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1.
Molecules ; 24(17)2019 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-31470598

RESUMO

A strategy is devised to synthesize zwitterionic acetylated cellulose nanofibrils (CNF). The strategy included acetylation, periodate oxidation, Schiff base reaction, borohydride reduction, and a quaternary ammonium reaction. Acetylation was performed in glacial acetic acid with a short reaction time of 90 min, yielding, on average, mono-acetylated CNF with hydroxyl groups available for further modification. The products from each step were characterized by FTIR spectroscopy, ζ-potential, SEM-EDS, AFM, and titration to track and verify the structural changes along the sequential modification route.


Assuntos
Celulose/síntese química , Técnicas de Química Sintética , Nanofibras/química , Ácido Acético/química , Acetilação , Boroidretos/química , Celulose/análogos & derivados , Humanos , Nanofibras/ultraestrutura , Oxirredução , Compostos de Amônio Quaternário/química , Bases de Schiff/química
2.
Carbohydr Polym ; 223: 115059, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31426985

RESUMO

Fast-swelling, porous cellulose hydrogels (PCHs) were generated via simple acid treatment of cellulose hydrogel prepared in NaOH/urea medium. Structural characteristics of the PCHs were investigated by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Swelling behavior was assessed by measuring the swelling kinetics in deionized water. Mechanical properties were also examined. The results showed that acid treated PCHs had many more micropores, mesopores and macropores, and PCH-6% displayed a high specific surface area of 33.98 m2/g. However, cellulose hydrogel without acid treatment had a low specific surface area (2.499 m2/g). Mechanical property of hydrogel was found to be slightly deteriorated with the improvement of porous structure. The equilibrium swelling rate of PCHs had drastically improvement after acid treatment. This porous cellulose hydrogel skeleton presents a wide range of possibilities for the further development of fast swelling cellulose-based functional hydrogel.


Assuntos
Celulose/química , Hidrogéis/química , Ureia/química , Ácido Acético/química , Força Compressiva , Epicloroidrina/química , Linho/química , Hidrogéis/síntese química , Porosidade
3.
Anticancer Res ; 39(8): 4511-4516, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31366553

RESUMO

BACKGROUND/AIM: Gluconacetobacter hansenii (G. hansenii) is an acetic acid bacterium of vinegar production. Its anti-allergic effect on mice upon oral administration was examined. MATERIALS AND METHODS: The amount of LPS was measured by the Limulus reaction. Mice were sensitized by peritoneal and intranasal administration of cedar pollen and alum followed by oral administration of 30 or 150 mg/kg of heated G. hansenii cells. Pollen was administered intranasally to evaluate nasal symptoms, and at 8 weeks, IgE and IL-10 levels in blood were measured by ELISA. RESULTS: The amount of LPS in dried bacterial cells was 10.4±3.3 mg/g. In the cedar pollinosis model of mice, a significant reduction was observed in nose scratching of both groups administered with the bacterial cells (30, 150 mg/kg). CONCLUSION: G. hansenii contains LPS, and its oral administration showed an anti-allergic effect by a significant mitigation of the symptoms in a pollen allergy mouse model.


Assuntos
Antialérgicos/administração & dosagem , Gluconacetobacter/imunologia , Pólen/efeitos adversos , Rinite Alérgica Sazonal/prevenção & controle , Ácido Acético/química , Administração Oral , Alérgenos/efeitos adversos , Animais , Antialérgicos/imunologia , Modelos Animais de Doenças , Humanos , Imunoglobulina E/imunologia , Camundongos , Rinite Alérgica Sazonal/microbiologia , Rinite Alérgica Sazonal/patologia
4.
Environ Sci Pollut Res Int ; 26(27): 28173-28187, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31363970

RESUMO

Composting is an attractive way to recycle organic wastes because the product (compost) can be used as an organic fertilizer or a culture substrate. This study assessed coal fly ash (CFA; at 0, 15, and 35%) and/or vinegar residue (VR; at 0, 35, and 55%) as additives in the green waste (GW) composting process. Compost maturity was assessed based on the following indicators: water-holding capacity, pH, total organic carbon, electrical conductivity, total Kjeldahl nitrogen, and germination index. Other important compost properties that were determined included germination percentage and root length of seeds in a germination assay, crude fiber degradation, specific UV absorption, E4/E6 ratio, microbial numbers (culturable bacteria and volatile fatty acid-degrading bacteria), enzyme activities (dehydrogenase, ß-glucosidase, acid-phosphatase, urease, and ortho-diphenol oxidase), and available nutrients. When added together, CFA and VR improved all of these properties. As indicated by the maturity indicators and other properties, the best treatment (the combined addition of 15% CFA and 55% VR) required only 23 days to produce a mature and high quality compost.


Assuntos
Ácido Acético/química , Carbono/química , Cinza de Carvão/química , Nitrogênio/análise , Compostagem , Nitrogênio/química , Água
5.
J Sci Food Agric ; 99(14): 6546-6551, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31328269

RESUMO

BACKGROUND: Proteins recovery using hydrochloric acid (HCl) in acid-aided solubilization could cause greater loss in its functionality over alkali-aided solubilization. Moreover, using HCl in edible foods is also a health concern. Replacing HCl with organic acids for acid-aided solubilization could address these problems. The aim was to study the effect of organic acid (glacial acetic acid) as a replacement for HCl during pH shift processing on the characteristics and functionality of rohu (Labeo rohita) protein isolates. Rohu proteins were obtained by solubilizing at pH 3.0 and pH 11.0 using glacial acetic acid and sodium hydroxide (10 mol L-1 ). RESULTS: Results showed that solubilization at pH 11.0 gave higher protein yields (766.8 ± 2.4 g kg-1 ) compared to solubilization at pH 3.0 (735.7 ± 7.1 g kg-1 ) (P < 0.05). Isolates from acid-aided solubilization had higher whiteness and total pigment content over isolates obtained by alkali-aided solubilization. Rohu isolates recovered by alkaline solubilization showed higher water and oil holding capacity, gel strength, folding scores, foaming and emulsion capacity than acid processed isolates (P < 0.05). Solubilization of rohu proteins using glacial acetic acid produced isolates with low breaking force (149.0 g), low storage modulus (G') values and low folding test score (1.0) over the alkaline isolates (P < 0.05). CONCLUSION: Results indicated that, recovering rohu proteins using organic acid (glacial acetic acid) could produce isolates with poor functional properties, while using the organic acid to precipitate the proteins solubilized by alkali-aided processing could produce proteins with better yields and functionality. © 2019 Society of Chemical Industry.


Assuntos
Fracionamento Químico/métodos , Proteínas de Peixes/isolamento & purificação , Manipulação de Alimentos/métodos , Ácido Acético/química , Animais , Cyprinidae , Proteínas de Peixes/química , Concentração de Íons de Hidrogênio , Solubilidade
6.
Pan Afr Med J ; 32: 174, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31303943

RESUMO

Introduction: Precancerous cervical lesion is significantly a health problem globally. Thus, screening targeting women between the ages of 17-60 is being undertaken in developing countries, including Cameroon. Over 50% (7.8 per 100,000) women die of cervical cancer every year. This study was to determine the prevalence of precancerous cervical lesion, the age demography and access the risk factor. Methods: A hospital-based cross-sectional study was conducted from August 09th to October 17th 2017. A total of 60 women participated, and were screened for precancerous cervical lesion. Data were collected by using a questionnaire. Visual inspection with acetic acid and visual inspection with Lugol's iodine was applied for the screening. SPSS version 16.0 was used for data entry and analysis. Logistic regression analysis was fitted and odds ratios with 95% confidence intervals and p-values were computed to identify factors associated with precancerous cervical cancer lesion. Results: Out of 60 study participants, 2(3.33%) were found to be positive for precancerous cervical cancer lesion. Conclusion: The prevalence of precancerous cervical lesion in women that consulted at the Mezam polyclinic is high.


Assuntos
Colo do Útero/patologia , Programas de Rastreamento/métodos , Lesões Pré-Cancerosas/epidemiologia , Neoplasias do Colo do Útero/diagnóstico , Ácido Acético/química , Adolescente , Adulto , Camarões/epidemiologia , Estudos Transversais , Feminino , Humanos , Iodetos/química , Modelos Logísticos , Pessoa de Meia-Idade , Lesões Pré-Cancerosas/diagnóstico , Prevalência , Fatores de Risco , Inquéritos e Questionários , Neoplasias do Colo do Útero/epidemiologia , Adulto Jovem
7.
Sensors (Basel) ; 19(14)2019 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-31336702

RESUMO

Photonic nanoarchitectures in the wing scales of butterflies and moths are capable of fast and chemically selective vapor sensing due to changing color when volatile vapors are introduced to the surrounding atmosphere. This process is based on the capillary condensation of the vapors, which results in the conformal change of the chitin-air nanoarchitectures and leads to a vapor-specific optical response. Here, we investigated the optical responses of the wing scales of several butterfly and moth species when mixtures of different volatile vapors were applied to the surrounding atmosphere. We found that the optical responses for the different vapor mixtures fell between the optical responses of the two pure solvents in all the investigated specimens. The detailed evaluation, using principal component analysis, showed that the butterfly-wing-based sensor material is capable of differentiating between vapor mixtures as the structural color response was found to be characteristic for each of them.


Assuntos
Borboletas , Mariposas , Compostos Orgânicos Voláteis , Asas de Animais/química , Asas de Animais/fisiologia , Ácido Acético/análise , Ácido Acético/química , Animais , Borboletas/fisiologia , Etanol , Masculino , Mariposas/fisiologia , Óptica e Fotônica , Pigmentação , Análise de Componente Principal , Espectrofotometria/instrumentação , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/química , Asas de Animais/anatomia & histologia
8.
Molecules ; 24(14)2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31340614

RESUMO

Photoreactions of acetonitrile solutions of 3,3-diaryl-1,1-dicyano-2-methylprop-1-enes (1a-c) with allyltrimethylsilane (2) in the presence of phenanthrene as a photoredox catalyst and acetic acid as a proton source formed photoallylation (3) and photoreduction (4) products via photoinduced electron transfer pathways. When (S)-mandelic acid was used as the proton source, the reactions proceeded with 3.4 and 4.8 %ee for formation of 3 and 4, respectively. The results of studies of the effect of aryl ring substituents and several chiral carboxylic acids suggested that the enantioselectivities of the reactions are governed by steric controlled proton transfer in intermediate complexes formed by π-π and OH-π interactions of anion radicals derived from 1a-c and chiral carboxylic acids.


Assuntos
Ácidos Carboxílicos/química , Nitrilos/química , Fenantrenos/química , Prótons , Compostos de Trimetilsilil/química , Ácido Acético/química , Alcenos/química , Ânions , Catálise , Radicais Livres , Hidrogenação , Luz , Processos Fotoquímicos , Estereoisomerismo
9.
Artigo em Inglês | MEDLINE | ID: mdl-31361183

RESUMO

A simultaneous headspace-gas chromatography/mass spectrometry (HS-GC/MS) method was developed and validated to determine the migration of 12 volatile organic compounds (methanol, acetone, methylethylketone, ethylacetate, isopropylalcohol, benzene, toluene, ethylbenzene, xylene, cumene, propylbenzene, and styrene) from food contact materials into food simulants (water, 4% acetic acid, 50% ethanol, and n-heptane). The limits of detection and quantification were 0.007-0.201 mg L-1 and 0.023-0.668 mg L-1, respectively. The method was applied to 205 samples of paper/paperboard, polyethylene, polypropylene, polystyrene, and polyethylene terephthalate. The estimated daily intake (EDI) was calculated using the migration results. Exposure assessments were carried out to compare the EDI to the tolerable daily intake (TDI); the results indicated that the EDI of styrene represented only a small percentage (8.0%) of the TDI. This analytical method will be a useful tool to examine levels of various volatile compounds migrating from food packaging to food simulants using HS-GC/MS method.


Assuntos
Análise de Alimentos , Contaminação de Alimentos/análise , Embalagem de Alimentos , Compostos Orgânicos Voláteis/análise , Ácido Acético/química , Etanol/química , Cromatografia Gasosa-Espectrometria de Massas , Heptanos/química , Temperatura Ambiente , Água/química
10.
Molecules ; 24(11)2019 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-31181702

RESUMO

: Pectin was extracted from apple (Malus domestica 'Falticeni') pomace with Celluclast 1.5L, at doses of 20, 40, and 60 µL/g of material. The temperature and time of extraction were varied on three levels-temperature-40, 50, and 60 °C; time-12, 18, and 24 h. For each experiment, the extraction yield (R2 = 0.8905), the galacturonic acid content (R2 = 0.9866), and the degree of esterification (R2 = 0.9520) of pectin was determined. Response surface methodology (RSM) was implemented via a Box-Behnken design, to optimize pectin extraction. In the optimum extraction conditions (temperature of 48.3 °C, extraction time of 18 h 14 min, and enzyme dose of 42.5 µL/g of pomace), the design predicted a 6.76% yield with a galacturonic acid content of 97.46 g/100 g of pectin and a degree of esterification of 96.02%. FT-IR analysis of the pectin sample obtained in these conditions showed a chemical structure similar to that of commercial apple and citrus pectin.


Assuntos
Enzimas/metabolismo , Malus/química , Pectinas/isolamento & purificação , Ácido Acético/química , Fracionamento Químico , Esterificação , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Cinética , Temperatura Ambiente
11.
Nutrients ; 11(6)2019 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-31159256

RESUMO

Stevia is a natural low-calorie sweetener that is growing in popularity in food and beverage products. Despite its widespread use, little is understood of its impact on the gut microbiota, an important environmental factor that can mediate metabolism and subsequent obesity and disease risk. Furthermore, given previous reports of dysbiosis with some artificial low-calorie sweeteners, we wanted to understand whether prebiotic consumption could rescue potential stevia-mediated changes in gut microbiota. Three-week old male Sprague-Dawley rats were randomized to consume: (1) Water (CTR); (2) Rebaudioside A (STV); (3) prebiotic (PRE); (4) Rebaudioside A + prebiotic (SP) (n = 8/group) for 9 weeks. Rebaudioside was added to drinking water and prebiotic oligofructose-enriched inulin added to control diet (10%). Body weight and feces were collected weekly and food and fluid intake biweekly. Oral glucose and insulin tolerance tests, gut permeability tests, dual X-ray absorptiometry, and tissue harvest were performed at age 12 weeks. Rebaudioside A consumption alone did not alter weight gain or glucose tolerance compared to CTR. Rebaudioside A did, however, alter gut microbiota composition and reduce nucleus accumbens tyrosine hydroxylase and dopamine transporter mRNA levels compared to CTR. Prebiotic animals, alone or with Rebaudioside A, had reduced fat mass, food intake, and gut permeability and cecal SCFA concentration. Adding Rebaudioside A did not interfere with the benefits of the prebiotic except for a significant reduction in cecal weight. Long-term low-dose Rebaudioside A consumption had little effect on glucose metabolism and weight gain; however, its impact on gut microbial taxa should be further examined in populations exhibiting dysbiosis such as obesity.


Assuntos
Encéfalo/metabolismo , Diterpenos de Caurano/administração & dosagem , Dopamina/metabolismo , Microbioma Gastrointestinal/efeitos dos fármacos , Ácido Acético/química , Animais , Ceco/metabolismo , Ácidos Graxos Voláteis/química , Inulina/administração & dosagem , Inulina/farmacologia , Masculino , Oligossacarídeos/administração & dosagem , Oligossacarídeos/farmacologia , Ácidos Pentanoicos/química , Prebióticos/administração & dosagem , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley
12.
Carbohydr Polym ; 219: 162-171, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31151513

RESUMO

Rheological behaviors of microbial polysaccharides with different substituents in aqueous solutions have been systematically investigated. Both the saccharide side chains and acetyl substituents improve the gelation of welan gum (WG), diutan gum (DG) and gellan gum (GG) in pure water at 25 °C. For the polysaccharides with saccharide side chains (WG and DG), the relationship between the apparent viscosity and concentration conforms to the linear equation, while that of the polysaccharide with acetyl (GG) is exponential. More importantly, the roles of substituents on the stability of the molecular conformation of polysaccharides are significantly depended on the surrounding environment. Disaccharide side chains promote the stability of helical conformation and gel aggregates of GG at high temperature (85 °C) or in the presence of inorganic salts with the ionic strength of 2.0 mol L-1. The stability of gel structure containing acetyl (GG) shows higher temperature/salt sensitivity. Additionally, deacylated gellan gum (GG(d)) solutions transform into hydrogels in the presence of dodecyltrimethylammonium bromide (DTAB). This study will help to obtain a better understanding on the rheological properties of polysaccharides with respect to the conformation and applications.


Assuntos
Bactérias/metabolismo , Hidrogéis/química , Polissacarídeos Bacterianos/química , Reologia , Tensoativos/química , Ácido Acético/química , Concentração Osmolar , Sais/química , Soluções/química , Temperatura Ambiente , Viscosidade
13.
Meat Sci ; 156: 214-221, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31212237

RESUMO

Biltong is an Ready to Eat (RTE) shelf stable salted/dried meat product stored under ambient conditions. The effect of vinegar addition during salting, weight loss during drying and packaging (modified atmosphere and vacuum) on the physicochemical and microbiological properties of beef biltong over a 3 months storage at 25 °C was investigated. Biltong dried to ~50% weight loss had a moisture content of ~50 g/100 g, salt content of 7.49 g/100 g and water activity >0.81 whilst biltong dried to 65% weight loss had a moisture content of 30 g/100 g, salt content of 7.14 g/100 g and water activity <0.78. Packaging method had no effect. Vinegar decreased the pH of biltong to 4.91, delayed the growth of total viable counts and reduced the coliforms count but not the yeasts and moulds. Escherichia coli was below the detection limit of 1 log cfu/g, Salmonella spp. and Listeria monocytogenes were absent and Staphylococcus aureus counts were <1.3 log cfu/g.


Assuntos
Ácido Acético/química , Produtos da Carne/análise , Produtos da Carne/microbiologia , Animais , Bovinos , Dessecação/métodos , Enterobacteriaceae , Manipulação de Alimentos/métodos , Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Fungos , Cloreto de Sódio na Dieta
14.
Chem Commun (Camb) ; 55(53): 7683-7686, 2019 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-31204739

RESUMO

An easy access to topical gels (both hydro- and organogels) derived from an anti-cancer prodrug namely 5-fluorouracil acetic acid (5-FuA) achieved by exploiting a simple salt formation strategy is reported for the first time. Nearly 85% of the salts synthesized were gelators. Single crystal structures of some of the gelator salts revealed an intriguing hydrogen bonding network including double stranded 1D chains stabilized through uracil-uracil complementary interactions and the crystal structures of the gelator salts corroborated well with the hypothesis based on which the gelators were designed. Studies indicated that both the hydrogel and the methyl salicylate gel of the gelator salt FuA-15 were suitable for self-drug-delivery application.


Assuntos
Ácido Acético/farmacologia , Antineoplásicos/farmacologia , Sistemas de Liberação de Medicamentos , Fluoruracila/farmacologia , Pró-Fármacos/farmacologia , Ácido Acético/síntese química , Ácido Acético/química , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Fluoruracila/síntese química , Fluoruracila/química , Géis/síntese química , Géis/química , Géis/farmacologia , Humanos , Ligações de Hidrogênio , Estrutura Molecular , Tamanho da Partícula , Pró-Fármacos/síntese química , Pró-Fármacos/química , Relação Estrutura-Atividade , Propriedades de Superfície
15.
Int J Biol Macromol ; 136: 911-919, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31226377

RESUMO

A new method for the molecular weight (MW) determination of chitosans by asymmetric flow field flow fractionation (AF-FFF or AF4) coupled with multi-angle light scattering (MALS) and differential refractive index (RI) detectors is proposed. The method allows the separation of polymer from molecular aggregates typically found in chitosan solutions making possible the accurate determination of MW distribution of the polymer. The effect of different experimental conditions on the obtained results has been evaluated and compared with those obtained from SEC-MALS-RI (size exclusion chromatography-MALS-RI). The chitosans analysed were from different biological sources and of varying degree of acetylation. AF4-MALS-RI results revealed that although aggregates are minimised when using a good solvent, a fraction still remains, and it is only completely eliminated by filtration through small pore sizes (≤0.45µm). This represents a limitation for the characterisation of high MW chitosan, where filtration can lead to considerable sample loss in the filter. The method described here has the advantage of not only allowing the identification and separation of the aggregates present, but also the accurate determination of the MW distribution for a wide range of chitosans of varying type where results are well correlated with those obtained by more conventional techniques.


Assuntos
Quitosana/química , Cromatografia em Gel , Fracionamento por Campo e Fluxo , Ácido Acético/química , Quitosana/isolamento & purificação , Difusão Dinâmica da Luz , Peso Molecular , Refratometria
16.
J Chromatogr A ; 1599: 115-124, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-30975531

RESUMO

European legislation has established a specific migration limit (SML) of 15 mg kg-1 for formaldehyde and 2.5 mg kg-1 for melamine. Formaldehyde resins are used in the manufacture of melamine kitchenware. Formaldehyde is listed in group 1 of the IARC list of carcinogenic compounds. To determine the quantity of formaldehyde and melamine as potential migrants from different types of melamine kitchenware (glass, mug, cutlery, big cup and bowl), a HPLC-DAD method has been implemented. This method is an alternative to the ones proposed in technical guidelines to determine formaldehyde by UV-vis spectrophotometry and melamine by HPLC. The final objective was to fit the migration kinetic curves of these two analytes in melamine kitchenware. After the method was validated, decision limit (CCα) and detection capability (CCß) were calculated for both analytes, when the probabilities of false positive (α) and false negative (ß) were fixed at 0.05; being CCß 0.269 mg L-1 and 0.311 mg L-1 for melamine and formaldehyde respectively. CCα and CCß were also calculated at the SML of both analytes. The migration testing were conducted with simulant B (3% acetic acid (w/v) in aqueous solution), the conditions of each exposure being 70 °C for 2 h. The quantities of melamine and formaldehyde found in the third exposure of the total kitchenware analysed were between 0.21 and 1.09 mg L-1 and between 0.55 and 3.86 mg L-1, respectively. Migration kinetic curves were built for each type of kitchenware with the data of sixteen consecutive migration cycles (70 °C each 30 min). The SML for melamine was surpassed in the mug, in the big cup and in the bowl after eleven, thirteen and one cycles, respectively. When more cycles were carried out in the mug, the values of the accumulated quantity of formaldehyde and melamine were 15.30 and 6.79 mg L-1, respectively, after thirty-two cycles. Both concentrations exceeded the corresponding SML.


Assuntos
Técnicas de Química Analítica/métodos , Cromatografia Líquida de Alta Pressão , Formaldeído/química , Triazinas/química , Ácido Acético/química , Técnicas de Química Analítica/normas , União Europeia , Cinética , Reprodutibilidade dos Testes
17.
Top Curr Chem (Cham) ; 377(3): 11, 2019 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-30949779

RESUMO

Despite its attractive features as a power source for direct alcohol fuel cells, utilization of ethanol is still hampered by both fundamental and technical challenges. The rationale behind the slow and incomplete ethanol oxidation reaction (EOR) with low selectivity towards CO2 on most Pt-based catalysts is still far from being understood, and a number of practical problems need to be addressed before an efficient and low-cost catalyst is designed. Some recent achievements towards solving these problems are presented. Pt film electrodes and Pt monolayer (PtML) electrodes on various single crystal substrates showed that EOR follows the partial oxidation pathway without C-C bond cleavage, with acetic acid and acetaldehyde as the final products. The role of the substrate lattice on the catalytic properties of PtML was proven by the choice of appropriate M(111) structure (M = Pd, Ir, Rh, Ru and Au) showing enhanced kinetics when PtML is under tensile strain on Au(111) electrode. Nanostructured electrocatalysts containing Pt-Rh solid solution on SnO2 and Pt monolayer on non-noble metals are shown, optimized, and characterized by in situ methods. Electrochemical, in situ Fourier transform infrared (FTIR) and X-ray absorption spectroscopy (XAS) techniques highlighted the effect of Rh in facilitating C-C bond splitting in the ternary PtRh/SnO2 catalyst. In situ FTIR proved quantitatively the enhancement in the total oxidation pathway to CO2, and in situ XAS confirmed that Pt and Rh form a solid solution that remains in metallic form through a wide range of potentials due to the presence of SnO2. Combination of these findings with density functional theory calculations revealed the EOR reaction pathway and the role of each constituent of the ternary PtRh/SnO2 catalyst. The optimal Pt:Rh:Sn atomic ratio was found by the two in situ techniques. Attempts to replace Rh with cost-effective alternatives for commercially viable catalysts has shown that Ir can also split the C-C bond in ethanol, but the performance of optimized Pt-Rh-SnO2 is still higher than that of the Pt-Ir-SnO2 catalyst.


Assuntos
Técnicas Eletroquímicas , Etanol/química , Platina/química , Acetaldeído/síntese química , Acetaldeído/química , Ácido Acético/síntese química , Ácido Acético/química , Catálise , Oxirredução
18.
J Biochem ; 166(3): 223-230, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31004484

RESUMO

Vinegar soaked black soybean is a traditional Chinese food widely used for the treatment of hypertension. While its pharmacodynamic substance was not fully unveiled. It contained abundant glutelin, thus the purpose of this study was to obtain potent antihypertensive peptides from vinegar soaked black soybean. Black soybean was soaked with vinegar and then glutelin was first catalyzed by alcalase. Ultrafiltration, ion exchange chromatography and reversed-phase high performance liquid chromatography were sequentially applied to separate and purify the angiotensin-I converting enzyme (ACE) inhibitory peptides from glutelin hydrolysates. As a result, the fraction L1-4 with the highest ACE inhibitory activity (83.41%) at the final concentration of 0.01 mg/ml was obtained and five peptides were then identified. These peptides were further optimized by virtual screening combining with in silico proteolysis. Finally, a novel tetrapeptide Phe-Gly-Ser-Phe (FGSF) was obtained. FGSF exhibited high in vitro ACE inhibitory activity (IC50 = 117.11 µM) and in vivo hypotensive effect which maximally reduced systolic blood pressure of 21.95 mmHg at 20 mg/kg body weight in spontaneously hypertensive rats. Our study demonstrated that FGSF derived from vinegar soaked black soybean might be used as a promising ingredient for pharmaceuticals against hypertension and its related diseases.


Assuntos
Inibidores da Enzima Conversora de Angiotensina/farmacologia , Anti-Hipertensivos/farmacologia , Glutens/química , Hipertensão/tratamento farmacológico , Oligopeptídeos/farmacologia , Soja/química , Ácido Acético/química , Inibidores da Enzima Conversora de Angiotensina/química , Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Animais , Anti-Hipertensivos/química , Anti-Hipertensivos/isolamento & purificação , Relação Dose-Resposta a Droga , Glutens/isolamento & purificação , Hipertensão/metabolismo , Masculino , Simulação de Acoplamento Molecular , Oligopeptídeos/química , Oligopeptídeos/isolamento & purificação , Peptidil Dipeptidase A/metabolismo , Ratos , Ratos Endogâmicos SHR , Relação Estrutura-Atividade
19.
Chem Commun (Camb) ; 55(34): 4957-4960, 2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-30958501

RESUMO

We report the synthesis of a bifunctional Janus graphene with silica microspheres as a template. The two sides of the Janus graphene are asymmetrically functionalized with ethylenediamine tetraacetic acid and octadecyl groups, making it capable of simultaneous enrichment of organic and inorganic targets in complex media. This work reveals a new route to design and fabricate multipurpose adsorbent materials.


Assuntos
Ácido Acético/química , Etilenodiaminas/química , Grafite/química , Dióxido de Silício/química , Microesferas , Tamanho da Partícula , Propriedades de Superfície
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 218: 248-262, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-31003050

RESUMO

Novel coumarin amino acid derivatives were synthesized. The structure of synthesized compounds has established on basis of different spectral data. The optimization geometry, frontier molecular orbitals (FMOs), thermodynamic parameters and chemical reactivity, were discussed using DFT\B3LYP by 6-311G* basis set, to identify a clear view for inter and intramolecular interaction of tested compounds. The molecular electrostatic potential (MEP) has plotted to investigate a recognition manner of synthesized compounds upon COX-2 receptor. All tested compounds showed a promising (NLOs) nonlinear optical properties. Bond dissociation energy (BDE) has studied to investigate a potency of these molecules against autoxidation mechanism Polynomial molecular docking logarithms have performed into the COX-2 active site for tested compounds. The docking protocol that has low RMSD has selected for discussion the binding affinity. The compounds with a high docking score 3,4,6-8,10 and 11 were selected for additional study against ADMET insilico, which showed that these compounds are a good oral bioavailability without observed carcinogenesis affect. The compounds (3,4,6-8,10 and 11) which that passed through docking and ADMET profile have examined their potency against (MCF-7) breast cancer cell in vitro. The compound 7 showed a highest potency against MCF-7 with IC50 value 0.39 µM. The QSAR model has created to discover the structural necessity inhibition of MCF-7. The derived QSAR model has a statistically significant with a good predictive power.


Assuntos
Ácido Acético/química , Ácido Acético/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Benzopiranos/química , Benzopiranos/farmacologia , Ácido Acético/síntese química , Antineoplásicos/síntese química , Benzopiranos/síntese química , Neoplasias da Mama/tratamento farmacológico , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Humanos , Células MCF-7 , Simulação de Acoplamento Molecular , Relação Quantitativa Estrutura-Atividade
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