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1.
Am J Physiol Heart Circ Physiol ; 318(5): H1185-H1197, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32243770

RESUMO

The primary function of the arterial microvasculature is to ensure that regional perfusion of blood flow is matched to the needs of the tissue bed. This critical physiological mechanism is tightly controlled and regulated by a variety of vasoactive compounds that are generated and released from the vascular endothelium. Although these substances are required for modulating vascular tone, they also influence the surrounding tissue and have an overall effect on vascular, as well as parenchymal, homeostasis. Bioactive lipids, fatty acid derivatives that exert their effects through signaling pathways, are included in the list of vasoactive compounds that modulate the microvasculature. Although lipids were identified as important vascular messengers over three decades ago, their specific role within the microvascular system is not well defined. Thorough understanding of these pathways and their regulation is not only essential to gain insight into their role in cardiovascular disease but is also important for preventing vascular dysfunction following cancer treatment, a rapidly growing problem in medical oncology. The purpose of this review is to discuss how biologically active lipids, specifically prostanoids, epoxyeicosatrienoic acids, sphingolipids, and lysophospholipids, contribute to vascular function and signaling within the endothelium. Methods for quantifying lipids will be briefly discussed, followed by an overview of the various lipid families. The cross talk in signaling between classes of lipids will be discussed in the context of vascular disease. Finally, the potential clinical implications of these lipid families will be highlighted.


Assuntos
Ácidos Graxos/metabolismo , Microvasos/metabolismo , Fosfolipídeos/metabolismo , Esfingolipídeos/metabolismo , Animais , Ensaios Enzimáticos/métodos , Fluorometria/métodos , Humanos , Espectrometria de Massas/métodos , Transdução de Sinais
2.
Bioresour Technol ; 309: 123380, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32325378

RESUMO

Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Acclimatization of freshwater microalgae to hypersaline conditions offers a means to reduce contamination. A freshwater Chlorella species was cultured in a gradient of salinities ranging from 5 to 40‰ and pulse amplitude modulated fluorometry recorded photosynthetic functioning. While the average salinity of seawater is 35‰, optimum acclimatization occurred at 20‰, at which point the growth rate (1.6 µg chl a L-1d-1) was not significantly different from the control (1.8 µg chl a L-1d-1). The maximum relative electron transfer rate was lower (9 to 12 µmol m-2s-1) at 5 to 20‰ as compared to 40‰ (28 µmol m-2s-1) where no algal growth was recorded. ATP and NADPH were thus shunted towards synthesis of molecules that offset cytoplasmic osmotic stress. Culturing this Chlorella strain in raceway ponds under saline conditions may reduce contamination and improve productivity.


Assuntos
Chlorella , Microalgas , Aclimatação , Fluorometria , Água Doce
3.
Am J Physiol Regul Integr Comp Physiol ; 318(5): R972-R980, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32233925

RESUMO

Mitochondria utilize the majority of oxygen (O2) consumed by aerobic organisms as the final electron acceptor for oxidative phosphorylation (OXPHOS) but also to generate reactive oxygen species (mtROS) that participate in cell signaling, physiological hormesis, and disease pathogenesis. Simultaneous monitoring of mtROS production and oxygen consumption (Jo2) from tissue mitochondrial preparations is an attractive investigative approach, but it introduces dynamic changes in media O2 concentration ([O2]) that can confound experimental results and interpretation. We utilized high-resolution fluorespirometry to evaluate Jo2 and hydrogen peroxide release (Jh2o2) from isolated mitochondria (Mt), permeabilized fibers (Pf), and tissue homogenates (Hm) prepared from murine heart and skeletal muscle across a range of experimental [O2]s typically encountered during respirometry protocols (400-50 µM). Results demonstrate notable variations in Jh2o2 across tissues and sample preparations during nonphosphorylating (LEAK) and OXPHOS-linked respiration states at 250 µM [O2] but a linear decline in Jh2o2 of 5-15% per 50-µM decrease in chamber [O2] in all samples. Jo2 was generally stable in Mt and Hm across [O2]s above 50 µM but tended to decline below 250 µM in Pf, leading to wide variations in assayed rates of Jh2o2/O2 across chamber [O2]s and sample preparations. Development of chemical background fluorescence from the H2O2 probe (Amplex Red) was also O2 sensitive, emphasizing relevant calibration considerations. This study highlights the importance of monitoring and reporting the chamber [O2] at which Jo2 and Jh2o2 are recorded during fluorespirometry experiments and provides a basis for selecting sample preparations for studies addressing the role of mtROS in physiology and disease.


Assuntos
Peróxido de Hidrogênio/metabolismo , Mitocôndrias Cardíacas/metabolismo , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Miocárdio/metabolismo , Consumo de Oxigênio , Oxigênio/metabolismo , Difosfato de Adenosina/metabolismo , Animais , Respiração Celular , Fluorometria , Cinética , Masculino , Camundongos , Modelos Biológicos , Fosforilação Oxidativa
4.
Food Chem ; 318: 126502, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32146311

RESUMO

A water-soluble, long-term stable, poly(sodium-p-styrenesulfonate)-enhanced and d-penicillamine stabilized argentum nanoclusters (PSS-DPA-AgNCs) was synthesized by a one-step ultraviolet radiation combined with microwave heating method. The effects of different types of polyelectrolytes and energy suppliers on the AgNCs photo-luminescence performance were investigated in detail. The prepared AgNCs are exhibited to be viable fluorescent method for 2-Mercapto-3-butanol (2-M-3-B), 3-Mercapto-2-butanone (3-M-2-B) and silicate (SiO32-) determinations. The fluorescence (FL) of PSS-DPA-AgNCs is quenched with the addition of 2-M-3-B/3-M-2-B/SiO32- mainly originating from a static quenching process. The method can monitor 2-M-3-B/3-M-2-B by fluorometry with a linear response in the range of 0.33-90.0/0.33-80.0 µM and a 74/250 nM detection limit (at 3σ/slope). For the SiO32- assay, corresponding data are 3.33-100.0 µM and 278 nM. Moreover, the proposed method was successfully used for the assays of two food flavors in the steamed bread and soda drinks, and silicate in the mineral water samples respectively.


Assuntos
Bebidas/análise , Pão/análise , Água Potável/análise , Fluorometria/métodos , Nanopartículas Metálicas/química , Polímeros/química , Ácido Silícico/análise , Prata/química , Ácidos Sulfônicos/química , Bioensaio , Fluorescência , Limite de Detecção , Raios Ultravioleta
5.
Ecotoxicol Environ Saf ; 194: 110417, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32171958

RESUMO

A fluorescence aptasensor for the highly specific and sensitive determination of tetrodotoxin was established with tetrodotoxin-aptamer as the recognition unit, berberine as the signal reporter and exonuclease I as the elimination agent for the background. Berberine has a weak fluorescence emission at 540 nm, and it can form the tetrodotoxin-aptamer/berberine complex, resulted in an increased fluorescence. After introducing exonuclease I, it can degrade the single strand oligonucleotides of tetrodotoxin-aptamer into the single nucleotide in the absence of tetrodotoxin, which lead to dramatic fluorescence quenching, and reduce the background signal of sensing system. Once tetrodotoxin is in the presence, tetrodotoxin-aptamer is converted into the stable neck ring conformation, which resists the degradation of exonuclease I and provides a more rigid micro-environment for the excited state of berberine, and then the strong fluorescence is observed. Based on the above properties, an ultrasensitive label-free fluorescence aptasensor for tetrodotoxin is established. The fluorescence aptasensor shows good analytical performance with the linear increase of fluorescence intensity at the tetrodotoxin concentration from 0.030 nM to 6.0 × 103 nM. The detection limit of 11.0 pM is much lower than that of other reported sensor methods.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Exodesoxirribonucleases/química , Fluorometria/métodos , Tetrodotoxina/análise , Animais , Berberina/química , Humanos , Limite de Detecção , Músculos/química , Tetraodontiformes , Tetrodotoxina/sangue
6.
Food Chem ; 315: 126296, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32014663

RESUMO

Some minor constituents of honey samples were determined through a fluorometric-chemical characterization method and related multifactorially with their antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa and with their geographical origin. Rotated principal component analysis identified five significant components in honey: three related to antibacterial activity and linked to phenolic compounds; Maillard products; proteins; the concentration of H2O2 at 3 and 24 h of incubation; and a tyrosine-containing entity. On the other hand, five constituents (phenolic compounds were the most relevant) allowed the classification of honey samples by geographical origin with 87% certainty. The results showed that phenolic compounds and Maillard products are related to the sustained production of H2O2 over time, which in turn boosts the antibacterial activity of honey. Native flora could promote this capability. The results showed the effect of geographic origin on the content of the analyzed minor constituents of honey, particularly phenolic compounds.


Assuntos
Mel/análise , Antibacterianos/farmacologia , Fluorometria , Peróxido de Hidrogênio/análise , Testes de Sensibilidade Microbiana , Fenóis/análise , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos
7.
Chemistry ; 26(25): 5717-5723, 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-31991020

RESUMO

Inorganic pyrophosphate (PPi) is considered as a diagnostic marker for various diseases such as cancer and vascular calcification. PPi also plays an important preservative role as an additive E450 in foodstuff. In this work, a selective FeIII -salen-based probe for PPi is described; this probe disassembles in the presence of the target analyte into its molecular blocks, 1,2-propanediamine and 3-chloro-5-formyl-4-hydroxybenzenesulfonic acid. The latter signaling unit leads to a fluorometric response. Compared with a related prototype, the new complex shows a 2.3-times stronger emission at 500 nm and a 155-times better selectivity of PPi over adenosine triphosphate (ATP). Importantly, the new probe was successfully applied for detecting E450 in foodstuff.


Assuntos
Trifosfato de Adenosina/química , Etilenodiaminas/química , Compostos Férricos/química , Fluorometria/métodos , Aditivos Alimentares/análise , Trifosfato de Adenosina/metabolismo , Aditivos Alimentares/química , Humanos
8.
J Photochem Photobiol B ; 203: 111766, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31927488

RESUMO

The photolysis of thiochrome (THC), an oxidation product of thiamine (vitamin B1) (THE), used for its fluorimetric assay, has been studied in the pH range 7.0-12.0. THC undergoes photooxidation to oxodihydrothiochrome (ODTHC) which is oxidized to a non-fluorescent compound (OP1) on UV irradiation. The kinetics of the consecutive first-order reactions: THC→k1ODTHC→k2OP1, has been evaluated and the values of first-order rate constants, k1 (0.58-4.20 × 10-5, s-1) and k2 (0.05-2.03 × 10-5, s-1), at pH 7.0-12.0 have been determined. The rates of degradation of THC and ODTHC are enhanced with pH and the second-order rate constants k1' and k2' for the OH- ion-catalyzed reaction are in the range of 0.002-58.3 M-1 s-1. The quantum yields of the photolysis of THC and ODTHC in the pH range 7.0-12.0 have been determined. THC, ODTHC and OP1 have been identified by chromatographic, spectrometric and fluorimetric methods. THC and ODTHC have similar fluorescence characteristics and emit at 450 and 445 nm, respectively. THC, ODTHC and OP1 with distinct absorption maxima (370, 344 and 290 nm, respectively) have been determined by a newly developed and validated multicomponent spectrometric method during the photolysis reactions. The on-line formation of THC by the photooxidation of THE may lead to the degradation of THC and give erroneous results in the fluorimetric assay of THE. A scheme for the photolysis reactions of THC in aqueous solution is presented.


Assuntos
Tiamina/análogos & derivados , Raios Ultravioleta , Catálise , Fluorometria , Concentração de Íons de Hidrogênio , Cinética , Oxirredução , Fotólise/efeitos da radiação , Tiamina/química
9.
Chemistry ; 26(10): 2098, 2020 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-31990111

RESUMO

Invited for the cover of this issue are the groups of Todd B. Marder at the Julius-Maximilians-Universität Würzburg and Ivo Piantanida at the Ruder Boskovic Institute. The image depicts the molecular structure of a bis-triarylborane-based chromophore that is simultaneously detecting ds-DNA and proteins. Read the full text of the article at 10.1002/chem.201903936.


Assuntos
DNA , RNA , Fluorometria , Estrutura Molecular
10.
Food Chem ; 312: 126089, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31896452

RESUMO

A fluorometric and colorimetric dual-mode sensing platform based on graphitic carbon nitrite quantum dots (g-CNQDs) and Fe (II)-bathophenanthroline complex (BPS-Fe2+) was designed to the sensitive detection of nitrite (NO2-) in sausage and water. In this system, the fluorescence of g-CNQDs was quenched by BPS-Fe2+ complex due to the inner filter effect (IFE). When NO2- was present, Fe2+ was oxidized by nitrite to form BPS-Fe3+ complex with BPS, leading to the recovery of the fluorescence from g-CNQDs. Therefore, we constructed a "turn-off-on" fluorescence probe for detection of NO2-. Moreover, with the increase of NO2- concentration, the color of the solution changed from red to colorless, so the UV-vis measurements and on-site visual detection were realized. The method is capable of detecting NO2- in the concentration range of 2.32-34.8 µM with good selectivity and high sensitivity. In addition, the method has the potential to determine NO2- in water samples and sausage samples.


Assuntos
Carbono/química , Grafite/química , Produtos da Carne/análise , Nitritos/química , Fenantrolinas/química , Pontos Quânticos , Água/química , Colorimetria , Fluorescência , Corantes Fluorescentes , Fluorometria , Compostos de Ferro/química
11.
Nat Chem Biol ; 16(1): 15-23, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31819272

RESUMO

The anticancer agent indisulam inhibits cell proliferation by causing degradation of RBM39, an essential mRNA splicing factor. Indisulam promotes an interaction between RBM39 and the DCAF15 E3 ligase substrate receptor, leading to RBM39 ubiquitination and proteasome-mediated degradation. To delineate the precise mechanism by which indisulam mediates the DCAF15-RBM39 interaction, we solved the DCAF15-DDB1-DDA1-indisulam-RBM39(RRM2) complex structure to a resolution of 2.3 Å. DCAF15 has a distinct topology that embraces the RBM39(RRM2) domain largely via non-polar interactions, and indisulam binds between DCAF15 and RBM39(RRM2), coordinating additional interactions between the two proteins. Studies with RBM39 point mutants and indisulam analogs validated the structural model and defined the RBM39 α-helical degron motif. The degron is found only in RBM23 and RBM39, and only these proteins were detectably downregulated in indisulam-treated HCT116 cells. This work further explains how indisulam induces RBM39 degradation and defines the challenge of harnessing DCAF15 to degrade additional targets.


Assuntos
Antineoplásicos/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular/química , Proteínas de Ligação a RNA/química , Sulfonamidas/farmacologia , Motivos de Aminoácidos , Calorimetria , Clonagem Molecular , Fluorometria , Células HCT116 , Células HEK293 , Humanos , Processamento de Imagem Assistida por Computador , Peptídeos e Proteínas de Sinalização Intracelular/genética , Cinética , Proteínas Nucleares/metabolismo , Peptídeos/química , Mutação Puntual , Ligação Proteica , Estrutura Quaternária de Proteína , Estrutura Secundária de Proteína , Proteoma , RNA Interferente Pequeno/metabolismo , Proteínas de Ligação a RNA/genética , Ubiquitina-Proteína Ligases/metabolismo
12.
Food Chem ; 310: 125812, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31734008

RESUMO

An eco-friendly method was used to synthesize carbon dots (CDs) from Rosemary leaves, as a carbon source. The as-synthesized CDs was applied as a fluorophore in an optical sensor after modification with molecularly imprinted polymers (MIPs) for determination of thiabendazole (TBZ). For this purpose, a silica shell using tetraethoxysilane (TEOS), as a Si source, was stabilized on the surface of CDs via reverse microemulsion technique. Following, MIPs were synthesized in the presence of TBZ as a template, using 3-aminopropyl triethoxysilane and TEOS as a functional monomer and a crosslinker, respectively. After optimization of the experimental parameters, a linear dynamic range of 0.03-1.73 µg/mL TBZ with a detection limit as 8 ng/mL were obtained for the suggested method. Finally, the proposed sensor was successfully applied for the determination of TBZ in apple, orange, and tomato juices. This sensor is a simple, rapid, selective, and non-expensive method for TBZ measurement.


Assuntos
Fluorometria/instrumentação , Sucos de Frutas e Vegetais/análise , Polímeros/síntese química , Pontos Quânticos/química , Tiabendazol/análise , Carbono/química , Corantes Fluorescentes/química , Fluorometria/métodos , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Química Verde , Limite de Detecção , Impressão Molecular/métodos , Silanos/química , Dióxido de Silício/química , Espectrometria de Fluorescência/métodos
13.
Chemistry ; 26(10): 2195-2203, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-31756013

RESUMO

A water-soluble tetracationic quadrupolar bis-triarylborane chromophore showed strong binding to ds-DNA, ds-RNA, ss-RNA, as well as to the naturally most abundant protein, BSA. The novel dye can distinguish between DNA/RNA and BSA by fluorescence emission separated by Δ ν ˜ =3600 cm-1 , allowing for the simultaneous quantification of DNA/RNA and protein (BSA) in a mixture. The applicability of such fluorimetric differentiation in vitro was demonstrated, strongly supporting a protein-like target as a dominant binding site of 1 in cells. Moreover, our dye also bound strongly to ss-RNA, with the unusual rod-like structure of the dye, decorated by four positive charges at its termini and having a hydrophobic core, acting as a spindle for wrapping A, C and U ss-RNAs, but not poly G, the latter preserving its secondary structure. To the best of our knowledge, such unmatched, multifaceted binding activity of a small molecule toward DNA, RNA, and proteins and the selectivity of its fluorimetric and chirooptic response makes the quadrupolar bis-triarylborane a novel chromophore/fluorophore moiety for biochemical applications.


Assuntos
Boranos/química , DNA/análise , Corantes Fluorescentes/química , Fluorometria/métodos , RNA/análise , Soroalbumina Bovina/análise , Tiofenos/química , Sítios de Ligação , Boranos/metabolismo , Dicroísmo Circular , DNA/química , Corantes Fluorescentes/metabolismo , Simulação de Dinâmica Molecular , RNA/química , RNA de Cadeia Dupla/análise , RNA de Cadeia Dupla/química , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Temperatura , Tiofenos/metabolismo
14.
J Pharm Biomed Anal ; 177: 112887, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31580989

RESUMO

In the present study we report a fully automated method for the determination of low levels of the genotoxic impurity hydrazine in allopurinol active pharmaceutical ingredient (API) and formulations based on the concept of zone-fluidics. Hydrazine reacts on-line with o-phthalaldehyde in a unique way, that is in acidic medium (pH < 1.5) and in the absence of nucleophilic reagents, to form a highly fluorescent hydrazone (λex/em = 318 / 376 nm). The adaptation of a 120 s long stopped-flow step at elevated temperature (70 °C) offered adequate sensitivity (LOD =0.9 µg L-1 or 0.1 ppm in the solid API) to meet the pharmacopoeia limits for the selected application. The analyte was separated efficiently from the excess of the API by on line solid phase extraction using a Hydrophilic-Lipophilic technology sorbent that provided direct retention of the more hydrophobic API without the need of wetting/conditioning steps. Percent recoveries ranged between 93.3 and 105.8%.


Assuntos
Alopurinol/análise , Carcinógenos/análise , Contaminação de Medicamentos/prevenção & controle , Hidrazinas/análise , Extração em Fase Sólida/métodos , Cromatografia Líquida de Alta Pressão/métodos , Eletrodos , Fluorometria/instrumentação , Fluorometria/métodos , Temperatura Alta , Interações Hidrofóbicas e Hidrofílicas , Limite de Detecção , Extração em Fase Sólida/instrumentação
15.
J Enzyme Inhib Med Chem ; 35(1): 306-310, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31797704

RESUMO

The differential scanning fluorimetry (DSF) screening of 5.692 fragments in combination with benzenesulfonamide (BSA) against bovine carbonic anhydrase (bCA) delivered >100 hits that either caused, on their own, a significant thermal shift (ΔTm, °C) in the protein melting temperature or significantly influenced the thermal shift observed for BSA alone. Three hits based on 1,2,3-triazole moiety represent the periphery of the recently reported potent inhibitors of hCA II, IX and XII which were efficacious in vivo. Such a re-discovery of suitable BSA periphery essentially validates the new fragment-based approach to the discovery of future CAIs. Structures of other validated fragment hits are reported.


Assuntos
Anidrase Carbônica II/antagonistas & inibidores , Anidrase Carbônica IX/antagonistas & inibidores , Inibidores da Anidrase Carbônica/farmacologia , Anidrases Carbônicas/metabolismo , Fluorometria , Sulfonamidas/farmacologia , Anidrase Carbônica II/metabolismo , Anidrase Carbônica IX/metabolismo , Inibidores da Anidrase Carbônica/síntese química , Inibidores da Anidrase Carbônica/química , Avaliação Pré-Clínica de Medicamentos , Humanos , Estrutura Molecular , Sulfonamidas/síntese química , Sulfonamidas/química
16.
J Enzyme Inhib Med Chem ; 35(1): 165-171, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31752557

RESUMO

Testing of an expanded, 800-compound set of analogues of the earlier described Strecker-type α-aminonitriles (selected from publicly available Enamine Ltd. Screening Collection) in thermal shift assay against bovine carbonic anhydrase (bCA) led to further validation of this new class of inhibitors and identification a new, refined chemotype represented by inhibitors with 10-improved potency. [Formula: see text].


Assuntos
Anidrase Carbônica II/antagonistas & inibidores , Inibidores da Anidrase Carbônica/farmacologia , Nitrilos/farmacologia , Animais , Anidrase Carbônica II/metabolismo , Inibidores da Anidrase Carbônica/síntese química , Inibidores da Anidrase Carbônica/química , Bovinos , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Fluorometria , Humanos , Estrutura Molecular , Nitrilos/síntese química , Nitrilos/química , Relação Estrutura-Atividade
17.
Talanta ; 208: 120425, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816696

RESUMO

A chicken egg white protein-protected gold nanocluster (CEW-AuNC) based fluorogenic biosensor, where protein was used as both reducing and protecting agent, was developed to determine the Cu(II)-induced prooxidant activity of natural antioxidants abundant in food and biological samples. Gold nanoclusters, prepared using egg white proteins, exhibited strong fluorescence. The prooxidant activity of the tested antioxidants was indirectly measured by their reducing action on Cu(II) to Cu(I), and the reduced cuprous ion was bound to the thiol groups in the CEW-AuNC structure, causing a decrease in fluorescence intensity. Epicatechin, catechin, epigallocatechin gallate, morin, rutin, quercetin, gallic, chlorogenic, and rosmarinic acids, glutathione, cysteine, N-acetyl cysteine, bilirubin, resveratrol, and α-tocopherol were studied as natural antioxidants. A fluorometric method showing a large Stokes shift with excitation/emission maxima at 360∕640 nm was developed to sensitively measure the decrease in the fluorescence of CEW-AuNC associated with the binding of copper(I) to the protein structure. Total prooxidant activities of the binary, ternary, and quaternary synthetic mixtures and of some food and synthetic serum samples were determined. The biosensor response was statistically compared to that of its spectrophotometric counterpart. This method can be used for the control of the oxidative stability of foods with a prolonged shelf life.


Assuntos
Técnicas Biossensoriais , Ouro/química , Nanoestruturas/química , Oxidantes/química , Ácidos Carbocíclicos/química , Antioxidantes/química , Bilirrubina/química , Mirtilos Azuis (Planta) , Cobre/química , Proteínas do Ovo/química , Flavonoides/química , Fluorometria , Sucos de Frutas e Vegetais , Malus , Oxirredução , Extratos Vegetais , Resveratrol/química , Compostos de Sulfidrila/química , Chá , Vinho
18.
Talanta ; 208: 120406, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31816742

RESUMO

Acetylcholinesterase (AChE) is an important enzyme associated with many nervous diseases, demonstrating the great need for smarter sensing platform with improved sensitivity, selectivity and simplified operation. A "turn on" fluorometric assay is described herein for AChE activity detection, according to the specific enzyme catalyzed reaction of acetylcholine (ATCh) by AChE, which generates thiocholine (TCh) as the product. The well-designed fluorescent probe HBTP possesses ESIPT (Excited State Intramolecular Proton Transfer) nature, leading to a larger Stokes shift, which could be quenched upon coordination with Cu2+. The fluorescence-silent HBTP-Cu2+ complex could be broken by TCh generated from reaction of ATCh with AChE, giving rise to HBTP release which originates from competitive coordination of TCh with Cu2+. This complex probe HBTP-Cu2+ offers a limit detection as low as 0.02 mU mL-1, which is lower than most reported literatures. Furthermore, both HBTP-Cu2+ and HBTP show little toxicity to live cells and is available in visualizing cellular AChE activity.


Assuntos
Benzotiazóis/química , Cobre/química , Corantes Fluorescentes/química , Fenóis/química , Acetilcolinesterase , Benzotiazóis/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Cobre/toxicidade , Fluorescência , Corantes Fluorescentes/toxicidade , Fluorometria , Células HEK293 , Humanos , Fenóis/toxicidade
19.
J Toxicol Sci ; 44(12): 821-832, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31813901

RESUMO

The Amino acid Derivative Reactivity Assay (ADRA) is an in chemico alternative to animal testing for the prediction of skin sensitization potential. Although co-elution of test chemicals and nucleophilic reagents during HPLC analysis is sometimes problematic when using the Direct Peptide Reactivity Assay (DPRA), it rarely occurs when using ADRA. Nevertheless, the application of either of these tests to multi-constituent substances requires nucleophilic reagents capable of selective detection. With this issue in mind, the authors developed an ADRA fluorescence detection method (ADRA-FL), which utilizes the natural fluorescence of ADRA nucleophilic reagents. In this study, we demonstrate the efficacy of ADRA-FL by testing 82 test chemicals used in the development of both DPRA and the conventional ADRA (ADRA-UV) as well as establish a threshold value for distinguishing sensitizers and non-sensitizers. Our results show that not only are depletion values obtained using ADRA-FL virtually identical to those obtained using ADRA-UV, the threshold value for either test is 4.9%. Additionally, in order to demonstrate the applicability of ADRA-FL to multi-constituent substances, we prepared test samples that consisted of a set of 10 non-sensitizers combined with one of 10 different sensitizers and tested each using ADRA-FL. The test results were concordant with those obtained using ADRA-UV. Also, because ADRA-FL chromatograms showed a significant decrease in multiple peaks as well as extremely stable baselines, we conclude that ADRA-FL is a highly selective and highly accurate mans of quantifying nucleophilic reagents that is applicable to a wide variety of chemical substances.


Assuntos
Acetilcisteína/química , Alanina/análogos & derivados , Alternativas aos Testes com Animais/métodos , Dermatite de Contato/etiologia , Fluorometria/métodos , Naftalenos/química , Compostos Orgânicos , Alanina/química , Modelos Teóricos , Compostos Orgânicos/química , Compostos Orgânicos/classificação , Compostos Orgânicos/toxicidade , Valor Preditivo dos Testes , Relação Quantitativa Estrutura-Atividade , Sensibilidade e Especificidade
20.
Mikrochim Acta ; 187(1): 12, 2019 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-31802244

RESUMO

A fluorometric method is described for the determination of fipronil, a frequently-used insecticide. It exploits the blue fluorescence of carbon quantum dots (CQDs) and the selectivity of molecularly imprinted silica (MIS). The MIS was prepared via the sol-gel method by using fipronil as the template, 3-aminopropyltriethoxysilane as functional monomer, and tetraethoxysilane as cross-linker in the presence of CQDs. The blue fluorescence of the CQD@MIS, with excitation/emission peaks at 340/422 nm, is quenched by fipronil. The assay works in the 0. 70 pM to 47 µM fipronil concentration range, and the limit of detection is 19 pM. The method was successfully applied to the quantitation of fipronil in spiked eggs, milk, and tap water. Recoveries between 83.8 and 114.0% were achieved. The corresponding relative standard deviations (RSD) are less than 6.67%. Graphical abstractSchematic representation of a high sensitivite and selectivite fluorescence nanoprobe constructed by combining the excellent fluorescence property of carbon quantum dots and the predicted selectivity of molecularly imprinted silica. It was applied to analyze fipronil in egg, milk and tap water, respectively.


Assuntos
Carbono/química , Fluorometria/métodos , Impressão Molecular , Pirazóis/análise , Pontos Quânticos/química , Dióxido de Silício/química , Animais , Calibragem , Água Potável/química , Contaminação de Alimentos/análise , Inocuidade dos Alimentos , Limite de Detecção , Leite/química , Óvulo/química , Propilaminas/química , Pirazóis/química , Silanos/química
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