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1.
Biochim Biophys Acta Biomembr ; 1862(2): 183113, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31672539

RESUMO

Multi-spanning membrane proteins usually require solubilization to allow proper purification and characterization, which generally impairs their structural and functional integrity. We have tested the efficacy of several commonly used detergents and membrane-mimicking nanodiscs with respect to solubilization, spectral properties, thermal stability and oligomeric profile of two membrane proteins from the eubacterial rhodopsin family, green proteorhodopsin (PR) and Gloeobacter violaceus rhodopsin (GR). Good solubilization was observed for the detergents TritonX-100 and dodecylphosphocholine (DPC), but DPC in particular strongly affected the thermal stability of PR and especially GR. The least deleterious effects were obtained with n-dodecyl-ß-D-maltopyranoside (DDM) and octyl glucose neopentyl glycol (OGNG), which adequately stabilized the native oligomeric and monomeric state of PR and GR, respectively. The transition from the oligomeric to the monomeric state is accompanied by a small red-shift. Both GR and PR were rather unstable in SMA-nanodiscs, but the highest thermal stability was realized by the MSP-nanodisc environment. The size of the MSP-nanodisc was too small to fit the PR hexamer, but large enough to contain the PR monomer and GR trimer. This permitted the comparison of the photocycle of trimeric GR in a membrane-mimicking (MSP-nanodisc) and a detergent (DDM) environment. The ultrarapid early phase of the photocycle (femto- to picosecond lifetimes) showed very similar kinetics in either environment, but the slower part, initiated with proton transfer and generation of the M intermediate, proceeded faster in the nanodisc environment. The implications of our results for the biophysical characterization of PR and GR are discussed.


Assuntos
Proteínas de Bactérias/química , Bicamadas Lipídicas/química , Nanopartículas/química , Rodopsina/química , Cianobactérias/química , Detergentes/química , Maltose/análogos & derivados , Maltose/química , Fosforilcolina/análogos & derivados , Fosforilcolina/química , Estabilidade Proteica , Tioglucosídeos/química
2.
Spectrochim Acta A Mol Biomol Spectrosc ; 224: 117399, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31344575

RESUMO

In this study, we analyzed some monofunctional Ru (II) complexes containing chlorine, bromine and fluorine atoms around the central atom. The best calculation level among HF, B3LYP and M062X methods for [Ru (Cl-Ph-tpy)(NN)X]+ (X = F, Cl, Br) was determined in the light of Benchmark analysis and according to this analysis results, the best level is shown as B3LYP-LANL2DZ/6-31G(d). In addition to this, the spectroscopic data (IR, NMR and UV-Vis) were also obtained in agreement with experimental results. The tendency of anticancer activity and structural activity relationship (SAR) parameters are predicted with some quantum chemical methods. Surface and contour diagrams, as well as electron densities on mentioned complexes were interpreted through theoretically obtained results. Finally, the anticancer activity tendency of the relevant complexes on the human cervical carcinoma cell line (ID: 1 M17) is supported by molecular docking calculations.


Assuntos
Flavinas/química , Glucosídeos/química , Rutênio/química , Tensoativos/química , Tioglucosídeos/química , Micelas , Simulação de Acoplamento Molecular , Espectrometria de Fluorescência
3.
Spectrochim Acta A Mol Biomol Spectrosc ; 224: 117346, 2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31344577

RESUMO

The photophysics and structural transition dynamics of a bio-active flavin lumichrome (LM) entrapped in two sugars based neutral surfactants were reported. Sugar-based surfactants, which were used for research purpose are potential environmentally friendly, green alternative amphiphilic surface active substance compared to other kinds of common surfactants. Here, two alkyl glucoside surfactants n-octyl-ß-D-glucopyranoside (OBG) and n-octyl-ß-D-thioglucopyranoside (OBTG) were used. This work is carried out by using steady-state absorption and fluorescence emission spectroscopy along with time-resolved fluorescence emission techniques. Photophysics of LM was modulated several folds in these two sugar-based neutral micelles. LM exhibits excitation and emission wavelength dependent fluorescence properties in these two sugars based neutral micelles. LM confined in the micellar environments exhibited structural transition dynamism, i.e. different kinds of conformers are equilibrated. Herein, different conformers of LM are identified and explained with the help of spectroscopic methods. From the fluorescence anisotropy measurement, it was found that the rotational relaxation time of LM in OBG micelle was more compared to that in OBTG micelle, which indicates that the LM molecule faced much more constrained environment in OBG micellar media.


Assuntos
Flavinas/química , Glucosídeos/química , Tensoativos/química , Tioglucosídeos/química , Flavinas/análise , Micelas , Modelos Moleculares , Espectrometria de Fluorescência
4.
Oxid Med Cell Longev ; 2019: 3206542, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31354905

RESUMO

Previous studies demonstrated that Bailcalin (BAI) prevented cardiac injuries under different disease models. Whether BAI protected against type 2 diabetes mellitus- (T2DM-) associated cardiomyopathy was investigated in this study. T2DM was established by the combination of streptozotocin injection and high-fat diet in mice. BAI was administered daily for 6 months. After evaluating cardiac functions, mice hearts were removed and processed for morphological, biochemical, and molecular mechanism analyses. Neonatal rat cardiomyocytes (NRCM) were isolated and treated with high glucose and palmitate (HG/Pal) for in vitro investigation. BAI significantly ameliorated T2DM-induced cardiomyocyte hypertrophy, interstitial fibrosis, and lipid accumulation accompanied by markedly improved cardiac functions in diabetic mice. Mechanically, BAI restored decreased phosphorylation of AMPK and enhanced expression and nuclei translocation of Nrf2. In in vitro experiments, BAI also prevented NRCM from HG/Pal-induced apoptosis and oxidative stress injuries by increasing p-AMPK and Nrf2 accumulation. The means by which BAI restored p-AMPK seemed to be related to the antioxidative effects of Nrf2 after silencing AMPK or Nrf2 in NRCM. Furthermore, BAI regulated Nrf2 by inhibiting Nrf2 ubiquitination and consequent degradation mediated by Keap1. This study showed that BAI alleviated diabetes-associated cardiac dysfunction and cardiomyocyte injuries in vivo and in vitro via Keap1/Nrf2/AMPK-mediated antioxidation and lipid-lowering effects. BAI might be a potential adjuvant drug for diabetes cardiomyopathy treatment.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Cardiomiopatias Diabéticas/tratamento farmacológico , Cardiomiopatias Diabéticas/prevenção & controle , Proteína 1 Associada a ECH Semelhante a Kelch/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Tioglucosídeos/farmacologia , Animais , Antioxidantes , Diabetes Mellitus Tipo 2/tratamento farmacológico , Cardiomiopatias Diabéticas/patologia , Modelos Animais de Doenças , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Transfecção
5.
Carbohydr Res ; 471: 56-63, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30439547

RESUMO

A gold-catalyzed glucosylation method using an o-ethynylphenyl ß-D-1-thioglucoside as donor is described. The reaction proceeds in a mostly SN2 pathway. A series of α-D-glucosides are obtained in good yields and with up to 19:1 α-selectivity.


Assuntos
Glucosídeos/síntese química , Ouro/química , Tioglucosídeos/química , Sequência de Carboidratos , Catálise , Glucosídeos/química , Glicosilação , Estereoisomerismo , Especificidade por Substrato
6.
Int J Pharm ; 552(1-2): 388-393, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30300707

RESUMO

Galactosyltransferases are a family of enzymes responsible for the synthesis of glycan chains which are involved in cell proliferation, adhesion and apoptosis. A recently synthesized galactosyltransferase inhibitor, 2-naphthyl 2-butanamido-2-deoxy-1-thio-ß-D-glucopyranoside (612), has been found to selectively inhibit ß1,4-galactosyltransferase over ß1,3-galactosyltransferase and, therefore, has potential to suppress the synthesis of cancer associated epitopes. However, the application of this inhibitory activity in biological systems remains unknown. In this study, 612 was introduced into a cationic liposome (LP) delivery system, and the anti-proliferative effects of both free and the LP-incorporated 612 (612-LP) were investigated in A549 lung cancer cells, which actively express anionic sialic acid moieties on the surfaces of cells. The anti-proliferative effects were evaluated via MTT assays. The results revealed that free 612 and empty LP impose neither anti-proliferative nor apoptotic effects on cancer cells at low doses, whereas the 612-LP system inhibited cancer cell growth at a concentration as low as 0.1 µg/mL after 3 days of incubation, suggesting that this formulation enabled efficient delivery of 612 into cells and promoted the anti-proliferative activity of 612 against cancer cells. Therefore, this highly specific inhibitor 612 has the potential for development as an effective anti-cancer agent and merits further investigation.


Assuntos
Antineoplásicos/administração & dosagem , N-Acetil-Lactosamina Sintase/antagonistas & inibidores , Tioglucosídeos/administração & dosagem , Células A549 , Sobrevivência Celular/efeitos dos fármacos , Glicosilação , Humanos , Lipossomos
7.
J Chromatogr A ; 1575: 49-58, 2018 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-30262393

RESUMO

Endotoxins are complex molecules and one of the most challenging impurities requiring separation in biopharmaceutical protein purification processes. Usually these contaminants are cleared during the downstream process, but if endotoxin interacts with the target protein it becomes difficult to remove. In the present study we identified a detergent, octyl-ß-D-1-thioglucopyranoside (OTG), that disrupted endotoxin-protein interactions. The integration of this detergent into washes on several chromatography media was demonstrated to provide a separation tool for decreasing endotoxin from target proteins. This study also examined the mechanism of OTG endotoxin-protein disruption through phase modification incubation and chromatographic studies. The non-ionic OTG wash was shown to break both hydrophobic and electrostatic interactions between the endotoxin and protein. This mechanism contrasts with the breaking of hydrophobic interactions by washing with known endotoxin decreasing Triton X-100 detergent. The difference in mechanisms likely results in the ability of OTG to decrease endotoxin to levels less than those resulting from a detergent wash such as Triton X-100. Finally, we show the impact of the OTG endotoxin removal tool on the biopharmaceutical industry. While maintaining monomer purity and activity levels, endotoxin removal from a fusion protein allowed for decreased background levels in a T cell functional assay. The lowered baseline of T cell responses allowed for more effective detection of molecular interaction with the cells. The detergent wash can be used to both decrease the overall level of endotoxin in a purified protein solution and to enable more effective screening of lead candidate molecules.


Assuntos
Química Farmacêutica/métodos , Cromatografia de Afinidade , Endotoxinas/isolamento & purificação , Tioglucosídeos/química , Endotoxinas/química , Octoxinol/química
8.
Mol Nutr Food Res ; 62(20): e1800588, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30091516

RESUMO

SCOPE: Different metabolic and excretion pathways of the benzyl glucosinolate breakdown products benzyl isothiocyanate and benzyl cyanide are investigated to obtain information about their multiple fate after ingestion. Detailed focus is on the so far underestimated transformation/excretion pathways-protein conjugation and exhalation. METHODS AND RESULTS: Metabolites, protein conjugates, and non-conjugated isothiocyanates are determined in plasma, urine, and breath of seven volunteers after consuming freeze-dried nasturtium or bread enriched with nasturtium. Samples are collected up to 48 h at selected time points. The metabolites of the mercapturic acid pathway are detectable in plasma up to 24 h after consumption. Additionally, mercapturic acid is the main metabolite in urine, but non-conjugated benzyl isothiocyanate is detectable as well. Protein conjugates show high amounts in plasma even 48 h after consumption. In breath, benzyl isothiocyanate and benzyl cyanide are detectable up to 48 h after consumption. CONCLUSION: Isothiocyanates are not only metabolized via the mercapturic acid pathway, but also form protein conjugates in blood and are exhaled. To balance intake and excretion, it is necessary to investigate all potential metabolites and excretion routes. This has important implications for the understanding of physiological and pharmacological effects of isothiocyanate-containing products.


Assuntos
Nasturtium , Tiocianatos/farmacocinética , Tioglucosídeos/farmacocinética , Acetonitrilos/sangue , Acetonitrilos/farmacocinética , Acetonitrilos/urina , Acetilcisteína/sangue , Acetilcisteína/urina , Adulto , Pão , Testes Respiratórios/métodos , Feminino , Alimentos Fortificados , Humanos , Pessoa de Meia-Idade , Folhas de Planta , Tiocianatos/sangue , Tiocianatos/metabolismo , Tiocianatos/urina , Tioglucosídeos/sangue , Tioglucosídeos/metabolismo , Tioglucosídeos/urina
9.
Phys Chem Chem Phys ; 20(2): 1091-1097, 2018 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-29238765

RESUMO

We discuss spin injection and spin valves, which are based on organic and biomolecules, that offer the possibility to overcome some of the limitations of solid-state devices, which are based on ferromagnetic metal electrodes. In particular, we discuss spin filtering through bacteriorhodopsin in a solid state biomolecular spin valve that is based on the chirality induced spin selectivity (CISS) effect and shows a magnetoresistance of ∼2% at room temperature. The device is fabricated using a layer of bacteriorhodopsin (treated with n-octyl-thioglucoside detergent: OTG-bR) that is adsorbed on a cysteamine functionalized gold electrode and capped with a magnesium oxide layer as a tunneling barrier, upon which a Ni top electrode film is placed and used as a spin analyzer. The bR based spin valves show an antisymmetric magnetoresistance response when a magnetic field is applied along the direction of the current flow, whereas they display a positive symmetric magnetoresistance curve when a magnetic field is applied perpendicular to the current direction.


Assuntos
Bacteriorodopsinas/química , Imãs , Eletrodos , Elétrons , Ouro , Campos Magnéticos , Tioglucosídeos
10.
J Agric Food Chem ; 65(15): 3167-3178, 2017 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-28343387

RESUMO

A system of benzylic glucosinolates was found and characterized in common pepperweed, Lepidium densiflorum Schrad. The major glucosinolate was the novel 4-hydroxy-3,5-dimethoxybenzylglucosinolate (3,5-dimethoxysinalbin), present at high levels in seeds, leaves, and roots. Medium-level glucosinolates were 3,4-dimethoxybenzylglucosinolate and 3,4,5-trimethoxybenzylglucosinolate. Minor glucosinolates included benzylglucosinolate, 3-hydroxy- and 3-methoxybenzylglucosinolate, 4-hydroxybenzylglucosinolate (sinalbin), the novel 4-hydroxy-3-methoxybenzylglucosinolate (3-methoxysinalbin), and indole-type glucosinolates. A biosynthetic connection is suggested. NMR, UV, and ion trap MS/MS spectral data are reported, showing contrasting MS fragmentation of p-hydroxyls and p-methoxyls. Additional investigations by GC-MS focused on glucosinolate hydrolysis products. Whereas glucosinolates generally yielded isothiocyanates, the dominating 3,5-dimethoxysinalbin with a free p-hydroxyl group produced the corresponding alcohol and syringaldehyde (4-hydroxy-3,5-dimethoxybenzaldehyde). After thermal deactivation of the endogenous myrosinase enzyme, massive accumulation of the corresponding nitrile was detected. This case study points out how non-isothiocyanate glucosinolate hydrolysis products are prevalent in nature and of interest in both plant-pathogen interactions and human health.


Assuntos
Isotiocianatos/química , Lepidium/química , Extratos Vegetais/química , Tiocianatos/química , Tioglucosídeos/química , Hidrólise , Estrutura Molecular , Folhas de Planta/química , Sementes/química , Espectrometria de Massas em Tandem
11.
PLoS One ; 11(9): e0162397, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27622707

RESUMO

Nasturtium (Tropaeolum majus L.) contains high concentrations of benzylglcosinolate. We found that a hydrolysis product of benzyl glucosinolate-the benzyl isothiocyanate (BITC)-modulates the intracellular localization of the transcription factor Forkhead box O 1 (FOXO1). FoxO transcription factors can antagonize insulin effects and trigger a variety of cellular processes involved in tumor suppression, longevity, development and metabolism. The current study evaluated the ability of BITC-extracted as intact glucosinolate from nasturtium and hydrolyzed with myrosinase-to modulate i) the insulin-signaling pathway, ii) the intracellular localization of FOXO1 and, iii) the expression of proteins involved in gluconeogenesis, antioxidant response and detoxification. Stably transfected human osteosarcoma cells (U-2 OS) with constitutive expression of FOXO1 protein labeled with GFP (green fluorescent protein) were used to evaluate the effect of BITC on FOXO1. Human hepatoma HepG2 cell cultures were selected to evaluate the effect on gluconeogenic, antioxidant and detoxification genes and protein expression. BITC reduced the phosphorylation of protein kinase B (AKT/PKB) and FOXO1; promoted FOXO1 translocation from cytoplasm into the nucleus antagonizing the insulin effect; was able to down-regulate the gene and protein expression of gluconeogenic enzymes; and induced the gene expression of antioxidant and detoxification enzymes. Knockdown analyses with specific siRNAs showed that the expression of gluconeogenic genes was dependent on nuclear factor (erythroid derived)-like2 (NRF2) and independent of FOXO1, AKT and NAD-dependent deacetylase sirtuin-1 (SIRT1). The current study provides evidence that BITC might have a role in type 2 diabetes T2D by reducing hepatic glucose production and increasing antioxidant resistance.


Assuntos
Gluconeogênese/efeitos dos fármacos , Gluconeogênese/genética , Tiocianatos/farmacologia , Tioglucosídeos/farmacologia , Tropaeolum/química , Acetilcisteína/farmacologia , Transporte Ativo do Núcleo Celular/efeitos dos fármacos , Antioxidantes/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Proteína Forkhead Box O1/antagonistas & inibidores , Proteína Forkhead Box O1/genética , Proteína Forkhead Box O1/metabolismo , Expressão Gênica/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Gluconeogênese/fisiologia , Glucose-6-Fosfatase/genética , Células Hep G2 , Humanos , Hipoglicemiantes/química , Hipoglicemiantes/farmacologia , Isotiocianatos/química , Isotiocianatos/farmacologia , Fator 2 Relacionado a NF-E2/antagonistas & inibidores , Fator 2 Relacionado a NF-E2/genética , Fosfoenolpiruvato Carboxiquinase (ATP)/genética , Plantas Medicinais/química , Transporte Proteico/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Proteínas Proto-Oncogênicas c-akt/genética , RNA Interferente Pequeno/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Sirtuína 1/antagonistas & inibidores , Sirtuína 1/genética , Tiocianatos/química , Tioglucosídeos/química
12.
Carbohydr Res ; 426: 33-9, 2016 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-27058294

RESUMO

2-Azido-2-deoxy-1-thioglucoside donors with an electron withdrawing group at position 6 were employed to study the stereoselectivity of the glycosylation reaction with several acceptors, ranging from unhindered small primary alcohols to other sugars and steroids, using NIS/TfOH as promoter. p-Tolyl 2-azido-3,4-di-O-benzyl-6-O-chloroacetyl-2-deoxy-1-thio-α/ß-D-glucopyranoside afforded the higher α-selectivity, showing that a stronger electron withdrawing ester at O-6 influenced the anomeric selectivity towards the 1,2-cis glucosides. The anomeric stereoselectivity was highly dependent on the acceptor.


Assuntos
Álcoois/química , Carboidratos/química , Esteroides/química , Tioglucosídeos/química , Configuração de Carboidratos , Glicosilação , Estereoisomerismo
13.
Nat Prod Res ; 30(15): 1675-81, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26795632

RESUMO

Three new sulphur glycosides, raphanuside B-D (1-3), together with a known sulphur glycoside, raphanuside (4) were isolated from the decoction of the seeds of Descurainia sophia (L.) Webb ex Prantl, and the compound 4 was reported for the first time from this plant. Their structures were identified by means of UV, IR, 1D, 2D NMR (HSQC, HMBC and NOESY) and HR-ESI-MS spectroscopic data.


Assuntos
Brassicaceae/química , Glicosídeos/isolamento & purificação , Pirogalol/análogos & derivados , Tioglucosídeos/isolamento & purificação , Glicosídeos/química , Espectroscopia de Ressonância Magnética , Pirogalol/química , Pirogalol/isolamento & purificação , Sementes/química , Espectrometria de Massas por Ionização por Electrospray , Tioglucosídeos/química
14.
Mol Nutr Food Res ; 60(3): 652-60, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26610401

RESUMO

SCOPE: Benzyl isothiocyanate (BITC), which occurs in Brassicales, has demonstrated chemopreventive potency and cancer treatment properties in cell and animal studies. However, fate of BITC in human body is not comprehensively studied. Therefore, the present human intervention study investigates the metabolism of the glucosinolate (GSL) glucotropaeolin and its corresponding BITC metabolites. Analyzing BITC metabolites in plasma and urine should reveal insights about resorption, metabolism, and excretion. METHODS AND RESULTS: Fifteen healthy men were randomly recruited for a cross-over study and consumed 10 g freeze-dried Indian cress as a liquid preparation containing 1000 µmol glucotropaeolin. Blood and urine samples were taken at several time points and investigated by LC-ESI-MS/MS after sample preparation using SPE. Plasma contained high levels of BITC-glutathione (BITC-GSH), BITC-cysteinylglycine (BITC-CysGly), and BITC-N-acetyl-L-cysteine (BITC-NAC) 1-5 h after ingestion, with BITC-CysGly appearing as the main metabolite. Compared to human plasma, the main urinary metabolites were BITC-NAC and BITC-Cys, determined 4-6 h after ingestion. CONCLUSION: This study confirms that consumption of Indian cress increases the concentration of BITC metabolites in human plasma and urine. The outcome of this human intervention study supports clinical research dealing with GSL-containing innovative food products or pharmaceutical preparations.


Assuntos
Tiocianatos/farmacocinética , Tioglucosídeos/farmacocinética , Tropaeolum , Disponibilidade Biológica , Estudos Cross-Over , Humanos , Isotiocianatos/farmacocinética , Masculino , Experimentação Humana não Terapêutica , Distribuição Aleatória , Espectrometria de Massas em Tandem , Tiocianatos/metabolismo , Tioglucosídeos/metabolismo , Tropaeolum/química
15.
J Biol Inorg Chem ; 20(6): 1005-20, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26202908

RESUMO

While N-heterocyclic carbenes (NHC) are ubiquitous ligands in catalysis for organic or industrial syntheses, their potential to form transition metal complexes for medicinal applications has still to be exploited. Within this frame, we synthesized new homo- and heterobimetallic complexes based on the Au(I)-NHC scaffold. The compounds were synthesized via a microwave-assisted method developed in our laboratories using Au(I)-NHC complexes carrying a pentafluorophenol ester moiety and another Au(I) phosphane complex or a bipyridine ligand bearing a pendant amine function. Thus, we developed two different methods to prepare homo- and heterobimetallic complexes (Au(I)/Au(I) or Au(I)/Cu(II), Au(I)/Ru(II), respectively). All the compounds were fully characterized by several spectroscopic techniques including far infrared, and were tested for their antiproliferative effects in a series of human cancer cells. They showed moderate anticancer properties. Their toxic effects were also studied ex vivo using the precision-cut tissue slices (PCTS) technique and initial results concerning their reactivity with the seleno-enzyme thioredoxin reductase were obtained.


Assuntos
Antineoplásicos/síntese química , Antineoplásicos/uso terapêutico , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/uso terapêutico , Compostos Organoáuricos/síntese química , Tioglucosídeos/síntese química , Tioglucosídeos/uso terapêutico , Animais , Linhagem Celular Tumoral , Cobre , Glutationa Redutase/antagonistas & inibidores , Humanos , Compostos Organoáuricos/uso terapêutico , Ratos , Saccharomyces cerevisiae , Proteínas de Saccharomyces cerevisiae , Tiorredoxina Redutase 1/antagonistas & inibidores , Tiorredoxina Redutase 2/antagonistas & inibidores
16.
Plant J ; 81(6): 961-72, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25600688

RESUMO

The localization of metabolites on plant surfaces has been problematic because of the limitations of current methodologies. Attempts to localize glucosinolates, the sulfur-rich defense compounds of the order Brassicales, on leaf surfaces have given many contradictory results depending on the method employed. Here we developed a matrix-assisted laser desorption-ionization (MALDI) mass spectrometry protocol to detect surface glucosinolates on Arabidopsis thaliana leaves by applying the MALDI matrix through sublimation. Quantification was accomplished by spotting glucosinolate standards directly on the leaf surface. The A. thaliana leaf surface was found to contain approximately 15 nmol of total glucosinolate per leaf with about 50 pmol mm(-2) on abaxial (bottom) surfaces and 15-30 times less on adaxial (top) surfaces. Of the major compounds detected, 4-methylsulfinylbutylglucosinolate, indol-3-ylmethylglucosinolate, and 8-methylsulfinyloctylglucosinolate were also major components of the leaf interior, but the second most abundant glucosinolate on the surface, 4-methylthiobutylglucosinolate, was only a trace component of the interior. Distribution on the surface was relatively uniform in contrast to the interior, where glucosinolates were distributed more abundantly in the midrib and periphery than the rest of the leaf. These results were confirmed by two other mass spectrometry-based techniques, laser ablation electrospray ionization and liquid extraction surface analysis. The concentrations of glucosinolates on A. thaliana leaf surfaces were found to be sufficient to attract the specialist feeding lepidopterans Plutella xylostella and Pieris rapae for oviposition. The methods employed here should be easily applied to other plant species and metabolites.


Assuntos
Arabidopsis/metabolismo , Butiratos/metabolismo , Glucosinolatos/metabolismo , Folhas de Planta/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Tioglucosídeos/metabolismo , Animais , Borboletas/fisiologia , Feminino , Mariposas/fisiologia , Oviposição
17.
Org Biomol Chem ; 12(36): 7119-26, 2014 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-25098670

RESUMO

An α-S-(1→6)-linked pentaglucosyl thiol has been synthesized in a convenient and stereoselective way. Key steps of the synthesis involved thioglycosylation of 6-iodinated sugars with α-glycosyl thiols under phase transfer conditions. The α-configuration of glycosidic linkages was thus introduced prior to the coupling steps, and relied on the intrinsic configurational stability of α-glycosyl thiols. This work also demonstrated the great utility of MMTr as an effective anomeric S-protecting group.


Assuntos
Oligossacarídeos/química , Oligossacarídeos/síntese química , Compostos de Sulfidrila/química , Compostos de Sulfidrila/síntese química , Tioglucosídeos/síntese química , Glicosilação , Estrutura Molecular , Estereoisomerismo , Tioglucosídeos/química
18.
J Agric Food Chem ; 62(30): 7423-9, 2014 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-24998843

RESUMO

Meadowfoam (Limnanthes alba Hartw. ex Benth.) is an oilseed crop grown in the Willamette Valley of Oregon. Meadowfoam seed meal (MSM), a byproduct after oil extraction, contains 2-4% glucosinolate (glucolimnanthin). Activated MSM, produced by adding freshly ground myrosinase-active meadowfoam seeds to MSM, facilitates myrosinase-mediated formation of glucosinolate-derived degradation products with herbicidal activity. In the activated MSM, glucolimnanthin was converted into 3-methoxybenzyl isothiocyanate ("isothiocyanate") within 24 h and was degraded by day three. 3-Methoxyphenylacetonitrile ("nitrile") persisted for at least 6 days. Methoxyphenylacetic acid (MPAA), a previously unknown metabolite of glucolimnanthin, appeared at day three. Its identity was confirmed by LC-UV and high resolution LC-MS/MS comparisons with a standard of MPAA. Isothiocyanate inhibited lettuce germination 8.5- and 14.4-fold more effectively than MPAA and nitrile, respectively. Activated MSM inhibited lettuce germination by 58% and growth by 72% compared with the control. Results of the study suggest that MSM has potential uses as a pre-emergence bioherbicide.


Assuntos
Glucosinolatos/química , Glucosinolatos/farmacologia , Magnoliopsida/química , Sementes/química , Biodegradação Ambiental , Bioensaio , Cromatografia Líquida , Glicosídeo Hidrolases/metabolismo , Herbicidas/farmacologia , Isotiocianatos/metabolismo , Espectrometria de Massas em Tandem , Tiocianatos/farmacologia , Tioglucosídeos/farmacologia
19.
Angew Chem Int Ed Engl ; 53(15): 3894-8, 2014 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-24616005

RESUMO

Thiol-ene coupling (TEC) reactions emerged as one of the most useful processes for coupling different molecular units under reaction mild conditions. However, TEC reactions involving weak CH bonds (allylic and benzylic fragments) are difficult to run and often low yielding. Mechanistic studies demonstrate that hydrogen-atom transfer processes at allylic and benzylic positions are responsible for the lack of efficiency of the radical-chain process. These competing reactions cannot be prevented, but reported herein is a method to repair the chain process by running the reaction in the presence of triethylborane and catechol. Under these reaction conditions, a unique repair mechanism leads to an efficient chain reaction, which is demonstrated with a broad range of anomeric O-allyl sugar derivatives including mono-, di-, and tetrasaccharides bearing various functionalities and protecting groups.


Assuntos
Compostos Alílicos/química , Tioglucosídeos/síntese química , Boranos , Técnicas de Química Combinatória , Glicosídeos , Estrutura Molecular , Estereoisomerismo , Tioglucosídeos/química
20.
Arch Biochem Biophys ; 537(1): 1-4, 2013 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-23811198

RESUMO

A new, very efficient, class of thioglycoside substrates has been found for ß-glucosidase. While thioglycosides are usually resistant to hydrolysis, even in the presence of acids or most glycohydrolases, the ß-D-glucopyranosides of 2-mercaptobenzimidazole (GlcSBiz) and 2-mercaptobenzoxazole (GlcSBox) have been found to be excellent substrates for ß-glucosidase from both sweet almond (a family 1 glycohydrolase) and Aspergillus niger (a family 3 glycohydrolase), reacting nearly as well as p-nitrophenyl ß-D-glucoside. The enzyme-catalyzed hydrolysis of GlcSBiz proceeds with retention of configuration. As with the (1000-fold slower) hydrolysis of phenyl thioglucosides catalyzed by the almond enzyme, the pL (pH/pD)-independent kcat/KM does not show a detectable solvent deuterium kinetic isotope effect (SKIE), but unlike the hydrolysis of phenyl thioglucosides, a modest SKIE is seen on kcat [(D2O)kcat=1.28 (±0.06)] at the pL optimum (5.5≤pL≤6.6). A solvent isotope effect is also seen on the KM for the N-methyl analog of GlcSBiz. These results suggest that the mechanism for the hydrolysis of the ß-thioglucoside of 2-mercaptobenzimidazole and of 2-mercaptobenzoxazole involves remote site protonation (at the ring nitrogen) followed by cleavage of the thioglucosidic bond resulting in the thione product.


Assuntos
Tioglucosídeos/química , beta-Glucosidase/química , Sítios de Ligação , Ativação Enzimática , Estabilidade Enzimática , Ligação Proteica , Especificidade por Substrato
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