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1.
Biol Trace Elem Res ; 202(1): 319-331, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37020163

RESUMO

Perfluoro octane sulfonate (PFOS) and cadmium (Cd) are toxic elements in the environment. As a micronutrient trace element, selenium (Se) can mitigate the adverse effects induced by PFOS and Cd. However, few studies have examined the correlation between Se, PFOS and Cd in fish. The present study focused on the antagonistic effects of Se on PFOS+Cd-induced accumulation in the liver of zebrafish. The fish was exposed to PFOS (0.08mg/L), Cd (1mg/L), PFOS+ Cd (0.08 mg/L PFOS+1 mg/L Cd), L-Se (0.07mg/L Sodium selenite +0.08mg/L PFOS+1mg/L Cd), M-Se (0.35mg/L Sodium selenite + 0.08mg/L PFOS+ 1 mg/L Cd), H-Se (1.75 mg/L Sodium selenite + 0.08 mg/L PFOS+ 1mg/L Cd) for 14d. The addition of selenium to fish exposed to PFOS and Cd has been found to have significant positive effects. Specifically, selenium treatments can alleviate the adverse effects of PFOS and Cd on fish growth, with a 23.10% improvement observed with the addition of T6 compared to T4. In addition, selenium can alleviate the negative effects of PFOS and Cd on antioxidant enzymes in zebrafish liver, thus reducing the liver toxicity caused by PFOS and Cd. Overall, the supplementation of selenium can reduce the health risks to fish and mitigate the injuries caused by PFOS and Cd in zebrafish.


Assuntos
Selênio , Oligoelementos , Animais , Peixe-Zebra , Selênio/farmacologia , Cádmio/toxicidade , Selenito de Sódio/farmacologia , Octanos
2.
J Oleo Sci ; 72(3): 257-262, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36878579

RESUMO

Lecithin is known to undergo heat induced deterioration by the Maillard reaction between 1 mol of any sugar, except 2-deoxy sugar, and 2 mol of phosphatidylethanolamine (PE). However, we have previously reported that adding fatty acid metal salts can inhibit heat deterioration of soybean lecithin (SL). To clarify the mechanism of inhibition, 1,2-di-O-stearoyl-sn-glycero-3-phosphatidylethanolamine (DSPE), d-glucose, and calcium stearate or calcium decanoate were heated in octane. When DSPE and d-glucose with calcium stearate or calcium decanoate were heated in the octane, the heat deterioration of DSPE was significantly inhibited, and no increase in UV absorption at 350 nm was observed. From these reactant solutions, one compound having a phosphate group and no primary amine was isolated, and NMR spectra confirmed that two molar of stearic acid derived from DSPE were coordinated to the amino group and phosphate group of DSPE. Therefore, we concluded that adding fatty acid metal salts reduced the nucleophilic reactivity of the amino group of PE and inhibited the Maillard reaction with sugars because two molar of fatty acid derived from PE coordinated to the amino group and phosphate group of PE.


Assuntos
Cálcio , Açúcares , Octanos , Sais , Fosfatidiletanolaminas , Reação de Maillard , Decanoatos , Lecitinas , Ácidos Graxos , Glucose
3.
Fitoterapia ; 165: 105389, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36586626

RESUMO

Two new polycyclic polyprenylated acylphloroglucinols (PPAPs) possessing a rare benzoyl substituted bicyclo[3.2.1]octane core, hyperxylones A (1) and B (2), along with three new dearomatized isoprenylated acylphloroglucinols (DIAPs), hyperxylones C - E (3-5), were isolated from the roots of Hypericum beanii. The structures of 1-5 were determined by high-resolution electrospray ionization mass spectroscopy (HRESIMS) and 1D/2D nuclear magnetic resonance (NMR) spectroscopic analyses, gauge-independent atomic orbital (GIAO) NMR calculations, and electronic circular dichroism (ECD) calculations. Compounds 1 and 2 were biomimetically semi-synthesized starting from 5 and 4, respectively, enabling the correct stereochemical assignment of 5 and 4. Moreover, compounds 1 and 2 showed anti-nonalcoholic steatohepatitis (NASH) activity by inhibiting lipid deposition in L02 cells; compounds 3 and 5 exhibited nitric oxide (NO) inhibitory activity in lipopolysaccharides (LPS)-induced RAW264.7 cells.


Assuntos
Hypericum , Hypericum/química , Octanos , Floroglucinol/farmacologia , Floroglucinol/química , Estrutura Molecular
4.
Small ; 18(30): e2201359, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35768281

RESUMO

In this work, electrocatalytic upgrade of n-valeraldehyde to octane with higher activity and selectivity is achieved over Au single-atom catalysts (SACs)-NiMn2 O4 spinel synergetic composites. Experiments combined with density functional theory calculation collaboratively demonstrate that Au single-atoms occupy surface Ni2+ vacancies of NiMn2 O4 , which play a dominant role in n-valeraldehyde selective oxidation. A detailed investigation reveals that the initial n-valeraldehyde molecule preferentially adsorbs on the Mn tetrahedral site of NiMn2 O4 spinel synergetic structures, and the subsequent n-valeraldehyde molecule easily adsorbs on the Ni site. Specifically, Au single-atom surficial derivation over spinel lowers the adsorption energy (Eads ) of the initial n-valeraldehyde molecule, which will facilitate its adsorption on the Mn site of Au SACs-NiMn2 O4 . Furthermore, the single-atom Au surficial derivation not only alters the electronic structure of Au SACs-NiMn2 O4 but also lower the Eads of subsequent n-valeraldehyde molecule. Hence, the subsequent n-valeraldehyde molecules prefer adsorption on Au sites rather than Ni sites, and the process of two alkyl radicals originating from Mn-C4 H9 and Au-C4 H9 dimerization into an octane is accordingly accelerated. This work will provide an avenue for the rational design of SACs and supply a vital mechanism for understanding the electrocatalytic upgrade of n-valeraldehyde to octane.


Assuntos
Óxido de Magnésio , Octanos , Aldeídos , Óxido de Alumínio , Catálise
5.
Sci Total Environ ; 802: 149863, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34525749

RESUMO

The depletion of fuel production and raising ecological issues have paid the progress of biofuels in the entire world. Among different biofuels is introducing renewable fuel additives as prospective beneficial blendstocks towards fulfilling systematic, low-carbon technologies internal combustion engines. This research article proposes a new approach to formulate a Fuzzy modeling for examining various promising alternative renewable oxygenated compounds, including ethanol, isopropanol, MTBE, and 2-methyl furan into heavy hydrocracked gasoline a base fuel. No previous study has utilized Fuzzy modeling in formulation of producing high octane fuel based on renewable additives compounds. The effect of selected additives was investigated on the antiknock characteristics. The results reported that the quality and quantity of heavy hydrocracked naphtha have been reinforced, using low carbon oxygenates. Besides, the acquired results provided the possibility to determine the optimum range of selected renewable oxygenates percentages of 30-50% wt. The calculated data of Fuzzy modeling were verified with experimental results. It illustrated that predicted environmental gasoline yields agreed well with experimental results. Finally, low carbon liquid fuel could contribute to produce high quality environmental gasoline, improve environmental characteristics, in terms of decreasing greenhouses emissions, and maximize the vehicles technologies.


Assuntos
Gasolina , Petróleo , Biocombustíveis , Octanos , Estudos Prospectivos , Emissões de Veículos
6.
World J Microbiol Biotechnol ; 37(7): 122, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34151386

RESUMO

The contamination of the environment by crude oil and its by-products, mainly composed of aliphatic and aromatic hydrocarbons, is a widespread problem. Biodegradation by bacteria is one of the processes responsible for the removal of these pollutants. This study was conducted to determine the abilities of Burkholderia sp. B5, Cupriavidus sp. B1, Pseudomonas sp. T1, and another Cupriavidus sp. X5 to degrade binary mixtures of octane (representing aliphatic hydrocarbons) with benzene, toluene, ethylbenzene, or xylene (BTEX as aromatic hydrocarbons) at a final concentration of 100 ppm under aerobic conditions. These strains were isolated from an enriched bacterial consortium (Yabase or Y consortium) that prefer to degrade aromatic hydrocarbon over aliphatic hydrocarbons. We found that B5 degraded all BTEX compounds more rapidly than octane. In contrast, B1, T1 and X5 utilized more of octane over BTX compounds. B5 also preferred to use benzene over octane with varying concentrations of up to 200 mg/l. B5 possesses alkane hydroxylase (alkB) and catechol 2,3-dioxygenase (C23D) genes, which are responsible for the degradation of alkanes and aromatic hydrocarbons, respectively. This study strongly supports our notion that Burkholderia played a key role in the preferential degradation of aromatic hydrocarbons over aliphatic hydrocarbons in the previously characterized Y consortium. The preferential degradation of more toxic aromatic hydrocarbons over aliphatics is crucial in risk-based bioremediation.


Assuntos
Burkholderia/metabolismo , Cupriavidus/metabolismo , Hidrocarbonetos Aromáticos/metabolismo , Octanos/metabolismo , Pseudomonas/metabolismo , Técnicas de Tipagem Bacteriana , Benzeno/metabolismo , Derivados de Benzeno/metabolismo , Biodegradação Ambiental , Burkholderia/classificação , Burkholderia/genética , Catecol 2,3-Dioxigenase/genética , Cupriavidus/classificação , Cupriavidus/genética , Citocromo P-450 CYP4A/genética , DNA Bacteriano , Microbiologia Ambiental , Poluentes Ambientais/metabolismo , Campos de Petróleo e Gás/microbiologia , Petróleo/microbiologia , Pseudomonas/classificação , Pseudomonas/genética , RNA Ribossômico 16S , Tolueno/metabolismo , Xilenos/metabolismo
7.
J Med Chem ; 63(24): 15802-15820, 2020 12 24.
Artigo em Inglês | MEDLINE | ID: mdl-33306385

RESUMO

The diazabicyclooctanes (DBOs) are a class of serine ß-lactamase (SBL) inhibitors that use a strained urea moiety as the warhead to react with the active serine residue in the active site of SBLs. The first in-class drug, avibactam, as well as several other recently approved DBOs (e.g., relebactam) or those in clinical development (e.g., nacubactam and zidebactam) potentiate activity of ß-lactam antibiotics, to various extents, against carbapenem-resistant Enterobacterales (CRE) carrying class A, C, and D SBLs; however, none of these are able to rescue the activity of ß-lactam antibiotics against carbapenem-resistant Acinetobacter baumannii (CRAB), a WHO "critical priority pathogen" producing class D OXA-type SBLs. Herein, we describe the chemical optimization and resulting structure-activity relationship, leading to the discovery of a novel DBO, ANT3310, which uniquely has a fluorine atom replacing the carboxamide and stands apart from the current DBOs in restoring carbapenem activity against OXA-CRAB as well as SBL-carrying CRE pathogens.


Assuntos
Acinetobacter/efeitos dos fármacos , Antibacterianos/farmacologia , Enterobacteriaceae/efeitos dos fármacos , Octanos/química , beta-Lactamases/química , Animais , Antibacterianos/química , Antibacterianos/metabolismo , Sítios de Ligação , Carbapenêmicos/farmacologia , Avaliação Pré-Clínica de Medicamentos , Farmacorresistência Bacteriana/efeitos dos fármacos , Meia-Vida , Camundongos , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Octanos/metabolismo , Octanos/farmacologia , Estereoisomerismo , Relação Estrutura-Atividade , Inibidores de beta-Lactamases/química , Inibidores de beta-Lactamases/metabolismo , Inibidores de beta-Lactamases/farmacologia , beta-Lactamases/metabolismo
8.
Sci Rep ; 9(1): 19108, 2019 12 13.
Artigo em Inglês | MEDLINE | ID: mdl-31836776

RESUMO

Tenuifolin was used as a reliable chemical marker for the quality control of Radix Polygalae. The determination of tenuifolin is challenging because the analyte molecule lacks a suitable chromophore. The aim of this study was to establish a microemulsion high-performance liquid chromatography (MELC) method which is robust and sensitive, and can separate and determine tenuifolin in Radix Polygalae using an oil-in-water (O/W) microemulsion mobile phase. The separations were performed on a C18 (4.6 × 250 mm, 5 µm) column at 25 °C using a flow rate of 1.0 mL/min, and an ultraviolet detection wavelength of 210 nm. The microemulsion mobile phase comprised 2.8% (w/v) sodium dodecyl sulfate (SDS), 7.0% (v/v) n-butanol, 0.8% (v/v) n-octane and 0.1% (v/v) aqueous orthophosphate buffer (H3PO4). The linearity analysis of tenuifolin showed a correlation coefficient of 0.9923 in the concentration range of 48.00-960.00 µg/mL. The accuracy of the method based on three concentration levels ranged from 96.23% to 99.28%; the limit of detection (LOD) was 2.34 µg/mL, and the limit of quantification (LOQ) was 6.76 µg/mL. The results of our study indicated that the optimized MELC method was sensitive and robust, and can be widely applied for the separation and determination of tenuifolin in Radix Polygalae.


Assuntos
Cromatografia Líquida de Alta Pressão , Diterpenos do Tipo Caurano , Medicamentos de Ervas Chinesas , Emulsões , Saponinas , 1-Butanol , Soluções Tampão , Cromatografia Líquida de Alta Pressão/métodos , Diterpenos do Tipo Caurano/análise , Medicamentos de Ervas Chinesas/análise , Química Verde , Limite de Detecção , Modelos Lineares , Octanos , Tamanho da Partícula , Fosfatos , Raízes de Plantas/química , Polygala/química , Controle de Qualidade , Reprodutibilidade dos Testes , Saponinas/análise , Sensibilidade e Especificidade , Dodecilsulfato de Sódio , Espectrofotometria Ultravioleta , Tensoativos , Temperatura
9.
J Asian Nat Prod Res ; 19(10): 974-980, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28140664

RESUMO

Two new phenolic acid helisterculins C (1) and D (2) were isolated from the whole plant of Clerodendranthus spicatus. Their structures were elucidated on the basis of 1D and 2D NMR, MS, and CD analysis. Compound 1 possesses an unusual bicyclol [2. 2. 2] octane moiety which is rare in the previously isolated phenolic acid derivatives. The two compounds were tested in vitro for neuroprotective activities against 6-OHDA-induced cell death in SH-SY5Y cells, and the result showed that compounds 1 and 2 displayed moderate neuroprotective activity with the IC50 values of 17.4 and 21.3 µM, respectively.


Assuntos
Medicamentos de Ervas Chinesas/isolamento & purificação , Hidroxibenzoatos/isolamento & purificação , Lamiaceae/química , Fármacos Neuroprotetores/isolamento & purificação , Morte Celular/efeitos dos fármacos , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/farmacologia , Hidroxibenzoatos/química , Hidroxibenzoatos/farmacologia , Concentração Inibidora 50 , Estrutura Molecular , Fármacos Neuroprotetores/química , Fármacos Neuroprotetores/farmacologia , Ressonância Magnética Nuclear Biomolecular , Octanos , Oxidopamina
10.
Environ Pollut ; 221: 398-406, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27939633

RESUMO

Methane emissions in oil sands tailings ponds are sustained by anaerobic biodegradation of unrecovered hydrocarbons. Naphtha (primarily C6-C10; n- iso- and cycloalkanes) is commonly used as a solvent during bitumen extraction process and its residue escapes to tailings ponds during tailings deposition. To investigate biodegradability of hydrocarbons in naphtha, mature fine tailings (MFT) collected from Albian and CNRL tailings ponds were amended with CNRL naphtha at ∼0.2 wt% (∼2000 mg L-1) and incubated under methanogenic conditions for ∼1600 d. Microbial communities in both MFTs started metabolizing naphtha after a lag phase of ∼100 d. Complete biodegradation/biotransformation of all n-alkanes (except partial biodegradation of n-octane in CNRL MFT) followed by major iso-alkanes (2-methylpentane, 3-methylhexane, 2- and 4-methylheptane, iso-nonanes and 2-methylnonane) and a few cycloalkanes (derivatives of cyclopentane and cyclohexane) was observed during the incubation. 16S rRNA gene pyrosequencing showed dominance of Peptococcaceae and Anaerolineaceae in Albian MFT and Anaerolineaceae and Syntrophaceae in CNRL MFT bacterial communities with co-domination of Methanosaetaceae and "Candidatus Methanoregula" in archaeal populations during active biodegradation of hydrocarbons. The findings extend the known range of hydrocarbons susceptible to methanogenic biodegradation in petroleum-impacted anaerobic environments and help refine existing kinetic model to predict greenhouse gas emissions from tailings ponds.


Assuntos
Alcanos/análise , Monitoramento Ambiental , Poluentes Ambientais/metabolismo , Hidrocarbonetos/análise , Campos de Petróleo e Gás , Alcanos/metabolismo , Archaea/metabolismo , Biodegradação Ambiental , Poluentes Ambientais/análise , Hexanos/análise , Hexanos/metabolismo , Hidrocarbonetos/metabolismo , Metano/metabolismo , Octanos , Pentanos/análise , Pentanos/metabolismo , Petróleo/metabolismo , Lagoas , RNA Ribossômico 16S , Microbiologia da Água
11.
Fitoterapia ; 105: 61-5, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26073946

RESUMO

Four new phenolic acids, clerodens A-D (1-4) possessing an unusual bicycle [2.2.2] octane moiety were isolated from the whole plants of Clerodendranthus spicatus. Their structures were elucidated by extensive spectroscopic methods, including NMR, MS, and ECD data. All isolates were evaluated for their anti-inflammatory activities on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7, and compound 4 showed significant inhibitory activities with IC50 value of 6.8 µM.


Assuntos
Anti-Inflamatórios/química , Hidroxibenzoatos/química , Lamiaceae/química , Octanos/química , Animais , Anti-Inflamatórios/isolamento & purificação , Hidroxibenzoatos/isolamento & purificação , Concentração Inibidora 50 , Camundongos , Estrutura Molecular , Óxido Nítrico/metabolismo , Octanos/isolamento & purificação , Células RAW 264.7
12.
Environ Sci Technol ; 48(19): 11064-71, 2014 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-25224603

RESUMO

Increasing the octane rating of the U.S. gasoline pool (currently ∼ 93 Research Octane Number (RON)) would enable higher engine efficiency for light-duty vehicles (e.g., through higher compression ratio), facilitating compliance with federal fuel economy and greenhouse gas (GHG) emissions standards. The federal Renewable Fuels Standard calls for increased renewable fuel use in U.S. gasoline, primarily ethanol, a high-octane gasoline component. Linear programming modeling of the U.S. refining sector was used to assess the effects on refining economics, CO2 emissions, and crude oil use of increasing average octane rating by increasing (i) the octane rating of refinery-produced hydrocarbon blendstocks for oxygenate blending (BOBs) and (ii) the volume fraction (Exx) of ethanol in finished gasoline. The analysis indicated the refining sector could produce BOBs yielding finished E20 and E30 gasolines with higher octane ratings at modest additional refining cost, for example, ∼ 1¢/gal for 95-RON E20 or 97-RON E30, and 3-5¢/gal for 95-RON E10, 98-RON E20, or 100-RON E30. Reduced BOB volume (from displacement by ethanol) and lower BOB octane could (i) lower refinery CO2 emissions (e.g., ∼ 3% for 98-RON E20, ∼ 10% for 100-RON E30) and (ii) reduce crude oil use (e.g., ∼ 3% for 98-RON E20, ∼ 8% for 100-RON E30).


Assuntos
Etanol/análise , Gasolina/economia , Octanos/análise , Poluentes Atmosféricos/análise , Carbono/análise , Dióxido de Carbono/análise , Combustíveis Fósseis/análise , Modelos Teóricos , Oxigênio/química , Petróleo/análise , Padrões de Referência , Termodinâmica , Estados Unidos
13.
Appl Biochem Biotechnol ; 174(6): 2236-44, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25173674

RESUMO

In this study, it was the first report that the Brevibacterium lutescens CCZU12-1 was employed as a sulfur removing bacteria. Using dibenzothiophene (DBT) as the sole sulfur source, B. lutescens could selectively degrade DBT into 2-hydroxybiphenyl (2-HBP) via the "4S" pathway. In the basal salt medium (BSM) supplemented with 0.25 mM DBT and 0.5 g/L Tween-80, high desulfurization rate (100 %) was obtained by growth cells after 60 h. Furthermore, the n-octane-water (10:90, v/v) biphasic system was built for the biodesulfurization by resting cells. Moreover, a combination of magnetic nano Fe3O4 particles with calcium alginate immobilization was used for enhancing biodesulfurization. In this n-octane-water biphasic system, immobilized B. lutescens cells could be reused for not less than four times. Therefore, B. lutescens CCZU12-1 shows high potential in the biodesulfurization.


Assuntos
Brevibacterium/citologia , Brevibacterium/metabolismo , Octanos/química , Enxofre/química , Tiofenos/química , Tiofenos/metabolismo , Água/química , Biocatálise , Células Imobilizadas/metabolismo
14.
J Chromatogr Sci ; 51(2): 155-60, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22824329

RESUMO

Volatile chemicals are a group of very important compounds in natural products. Curcuma rhizome, which contains many bioactive volatile compounds, is a traditional Chinese medicine that has long been used for the treatment of several diseases. In the present study, a microemulsion electrokinetic chromatography (MEEKC) method was developed for the analysis of four volatile components in Curcuma rhizome, including germacrone, furanodiene, curcumenol and curdione. Experimental parameters, including the pH, type and concentrations of background electrolyte, and microemulsion compositions (type and concentrations of surfactant, co-surfactant and oil phase) were intensively investigated. Finally, the primary compounds in the methanol extract of Curcuma rhizome were separated within 30 min using a running buffer composed of 2.31% w/v (80 mmol/L) sodium dodecyl sulfate (SDS), 0.91% w/v (80 mmol/L) 1-octane, 6.95% w/v (937.5 mmol/L) 1-butanol and 1.88% w/v (312.5 mmol/L) propanol in a 5-mM borate buffer (pH 8.1). The contents of the four investigated compounds were determined in the rhizome from C. phaeocaulis. The results showed that the developed MEEKC method provided an alternative tool for the analysis of volatile components, especially those of heat-sensitive compounds from natural products.


Assuntos
Cromatografia Capilar Eletrocinética Micelar/métodos , Curcuma/química , Medicamentos de Ervas Chinesas/química , Rizoma/química , Sesquiterpenos/análise , Furanos/análise , Furanos/química , Compostos Heterocíclicos com 2 Anéis/análise , Compostos Heterocíclicos com 2 Anéis/química , Concentração de Íons de Hidrogênio , Limite de Detecção , Modelos Lineares , Octanos/química , Reprodutibilidade dos Testes , Sesquiterpenos/química , Dodecilsulfato de Sódio , Tensoativos/química
15.
J Colloid Interface Sci ; 387(1): 65-73, 2012 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-22958854

RESUMO

The influence of interfacial crosslinking, layer thickness and layer density on the kinetics of Ostwald ripening in multilayered emulsions at different temperatures was investigated. Growth rates of droplets were measured by monitoring changes in the droplet size distributions of 0.5% (w/w) n-octane, n-decane, and n-dodecane oil-in-water emulsions using static light scattering. Lifshitz-Slyozov-Wagner theory was used to calculate Ostwald ripening rates. A sequential two step process, based on electrostatic deposition of sugar beet pectin onto fish gelatin or whey protein isolate (WPI) interfacial membranes, was used to manipulate the interfacial properties of the oil droplets. Laccase was added to the fish gelatin-beet pectin emulsions to promote crosslinking of adsorbed pectin molecules via ferulic acid groups, whereas heat was induced to promote crosslinking of WPI and helix coil transitions of fish gelatin. Ripening rates of single-layered, double-layered and crosslinked emulsions increased as the chain length of the n-alkanes decreased. Emulsions containing crosslinked fish gelatin-beet pectin coated droplets had lower droplet growth rates (3.1±0.3×10(-26) m(3)/s) than fish gelatin-stabilized droplets (7.3±0.2×10(-26) m(3)/s), which was attributed to the formation of a protective network. Results suggest that physical or enzymatic biopolymer-crosslinking of interfaces may reduce the molecular transport of alkanes between the droplets in the continuous phase.


Assuntos
Emulsões/química , Gelatina/química , Óleos/química , Pectinas/química , Água/química , Alcanos/química , Animais , Beta vulgaris/química , Peixes , Temperatura Alta , Lacase/metabolismo , Octanos/química , Tamanho da Partícula , Pectinas/metabolismo , Eletricidade Estática , Trametes/enzimologia
16.
Anal Chem ; 84(18): 7874-80, 2012 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-22845833

RESUMO

A new method to determine Pb isotope ratio without ion-exchange-matrix separation is proposed. After acid digestion, Pb was ethylated to Et(4)Pb, separated from the digested solution (black shale, asphaltene, crude oil and kerogen) by extraction in isooctane, and then injected into a gas chromatograph coupled to a multicollector inductively coupled plasma mass spectrometer. Seven isotopes ((202)Hg, (203)Tl, (204)Pb, (205)Tl, (206)Pb, (207)Pb, (208)Pb) were monitored simultaneously with peak duration of 23 s. GC elution was operated under wet plasma conditions where a thallium standard solution was introduced to the mass spectrometer for mass bias correction. The total time of the procedure (sample preparation and analysis, after acid digestion) was reduced by a factor of 15 compared to conventional-continuous sample introduction. Data treatment was carried out using the linear regression slope method. Mass bias was corrected using the double correction method (first thallium normalization followed by classical bracketing). For the (208/206)Pb and (207/206)Pb ratios, precision (2RSD(EXT), n = 21) was 49 and 69 ppm, and the bias between experimental results and reference values was better than 0.0033 and 0.0007 ‰, when injecting 1.2 ng of ethylated Pb SRM NIST 981 solution. Results obtained by this method were validated by comparison with those obtained via conventional-continuous sample introduction. The applicability of this approach was demonstrated with the analysis of black shale, asphaltene, crude oil and kerogen samples.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Chumbo/análise , Petróleo/análise , Hidrocarbonetos/química , Isótopos/análise , Mercúrio/química , Octanos/química , Tálio/química
17.
Environ Microbiol ; 13(10): 2808-19, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21895911

RESUMO

Long-chain alkanes are a major component of crude oil and therefore potentially good indicators of hydrocarbon spills. Here we present a set of new bacterial bioreporters and assays that allow to detect long-chain alkanes. These reporters are based on the regulatory protein AlkS and the alkB1 promoter from Alcanivorax borkumensis SK2, a widespread alkane degrader in marine habitats. Escherichia coli cells with the reporter construct reacted strongly to octane in short-term (6 h) aqueous suspension assays but very slightly only to tetradecane, in line with what is expected from its low water solubility. In contrast, long-term assays (up to 5 days) with A. borkumensis bioreporters showed strong induction with tetradecane and crude oil. Gel-immobilized A. borkumensis reporter cells were used to demonstrate tetradecane and crude oil bioavailability at a distance from a source. Alcanivorax borkumensis bioreporters induced fivefold more rapid and more strongly when allowed physical contact with the oil phase in standing flask assays, suggesting a major contribution of adhered cells to the overall reporter signal. Using the flask assays we further demonstrated the effect of oleophilic nutrients and biosurfactants on oil availability and degradation by A. borkumensis. The fluorescence signal from flask assays could easily be captured with a normal digital camera, making such tests feasible to be carried out on, e.g. marine oil responder vessels in case of oil accidents.


Assuntos
Alcanivoraceae/metabolismo , Alcanos/metabolismo , Octanos/metabolismo , Alcanivoraceae/genética , Disponibilidade Biológica , Escherichia coli/genética , Escherichia coli/metabolismo , Genes Reporter , Petróleo/metabolismo , Plasmídeos
18.
J Agric Food Chem ; 59(17): 9443-7, 2011 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-21797277

RESUMO

The utilization of biosurfactants for the bioremediation of contaminated soil is not yet well established, because of the high production cost of biosurfactants. Consequently, it is interesting to look for new biosurfactants that can be produced at a large scale, and it can be employed for the bioremediation of contaminated sites. In this work, biosurfactants from Lactobacillus pentosus growing in hemicellulosic sugars solutions, with a similar composition of sugars found in trimming vine shoot hydrolysates, were employed in the bioremediation of soil contaminated with octane. It was observed that the presence of biosurfactant from L. pentosus accelerated the biodegradation of octane in soil. After 15 days of treatment, biosurfactants from L. pentosus reduced the concentration of octane in the soil to 58.6 and 62.8%, for soil charged with 700 and 70,000 mg/kg of hydrocarbon, respectively, whereas after 30 days of treatment, 76% of octane in soil was biodegraded in both cases. In the absence of biosurfactant and after 15 days of incubation, only 1.2 and 24% of octane was biodegraded in soil charged with 700 and 70,000 mg/kg of octane, respectively. Thus, the use of biosurfactants from L. pentosus, as part of a well-designed bioremediation process, can provide mechanisms to mobilize the target contaminants from the soil surface to make them more available to the microbial population.


Assuntos
Biodegradação Ambiental , Lactobacillus/metabolismo , Octanos/química , Poluentes do Solo/química , Tensoativos/química , Tensoativos/metabolismo , Fenômenos Químicos , Descontaminação/métodos , Octanos/análise , Solo/química , Poluentes do Solo/análise , Tensoativos/economia
19.
Bioresour Technol ; 102(14): 7154-8, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21565494

RESUMO

Novel modification methods for lipase biocatalysts effective in hydrolysis of fish oil for enrichment of polyunsaturated fatty acids (PUFAs) were described. Based on conventional immobilization in single aqueous medium, immobilization of lipase in two phase medium composed of buffer and octane was employed. Furthermore, immobilization (in single aqueous or in two phase medium) coupled to fish oil treatment was integrated. Among these, lipase immobilized in two phase medium coupled to fish oil treatment (IMLAOF) had advantages over other modified lipases in initial reaction rate and hydrolysis degree. The hydrolysis degree increased from 12% with the free lipase to 40% with IMLAOF. Strong polar and hydrophobic solvents had negative impact on immobilization-fish oil treatment lipases, while low polar solvents were helpful to maintain the modification effect of immobilization-fish oil treatment. After five cycles of usage, the immobilization-fish oil treatment lipases still maintained more than 80% of relative hydrolysis degree.


Assuntos
Biotecnologia/métodos , Enzimas Imobilizadas/metabolismo , Ácidos Graxos Insaturados/metabolismo , Óleos de Peixe/farmacologia , Lipase/metabolismo , Animais , Soluções Tampão , Ácidos Docosa-Hexaenoicos/análise , Ácido Eicosapentaenoico/análise , Estabilidade Enzimática/efeitos dos fármacos , Geotrichum/efeitos dos fármacos , Geotrichum/enzimologia , Hidrólise/efeitos dos fármacos , Octanos/farmacologia , Reciclagem , Solventes/farmacologia , Temperatura
20.
Colloids Surf B Biointerfaces ; 87(1): 54-60, 2011 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-21621398

RESUMO

Wetting properties of commercial Al(2)O(3) plates contacted with dipalmitoylphosphatidylcholine (DPPC) or DPPC+enzyme (phospholipase PLA(2)) in NaCl solution were determined by thin layer wicking and with the help of Washburn equation. Van Oss et al.'s approach to interfacial free energy interactions was applied to determining the solid surface free energy components. Wicking experiments were performed both for bare and alumina plates precontacted overnight with the probe liquid saturated vapours, as well as the untreated and DPPC (or DPPC+PLA(2)) treated alumina plates. For this purpose the penetration rates of n-octane, water and formamide were measured. From these experiments it resulted that original alumina surface is strongly polar with electron-donor interactions originating from the surface hydroxyl groups. Adsorption of DPPC on Al(2)O(3) plates slightly increased the hydrophobic character of the alumina surface (considerable decrease of the electron-donor, γ(s)(-) parameter and γ(s)(AB) component was visible) in such a way that the hydrocarbon chains were directed outwards and the polar part towards the alumina surface. However, after the enzyme action the products of DPPC hydrolysis by PLA(2) (palmitic acid and lysophosphatidylcholine) increased again the hydrophilic character of Al(2)O(3) surface (a minor increase in γ(s)(AB) component and drastic increase of the electron-donor γ(s)(-) parameter was noticeable). After treatment with DPPC or DPPC+enzyme PLA(2) solution the changes of the total surface free energy of alumina and its Lifshits-van der Waals (γ(s)(LW)) component were in the range 7-10 mJ/m(2), but the most considerable and delivering more interesting information were the changes of the electron-donor (γ(s)(-)) parameter ranging from 27 to 35 mJ/m(2). Moreover, the changes of the alumina surface wettability were dependent on the time of the enzyme contacting with DPPC in NaCl solution. On the basis of the obtained results it seems that the thin layer wicking method can be an additional useful tool in investigations of the effect of phospholipid and PLA(2) action on the hydrophilic-hydrophobic character of alumina surface.


Assuntos
1,2-Dipalmitoilfosfatidilcolina/farmacologia , Óxido de Alumínio/química , Fosfolipases A2/farmacologia , Animais , Formamidas/química , Octanos/química , Tamanho da Partícula , Cloreto de Sódio/química , Termodinâmica , Fatores de Tempo , Volatilização/efeitos dos fármacos , Molhabilidade/efeitos dos fármacos
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