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1.
Chemosphere ; 240: 124877, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31541898

RESUMO

An anaerobic stable mixed culture dominated by bacteria belonging to the genera Dehalobacterium, Acetobacterium, Desulfovibrio, and Wolinella was used as a model to study the microbial interactions during DCM degradation. Physiological studies indicated that DCM was degraded in this mixed culture at least in a three-step process: i) fermentation of DCM to acetate and formate, ii) formate oxidation to CO2 and H2, and iii) H2/CO2 reductive acetogenesis. The 16S rRNA gene sequencing of cultures enriched with formate or H2 showed that Desulfovibrio was the dominant population followed by Acetobacterium, but sequences representing Dehalobacterium were only present in cultures amended with DCM. Nuclear magnetic resonance analyses confirmed that acetate produced from 13C-labelled DCM was marked at the methyl ([2-13C]acetate), carboxyl ([1-13C]acetate), and both ([1,2-13C]acetate) positions, which is in accordance to acetate formed by both direct DCM fermentation and H2/CO2 acetogenesis. The inhibitory effect of ten different co-contaminants frequently detected in groundwaters on DCM degradation was also investigated. Complete inhibition of DCM degradation was observed when chloroform, perfluorooctanesulfonic acid, and diuron were added at 838, 400, and 107 µM, respectively. However, the inhibited cultures recovered the DCM degradation capability when transferred to fresh medium without co-contaminants. Findings derived from this work are of significant relevance to provide a better understanding of the synergistic interactions among bacteria to accomplish DCM degradation as well as to predict the effect of co-contaminants during anaerobic DCM bioremediation in groundwater.


Assuntos
Cloreto de Metileno/química , Anaerobiose
2.
J Environ Sci (China) ; 86: 187-194, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31787183

RESUMO

Enzymatic electrolysis cell (EEC) has advantages over microbial electrolysis cell (MEC) due to the needless of microbe inoculation and high-efficiency of enzymatic reaction. In this study, an EEC was first applied to achieve the effective degradation of halogenated organic pollutants and dichloromethane (CH2Cl2) was utilized as a model pollutant. The results indicate that the degradation efficiency of CH2Cl2 after 2 hr reaction in the EEC was almost 100%, which was significantly higher than that with enzyme (51.1%) or current (19.0%). The current induced the continuous regeneration of reduced glutathione (GSH), thus CH2Cl2 was degraded under the catalysis of GSH-dependent dehalogenase through stepwise dechlorination, and successively formed monochloromethane (CH3Cl) and methane (CH4). The kinetic result shows that with a current of 15 mA, the maximum specific degradation rate of CH2Cl2 (3.77 × 10-3hr-1) was increased by 5.7 times. The optimum condition for CH2Cl2 dechlorination was also obtained with pH, current and temperature of 7.0, 15 mA and 35°C, respectively. Importantly, this study helps to understand the behavior of enzymes and the fate of halogenated organic pollutants with EEC, providing a possible treatment technology for halogenated organic pollutants.


Assuntos
Cloreto de Metileno/química , Biodegradação Ambiental , Catálise , Eletrólise , Eletrólitos , Cinética , Metano
3.
Chemosphere ; 235: 1146-1153, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561305

RESUMO

Waste is a misplaced resource. Herein, anionic (orange II sodium salt and Ponceau 2R) and cationic (Rhodamine B and Methylene blue) dye wastewater assisted photo-treatment (referred as DAPT) method was developed to modify sol-gel synthesized CeO2-TiO2 (CeTi) mixed oxide catalyst. Catalytic activity test results showed that both anionic and cationic dye wastewater could be used as "fuel" of photo-treatment to enhance the activity of CeTi catalyst in NO reduction and dichloromethane oxidation. Characterization and DFT calculation results revealed that DAPT process increased the amount of Ce3+ ions on CeTi samples, which could induce the formation of Ce-VO-Ti (oxygen vacancy (VO) in Ce-O-Ti short range structure). These Ce-VO-Ti defects not only could be adsorption sites for NH3, dichloromethane and oxygen, but also promoted the redox shift of Ce3++ Ti4+ ⇋ Ce4++ Ti3+ by enhancing the oxidizability of Ce4+ and Ti4+ species. Furthermore, defects changed the polarity of Ce-O and Ti-O, which was conducive to the activation of lattice oxygen. All these improvements contributed to the excellent catalytic activity of CeTi catalysts. We expected this work to be instructive on constructing structure-activity over CeO2-TiO2 based catalysts and utilizing dye wastewater.


Assuntos
Cério/química , Cloreto de Metileno/química , Óxido Nítrico/química , Titânio/química , Águas Residuárias/química , Adsorção , Catálise , Corantes , Oxirredução , Oxigênio/química
4.
J Environ Sci (China) ; 84: 59-68, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31284917

RESUMO

A catalyst based on mixed V-Ni oxides supported on TiO2 (Ni-V/TiO2) was obtained using the sol-gel method. Its catalytic performance relative to dichloromethane (DCM) degradation was investigated. Characterization and analysis were conducted using transmission electron microscopy, H2 temperature-programmed reduction, pyridine-Fourier transform infrared spectroscopy (FTIR) characterization, and X-ray diffraction. Results showed that the original hollow anatase structure of pure TiO2 was well-maintained after Ni-V loading. The loading of NiO-VOx not only significantly improved the stability of pure TiO2 but also inhibited the formation of the by-product monochloromethane (MCM). Among the series of Ni-V/TiO2 catalysts, 4%Ni-V/TiO2 possessed the highest catalytic activity, with 90% DCM conversion at only 203°C. No by-products and no significant changes in the catalytic activity were observed during combustion of DCM after 100 hr of a continuous stability test. Furthermore, thermogravimetric analysis (O2-TG) and energy dispersive spectrometer (EDS) characterization of the used 4%Ni-V/TiO2 catalyst revealed that no coke deposition or chlorine species could be detected on the catalyst surface.


Assuntos
Cloreto de Metileno/química , Titânio/química , Catálise , Oxirredução
5.
Molecules ; 24(14)2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31311194

RESUMO

Epithelial-to-mesenchymal transition (EMT) is increasingly recognized as contributing to the pathogenesis of idiopathic pulmonary fibrosis. Therefore, novel plant-based natural, active compounds have been sought for the treatment of fibrotic EMT. The aim of the present study was to investigate the inhibitory effects of Astilbe rubra on TGF-ß1-induced EMT in lung alveolar epithelial cells (A549). A. rubra was subjected to extraction using 70% ethanol (ARE), and ethanol extracts of the aerial part and that of the rhizome were further partitioned using various solvents. Protein expression and cell motility were investigated to evaluate the inhibitory effects of ARE on EMT. EMT occurred in A549 cells treated with TGF-ß1, but was prevented by co-treatment with ARE. The dichloromethane fractions showed the strongest inhibitory effect on TGF-ß1-induced EMT. ß-Peltoboykinolic acid was isolated from the dichloromethane fractions of A. rubra by activity-oriented isolation. ß-Peltoboykinolic acid not only attenuated TGF-ß1-induced EMT, but also the overproduction of extracellular matrix components including type I collagen and fibronectin. The Smad pathway activated by TGF-ß1 was inhibited by co-treatment with ß-peltoboykinolic acid. Taken together, these results indicate that ß-peltoboykinolic acid from A. rubra and dichloromethane fractions shows potential as an antifibrotic agent in A549 cells treated with TGF-ß1.


Assuntos
Células Epiteliais Alveolares/citologia , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Cloreto de Metileno/farmacologia , Saxifragaceae/química , Fator de Crescimento Transformador beta1/efeitos adversos , Células A549 , Células Epiteliais Alveolares/efeitos dos fármacos , Células Epiteliais Alveolares/metabolismo , Movimento Celular/efeitos dos fármacos , Colágeno Tipo I/metabolismo , Fibronectinas/metabolismo , Fibrose , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Cirrose Hepática/tratamento farmacológico , Cirrose Hepática/metabolismo , Cloreto de Metileno/química , Componentes Aéreos da Planta/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Rizoma/química , Transdução de Sinais/efeitos dos fármacos
6.
J Immunoassay Immunochem ; 40(5): 459-472, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31204615

RESUMO

Several plants of Satureja genus have shown anti-tumor activity. We investigated the antileukemia effects of different fractions of Satureja hortensis (Summer savory). The growth inhibitory effect of S. hortensis fractions on K562 and Jurkat leukemia cells were determined by MTT assay. The most effective fractions were analyzed by flow cytometry and colorimetric assay for apoptosis induction and cell cycle changes. Various fractions from S. hortensis showed growth inhibitory effects on leukemia cells, among them two hexane and dichloromethane fractions with IC50 values of 32.1-47.8 µg/ml (K562) and 44.3-45.7 µg/ml (Jurkat) were the most effective. According to annexin V staining, both of these fractions significantly induced apoptosis at 50µg/ml in K562 (hexane; 73.06 ± 5.11% and dichloromethane; 96.14 ± 2.33%) and Jurkat cells (hexane; 78.85 ± 11.9% and dichloromethane; 94.05 ± 2.47%) 48 h after treatment. They increased cell accumulation in sub-G1 phase (>50%, p < .001) and decreased number of cells in G0-G1, S and G2M phases. The fractions significantly increased the caspase-3 activity in both cell lines (≈2.5-3.5 fold of untreated cells). Hexane and dichloromethane fractions of S. hortensis had the capacity to induce death and change the cell cycle distribution in leukemia cells; therefore they might be good candidates for more studies in regard to their possible therapeutic usefulness in leukemia.


Assuntos
Ciclo Celular/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Hexanos/farmacologia , Leucemia de Células T/patologia , Cloreto de Metileno/farmacologia , Extratos Vegetais/farmacologia , Satureja/química , Proliferação de Células/efeitos dos fármacos , Colorimetria , Relação Dose-Resposta a Droga , Hexanos/química , Hexanos/isolamento & purificação , Humanos , Células Jurkat , Células K562 , Leucemia de Células T/tratamento farmacológico , Cloreto de Metileno/química , Cloreto de Metileno/isolamento & purificação , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação
7.
Chemosphere ; 233: 687-696, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31195273

RESUMO

Formerly classified as naphthenic acids, "naphthenic acids fraction compounds" (NAFC) have become the subject of increasing research, in particular in view of their ubiquitous presence in the Canadian oil sands of Northern Alberta and oil sands process-affected waters (OSPW). NAFC, defined herein as the polar acid-extractable organics fraction of OSPW extractable in dichloromethane, are released into OSPW during the aqueous extraction of oil sands. A method for determining total NAFC concentration based on acidification, liquid-liquid extraction, and Fourier-Transform Infrared Spectroscopy (FT-IR) was developed by Jivraj et al. in 1995. It has become widely used in the oil sands industry for routine monitoring of NAFC. Since then, multiple variations of the method are practiced by different laboratories using different calibration materials and different extraction solvents, differences which were found to affect the results by as much as 38 and 64 percent respectively. The goal of this study was to establish a robust method for routinely quantifying NAFC that does not require complex and expensive laboratory equipment such as mass spectrometers. Described improvements include a semi-automated rolling extraction and the use of a vacuum evaporator unit to reduce the method's environmental impact. The improved FT-IR method avoids emulsions, is precise, provides good agreement with gravimetric determinations of NAFC, increases sample throughput, is inexpensive compared to MS methods, and offers a typical reporting limit of 0.1 mg kg-1. The residue recovered by this method with minimal losses can be further analyzed by MS techniques to characterize and identify individual NAFC components if desired.


Assuntos
Ácidos Carboxílicos/análise , Monitoramento Ambiental/métodos , Extração Líquido-Líquido , Campos de Petróleo e Gás , Poluentes Químicos da Água/análise , Alberta , Calibragem , Espectrometria de Massas , Cloreto de Metileno/química , Compostos Orgânicos , Espectroscopia de Infravermelho com Transformada de Fourier , Água/química
8.
Molecules ; 24(12)2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31200488

RESUMO

Platelets are an important component of the initial response to vascular endothelial injury; however, platelet dysfunction induces the acute clinical symptoms of thrombotic disorders, which trigger severe cardiovascular diseases such as myocardial infarction, ischemia, and stroke. In this study, we investigated the Dryopteris crassirhizoma's antiplatelet activity. A water extract of D. crassirhizoma (WDC) was partitioned into dichloromethane (DCM), ethyl acetate, n-butyl alcohol, and water. Among these four fractions, the DCM fraction potently inhibited the collagen-stimulated platelet aggregation in a concentration-dependent manner. From this fraction, five different acylphloroglucinol compounds and one flavonoid were isolated by activity-guided column chromatography. They were identified by comparing their mass, 1H-, and 13C-NMR spectral data with those reported in the literature. Quantifying the six compounds in WDC and its DCM fraction by high-performance liquid chromatography (HPLC) revealed that butyryl-3-methylphloroglucinol (compound 4) was the most abundant in these samples. Additionally, butyryl-3-methylphloroglucinol showed the strongest inhibitory activity in the collagen- and arachidonic acid (AA)-induced platelet aggregation, with inhibition ratios of 92.36% and 89.51% in the collagen and AA-induced platelet aggregation, respectively, without cytotoxicity. On the active concentrations, butyryl-3-methylphloroglucinol significantly suppressed the convulxin-induced platelet activation. Regarding the structure-activity relationships for the five acylphloroglucinol compounds, our results demonstrated that the functional butanonyl, methoxy, and hydroxy groups in butyryl-3-methylphloroglucinol play important roles in antiplatelet activity. The findings indicate that acylphloroglucinols, including butyryl-3-methylphloroglucinol from D. crassirhizom, possess an antiplatelet activity, supporting the use of this species for antiplatelet remedies.


Assuntos
Plaquetas/fisiologia , Dryopteris/química , Animais , Cromatografia Líquida de Alta Pressão , Masculino , Cloreto de Metileno/química , Estrutura Molecular , Extratos Vegetais/química , Ativação Plaquetária , Agregação Plaquetária , Coelhos
9.
Drug Res (Stuttg) ; 69(10): 551-558, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31141826

RESUMO

Pycnanthus angolensis (Welw) Warb., Myristicaceae, is used extensively in ethnomedicine. Numerous health benefits have been ascribed to the use of different parts of P. angolensis including its role in cognitive function and inflammatory conditions. Hence, this study was undertaken to investigate the effect of stem bark of the plant on memory function in mice.The plant material was pulverized into powder and extracted by maceration with 80% methanol at room temperature for 48 h. This was subsequently fractionated using N-hexane, Dichloromethane (DCM) and Ethyl acetate. The Dichloromethane fraction which is the most potent fraction (25, 50 and 100 mg/kg) was evaluated for memory enhancing activity using the Y-maze (YMT), morris water maze (MWM) and the elevated plus maze (EPM) on D-galactose plus scopolamine and ketamine induced amnesia. The antioxidant markers and acetylcholinesterase (AChE) inhibiting effect of DCM were also investigated.The results obtained from the behavioural study indicates that the DCM fraction significantly (p<0.05) increased alternation behaviour of mice in the YMT, decreased the escape latency in the MWM paradigm and decreased the transfer latency in the EPM. Biochemically, DCM increased glutathione, and superoxide dismutase, but decreased malondialdehyde and AChE activity in the brain.The findings therefore suggests that the DCM possesses significant memory enhancing activity, which may be due to enhancement of antioxidant activity and cholinergic transmission. The attenuation of the effect of ketamine by the DCM may possibly result from an increase in NMDA receptor mediated neurotransmission and attenuation of oxidative stress.


Assuntos
Amnésia/tratamento farmacológico , Encéfalo/efeitos dos fármacos , Inibidores da Colinesterase/farmacologia , Myristicaceae/química , Extratos Vegetais/farmacologia , Acetilcolinesterase/metabolismo , Amnésia/induzido quimicamente , Amnésia/patologia , Animais , Encéfalo/patologia , Inibidores da Colinesterase/isolamento & purificação , Inibidores da Colinesterase/uso terapêutico , Modelos Animais de Doenças , Galactose/toxicidade , Humanos , Ketamina/toxicidade , Masculino , Aprendizagem em Labirinto , Cloreto de Metileno/química , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Casca de Planta/química , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/uso terapêutico , Receptores de N-Metil-D-Aspartato/metabolismo , Escopolamina/toxicidade , Transmissão Sináptica/efeitos dos fármacos
10.
J Chromatogr A ; 1601: 385-387, 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31122730

RESUMO

Although the inverse gas chromatography technique has been used to measure the surface acid-base properties for almost 50 years, several basic problems still hinder its further development and application. One of the problems is that for the polar probe molecules of dichloromethane, acetone, ethyl acetate, tetrahydrofuran, and ethanol, the molecular area of each probe has different values in literature. In this paper, we point out the incorrect molecular area values presented in the literature by comparing these values with those indicated in Smallwood's Handbook of Organic Solvent Properties. The correct molecular area values of 11 polar probes are determined by plotting the molecular areas of the polar probes versus the van der Waals surface areas reported in the handbook. The correct molecular areas for six common polar probes, namely, dichloromethane, trichloromethane, acetone, ethyl acetate, diethyl ether, and tetrahydrofuran, are 38.0, 44.0, 42.5, 48.0, 47.0, and 45.0 Å2, respectively. Benzene is a specific molecule with a conjugated π-bond structure, and its molecular area is estimated to be larger than that of other molecules. Therefore, benzene is unsuitable for use as a probe molecule.


Assuntos
Cromatografia Gasosa/métodos , Cromatografia Gasosa/normas , Sondas Moleculares/química , Acetatos/química , Acetona/química , Ácidos/química , Etanol/química , Furanos/química , Cloreto de Metileno/química , Solventes/química , Propriedades de Superfície , Termodinâmica
11.
Lett Appl Microbiol ; 69(1): 57-63, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31002429

RESUMO

This study aimed to evaluate the antimicrobial activity of the dichloromethane fraction (DCMF) from the stem bark of Mimosa caesalpiniifolia and its effect on the activity of conventional antibiotics against Staphylococcus aureus strains overexpressing specific efflux pump genes. DCMF showed activity against S. aureus, Staphylococcus epidermidis and Candida albicans. Addition of DCMF at subinhibitory concentrations to the growth media enhanced the activity of norfloxacin, ciprofloxacin and ethidium bromide against S. aureus strains overexpressing norA suggesting the presence of efflux pump inhibitors in its composition. Similar results were verified for tetracycline against S. aureus overexpressing tetK, as well as, for ethidium bromide against S. aureus overexpressing qacC. These results indicate that M. caesalpiniifolia is a source of molecules able to modulate the fluoroquinolone- and tetracycline-resistance in S. aureus probably by inhibition of NorA, TetK and QacC respectively. SIGNIFICANCE AND IMPACT OF THE STUDY: Drug resistance is a common problem in patients with infectious diseases. Dichloromethane fraction from the stem bark of Mimosa caesalpiniifolia showed antimicrobial activity against Gram-positive bacterium Staphylococcus aureus and against Candida albicans, but did not show activity against Gram-negative specie Escherichia coli. Moreover, this fraction was able to potentiate the action of norfloxacin, ciprofloxacin and tetracycline against S. aureus strains overexpressing different efflux pump genes. Thus, Mimosa caesalpiniifolia is a source of efflux pump inhibitors which could be used in combination with fluoroquinolones or tetracycline in the treatment of infectious diseases caused by S. aureus strains overexpressing efflux pump genes.


Assuntos
Antibacterianos/farmacologia , Candida albicans/efeitos dos fármacos , Mimosa/química , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus epidermidis/efeitos dos fármacos , Antiporters/genética , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Ciprofloxacino/farmacologia , Resistência a Múltiplos Medicamentos/genética , Etídio/farmacologia , Fluoroquinolonas/farmacologia , Humanos , Cloreto de Metileno/química , Testes de Sensibilidade Microbiana , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/metabolismo , Norfloxacino/farmacologia , Casca de Planta/química , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/genética , Tetraciclina/farmacologia , Resistência a Tetraciclina/genética
12.
J Pharm Biomed Anal ; 166: 128-138, 2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30640043

RESUMO

In this study, different solvent extracts (methanol, dichloromethane and n-hexane) from aerial and stem parts of Buxus papillosa C.K. Schneid (Buxaceae) were investigated for a panoply of bioassays. Biological profiles were established by determining antioxidant and enzyme inhibition profiles. Toxicity was tested using MTT cell viability assay on five different human cancer cell lines i.e, MCF-7, MDA-MB-231, CaSki, DU-145 and SW-480. For chemical fingerprinting, total bioactive contents and UHPLC-MS secondary metabolites profile were determined. Generally, both aerial and stem methanol extracts had highest total bioactive contents, radical scavenging and reducing power potential. DCM and n-hexane extracts were found to be most active for total antioxidant and metal chelating activity. The UHPLC-MS analysis of methanol extracts revealed the presence of several phenolic, flavonoid, alkaloid, saponin and depsipeptide derivatives. All the extracts were significantly active against butyrylcholinesterase, whereas moderate inhibition was observed for acetylcholinesterase, α-glucosidase and urease. Similarly, a considerable level of cytotoxicity was observed against all the tested cell lines with IC50 values ranging from 26 to 225.9 µg/mL. Aerial methanol and stem n-hexane extracts were found to be most cytotoxic. Principal component analysis was also performed to find any possible correlation between biological activities and total bioactive contents. On the basis of our findings, B. papillosa may be considered as promising source of bioactive molecules.


Assuntos
Buxus/química , Extratos Vegetais/farmacologia , Extratos Vegetais/farmacocinética , Extratos Vegetais/toxicidade , Polifenóis/análise , Antioxidantes/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Inibidores da Colinesterase/farmacologia , Hexanos/química , Humanos , Metanol/química , Cloreto de Metileno/química , Componentes Aéreos da Planta/química , Extratos Vegetais/química , Caules de Planta/química
13.
Photochem Photobiol Sci ; 18(1): 253-258, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30357242

RESUMO

A photochemically chemically active noncanonical amino acid para-azido-l-phenylalanine widely used in biology was found to be metabolized by Saccharomyces cerevisiae. Contrary to multiple reports, the azide moiety is not reduced to the corresponding amine. The amino acid's concentration was found to decline somewhat with time which was due, at least in part, to modification of the amino acid side chain. The metabolite was found to be photochemically active and further characterization concluded the azide moiety was still intact. This work also goes onto highlight paramount areas of concern with regards to (photo)chemical compatibility, handling, and fidelity in genetically encoding aryl azide amino acids.


Assuntos
Azidas/análise , Fenilalanina/análogos & derivados , Fenilalanina/análise , Saccharomyces cerevisiae/metabolismo , Azidas/química , Desaminação , Cloreto de Metileno/análise , Cloreto de Metileno/química , Ressonância Magnética Nuclear Biomolecular , Fenilalanina/química , Processos Fotoquímicos , Fotólise , Espectroscopia de Infravermelho com Transformada de Fourier
14.
Photochem Photobiol Sci ; 18(1): 80-91, 2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30320862

RESUMO

Rifampicin (Rif) is an effective antibiotic against mycobacterial infections and a wide range of Gram-positive and Gram-negative bacteria. The geometry, conformation and the intramolecular H-bond network of Rif can affect its antibacterial efficiency. In this work, we report on the excited-state dynamics of Rif in sodium phosphate buffer and dichloromethane solutions using femtosecond time-resolved spectroscopic methods. The femtosecond UV-Vis-nearIR transient absorption and fluorescence up-conversion experiments reveal an ultrafast (<100 fs) Franck-Condon relaxation with a partial charge transfer character in S1, and a short-lived emission (τ∼ 6 ps) due to a non-radiative relaxation to the ground state, associated with the stretching of the vibrational mode of the Rif internal H-bond network. The large Stokes-shifted emission (∼6800 cm-1) indicates a significant electronic change in the excited-state. In deuterated potassium phosphate buffer, the decay time becomes longer (∼20 ps). The large kinetic isotope effect (KIE) of ∼4 on the decay rate indicates that the stretching modes of the internal H-bond network are slowed by the H/D isotope substitution. The results provide new information on the dynamics of Rif structures and the related processes in aqueous solutions, showing that the internal H-bonding interactions are the ones that govern the ground and excited state properties of Rif but water molecules exert additional stabilization of its zwitterionic form through intermolecular H-bonds, which is responsible for its high antimicrobial activity.


Assuntos
Antibióticos Antituberculose/química , Rifampina/química , Água/química , Tampões (Química) , Deutério/química , Corantes Fluorescentes/química , Hidrogênio/química , Ligações de Hidrogênio , Isótopos , Cloreto de Metileno/química , Fosfatos/química , Compostos de Potássio/química
15.
Chemosphere ; 214: 553-562, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30286422

RESUMO

In recent years, significant effort has been made in the development of novel catalysts for the total oxidation of chlorinated volatile organic compounds. In this work the catalytic activity of Cu doped cerium-titanium binary oxides for the oxidation of dichloromethane (DCM) have been studied for the first time. Combining catalysts characterization and activity data, it was found that Cu ions can uniformly disperse into titanium dioxide to form solid solution and induce the creation of additional surface oxygen species on the catalysts surface, while moderate amount of Ce ions are still needed for the activation of CCl. Detailed analysis of the in-situ FTIR experiment results revealed that the surface oxygen species, especially the hydroxyl groups associated with Cu ions, can promote the deep oxidation of the intermediate species formed in the nucleophilic substitution process occurred on the active sites of catalysts surface. The sample with the Cu/Ce molar ratio of 1:3 obtained a better CO2 selectivity than that reached with cerium-titanium binary oxides. Meanwhile, according to element balance analysis, removal of chlorine from the catalyst surface was also promoted by Cu doping.


Assuntos
Cério/química , Cobre/química , Gases/química , Cloreto de Metileno/química , Titânio/química , Catálise , Oxirredução
16.
J Stroke Cerebrovasc Dis ; 28(3): 751-760, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30528673

RESUMO

BACKGROUND: Piper nigrum L. and Piper longum L. consist a classic formula in traditional Chinese Hui medicine and are widely used in treatment of stroke. To examine the therapeutic effect of neuron injury after apoplexy, we used a permanent middle cerebral artery occlusion model in rats to investigate the effects of dichloromethane fraction (DF) of Piper nigrum L. and Piper longum L. MATERIALS AND METHODS: After subjecting the rats to permanent middle cerebral artery occlusion, DF (100 and 200 mg/kg) were administered for 14 days. Neurological deficits and the degree of cerebral tissue injury was detected by 2,3,5-Triphenyltetrazolium Chloride Staining Hematoxylin and eosin staining and Nissl staining. Postsynaptic density protein 95 (PSD-95), synapsin-I (syn-I), and α-synuclein (α-syn) were stained by immunohistochemistry. PSD-95, Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMK II), phosphorylated CaMK II (p-CaMK II), CaM, N-methyl D-aspartate receptor subtype 2B (NR2B) expression were detected by Western blot. Meanwhile, phytochemical profile of DF was determined through ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). RESULTS: DF alleviated neurological deficits and markedly prevented ischemia-induced cellular damage. Immunohistochemical micrographs revealed that PSD-95 and syn-I proteins increased, and α-syn presented reduced expression in brain samples from the sham group. Western blot analyses revealed that the model group exhibited a noticeable reduction in PSD-95, p-CaMK II, CaM, and NR2B. The DF-treated model group exhibited increased PSD-95, p-CaMK II, CaM, and NR2B. UPLC-Q-TOF/MS analysis revealed eight main components of DF, of which piperine accounted for the largest proportion.


Assuntos
Encéfalo/efeitos dos fármacos , Infarto da Artéria Cerebral Média/prevenção & controle , Cloreto de Metileno/química , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Piper nigrum , Piper , Extratos Vegetais/farmacologia , Solventes/química , Animais , Comportamento Animal/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Encéfalo/fisiopatologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Calmodulina/metabolismo , Modelos Animais de Doenças , Proteína 4 Homóloga a Disks-Large/metabolismo , Infarto da Artéria Cerebral Média/metabolismo , Infarto da Artéria Cerebral Média/patologia , Infarto da Artéria Cerebral Média/fisiopatologia , Masculino , Atividade Motora/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Fármacos Neuroprotetores/isolamento & purificação , Fosforilação , Piper/química , Piper nigrum/química , Extratos Vegetais/isolamento & purificação , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapsinas/metabolismo , alfa-Sinucleína/metabolismo
17.
Ecotoxicol Environ Saf ; 170: 148-155, 2019 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-30529613

RESUMO

The purpose of this study was to develop a novel and sensitive method for the analysis of carbazole and polyhalogenated carbazoles (PHCs) in sediment using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Briefly, 5.0 g of freeze-dried sediment samples were extracted with dichloromethane using pressurized liquid extraction (PLE). The extract was purified with Florisil solid phase extraction cartridge, filtered through 0.22 µm polytetrafluoroethylene filter using a glass syringe, followed by LC-MS/MS analysis. Besides parameters for LC-MS/MS analysis, sample preparation procedures (including solvents for PLE, sorbents for cleanup, and filters for sample filtration) were optimized. The limits of detection and limits of quantification of target compounds were in the ranges of 3.0 × 10-3 to 0.22 ng g-1 dry weight (d.w.) and 1.0 × 10-2 to 0.75 ng g-1 d.w., respectively. The recoveries of target compounds in the spiked sediments at 2.0 ng g-1 d.w. and 10 ng g-1 d.w. were 64.8-91.8% and 70.9-124.7%, respectively, with relative standard deviations being less than 13.2%. Except that 36-BCZ had positive matrix effects of 63.3%, the sediment matrices generally displayed low or medium negative matrix effects on the other target compounds during LC-MS/MS analysis. The developed method was applied in the analysis of carbazoles and PHCs in sediment samples from Jiulong River, Fujian, China and all the target compounds were detected in the samples.


Assuntos
Carbazóis/análise , Cromatografia Líquida , Sedimentos Geológicos/química , Espectrometria de Massas em Tandem , China , Limite de Detecção , Silicatos de Magnésio/química , Cloreto de Metileno/química , Politetrafluoretileno/análise , Reprodutibilidade dos Testes , Rios/química , Extração em Fase Sólida
18.
Mar Pollut Bull ; 136: 248-256, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30509805

RESUMO

Conventional methods for determination of polycyclic aromatic compounds (PACs) in sediments usually require large sample sizes (grams) and solvent volumes (at least 100 mL) through the employment of Soxhlet extraction, which is both time (hours) and energy consuming, among other disadvantages. We developed a new analytical protocol for the determination of PACs in sediments using microextraction, which requires small sample masses (25 mg), 500 µL of acetonitrile-dichloromethane mix and sonication for 23 min, followed by GC-MS analysis. The method was validated using the certified reference material SRM 1941b - NIST organic marine sediment, as well as internal deuterated standards. Seventeen PAHs, seven nitro-PAHs and one quinone were detected and quantified. The mean concentrations were 90.4 ng g-1 for PAHs, 179.2 ng g-1 for nitro-PAHs and 822.5 ng g-1 for quinones. The proposed method showed good sensitivity, linearity, precision and accuracy for the determination of PAC in sediments samples.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Sedimentos Geológicos/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Acetonitrilos/química , Brasil , Fracionamento Químico/métodos , Cloreto de Metileno/química , Nitratos/química , Oxigênio/química , Hidrocarbonetos Policíclicos Aromáticos/química , Quinonas/análise , Reprodutibilidade dos Testes , Rios , Poluentes Químicos da Água/química
19.
Int J Mol Sci ; 19(11)2018 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-30453554

RESUMO

Reflux esophagitis (RE) is a gastrointestinal disease caused by the reflux of gastric acid and stomach contents, and it leads to esophageal damage. Therefore, it is necessary to study the improvement of esophageal damage on a RE-induced model. The present study was accomplished to demonstrate the protective effects of a dichloromethane fraction of Geranium koreanum (DGK) plant on esophageal damage in an acute RE rat model. First, we examined the potential of anti-inflammatory effects of various fractions measured by cell cytotoxicity, morphological changes and nitric oxide (NO) production on lipopolysaccharide (LPS)-induced Raw 264.7 macrophage cells. Then, to evaluate the protective effects on RE, rats were partitioned into the following groups: normal control, RE-induced control and RE rats pre-treated with DGK 100 and 200 mg/kg body weight. The esophageal mucosal ulcer ratio was measured by the Image J program and histological changes were examined using a hematoxylin and eosin staining of the esophageal mucosa. The expression of pro-inflammatory proteins, cytokines and tight junction proteins involved in the esophageal mucosal damage were investigated using Western blotting and an enzyme-linked immunosorbent assay (ELISA) kit with esophagus tissue. DGK chemical profile and phenolic contents were analyzed by liquid chromatography-mass spectrometry (LC-MS/MS). The results showed that DGK exhibited anti-inflammatory effects against LPS-stimulated cells by significantly inhibiting NO production. Additionally, the results in vivo showed that improvement effects of DGK on esophageal mucosal damage. The expression of inflammatory proteins involved in nuclear factor κB (NF-κB) signaling pathways and tight junction protein (claudin-4 and -5) were significantly decreased in esophageal mucosa. We found the potential of DGK as source of replacement therapy products for inflammatory and RE disease.


Assuntos
Anti-Inflamatórios/uso terapêutico , Esofagite Péptica/tratamento farmacológico , Esôfago/patologia , Geranium/química , Cloreto de Metileno/química , Extratos Vegetais/uso terapêutico , Animais , Anti-Inflamatórios/farmacologia , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cromatografia Líquida , Claudinas/metabolismo , Esofagite Péptica/patologia , Esôfago/efeitos dos fármacos , Inflamação/complicações , Inflamação/patologia , Lipopolissacarídeos , Camundongos , Membrana Mucosa/efeitos dos fármacos , Membrana Mucosa/patologia , Óxido Nítrico/biossíntese , Óxido Nítrico Sintase Tipo II/metabolismo , Extratos Vegetais/farmacologia , Polifenóis/análise , Células RAW 264.7 , Ratos , Espectrometria de Massas em Tandem , Junções Íntimas/metabolismo
20.
J Am Chem Soc ; 140(49): 17297-17307, 2018 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-30424604

RESUMO

This work provides a platform for the rapid generation of superstructure assemblies with a wide range of lengths that can be used to access a variety of metal-organic complex-based soft superstructures. Metallacage-based microneedles that are nanometers in diameter and millimeters in length were generated in dichloromethane and ethyl acetate; their size could be controlled by adjusting the ratio of the two solvents. Interestingly, microflower structures could be formed by further assembly of the microneedles during solvent evaporation. Our study establishes a feasible method designed to broaden the range of suprastructures with emissions from blue and green to red through the co-assembly of lysine-modified perylene. Similar to the co-assembly of lysine-modified perylene with microflowers, chlorophyll-a and vitamin B12 were introduced into the microflowers during the assembly process, which may be exploited in studies of energy capture and nerve repair in the future.


Assuntos
Complexos de Coordenação/química , Ácidos Dicarboxílicos/química , Substâncias Macromoleculares/química , Piridinas/química , Estilbenos/química , Acetatos/química , Adsorção , Clorofila A/química , Substâncias Macromoleculares/síntese química , Cloreto de Metileno/química , Microtecnologia/métodos , Tamanho da Partícula , Perileno/análogos & derivados , Platina/química , Vitamina B 12/química
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