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1.
Toxicol Lett ; 341: 94-106, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33539969

RESUMO

Enzymatic conjugation of glutathione (GSH) to trichloroethylene (TCE) followed by catabolism to the corresponding cysteine-conjugate, S-(dichlorovinyl)-L-cysteine (DCVC), and subsequent bioactivation by renal cysteine conjugate beta-lyases is considered to play an important role in the nephrotoxic effects observed in TCE-exposed rat and human. In this study, it is shown for the first time that three regioisomers of GSH-conjugates of TCE are formed by rat and human liver fractions, namely S-(1,2-trans-dichlorovinyl)-glutathione (1,2-trans-DCVG), S-(1,2-cis-dichlorovinyl)-glutathione (1,2-cis-DCVG) and S-(2,2-dichlorovinyl)-glutathione (2,2-DCVG). In incubations of TCE with rat liver fractions their amounts decreased in order of 1,2-cis-DCVG > 1,2-trans-DCVG > 2,2-DCVG. Human liver cytosol showed a more than 10-fold lower activity of GSH-conjugation, with amounts of regioisomers decreasing in order 2,2-DCVG > 1,2-trans-DCVG > 1,2-cis-DCVG. Incubations with recombinant human GSTs suggest that GSTA1-1 and GSTA2-2 play the most important role in human liver cytosol. GSTP1-1, which produces regioisomers in order 1,2-trans-DCVG > 2,2-cis-DCVG > 1,2-cis-DCVG, is likely to contribute to extrahepatic GSH-conjugation of TCE. Analysis of the products formed by a beta-lyase mimetic model showed that both 1,2-trans-DCVC and 1,2-cis-DCVC are converted to reactive products that form cross-links between the model nucleophile 4-(4-nitrobenzyl)-pyridine (NBP) and thiol-species. No NBP-alkylation was observed with 2,2-DCVC corresponding to its low cytotoxicity and mutagenicity. The lower activity of GSH-conjugation of TCE by human liver fractions, in combination with the lower fraction of potential nephrotoxic and mutagenic 1,2-DCVG-isomers, suggest that humans are at much lower risk for TCE-associated nephrotoxic effects than rats.


Assuntos
Glutationa Transferase/metabolismo , Glutationa/análogos & derivados , Glutationa/metabolismo , Tricloroetileno/farmacologia , Animais , Cromatografia Líquida , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Glutationa Transferase/genética , Humanos , Fígado , Masculino , Estrutura Molecular , Ratos , Ratos Wistar , Proteínas Recombinantes , Solventes/farmacologia , Especificidade da Espécie
2.
J Biosci Bioeng ; 131(5): 491-500, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33610455

RESUMO

Cyanobacteria hold promise as cell factories for the photoautotrophic conversion of carbon dioxide to useful chemicals. For the eventual commercial viability of such processes, cyanobacteria need to be engineered for (i) efficient channeling of carbon flux toward the product of interest and (ii) improved product tolerance, the latter being the focus of this study. We chose the recently reported, fast-growing, high light and CO2 tolerant cyanobacterium Synechococcus elongatus PCC 11801 for adaptive laboratory evolution. In two parallel experiments that lasted over 8400 h of culturing and 100 serial passages, S. elongatus PCC 11801 was evolved to tolerate 5 g/L n-butanol or 30 g/L 2,3-butanediol representing a 100% improvement in concentrations tolerated. The evolved strains retained alcohol tolerance even after being passaged several times without the alcohol stress suggesting that the changes were permanent. Whole genome sequencing of the n-butanol evolved strains revealed mutations in a number of stress responsive genes encoding translation initiation factors, RpoB and an ABC transporter. In 2,3-butanediol evolved strains, genes for ClpC, a different ABC transporter, glyceraldehyde-3-phosphate dehydrogenase and phosphoribulokinase were found to be mutated. Furthermore, the evolved strains showed significant improvement in tolerance toward several other alcohols. Notably, the n-butanol evolved strain could tolerate up to 32 g/L ethanol, thereby making it a promising host for photosynthetic production of biofuels via metabolic engineering.


Assuntos
Evolução Molecular Direcionada , Solventes/farmacologia , Synechococcus/efeitos dos fármacos , Synechococcus/genética , Álcoois/farmacologia , Biocombustíveis , Dióxido de Carbono/metabolismo , Fotossíntese/efeitos dos fármacos , Synechococcus/metabolismo
3.
Int J Biol Macromol ; 171: 382-388, 2021 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-33434547

RESUMO

The current study heterologously expressed a cutinase from Fusarium verticillioides by Pichia pastoris and investigated its properties and effects on the hydrolysis of rice straw. The optimal pH and temperature for F. verticillioides cutinase were 8.0 and 50 °C, respectively. F. verticillioides cutinase had poor thermal stability and could be inhibited by some metal ions, inhibitors, and detergents (5 mM), including Ni2+, Zn2+, Cu2+, Ca2+, Mn2+, sodium dodecyl sulfate, EDTA, and Tween-20. F. verticillioides cutinase could tolerate 15% methanol and dimethyl sulfoxide but was significantly repressed by 15% ethanol and acetone with 48% and 63% residual activity, respectively. F. verticillioides cutinase could degrade the cuticle of rice straw with palmitic acid and stearic acid as the main products. However, the dissolving sugars released from the rice straw treated with F. verticillioides cutinase were significantly reduced by 29.2 µg/mL compared with the control (107.9 µg/mL). Similarly, the reducing sugars produced from the cellulase hydrolysis of rice straw pretreated with F. verticillioides cutinase were reduced by 63.5 µg/mL relative to the control (253.6 µg/mL). Scanning electron microscopy results showed that numerous tuberculate or warty protrusions were present nearly everywhere on the surface of rice straw treated with F. verticillioides cutinase, and some protrusions even covered and blocked the stomata of the rice straw surface. Current limited data indicate that F. verticillioides cutinase might not be an appropriate choice for improving the utilization of agricultural straws.


Assuntos
Hidrolases de Éster Carboxílico/farmacologia , Proteínas Fúngicas/farmacologia , Fusarium/enzimologia , Oryza , Caules de Planta/efeitos dos fármacos , Hidrolases de Éster Carboxílico/biossíntese , Hidrolases de Éster Carboxílico/genética , Celulase/farmacologia , Detergentes/farmacologia , Ácidos Graxos/isolamento & purificação , Fermentação , Proteínas Fúngicas/biossíntese , Proteínas Fúngicas/genética , Concentração de Íons de Hidrogênio , Hidrólise , Microbiologia Industrial/métodos , Metais/farmacologia , Oryza/química , Caules de Planta/química , Proteínas Recombinantes/farmacologia , Solventes/farmacologia , Açúcares/isolamento & purificação
4.
J Ethnopharmacol ; 269: 113687, 2021 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-33309916

RESUMO

ETHNOPHARMACOLOGICAL RELEVANCE: Snake bite is a major occupational hazard in tropical and subtropical countries including India as per the World Health Organization. Naja naja (Indian cobra) and Daboia russelli (Russell's viper) are the two poisonous snakes commonly associated with human mortality in India. Andrographis serpyllifolia (Rottler ex Vahl) Wight has been documented in ethnobotanical records as a plant possessing potent anti-snake venom activity. AIM OF THE STUDY: The present study is aimed for systematic evaluation of in vitro anti-venom potential of various solvent based leaf extracts of A. serpyllifolia against toxic venom enzymes of Naja naja and Daboia russelli. MATERIALS AND METHODS: Different solvent based leaf extracts of A. serpyllifolia were tested against the snake venoms of Naja naja and Daboia russelli obtained from Irula Snake Catchers Industrial Co-operative Society Limited, Kancheepuram, Tamil nadu, India. Three different in vitro neutralization assays such as indirect hemolysis, procoagulent and lytic activities and seven in vitro enzyme inhibition assays such as protease, acetylcholinesterase, phosphomonoesterase, phosphodiesterase, 5'nucleotidase, phospholipase A2, hyaluronidase and post synaptic acetylcholine receptor binding activity were carried out according to standard protocols. The results were analyzed using the standard ANOVA procedures. RESULTS: Among various solvent based leaf extracts of A. serpyllifolia tested, aqueous extract showed maximum neutralizing and inhibitory activities against Naja naja and Daboia russelli venoms. CONCLUSIONS: The various in vitro enzymatic studies reveal that the aqueous leaf extract of A. serpyllifolia plant could inhibit most of the toxic enzymes of the Naja naja and Daboia russelli venoms which could be further confirmed by in vivo studies.


Assuntos
Andrographis , Antivenenos/farmacologia , Venenos Elapídicos/antagonistas & inibidores , Extratos Vegetais/farmacologia , Solventes/farmacologia , Venenos de Víboras/antagonistas & inibidores , Animais , Antivenenos/isolamento & purificação , Relação Dose-Resposta a Droga , Venenos Elapídicos/isolamento & purificação , Naja naja , Extratos Vegetais/isolamento & purificação , Folhas de Planta , Solventes/isolamento & purificação , Venenos de Víboras/isolamento & purificação
5.
Nicotine Tob Res ; 22(Suppl 1): S14-S24, 2020 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-33320250

RESUMO

INTRODUCTION: Chemical elements and their toxicity were evaluated in electronic cigarette (EC) solvents, fluids, and aerosols. AIMS AND METHODS: Element identification and quantification in propylene glycol (PG), glycerin (G), refill fluids before and after use, and aerosols was done using inductively coupled plasma optical emission spectrometry. Cytotoxicity and oxidative stress were evaluated using in vitro assays. RESULTS: Seven elements were present in PG, G, and popular refill fluids, and they transferred to aerosols made with ECs. Selenium was in all products (0.125-0.292 mg/L), while arsenic, aluminum, and tin were frequently in solvent and refill fluid samples at lower concentrations. Iron, chromium, copper, nickel, zinc, and lead were only detected in fluid after EC use, indicating they came from heated atomizers. Elements transferred most efficiently to aerosols made with second-/third-generation ECs. Of the elements in fluid, selenium and arsenic were the most cytotoxic to human bronchial epithelial cells (BEAS-2B) and pulmonary fibroblasts in the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay. Selenium increased superoxide production in mitochondria and nucleoli and elevated selenoprotein H in nucleoli of BEAS-2B cells at concentrations found in EC aerosols (10 nM or 0.002 mg/L). CONCLUSIONS: Elements in EC aerosols came from both e-fluids and atomizing units. Within second-/third-generation products, transfer became more efficient as power increased. In vitro responses occurred at concentrations of selenium found in some EC aerosols. Human exposure to chemical elements in ECs could be reduced by regulating (decreasing) allowable EC power and by improving the purity of PG and G. IMPLICATIONS: PG, G, refill fluids, and e-fluids contained potentially toxic chemical elements that transferred to aerosols. Transfer was more efficient in second- and third-generation EC products and increased as power increased. Selenium and arsenic were the most cytotoxic of the elements tested in the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide assay. Selenium tetrachloride-induced oxidative stress in BEAS-2B cells, but not in human pulmonary fibroblasts. All fluids contained selenium above the concentration that induced oxidative stress in human bronchial epithelial cells. Selenium increased superoxide in mitochondria and nucleoli and increased selenoprotein H, a redox responsive DNA-binding protein that is upregulated by superoxide and an indicator of nucleolar stress. EC users are exposed to elements in aerosols, which may with chronic exposure contribute to diseases associated with oxidative stress.


Assuntos
Aerossóis/farmacologia , Sistemas Eletrônicos de Liberação de Nicotina/estatística & dados numéricos , Células Epiteliais/patologia , Pulmão/patologia , Estresse Oxidativo/efeitos dos fármacos , Oxirredutases/antagonistas & inibidores , Solventes/farmacologia , Células Cultivadas , Células Epiteliais/efeitos dos fármacos , Humanos , Pulmão/efeitos dos fármacos , Nebulizadores e Vaporizadores/estatística & dados numéricos
6.
Acta Odontol Latinoam ; 33(2): 135-142, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32920616

RESUMO

This study evaluated the influence of the mode and time of solvent evaporation on the tensile strength (TS), flexural strength (FS) and elastic modulus (EM) of two adhesive systems: Scotchbond Multipurpose (SBMP) and Clearfil SE (CSEB). For this purpose, rectangular samples (2x1x7 mm) were prepared with 10 µL of primer and the solvents were evaporated with air spray at (23±1) ºC, (40±1) ºC and negative control (without spray). For each temperature, the times of 5, 20, 30, and 60 seconds were investigated. The statistical results showed that evaporation at 40±1ºC resulted in better EM for the two adhesives tested and all the evaporation times evaluated. However, there were no significant differences between the times and modes of evaporation for TS. The results of this study indicate that evaporation at a temperature of (40±1) °C could improve the elastic modulus of both adhesives tested, regardless of the evaporating time.


Assuntos
Adesivos/química , Cimentos Dentários/química , Adesivos Dentinários/química , Solventes/farmacologia , Resistência à Tração , Dessecação , Humanos , Teste de Materiais , Volatilização
7.
Vet Microbiol ; 243: 108641, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32273020

RESUMO

Riemerella anatipestifer is a Gram-negative bacterium, which is an important pathogen infecting ducks and resistant to various antibiotics. The efflux pump is an important resistance mechanism of Gram-negative bacteria, but little research has been done in R. anatipestifer. In this study, the drug resistance mediated by RIA_1614 gene of R. anatipestifer RA-GD strain was studied, because the gene was presumed to be an efflux pump component of ABC. Firstly, the deletion strain RA-GD△RIA_1614 and complemented strain RA-GD△RIA_1614 pCPRA::RIA_1614 were constructed. Then, MICs of various antimicrobial agents to parent and deletion strains and the tolerance of the strains to organic solvents were detected to screen the substrates for RIA_1614 gene. Moreover, the transcription levels of RIA_1614 gene in the parent and the complemented strains exposed to the substrates were detected by quantitative real-time RT-PCR. Furthermore, the efflux abilities of parent, deletion and complemented strains to substrates were determined by antibiotic accumulation test. In addition, in vitro competition ability and virulence of the strains were also detected. The results showed that the deletion strain was more sensitive to aminoglycosides and organic solvents than parental strain RA-GD. When RA-GD and complemented strain were exposed to sub-repression levels of aminoglycosides and organic solvents, the transcription levels of RIA_1614 gene were significantly up-regulated. Sodium o-vanadate inhibitor assay confirmed that RIA_1614 protein contributed to amikacin and streptomycin resistance and organic solvent tolerance. Streptomycin accumulation test showed that the RIA_1614 protein was able to export streptomycin, and the addition of ATPase inhibitor sodium o-vanadate increased the accumulation of streptomycin, indicating that RIA_1614 protein was an ATP-dependent efflux transporter. Growth and competition experiments revealed that RIA_1614 protein had no significant effect on growth of RA-GD, but decreased in vitro competition ability of the strain. Furthermore, pathogenicity tests showed that RIA_1614 protein involved in the virulence of the strain. Based on the results and amino acid sequence analysis, it was determined that RIA_1614 protein was a member of ABC efflux pumps, and the protein was named RanB.


Assuntos
Transportadores de Cassetes de Ligação de ATP/genética , Aminoglicosídeos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Proteínas de Membrana Transportadoras/genética , Riemerella/efeitos dos fármacos , Solventes/farmacologia , Transportadores de Cassetes de Ligação de ATP/classificação , Animais , Patos/microbiologia , Deleção de Genes , Genes MDR/genética , Testes de Sensibilidade Microbiana , Compostos Orgânicos/farmacologia , Doenças das Aves Domésticas/microbiologia , Riemerella/genética , Riemerella/patogenicidade , Deleção de Sequência , Solventes/química
8.
PLoS One ; 15(2): e0228543, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32045426

RESUMO

Two molecules, 7-(diethylamino)coumarin-3-carbohydrazide (DCCH) and fluorescein-5-thiosemicarbazide (FTSC) were investigated in different solvents, under varying pH conditions regarding their spectroscopic properties for the usage as a Förster Resonance Energy Transfer (FRET) pair to study the molecular interaction between cellulosic surfaces. All the relevant spectroscopic properties to determine the Förster distance were measured and the performance as a FRET system was checked. From the results, it is clear that the environmental conditions need to be accurately controlled as both, but especially the FTSC dyes are sensitive to changes. For high enough concentrations positive FRET systems were observed in DMF, DMSO, H2O, THF and alkaline DMF. However due to the low quantum yield of the unmodified DCCH throughout the investigated parameter range and the strong environmental dependency of FTSC, both dyes are not preferable for being used in a FRET system for studying interaction between cellulosic surfaces.


Assuntos
Cumarínicos/química , Fluoresceínas/química , Transferência Ressonante de Energia de Fluorescência/métodos , Hidrazinas/química , Solventes/química , Análise Espectral/métodos , Transferência de Energia/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Solventes/farmacologia , Espectrometria de Fluorescência/métodos , Espectrofotometria Ultravioleta/métodos
9.
PLoS One ; 15(2): e0228908, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32107483

RESUMO

The aim of the current study was to develop membrane-based transdermal patches of lornoxicam gel using oleic acid (OA)and propylene glycol (PG) as penetration enhancers to improve drug delivery across the skin and to evaluate in vivo analgesic and anti-inflammatory activity. For this purpose, nine formulations were developed in accordance with 32 factorial design using Design Expert® 11. The concentration of propylene glycol (X1) and oleic acid (X2) were selected as independent variable whereas Q10 (Y1), flux (Y2) and lag time (Y3) were considered as the response variables. The impact of drug loading, surface area, gel concentration, membrane variation and agitation speed on drug release and permeation was also studied. The skin sensitivity reaction, analgesic activity and anti-inflammatory action of the optimized patch were also determined in Albino Wistar rats. Stability studies were performed for three months at three different temperature conditions. The result suggests that a membrane-based system with controlled zero-order drug release of 95.8 ± 1.121% for 10 h exhibiting flux of 126.51±1.19 µg/cm2/h and lag time of 0.908 ±0.57h was optimized with the desired analgesic and anti-inflammatory effect can be obtained by using propylene glycol and oleic acid co-solvents as a penetration enhancer. The patch was also found stable at 4˚C for a period of 6.44 months. Formulation F9 comprising of 10% PG and 3% OA was selected as an optimized formulation. The study demonstrates that the fabricated transdermal system of lornoxicam can deliver the drug through the skin in a controlled manner with desired analgesic and anti-inflammatory activity and can be considered as a suitable alternative of the oral route.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Piroxicam/análogos & derivados , Administração Cutânea , Analgésicos/farmacologia , Animais , Anti-Inflamatórios não Esteroides/farmacologia , Química Farmacêutica , Preparações de Ação Retardada/farmacologia , Géis/metabolismo , Masculino , Ácido Oleico/farmacologia , Piroxicam/farmacologia , Propilenoglicol/farmacologia , Ratos , Ratos Wistar , Pele/metabolismo , Absorção Cutânea/fisiologia , Solventes/farmacologia , Adesivo Transdérmico
10.
J Biotechnol ; 308: 21-26, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31758968

RESUMO

The asymmetric resolution of racemic 1-phenyl-1,2-ethanediol (PED) to (S)-PED by Kurthia gibsonii SC0312 (K. gibsonii SC0312) was conducted in a biphasic system comprised of an organic solvent and aqueous phosphate buffer. The impacts of organic solvents on the whole cell catalytic activity, metabolic activity, membrane integrity, and material distribution were first evaluated. The results showed that all organic solvents, except for dibutyl phthalate, showed a detrimental effect on the metabolic activity of the cells, especially for those with low log P values. All organic solvents were capable of changing the membrane permeability and membrane integrity of the cells. Moreover, some organic solvents showed a good extraction of the oxidation product. Finally, a high yield of 47.7 % of (S)-PED was obtained by the asymmetric resolution of racemic PED using K. gibsonii SC0312 in a biphasic system under the optimal conditions: racemic PED 120 mM, temperature 35 °C, reaction time 6 h, 180 rpm, and a volume ratio of dibutyl phthalate to aqueous phosphate buffer of 1:1. The optical purity of (S)-PED increased from 51.3 % to >99 %. This work described an efficient approach to improve reaction efficiency, and constructed a highly effective biphasic reaction system for the fabrication of (S)-PED via K. gibsonii SC0312.


Assuntos
Etilenoglicóis/química , Planococáceas/crescimento & desenvolvimento , Catálise , Permeabilidade da Membrana Celular/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Planococáceas/metabolismo , Solventes/farmacologia , Estereoisomerismo , Especificidade por Substrato
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 226: 117603, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31614275

RESUMO

In this report, the fluorescence properties of the antimuscarinic drug trimebutine maleate (TRB) were fully studied and characterized. TRB exhibited intrinsic fluorescence that is greatly dependent on the local environmental factors including the solvent nature and the pH. Yet, its fluorescence was not significantly influenced by the existence of some surface active agents and polymer. The outcomes of this investigation verified that TRB fluorescence emission is intense in ethanol: 1.0 M aqueous acetic acid (9:1, v/v) with emission maxima at 357 nm and excitation maxima at 270 nm. Whereas, going towards higher pH causes fluorescence quenching. These conditions permitted ultrasensitive fluorimetric determination of TRB over the concentration range of 2.00-1500.0 ng/mL with a lower detection limit of 0.40ng/mL Application for the determination of TRB in tablets, ampoule and suspension was successfully achieved with %recoveries ranged between 98.21-100.17%. Furthermore, a first order derivative fluorimetric method was validated for resolving and simultaneous determination of TRB and its degradation product and impurity, eudesmic acid (EUA) making use of the pH-mediated fluorescence spectral shift of EUA. An ethanolic solution containing acetate buffer (pH 5.3) was used for this goal with excitation at 255 nm and measurement of the first order derivative peak amplitudes at respective zero-crossing points of 375 and 351 nm over the corresponding concentration ranges of 20.00-500.00 and 10.00-300.00 ng/mL for TRB and EUA, respectively. The two methods were assessed regarding greenness and eco-friendship by the National Environmental Methods Index and analytical eco-scale score approaches which confirmed their excellent greenness and safety.


Assuntos
Fluorometria/métodos , Química Verde/métodos , Trimebutina/análogos & derivados , Trimebutina/análise , Calibragem , Contaminação de Medicamentos , Fluorescência , Fluorometria/normas , Química Verde/normas , Concentração de Íons de Hidrogênio , Inativação Metabólica , Limite de Detecção , Reprodutibilidade dos Testes , Solventes/química , Solventes/farmacologia , Espectrometria de Fluorescência/métodos , Trimebutina/química , Trimebutina/metabolismo
12.
Nicotine Tob Res ; 22(5): 791-797, 2020 04 21.
Artigo em Inglês | MEDLINE | ID: mdl-31403695

RESUMO

INTRODUCTION: Electronic nicotine delivery systems (ENDS) vary on a wide range of characteristics that may affect reinforcement value and use. One characteristic is the ratio of two solvents commonly used in most e-liquids: propylene glycol (PG) and vegetable glycerin (VG). The goal of this study was to understand how PG/VG ratio affects subjective effects, reinforcement value, and tobacco use patterns among current smokers who try using ENDS. AIMS AND METHODS: Current smokers with minimal ENDS use history (n = 30) sampled, in a double-blind fashion, three different e-liquids that varied in PG/VG ratio (70/30, 50/50, 0/100) while holding constant other aspects of the e-liquid and ENDS. Participants tried each e-liquid before rating the subjective effects on a modified version of the Cigarette Evaluation Questionnaire. Reinforcement value was assessed using a preference task where participants chose between the three e-liquids. The impact of each e-liquid on cigarette reinforcement was assessed using a modified version of the Cigarette Purchase Task. Participants were randomly assigned to receive one e-liquid to take home for 1 week. RESULTS: PG/VG ratio had minimal impact on most of the tested outcomes. Participants rated the highest PG concentration as having a stronger "throat hit" than the other two. There was no significant difference between the number of participants who preferred each of the PG/VG ratios in the preference assessment. PG/VG ratio did not affect cigarette or ENDS use during the sampling week. CONCLUSIONS: These data suggest that PG/VG ratio has minimal impact on subjective effects and reinforcement value in ENDS naive current smokers. IMPLICATIONS: These data suggest that PG/VG ratio, within the range that is commonly used, has minimal impact on subjective effects, reinforcement value, or uptake in current smokers with minimal ENDS experience.


Assuntos
Sistemas Eletrônicos de Liberação de Nicotina/estatística & dados numéricos , Glicerol/farmacologia , Propilenoglicol/farmacologia , Reforço Psicológico , Fumantes/psicologia , Verduras/química , Adulto , Comportamento do Consumidor , Método Duplo-Cego , Feminino , Humanos , Masculino , Solventes/farmacologia
13.
J Biotechnol ; 309: 68-74, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-31870685

RESUMO

Improving enzyme stability in the presence of organic solvent is crucial for non-aqueous catalysis. In this study, directed evolution was applied to improve the tolerance of metalloprotease PT121 towards organic solvent. In presence of acetonitrile and acetone, three mutants (T46Y, H224 F, and H224Y) of PT121 showed excellent solvent stability, which increased their half-lives by 1.2-3.5-fold as compared to the wild-type enzyme. Kinetic constants (KM and kcat values) of the caseinolysis reaction presented H224 F and H224Y mutants have higher affinity than the wild-type, but T46Y mutant were similar to those of the wild-type enzyme. Interestingly, combined mutants T46Y/H224 F and T46Y/H224Y mutants presented awesome stability and excellent caseinolytic activity. Molecular dynamic simulation suggest that improved enzyme stability may be attributed to extensive non-covalent bond network resulting in a more compact structure. Disruption of the disulphide bond formation between Cys-30 and Cys-58 residues in the F56 V mutant is possibly the reason behind its low stability among all the selected mutants. Additionally, T46Y/H224 F and T46Y/H224Y showed a higher peptide synthetic activity in the presence of organic solvents than the wild-type, which renders these mutant enzymes as promising biocatalysts for biotechnological applications.


Assuntos
Estabilidade Enzimática/efeitos dos fármacos , Metaloproteases/efeitos dos fármacos , Metaloproteases/metabolismo , Solventes/química , Solventes/farmacologia , Acetona/farmacologia , Acetonitrilas/farmacologia , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Cinética , Metaloproteases/química , Metaloproteases/genética , Simulação de Dinâmica Molecular , Mutagênese Sítio-Dirigida , Mutação
14.
Sheng Wu Gong Cheng Xue Bao ; 35(10): 1857-1869, 2019 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-31668034

RESUMO

Enzymes have a wide range of applications and great industrial potential. However, large-scale applications of enzymes are restricted by the harsh industrial environment, such as high temperature, strong acid/alkali, high salt, organic solvents, and high substrate concentration. Adaptive modification (such as rational or semi-rational design, directed evolution and immobilization) is the most common strategy to improve the catalysis of enzymes under industrial conditions. Here, we review the catalysis of enzymes in the industrial environment and various methods adopted for the adaptive modifications in recent years, to provide reference for the adaptive modifications of enzymes.


Assuntos
Biocatálise , Biotecnologia , Enzimas/química , Enzimas/metabolismo , Engenharia de Proteínas , Biocatálise/efeitos dos fármacos , Temperatura Alta , Concentração de Íons de Hidrogênio , Solventes/química , Solventes/farmacologia
15.
Sci Rep ; 9(1): 14390, 2019 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-31591515

RESUMO

Phytase is one of the most effective feed additives to increase the availability of phosphorus and minerals by catalyzing the hydrolysis of phytic acid. A modified appA gene (mappA) was transformed into soybean (Glycine max) under the control of a seed-specific promoter from common bean (Phaselous vulgaris). The soybean recombinant phytase showed optimal activity at pH 4.5 and 70 °C. A slight increase in enzyme activity occurred when the recombinant enzyme was pre-incubated with n-hexane. In addition, the phytase activity from our transgenic soybean does not reduce even after 2 hours of extraction with n-hexane at 55~65 °C. In conclusion, the oil extraction process using n-hexane does not inactivate the phytase expressed in the mAppA transgenic soybean, and the meal derived from the transgenic soybean processing can be used as feed supplement to livestock.


Assuntos
6-Fitase/genética , 6-Fitase/metabolismo , Ração Animal/análise , Soja/genética , Temperatura , Estabilidade Enzimática , Expressão Gênica , Cinética , Metais/farmacologia , Plantas Geneticamente Modificadas , Solventes/farmacologia
16.
Arch Oral Biol ; 108: 104538, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31476521

RESUMO

AIM: To investigate the effect of different alcohol concentrations on the development of apical periodontitis (AP) in rats. METHODS: Forty Wistar rats were arranged into five groups: (C) - control rats receiving sterile water as the only liquid; (G5) - animals receiving an alcohol solution at 5%, (G10) - alcohol solution at 10%, (G15) - alcohol solution at 15%, and (G20) - alcohol solution at 20%. The alcoholic solution or water was given to the groups as the sole source of hydration throughout the 30 days of the experiment. AP was induced in the mandibular molars on the first day. In the end, the animals were euthanized for histopathological and IL-1b, RANKL, OPG, and TRAP analyses. The Kruskal-Wallis test was used for nonparametric data, and ANOVA followed by the Tukey test were performed for parametric data, p < 0.05. RESULTS: G15 and G20 had a greater chronic inflammatory infiltrate (Score 3) and AP size bigger (1.59 ±â€¯0.41 and 1.83 ±â€¯0.38, respectively) than the C, G5 and G10 (p < 0.05). No significant difference was found in the IL-1b analyses. The G15 and G20 showed the highest immunolabeling pattern for RANKL and the lowest for OPG. The G20 had greater TRAP cells per mm (4.70 ±â€¯0.99) compared to the C, G5, and G10 (p < 0.05). Furthermore, G15 presented 3.92 ±â€¯0.64 TRAP cells/mm, higher than C (p < 0.05). CONCLUSIONS: G5 and G10 did not exert a protective or aggravating effect on the AP development. However, G15 and G20 had a significant effect on the AP severity, exacerbating the inflammation and osteoclast markers.


Assuntos
Etanol , Periodontite Periapical , Solventes , Animais , Etanol/farmacologia , Inflamação , Osteoclastos/efeitos dos fármacos , Ratos , Ratos Wistar , Solventes/farmacologia
17.
J Phys Chem B ; 123(40): 8378-8386, 2019 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-31509409

RESUMO

This study investigates the role of hydration and its relationship to the conformational equilibrium of the host molecule ß-cyclodextrin. Molecular dynamics simulations indicate that the unbound ß-cyclodextrin exhibits two state behavior in explicit solvent due to the opening and closing of its cavity. In implicit solvent, these transitions are not observed, and there is one dominant conformation of ß-cyclodextrin with an open cavity. Based on these observations, we investigate the hypothesis that the expulsion of thermodynamically unfavorable water molecules into the bulk plays an important role in controlling the accessibility of the closed macrostate at room temperature. We compare the results of the molecular mechanics analytical generalized Born plus nonpolar solvation approach to those obtained through grid inhomogeneous solvation theory analysis with explicit solvation to elucidate the thermodynamic forces at play. The work illustrates the use of continuum solvent models to tease out solvation effects related to the inhomogeneity and the molecular nature of water and demonstrates the key role of the thermodynamics of enclosed hydration in driving the conformational equilibrium of molecules in solution.


Assuntos
Solventes/farmacologia , beta-Ciclodextrinas/química , Simulação de Dinâmica Molecular , Conformação Proteica/efeitos dos fármacos , Termodinâmica
18.
Mol Microbiol ; 112(5): 1564-1575, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31468587

RESUMO

Hopanoids are a class of membrane lipids found in diverse bacterial lineages, but their physiological roles are not well understood. The ethanol fermenter Zymomonas mobilis features the highest measured concentration of hopanoids, leading to the hypothesis that these lipids can protect against the solvent toxicity. However, the lack of genetic tools for manipulating hopanoid composition in this bacterium has limited their further functional analysis. Due to the polyploidy (>50 genome copies per cell) of Z. mobilis, we found that disruptions of essential hopanoid biosynthesis (hpn) genes act as genetic knockdowns, reliably modulating the abundance of different hopanoid species. Using a set of hpn transposon mutants, we demonstrate that both reduced hopanoid content and modified hopanoid polar head group composition mediate growth and survival in ethanol. In contrast, the amount of hopanoids, but not their head group composition, contributes to fitness at low pH. Spectroscopic analysis of bacterial-derived liposomes showed that hopanoids protect against several ethanol-driven phase transitions in membrane structure, including lipid interdigitation and bilayer dissolution. We propose that hopanoids act through a combination of hydrophobic and inter-lipid hydrogen bonding interactions to stabilize bacterial membranes during solvent stress.


Assuntos
Anti-Infecciosos Locais/farmacologia , Tolerância a Medicamentos/genética , Etanol/farmacologia , Triterpenos/metabolismo , Zymomonas/genética , Membrana Celular/metabolismo , Lipídeos de Membrana/classificação , Lipídeos de Membrana/metabolismo , Solventes/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Zymomonas/efeitos dos fármacos
19.
Int J Biol Macromol ; 140: 1037-1046, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31449862

RESUMO

Azo dyes are the most widely applied chemical dyes that have also raised great concerns for environmental contamination and human health issues. There has been a growing interest in discovering bioremediation methods to degrade azo dyes for environmental and economic purposes. Azoreductases are key enzymes evolved in nature capable of degrading azo dyes. The current work reports the identification, expression, and properties of a novel azoreductase (AzoRed2) from Streptomyces sp. S27 which shows an excellent stability against pH change and organic solvents. To overcome the requirements of coenzyme while degrading azo dyes, we introduced a coenzyme regeneration enzyme, Bacillus subtilis glucose 1-dehydrogenase (BsGDH), to construct a recycling system in living cells. The whole-cell biocatalyst containing AzoRed2 and BsGDH was used to degrade a representative azo dye methyl red. The degradation rate of methyl red was up to 99% in 120 min with high substrate concentration (250 µM) and no external coenzyme added. The degradation rate was still 98% in the third batch trial. To sum up, a novel azoreductase with good properties was found, which was applied to construct whole-cell biocatalyst. Both the enzymes and whole-cell biocatalysts are good candidates for the industrial wastewater treatment and environmental restoration.


Assuntos
Compostos Azo/isolamento & purificação , NADH NADPH Oxirredutases/metabolismo , Streptomyces/enzimologia , Águas Residuárias/química , Sequência de Aminoácidos , Compostos Azo/química , Biocatálise , Biodegradação Ambiental , Detergentes/farmacologia , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Íons , Metais/farmacologia , NADH NADPH Oxirredutases/química , Filogenia , Solventes/farmacologia , Espectrofotometria Ultravioleta , Especificidade por Substrato , Temperatura
20.
Biomacromolecules ; 20(9): 3584-3591, 2019 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-31424919

RESUMO

Herein we demonstrated a novel lipase-catalyzed synthesis of isotactic D-/L-poly(aspartate-octanediol) ester containing long chain alcohols backbone and discovered their stereocomplex feature with an increased Tm for the first time. Simple design of monomer structures not only overcomes the inherent selectivity limitation of enzyme used, but also achieves totally isotactic polyester products. By crystallizing the mixed enantiopure isotactic polyesters in different solvents, the formation of amorphous mixture, homocrystallites or stereocomplex crystallites were observed, respectively. This study is expected to open up a new way to prepare various stereocomplex polyesters containing a long-chain aliphatic alcohol backbone and a wide variety of functional groups.


Assuntos
Álcoois/química , Poliésteres/química , Polímeros/química , Catálise , Cristalização , Etanol/química , Lipase/química , Poliésteres/síntese química , Poliésteres/farmacologia , Polímeros/síntese química , Polímeros/farmacologia , Solventes/química , Solventes/farmacologia
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