapeutic system consisting of mesoporous polydopamine nanoparticles (MPDA) to combat biofilm is reported for the first time. We develop a synergistic photothermal/photodynamic therapy (PTT/PDT) strategy aiming for biofilms eradication on titanium (Ti) implant, which is integrated with MPDA loading with photosensitizer Indocyanine Green (ICG) by π-π stacking. Specifically, MPDA is functionalized with RGD peptide to endow the modified Ti sample (Ti-M/I/RGD) with good cytocompatibility. More importantly, Ti-M/I/RGD implant remarkably kills Staphylococcus aureus (S. aureus) biofilm with an efficiency of 95.4% in vivo upon near infrared (NIR). After biofilm eradication, implant still displays great performance regarding osteogenesis and osseointegration. Overall, this study provides a PTT/PDT strtategy for the development of antibacterial Ti implants for potential orthpediac application.
Assuntos
Biofilmes , Fotoquimioterapia/métodos , Fototerapia/métodos , Titânio/química , Fosfatase Alcalina/metabolismo , Animais , Antibacterianos/farmacologia , Materiais Biocompatíveis , Substitutos Ósseos , Diferenciação Celular , Compostos de Diazônio/química , Verde de Indocianina/farmacologia , Indóis , Luz , Masculino , Nanopartículas Metálicas/química , Ortopedia , Osseointegração , Osteogênese , Fármacos Fotossensibilizantes/farmacologia , Polímeros , Desenho de Prótese , Piridinas/química , Ratos , Ratos Sprague-Dawley , Espectroscopia de Luz Próxima ao Infravermelho , Staphylococcus aureus/metabolismoRESUMO
Polyphenols are bioactive substances of vegetal origin with a significant impact on human health. The assessment of polyphenol intake and excretion is therefore important. The Folin-Ciocalteu (F-C) method is the reference assay to measure polyphenols in foods as well as their excretion in urine. However, many substances can influence the method, making it necessary to conduct a prior cleanup using solid-phase extraction (SPE) cartridges. In this paper, we demonstrate the use of the Fast Blue BB reagent (FBBB) as a new tool to measure the excretion of polyphenols in urine. Contrary to F-C, FBBB showed no interference in urine, negating the time-consuming and costly SPE cleanup. In addition, it showed excellent linearity (r2 = 0.9997), with a recovery of 96.4% and a precision of 1.86-2.11%. The FBBB method was validated to measure the excretion of polyphenols in spot urine samples from Spanish children, showing a good correlation between polyphenol intake and excretion.
Assuntos
Técnicas de Química Analítica/métodos , Polifenóis/urina , Criança , Compostos de Diazônio/química , Feminino , Humanos , Masculino , Extratos Vegetais/química , Polifenóis/metabolismoRESUMO
BACKGROUND: The relationships between the hydrophilic-lipophilic balance (HLB) of antioxidants (AOs) and their distributions and efficiencies in emulsions are not fully understood. Recent reports indicate that, for series of homologous antioxidants of different hydrophobicity, the variation of their efficiency with the HLB of the AO increases with the alkyl chain length up to a maximum (C3 -C8 ester) followed by a decrease (cut-off effect). RESULTS: We determined the distributions of a series of caffeic acid derivatives in intact soybean emulsions by employing a specifically designed chemical probe located in the interfacial region of the emulsion. We also determined the AO efficiencies in the very same emulsions. We demonstrate that the variation of the percentage of AO in the interfacial region of soybean oil-in-water emulsions with the AO HLB parallels that of their antioxidant efficiency. CONCLUSION: The results provide physical evidence that the variations in the efficiency of homologous series of antioxidants in emulsions are the result of differences in their distribution. The results confirm that, with other things being equal, there is a direct relationship between the percentage of AO in the interfacial region of the emulsions and their efficiency, providing a natural explanation, based on molecular properties, of the cut-off effect. © 2016 Society of Chemical Industry.
Assuntos
Antioxidantes/química , Ácidos Cafeicos/química , Emulsões Gordurosas Intravenosas/química , Modelos Químicos , Antioxidantes/análise , Ácidos Cafeicos/análise , Compostos de Diazônio/análise , Compostos de Diazônio/química , Emulsões , Interações Hidrofóbicas e Hidrofílicas , Indicadores e Reagentes/análise , Indicadores e Reagentes/química , Cinética , Estrutura Molecular , Peso Molecular , Óleo de Soja/química , Tensoativos/químicaRESUMO
An efficient palladium catalyzed C-H bond activation for the synthesis of benzo[c]chromen-6-ones using diazonium salts is described. In the presence of Pd(OAc)2, dppp, PivOH and K2CO3, the diazonium salt can be transformed into the product through a denitrogenation/C-H bond activation/cyclization sequence in acetonitrile. Altogether, nine structurally diverse substituted benzoLc]chromen-6-ones were prepared in excellent yields through two different methods.
Assuntos
Compostos de Diazônio/química , Compostos Heterocíclicos/química , Paládio/química , Catálise , Ciclização , Estrutura MolecularRESUMO
INTRODUCTION: Lipase inhibitory assays based on TLC bioautography have made recent progress; however, an assay with greater substrate specificity and quantitative capabilities would advance the efficacy of this particular bioassay. OBJECTIVE: To address these limitations, a new TLC bioautographic assay for detecting lipase inhibitors was developed and validated in this study. METHODS: The new TLC bioautographic assay was based on reaction of lipase with ß-naphthyl myristate and the subsequent formation of the purple dye between ß-naphthol and Fast Blue B salt (FBB). The relative lipase inhibitory capacity (RLIC) was determined by a TLC densitometry with fluorescence detection, expressed as orlistat equivalents in millimoles on a per sample weight basis. Six pure compounds and three natural extracts were evaluated for their potential lipase inhibitory activities by this TLC bioautographic assay. RESULTS: The ß-naphthyl myristate as the substrate improved the detection sensitivity and specificity significantly. The limit of detection (LOD) of this assay was 0.01 ng for orlistat, the current treatment for obesity. This assay has acceptable accuracy (92.07-105.39%), intra-day and inter-day precisions [relative standard deviation (RSD), 2.64-4.40%], as well as intra-plate and inter-plate precisions (RSD, 1.8-4.9%). CONCLUSION: The developed method is rapid, simple, stable, and specific for screening and estimation of the potential lipase inhibitors.
Assuntos
Cromatografia em Camada Fina/métodos , Avaliação Pré-Clínica de Medicamentos/métodos , Inibidores Enzimáticos/análise , Lipase/antagonistas & inibidores , Cromatografia em Camada Fina/instrumentação , Compostos de Diazônio/análise , Compostos de Diazônio/química , Inibidores Enzimáticos/farmacologia , Desenho de Equipamento , Hidrólise , Lactonas/análise , Limite de Detecção , Lipase/metabolismo , Miristatos/química , Miristatos/metabolismo , Orlistate , Extratos Vegetais/análise , Extratos Vegetais/farmacologia , Reprodutibilidade dos TestesRESUMO
A novel copper-catalyzed C-H arylation of heteroarenes with anilines by an in situ diazonium reaction is established by using silver nitrite (AgONO) as an unconventional nitrosating reagent under acid-free conditions. It provides a complementary approach for the C-H arylation of electron-rich heteroarenes with aromatic amines affording a variety of heterobiaryls in moderate to good yields.
Assuntos
Compostos de Anilina/química , Cobre/química , Compostos de Diazônio/química , Hidrocarbonetos Aromáticos/química , Nitritos/química , Compostos de Prata/química , CatáliseRESUMO
Three new protocols for the nucleophilic halogenations of diazoesters, diazophosphonates, and diazopiperidinylamides as complementary methods to our previously reported electrophilic halogenations are presented for the first time. On the basis of hypervalent α-aryliodonio diazo triflate salts 1A, 2A, and 3A, the corresponding halodiazo compounds are generated via nucleophilic halogenations with tetrabutylammonium halides or potassium halides. The products from subsequent catalytic intermolecular cyclopropanations of the halodiazoesters and halodiazophosphonates and thermal intramolecular C-H insertion of the brominated diazopiperidinylamide are obtained in moderate to good yields after two steps. DFT calculations are presented for the diazoesters to give insight into the mechanism and transition states of the nucleophilic substitutions with the neutral nucleophiles dimethyl sulfide and triethylamine and the bromination with Br(-).
Assuntos
Compostos de Diazônio/química , Hidrocarbonetos Halogenados/síntese química , Teoria Quântica , Hidrocarbonetos Halogenados/química , Estrutura MolecularRESUMO
Carbon nanotube membranes with inner diameter ranging from 1.5-7 nm were examined for enhanced electroosmotic flow. After functionalization via electrochemical diazonium grafting and carbodiimide coupling reaction, it was found that neutral caffeine molecules can be efficiently pumped via electroosmosis. An electroosmotic velocity as high as 0.16 cm s(-1) V(-1) has been observed. Power efficiencies were 25-110 fold improved compared to related nanoporous materials, which has important applications in chemical separations and compact medical devices. Nearly ideal electroosmotic flow was seen in the case where the mobile cation diameter nearly matched the inner diameter of the single-walled carbon nanotube resulting in a condition of using one ion is to pump one neutral molecule at equivalent concentrations.
Assuntos
Eletro-Osmose/métodos , Nanotubos de Carbono/química , Óxido de Alumínio/química , Cafeína/química , Cafeína/isolamento & purificação , Carbodi-Imidas/química , Cátions/química , Compostos de Diazônio/química , Impedância Elétrica , Membranas Artificiais , Compostos Organometálicos/química , Tamanho da PartículaRESUMO
A new method for the detection of phenolics in food systems was developed. This method is based on interactions of phenolics with Fast Blue BB diazonium salt in alkali pH, forming azo complexes, with the absorbance measured at 420 nm after 60 min. The linear regression correlations (R(2)) of gallic acid calibration standards were >0.99. The phenolic content (gallic acid equivalent) of samples analyzed yielded higher ratios (1.7-6.6) of the total phenolics by Fast Blue BB to Folin-Ciocalteu methods in most beverages and grain samples, but in flaxseed and some juice blends, the ratios were <1. The lower ratios suggest the presence of non-phenolic reducing constituents measured with the Folin-Ciocalteu method as "total phenolics". This method is simple and inexpensive and can be used to rapidly assess the total phenolics of foods and beverages.
Assuntos
Bebidas/análise , Grão Comestível/química , Análise de Alimentos/métodos , Fenol/análise , Sementes/química , Compostos de Diazônio/química , Flavonoides/análise , Frutas/química , Ácido Gálico/química , Indicadores e Reagentes , Modelos Lineares , Molibdênio , Fenóis/análise , Polifenóis , Chá/química , Compostos de TungstênioRESUMO
This paper reports the interest of the novel 4-carboxyphenyl-grafted screen-printed electrodes (4-CP-SPEs) for sub-nanomolar analysis of uranium in water samples. Electrodes were easily prepared via electrochemically reduction of the corresponding diazonium salt. The stability of the grafted layer has been clearly demonstrated. Uranium detection was then achieved by immersing the grafted electrode into the sample solution, followed by the electrochemical measurement of adsorbed U(VI) by square wave voltammetry. Adsorption time was investigated so as to find the best compromise between analysis time, repeatability and reproducibility. Limit of detection and quantitation reached 7 x 10(-10) and 2 x 10(-9) mol L(-1), respectively. Moreover, interference study was conducted with Zn(II), Cd(II), Pb(II) and Cu(II); no major interference was established. 4-CP-SPEs were finally applied for uranium determination in estuarine water demonstrating the convenience of these electrodes for environmental analysis.
Assuntos
Eletroquímica/métodos , Urânio/análise , Adsorção , Benzoatos/química , Cádmio/química , Cobre/química , Compostos de Diazônio/química , Eletroquímica/instrumentação , Eletrodos , Chumbo/química , Modelos Químicos , Nanotecnologia/instrumentação , Nanotecnologia/métodos , Reprodutibilidade dos Testes , Propriedades de Superfície , Poluentes Radioativos da Água/análise , Zinco/químicaRESUMO
Acetylcholinesterase inhibitors (AChEI) are currently still the best available pharmacotherapy for Alzheimer patients. Successful screening for new AChEI relies on effective and fast assays. Two colorimetric screening assays frequently used to search for new AChEI, namely a thin layer chromatography (TLC) assay with Fast Blue B salt as reagent and a 96-well plate assay based on Ellman's method, were compared. For the majority (83%) of the 138 test compounds of natural and synthetic origin, the results obtained with the two assays converged and both screening assays were considered suitable for the generation of new hits. Fifteen percent of investigated compounds were classified as active with the microplate assay but were shown to be inactive by TLC and about 2% were measured active by TLC but showed to be inactive with the microplate assay. These divergences were not due to the main differences between the experimental protocols of the two screening assays, namely the different colorimetric methods and pre-incubation of test compounds with acetylcholinesterase (AChE). They might be explained by the interaction of either AChE or test compounds with the silica of the TLC plates, resulting in an altered affinity of the enzyme for the compounds.