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1.
Food Chem ; 393: 133379, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-35691063

RESUMO

T-butanol is widely used in three-phase partitioning (TPP). This study used deep eutectic solvents (DESs) to substitute t-butanol for tomato peroxidase (POD) purification. DES-5 (menthol and octanoic acid) was screened as the optimal solvent. The extraction process was optimized using single-factor experiments. Thereafter, the major three factors were optimized by response surface methodology (RSM). When the ammonium sulfate ((NH4)2SO4) concentration was 42%, DES: crude extract (v/v) was 2:1, pH was 5.7, and extraction temperature was 30 °C, the recovery and purification fold reached a maximum of 104.71% and 9.76, respectively. The obtained tomato POD was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), which showed that this system could effectively purify POD. Finally, recycling studies indicated the good cycle stability of the DES. This TPP based on DESs is greener and more efficient, indicating that DESs can be good alternative solvents for further applications of TPP.


Assuntos
Lycopersicon esculentum , 1-Butanol , Butanóis , Peroxidase , Solventes , terc-Butil Álcool
2.
Food Chem ; 389: 133103, 2022 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-35504079

RESUMO

A novel and green one-step simultaneous extraction process of phycobiliproteins and polyunsaturated fatty acids (PUFAs) from wet Porphyridium biomass has been done and optimized by using three phase partitioning (TPP) process. Results showed that the coupling of ammonium sulfate and protein buoyancy-promoting t-butanol afforded the best TPP to extract phycobiliproteins and PUFAs in term of the extraction performance and cost-effectiveness. TPP process gave the best capability to simultaneously extract Porphyridium-derived phycobiliproteins and PUFAs in 20% ammonium sulfate, 0.5% biomass, and 1:0.5 slurry to t-butanol ratio at 100 rpm and 20 °C for 10 min of extraction time. Moreover, the established TPP system achieved excellent reproducibility in the extraction of Porphyridium biomass from different sources (Porphyridium cruentum and P. purpureum); and was successfully implemented in pilot-scale (20-L), indicating its industrial potential as a promising integrated approach to comprehensively exploit Porphyridium as a renewable bioresource for high-value bioproducts.


Assuntos
Porphyridium , Sulfato de Amônio , Biomassa , Ácidos Graxos Insaturados/metabolismo , Ficobiliproteínas , Porphyridium/metabolismo , Reprodutibilidade dos Testes , terc-Butil Álcool/metabolismo
3.
J Mol Model ; 28(6): 159, 2022 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-35596807

RESUMO

The reactivity of the fluoride ion towards alkyl halides is highly dependent on the solvating environment. In polar aprotic solvents with large counter-ions is highly reactive and produces substantial E2 product, whereas in polar protic solvents leads to slow kinetics and high selectivity for SN2 reactions. The use of a more complex environment with stoichiometric addition of tert-butanol to acetonitrile solvent is able to module the reactivity and selectivity of tetrabutylammonium fluoride (TBAF). In the present work, we have performed a detailed theoretical analysis of this complex reaction system by density functional theory, continuum solvation model, and including explicit tert-butanol molecules. A kinetic model based on the free energy profile was also used to predict the reactivity and selectivity. The results indicated that the TBAF(tert-butanol) complex plays the key role to increase the SN2 selectivity, whereas higher aggregates are not relevant. The E2 product is formed exclusively via free TBAF, because the solvating tert-butanol in the TBAF(tert-butanol) complex inhibits the E2 pathway. Our analysis suggests that diols or tetraols could produce an improved selectivity.


Assuntos
Halogenação , terc-Butil Álcool , Flúor , Cinética , Solventes
4.
J Phys Chem B ; 126(4): 869-877, 2022 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-35077175

RESUMO

The affinity of hydroxide ions for methyl hydration shells is assessed using a combined experimental and theoretical analysis of tert-butyl alcohol (TBA) dissolved in pure water and aqueous NaOH and NaI. The experimental results are obtained using Raman multivariate curve resolution (Raman-MCR) and a new three-component total least squares (Raman-TLS) spectral decomposition strategy used to highlight vibrational perturbations resulting from interactions between TBA and aqueous ions. The experiments are interpreted and extended with the aid of effective fragment potential molecular dynamics (EFP-MD) simulations, as well as Kirkwood-Buff calculations and octanol/water partition measurements, to relate TBA-ion distribution functions to TBA solubility changes. The combined experimental and simulation results reveal that methyl group hydration shells more strongly expel hydroxide than iodide anions, whose populations near the methyl groups of TBA are predicted to be correlated with sodium counterion localization near the TBA hydroxyl group.


Assuntos
Água , terc-Butil Álcool , Iodetos , Íons , Simulação de Dinâmica Molecular
5.
J Mol Graph Model ; 108: 108002, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34391199

RESUMO

The kinetics of the gas-phase atmospheric reaction of t-butanol with OH radicals is computationally studied using the CCSD(T)/aug-cc-pVTZ//M06-2X/6-311++G(d,p) level of calculation. The rate coefficients are evaluated for a wide temperature range of 250-1200 K and the calculated rate coefficient value of 0.83×10-12cm3molecule-1s-1 at 298K is in close agreement with experimental results. The H-abstraction from the -CH3 group is predicted to be the main reaction channel. A weak negative temperature dependence of rate coefficient is observed in 250-300 K. The study also highlighted the possibility of re-generation of OH radicals at higher temperature. The ozone formation potential of t-butanol in the troposphere has also been estimated and discussed.


Assuntos
Ozônio , Radical Hidroxila , Cinética , Temperatura , terc-Butil Álcool
6.
Amino Acids ; 53(9): 1455-1466, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34410506

RESUMO

Solid-phase synthesis of cyclic, branched or side-chain-modified peptides typically involves introduction of a residue carrying a temporary side-chain protecting group that undergoes selective on-resin removal. In particular, Nα-Fmoc-Nε-(4-methyltriphenylmethyl) (Mtt)-protected lysine and its shorter analogues are commercially available and extensively used in this context. Nevertheless, rapid reliable methods for on-resin removal of Mtt groups in the presence of tert-butyloxycarbonyl (Boc) groups are needed. Current commonly used conditions involve low concentrations (1-3%) of trifluoroacetic acid (TFA) in dichloromethane, albeit adjustment to each specific application is required to avoid premature removal of Boc groups or cleavage from the linker. Hence, a head-to-head comparison of several deprotection conditions was performed. The selected acids represent a wide range of acidity from TFA to trifluoroethanol. Also, on-resin removal of the N-(4-methoxytriphenylmethyl) (Mmt) and O-trityl groups (on serine) was investigated under similar conditions. The mildest conditions identified for Mtt deprotection involve successive treatments with 30% hexafluoroisopropanol (HFIP) or 30% perfluoro-tert-butanol [(CF3)3COH] in dichloromethane (3 × 5 or 3 × 15 min, respectively), while 30% HFIP, 30% (CF3)3COH, or 10% AcOH-20% trifluoroethanol (TFE) in CH2Cl2 (3 × 5 min) as well as 5% trichloroacetic acid in CH2Cl2 (3 × 2 min) enabled Mmt removal. Treatment with 1% TFA with/without 2% triisopropylsilane added (3 × 5 min), but also prolonged treatment with 30% (CF3)3COH (5 × 15 min), led to selective deprotection of an O-Trt group on a serine residue. In all cases, the sequences also contained N-Boc or O-tBu protecting groups, which were not affected by 30% HFIP or 30% (CF3)3COH even after a prolonged reaction time of 4 h. Finally, the optimized conditions involving HFIP or (CF3)3COH proved applicable also for selective deprotection of a longer resin-bound peptide [i.e., Ac-Gly-Leu-Leu-Lys(Mtt)-Arg(Pbf)-Ile-Lys(Boc)-Ser(tBu)-Leu-Leu-RAM-PS] as well as allowed for an almost complete deprotection of a Dab(Mtt) residue.


Assuntos
Peptídeos/síntese química , Resinas Sintéticas/química , Técnicas de Síntese em Fase Sólida/métodos , Ácido Trifluoracético/química , Compostos de Tritil/química , terc-Butil Álcool/química , Estrutura Molecular
7.
Environ Sci Technol ; 55(15): 10442-10450, 2021 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-34292702

RESUMO

The hydroxyl radical, •OH, is one of the most reactive free radicals and plays significant roles in the oxidative degradation of organic pollutants and the electron transfer of inorganic ions in natural and engineered environmental processes. To quantitatively determine the contribution of •OH to oxidative reactions, a specific scavenger, such as tert-butyl alcohol (TBA), is usually added to eliminate •OH effects. Although TBA is commonly assumed to transform •OH into oxidatively inert products, this study demonstrates that utilizing TBA as an •OH scavenger generates the secondary peroxyl radical (ROO•), influencing the oxidation of transition metals, such as Mn. Although ROO• is less reactive than •OH, it has an extended half-life and a longer diffusion distance that enables more redox reactions, such as the oxidation of Mn2+(aq) to MnIV oxide solids. In addition to promoting Mn2+(aq) oxidation kinetics, TBA can also affect the crystalline phases, oxidation states, and morphologies of Mn oxide solids. Thus, the oxidative roles of •OH in aqueous redox reactions cannot be examined simply by adding TBA: the effects of secondary ROO• must also be considered. This study urges a closer look at the potential formation of secondary radicals during scavenged oxidative reactions in environmental systems.


Assuntos
Radical Hidroxila , terc-Butil Álcool , Radicais Livres , Oxirredução , Estresse Oxidativo
8.
Chem Commun (Camb) ; 57(63): 7743-7757, 2021 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-34286714

RESUMO

As a versatile quantification and tracking technology, 19F magnetic resonance imaging (19F MRI) provides quantitative "hot-spot" images without ionizing radiation, tissue depth limit, and background interference. However, the lack of suitable imaging agents severely hampers its clinical application. First, because the 19F signals are solely originated from imaging agents, the relatively low sensitivity of MRI technology requires high local 19F concentrations to generate images, which are often beyond the reach of many 19F MRI agents. Second, the peculiar physicochemical properties of many fluorinated compounds usually lead to low 19F signal intensity, tedious formulation, severe organ retention, etc. Therefore, the development of 19F MRI agents with high sensitivity and with suitable physicochemical and biological properties is of great importance. To this end, perfluoro-tert-butanol (PFTB), containing nine equivalent 19F and a modifiable hydroxyl group, has outperformed most perfluorocarbons as a valuable building block for high performance 19F MRI agents. Herein, we summarize the development and application of PFTB-based 19F MRI agents and analyze the strategies to improve their sensitivity and physicochemical and biological properties. In the context of PFC-based 19F MRI agents, we also discuss the challenges and prospects of PFTB-based 19F MRI agents.


Assuntos
Meios de Contraste/química , Imagem por Ressonância Magnética de Flúor-19 , Fluorcarbonetos/química , terc-Butil Álcool/química
9.
J Am Soc Mass Spectrom ; 32(2): 497-508, 2021 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-33476148

RESUMO

Improving the mobile phase of electrospray oligonucleotides has been a major focus in the field of oligonucleotides. These improved mobile phases should reduce the charge state envelope of oligonucleotides coupled with electrospray ionization, which is key to reducing spectral complexity and increasing sensitivity. Traditional mobile phase compositions with fluorinated alcohol and alkylamine, like hexafluoroisopropanol (HFIP) and triethylamine (TEA), have a large amount of cationic adduction and many charge states. Utilizing different fluorinated alcohol and alkylamine combinations, like nonafluoro-tert-butyl alcohol (NFTB) and octylamine (OA), can selectively reduce the charge states analyzed. Other classes of biomolecules have been analyzed with anionic salts to stabilize complexes, increase the molecular peak detection, and even provide unique structural information about these molecules; however, there have been no studies using anionic salts with oligonucleotides. Our experiments systematically study the stability and binding of ammonium anionic salt. We show that anions selectively bind low charge states of these oligonucleotides. Ion-mobility measurements are made to determine the collision cross section (CCS) of these oligonucleotides with anion adduction. We utilize both a nucleic acid exact hard sphere simulation (EHSS) calibration and a protein calibration. We are able to show that NFTB/OA is a good choice for the study of oligonucleotides with reduced charge states for the binding of anionic salts and the determination of CCS using ion mobility.


Assuntos
Ânions/química , Oligonucleotídeos/química , Espectrometria de Massas por Ionização por Electrospray/métodos , Aminas/química , Aptâmeros de Nucleotídeos/química , Gases/química , Oligonucleotídeos Fosforotioatos/química , Solventes/química , Sulfatos/química , terc-Butil Álcool/química
10.
J Hazard Mater ; 411: 125104, 2021 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-33482503

RESUMO

Laccase is an effective biocatalyst in bioremediation process; however, the application of the enzyme is limited due to its cost, recovery, and stability. In this study, we developed, characterized and evaluated the efficiency of immobilized laccase on zinc oxide nanostructure to catalyze biodegradation of TBA in comparison to the suspended enzyme. The results showed that both immobilized and suspended laccase were capable of catalyzing TBA biodegradation; however, the efficiency of the immobilized laccase on TBA removal was higher than that of the suspended enzyme. The repeatability testing revealed the potential of the immobilized laccase for repeatedly catalyzing TBA biodegradation with storage capacity. While the Vmax of immobilized enzyme was higher than suspended laccase (2.25 ± 0.542 mg TBA/h∙U vs. 1.47 ± 0.185 mg TBA/h∙U), the km of the immobilized enzyme was higher than the suspended laccase (67.9 ± 20.5 mg TBA/L vs. 33.5 ± 7.10 mg TBA/L). This suggests that the immobilized laccase is better in TBA removal, but has lower affinity with TBA than the suspended enzyme. Thus, immobilization of the enzyme can be applied to increase the efficiency and minimize the use of laccase for TBA remediation.


Assuntos
Lacase , Óxido de Zinco , Catálise , Enzimas Imobilizadas , Concentração de Íons de Hidrogênio , terc-Butil Álcool
11.
Macromol Rapid Commun ; 42(3): e2000502, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33205586

RESUMO

The morphology of materials usually plays a significant role in their applications; the mechanical properties of the materials and characteristics such as specific surface area, surface energy, adsorbability, and wettability are dependent on the morphology. This study is focused on studying the effects of different tertiary butyl alcohol (TBA) aqueous solutions on the freeze-dried morphologies of chitin microspheres (CMs). By constructing a TBA/H2 O phase diagram, the underlying mechanisms of morphology change are explored. It is found that by freeze drying the CMs with 20 and 100 wt% TBA, a fine nanofiber weaved pore structure can be obtained. Away from these two ratios, the nanofibers are oppressed by the large crystals formed during the precool process or bind together due to the existence of water in the secondary drying stage, poor morphology and pore characteristics appearing. Moreover, the 20 wt% TBA freeze-drying route is conducive to split the CMs and other polysaccharide (PS) microspheres. The split method is also helpful for exploring the internal structure of the microspheres. Therefore, this study makes it possible to simplify the morphology control of CMs, which helps in the characterization of porous PS-based microspheres.


Assuntos
Quitina , terc-Butil Álcool , Dessecação , Liofilização , Microesferas
12.
Int J Biol Macromol ; 170: 490-502, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33383081

RESUMO

Candida antarctica lipase B (CALB) and Thermomyces lanuginose lipase (TLL) were co-immobilized on epoxy functionalized silica gel via an isocyanide-based multicomponent reaction. The immobilization process was carried out in water (pH 7) at 25 °C, rapidly (3 h) resulting in high immobilization yields (100%) with a loading of 10 mg enzyme/g support. The immobilized preparations were used to produce biodiesel by transesterification of palm oil. In an optimization study, response surface methodology (RSM) and central composite rotatable design (CCRD) methods were used to study the effect of five independent factors including temperature, methanol to oil ratio, t-butanol concentration and CALB:TLL ratio on the yield of biodiesel production. The optimum combinations for the reaction were CALB:TLL ratio (2.1:1), t-butanol (45 wt%), temperature (47 °C), methanol: oil ratio (2.3). This resulted in a FAME yield of 94%, very close to the predicted value of 98%.


Assuntos
Proteínas Fúngicas/química , Lipase/química , Óleo de Palmeira/química , Biocombustíveis , Enzimas Imobilizadas/química , Esterificação/efeitos dos fármacos , Metanol/química , Temperatura , terc-Butil Álcool/química
13.
Biophys Chem ; 267: 106480, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32987324

RESUMO

Imidazolium based IL's has gained vast interest in developing biological applications. Oligomerization and fibrillization of amyloid ß (1-42) peptide are mainly responsible for the extra-neuronal deposition of amyloid fibrils in neurodegenerative disorders like Alzheimer's disease (AD). Here, we report an effect of tert-BuOH-functional imidazolium ILs on oligomerization and fibrillization of amyloid ß (1-42) Peptide in vitro. In this study, a series of these [alkyl-tOHim][OMs] ILs with methyl sulphonate counter anion by varying alkyl chains were used. Among the seven protic ILs, four showed strong binding and inhibition activity for the formation of amyloid ß (1-42) aggregation by using Thioflavin T fluorescence binding assay. The secondary structural analysis of the peptide, pre-incubated with active ILs shows the loss of ordered ß-sheet amyloid structure. The longer alkyl chain ILs showed that an increased in amyloid binding and hence an inhibition effect on amyloid aggregation was enhanced. Thus, we propose that ILs could be presented as potential candidates for therapeutic intervention against Alzheimer's disease (AD).


Assuntos
Peptídeos beta-Amiloides/antagonistas & inibidores , Imidazóis/farmacologia , Líquidos Iônicos/farmacologia , Fragmentos de Peptídeos/antagonistas & inibidores , Agregados Proteicos/efeitos dos fármacos , terc-Butil Álcool/farmacologia , Peptídeos beta-Amiloides/biossíntese , Imidazóis/síntese química , Imidazóis/química , Líquidos Iônicos/síntese química , Líquidos Iônicos/química , Microscopia Eletrônica de Transmissão , Fragmentos de Peptídeos/biossíntese , Sais/síntese química , Sais/química , Sais/farmacologia , terc-Butil Álcool/química
14.
J Oleo Sci ; 69(10): 1281-1285, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-32908100

RESUMO

In this study two different strategy were followed to obtain a D-fructose-oleic acid ester. One of the strategies has been well established enzymatic synthesis of an ester bond. The other strategy excluded the biocatalyst and only used a mixture of two organic solvents as the reaction media, 2-methyl-2-butanol / dimethyl sulfoxide or tert-butanol / dimethyl sulfoxide for the production of D-fructose-oleic acid ester. Ester products obtained were characterised by using FT-IR, NMR, by MS. Product yield was also assessed by HPLC. Results of structural analyses and yield measurement indicated that two approaches produced almost identical ester products.


Assuntos
Dimetil Sulfóxido/química , Ésteres/síntese química , Frutose/síntese química , Ácido Oleico/síntese química , Pentanóis/química , terc-Butil Álcool/química , Animais , Biocatálise , Células Cultivadas , Cromatografia Líquida de Alta Pressão , Esterificação , Ésteres/química , Ésteres/toxicidade , Frutose/química , Frutose/toxicidade , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Ácido Oleico/química , Ácido Oleico/toxicidade , Espectroscopia de Infravermelho com Transformada de Fourier
15.
Mol Pharm ; 17(8): 3075-3086, 2020 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-32633520

RESUMO

The effect of tertiary butyl alcohol (TBA) as a cosolvent on the phase behavior of mannitol in frozen and freeze-dried systems was characterized using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD; laboratory and synchrotron sources). Solutions of mannitol (2 and 5% w/w) in TBA-water systems of different compositions (5 to 30% w/w TBA) were characterized, both during cooling and warming using DSC and XRD. At and below the TBA-water eutectic composition (22.5% w/w TBA), mannitol crystallization was completely inhibited in the frozen state, while it crystallized as anhydrous δ-mannitol in the final lyophile. The presence of mannitol did not affect the phase behavior of TBA. The ability of mannitol to serve as a cryoprotectant in frozen solutions, and as a bulking agent in final lyophile was evaluated using human serum albumin (HSA) as a model protein. When HSA in a TBA (5% w/w)-water solution containing mannitol (2% w/w) was freeze-thawed or freeze-dried, there was no evidence of HSA aggregation. Thus, when TBA was used as a cosolvent, mannitol exhibited dual functionality, serving as a cryoprotectant in frozen solutions and as a bulking agent in the final lyophile.


Assuntos
Manitol/química , Albumina Sérica Humana/química , terc-Butil Álcool/química , Química Farmacêutica/métodos , Cristalização/métodos , Composição de Medicamentos/métodos , Liofilização/métodos , Congelamento , Humanos , Síncrotrons , Água/química , Difração de Raios X/métodos
16.
J Oleo Sci ; 69(8): 907-912, 2020 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-32641616

RESUMO

D-ribose-oleic acid esters were produced with or without a biocatalyst, using in the same organic media, dimethyl sulfoxide (DMSO): tert-butanol (TBU) or 2-methyl-2-butanol (2M2B). The yield of the ester product was above 90% in both of the reactions. The biocatalyst used was lipase B of Candida antarctica. Molecular characterization was performed by using all the analytical methods available: IR, 1H-NMR and 13C-NMR, HSQC, and ESI-MS.


Assuntos
Biocatálise , Ésteres/síntese química , Proteínas Fúngicas/química , Lipase/química , Ácidos Oleicos/síntese química , Ribose/síntese química , Dimetil Sulfóxido/química , Esterificação , Ésteres/química , Ácidos Oleicos/química , Pentanóis/química , Ribose/química , terc-Butil Álcool/química
17.
J Oleo Sci ; 69(7): 737-742, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32612023

RESUMO

Esterification of D-glucose with oleic- and palmitic acids were carried out in the absence and presence of a biocatalyst, Candida antarctica lipase. The reaction medium was a mixture of dimethyl sulphoxide and tert-butanol (1:4, v/v). The reaction products were analysed by FTIR, 1H-NMR and 13C-NMR, HSQC, and by ESI-MS. Results indicated that the ester products formed were 6-O-glucose oleate and 6-O-glucose palmitate both in the absence and in the presence of the biocatalyst, with yields above 90%.


Assuntos
Biocatálise , Ésteres/síntese química , Glucose/química , Ácido Oleico/síntese química , Ácidos Oleicos/química , Palmitatos/síntese química , Ácidos Palmíticos/química , terc-Butil Álcool/química , Dimetil Sulfóxido/química , Esterificação , Proteínas Fúngicas/química , Lipase/química
18.
J Pharm Sci ; 109(6): 1905-1911, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32135168

RESUMO

Lyophilized biotherapeutics with high protein concentration may have long reconstitution times, which pose an inconvenience to the end user. This report describes 2 approaches that lead to reduction of reconstitution time: (1) incorporation of tert-butyl alcohol (TBA) in the prelyophilization formulation and (2) decreased headspace pressure in the final lyophilized vial. Cakes made from prelyophilization formulations containing a range of TBA concentrations were physically characterized. The stability of antibodies with TBA in the liquid and lyophilized states was evaluated under stress conditions. Reconstitution time was minimized (>50% reduction) at a TBA concentration of 5% w/v. Reduced headspace pressure in the lyophilized vial demonstrated greater than 50% reduction in reconstitution time at headspace pressures of less than 50 Torr.


Assuntos
terc-Butil Álcool , Estabilidade de Medicamentos , Liofilização
19.
Chemosphere ; 248: 125975, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32007772

RESUMO

Stable isotopes have been widely used to monitor remediation of environmental contaminants over the last decades. This approach gives a good mechanistic description of natural or assisted degradation of organic pollutants, such as methyl tert-butyl ether (MTBE). Since abiotic degradation seems to be the most promising assisted attenuation method, the isotopic fractionation associated with oxidation and hydrolysis processes need to be further investigated in order to understand better these processes and make their monitoring more efficient. In this study, position-specific isotope effects (PSIEs) associated with permanganate oxidation and acid hydrolysis of MTBE were determined using isotope ratio monitoring by 13C Nuclear Magnetic Resonance Spectrometry (irm-13C NMR) combined with isotope ratio monitoring by Mass Spectrometry (irm-MS). The use of this Position-Specific Isotopic Analysis (PSIA) method makes it possible to observe a specific normal isotope effect (IE) associated with each of these two abiotic degradation mechanisms. The present work demonstrates that the 13C isotope pattern of the main degradation product, tert-butyl alcohol (TBA), depends on the chemical reaction by which it is produced. Furthermore, this study also demonstrates that PSIA at natural abundance can give new insights into reaction mechanisms and that this methodology is very promising for the future of modeling the remediation of organic contaminants.


Assuntos
Compostos de Manganês/química , Éteres Metílicos/química , Modelos Químicos , Óxidos/química , Poluentes Químicos da Água/química , Isótopos de Carbono/análise , Fracionamento Químico/métodos , Hidrólise , Oxirredução , Poluentes Químicos da Água/análise , terc-Butil Álcool
20.
J Appl Toxicol ; 40(7): 979-990, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32059264

RESUMO

Owing to the use of ethyl tert-butyl ether (ETBE) as a fuel additive, the possible adverse effects of ETBE exposure have become a public concern. Our previous study showed that ETBE-induced toxicity in aldehyde dehydrogenase 2 (Aldh2) gene knockout (KO) mice was caused by its primary metabolite acetaldehyde, which was toxic. However, it is unclear whether tert-butyl alcohol (TBA), another main metabolite of ETBE, plays a role in ETBE-induced toxicity. To investigate this relationship, we analyzed the changes of TBA concentrations in tissues after ETBE exposure, and then evaluated the toxicity after direct TBA treatment in both KO and wild-type (WT) mice. An exposure to 500 ppm ETBE via inhalation resulted in the formation of its three metabolites, TBA, 2-methyl-1,2-propanediol and ethanol, whose concentrations in the liver, brain, fat and testis of male KO mice were significantly higher than the corresponding concentrations observed in male WT mice. Direct treatment to TBA (20 mg/mL of drinking water) caused significant changes in relative organ weights and histopathology, and increased levels of genetic damages in both types of mice. These toxic effects were also seen in KO mice exposed to a lower concentration of TBA (5 mg/mL), which was associated with increased oxidative stress in serum (reduced glutathione and reduced glutathione/oxidized glutathione ratio decreased). Our findings indicate that ALDH2 is involved in the metabolism of ETBE and TBA, and ALDH2 deficiency could greatly increase the sensitivity to TBA-induced toxicity.


Assuntos
Aldeído-Desidrogenase Mitocondrial/deficiência , Doença Hepática Induzida por Substâncias e Drogas/fisiopatologia , Deficiências Nutricionais/fisiopatologia , Camundongos Knockout/genética , terc-Butil Álcool/toxicidade , Animais , Variação Genética , Genótipo , Exposição por Inalação , Masculino , Camundongos , Modelos Animais , Testes de Toxicidade
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