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1.
Chemosphere ; 262: 128411, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33182135

RESUMO

Biocatalytic degradation technology has received a great deal of attention in water treatment because of its advantages of high efficiency, environmental friendliness, and no secondary pollution. Herein, for the first time, horseradish peroxidase and mediator syringaldehyde were co-immobilized into functionalized calcium alginate composite beads grafted with glycidyl methacrylate and dopamine. The resultant biocatalyst of the co-immobilized horseradish peroxidase-syringaldehyde system has displayed excellent catalytic performance to degrade indole in water. The degradation rate of 100% was achieved in the presence of hydrogen peroxide even if the indole concentration was changing from 25 mg/L to 500 mg/L. If only the free enzyme was used under the identical water treatment conditions, the degradation of indole could hardly be observed even when the concentration of indole is low at 25 mg/L. This was attributed to the effective co-immobilization of the enzyme and the mediator so that the catalytic activity of horseradish peroxidase and the synergistic catalytic action of syringaldehyde could be fully developed. Furthermore, while the spherical catalyst was operated in succession and reused for four cycles in 50 mg/L indole solution, the degradation rate remained 91.8% due to its considerable reusability. This research demonstrated and provided a novel biocatalytic approach to degrade indole in water by the co-immobilized horseradish peroxidase-syringaldehyde system as biocatalyst.


Assuntos
Benzaldeídos/química , Indóis/química , Alginatos , Biocatálise , Catálise , Enzimas Imobilizadas/metabolismo , Peroxidase do Rábano Silvestre/metabolismo , Peróxido de Hidrogênio/metabolismo
2.
Food Chem ; 338: 127822, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-32810813

RESUMO

In this study, a potential of covalent linkage approach for developing active edible coatings was examined. Vanillin and trans-cinnamaldehyde were bound to chitosan by Schiff base reaction and reductive amination. The modified polysaccharides were comprehensively characterized and applied as active coatings on fresh-cut melon. The covalent linkage allowed overcoming solubility problems with the lipophilic vanillin and cinnamaldehyde and neutralizing their volatility, producing well-adhered coatings that enhanced fruit quality and storability without sensorial impairment. The attached hydrophobic moieties also provided new polysaccharides with self-assembling ability. Their aggregates were loaded with antimicrobial citral and added to mandarin juice, resulting in up to 6 log CFU/mL microbial count reduction. Thus, the covalent linkage concept offers several advantages, especially when hydrophobic or volatile active agents are used. Further developed, it may become a safe and effective tool for the formation of advanced active edible coatings and delivery vehicles for direct applications on food products.


Assuntos
Acroleína/análogos & derivados , Benzaldeídos/química , Filmes Comestíveis , Polissacarídeos/química , Acroleína/química , Monoterpenos Acíclicos/química , Anti-Infecciosos/química , Quitosana/química , Citrus , Cucurbitaceae/metabolismo , Microbiologia de Alimentos , Conservação de Alimentos/métodos , Qualidade dos Alimentos , Armazenamento de Alimentos , Frutas/metabolismo , Sucos de Frutas e Vegetais/microbiologia , Interações Hidrofóbicas e Hidrofílicas
3.
Int J Food Microbiol ; 332: 108811, 2020 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-32835914

RESUMO

The aim of this study was to evaluate a hurdle strategy for orange-tangerine (OT) and orange-banana-mango-kiwi-strawberry (OBMKS) juices processing based on UV-C treatment assisted or not by mild heat and the addition of natural antimicrobials. Vanillin and citral emulsions were successfully encapsulated using maltodextrin and HI-CAP (5,18,3) and characterized. The susceptibility of Lactobacillus plantarum ATCC 8014, Escherichia coli ATCC 25922, and Saccharomyces cerevisiae KE 162 to binary mixtures of the encapsulated agents was examined in culture media according to the Berenbaum experimental design. The boundary between growth and non-growth as a function of vanillin and citral concentrations was predicted by means of the probabilistic model using logistic regression. Microbial inactivation achieved by pilot-scale UV-C light (0-390 mJ/cm2) on its own, assisted by mild heat (50 °C, UV-C/H) and combined with antimicrobials (1000 ppm vanillin plus 100 ppm citral) addition (UV-C + A/UV-C/H + A) was assessed in OT and OBMKS. Yeast induced damage in a model solution treated by UV-C + A was studied by flow cytometry (FC). All the antimicrobial mixtures resulted in additive effects (FICindex = 1), thus offering through the probabilistic models a range of formulation possibilities with antimicrobial capacity encompassing lower vanillin and citral concentrations compared to those required when used alone (Vrange = 0-1875 ppm plus Crange = 392-0 ppm). UV-C led up to 3.7-3.8, 2.4-3.6 and 1.5-1.6 log-reductions of E. coli, L. plantarum and S. cerevisiae in OT and OBMKS, respectively. A significant increase of 1.7-2.2, 2.1-2.7 and 4.1-5.3 log cycles in microbial inactivation was observed after UV-C/H treatment. Additional inactivation of 0.7-3.1 and 0.5-2.7 log reductions were observed for E. coli and S. cerevisiae, respectively, when UV-C + A and UV-C/H + A were applied in both juices. Therefore, the addition of antimicrobials to the UV-C treated juices, showed additive to synergistic effects on E. coli and S. cerevisiae, respectively along refrigerated storage. A shift from yeast cells with intact membrane and esterase activity in control samples to cells with permeabilized membrane in C + A, UV-C and UV-C + A samples were determined by FC. The shift was more noticeable in UV-C + A samples. Sublethally damaged cells were only detected in C + A and UV-C samples. This study demonstrates that combining a pilot-scale UV-C treatment with the addition of chosen binary mixtures of vanillin and citral, can ensure more than 5 log-reductions of E. coli, L. plantarum and S. cerevisiae in OT and OBKMS juice blends.


Assuntos
Monoterpenos Acíclicos/farmacologia , Benzaldeídos/farmacologia , Conservação de Alimentos/métodos , Sucos de Frutas e Vegetais/microbiologia , Raios Ultravioleta , Monoterpenos Acíclicos/química , Antibacterianos/química , Antibacterianos/farmacologia , Benzaldeídos/química , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Temperatura Alta , Viabilidade Microbiana/efeitos dos fármacos , Viabilidade Microbiana/efeitos da radiação
4.
Food Chem ; 329: 127181, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32502743

RESUMO

The compounds that the wood releases to the wine and the oxygen transmission rate (OTR) of the barrel define the final wine. The new possibility of choosing the OTR of the barrel allows the winemaker to globally control the ageing process. The aim of this work was to study the volatile composition of woods classified according to their OTR, which are used to build barrels for wine ageing. The results showed that volatile composition differs depending on wood OTR and the temperature reached during toasting. On the toasted side of the stave in contact with the wine, low OTR wood had a statistically higher content in furan compounds (5-hydroxymethylfurfural, furfural and 5-methylfurfural), acetovanillone and phenolic aldehydes (vanillin and syringaldehyde), while 4-ethylguaiacol and trans-ß-methyl-γ-octalactone were significantly higher in staves with a high OTR. The same red wine aged first for three months in high and low oxygenation barrels presents different characteristics.


Assuntos
Manipulação de Alimentos/métodos , Oxigênio/química , Quercus/química , Compostos Orgânicos Voláteis/química , Vinho/análise , Benzaldeídos/química , Cromatografia Gasosa , Análise Discriminante , Furanos/química , Guaiacol/química , Temperatura , Madeira/química
5.
Food Chem ; 328: 127098, 2020 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-32470775

RESUMO

Poly(1H-1,2,4-triazole-3-thiol) (poly(T3T)) conductive film was coated successfully on the gold electrode (Au). The electrochemical behavior of vanillin (VAN) was studied on the 1H-1,2,4-triazole-3-thiol-Au (T3T-Au) electrode. The determination of VAN was performed on the T3T-Au electrode using a differential pulse voltammetry (DPV) technique. In order to detect the concentration of VAN, suitable supporting electrolyte solution and pH value were determined. At pH 3 in HClO4 solution, the anodic peak current of VAN obtained with the T3T-Au electrode is 4.3 times greater than the bare Au electrode. The response oxidation peak current and concentration of VAN showed a good linear relationship in the range of 0.1-11.3 µM. The limit of detection was found as 0.04 µM. Besides, the reproducibility, repeatability, stability, and interference measurements were also assayed. This sensor was applied successfully for the detection of VAN in synthetic samples and various food samples.


Assuntos
Benzaldeídos/análise , Benzaldeídos/química , Eletroquímica/instrumentação , Ouro/química , Polímeros/química , Compostos de Sulfidrila/química , Triazóis/química , Eletrodos , Oxirredução , Reprodutibilidade dos Testes
6.
Chemosphere ; 255: 126893, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32402872

RESUMO

Syringol and syringaldehyde are widely present pollutants in atmosphere and wastewater due to lignin pyrolysis and draining of pulp mill effluents. The hydroxylation degradation mechanisms and kinetics and health effect assessment of them under high and low-NOx regimes in atmosphere and wastewater have been studied theoretically. The effect of pH on reaction mechanisms and rate constants in their ·OH-initiated degradation processes has been fully investigated. Results have suggested that aqueous solution played a positive role in the ·OH-initiated degradation reactions by decreasing the energy barriers of most reactions and changing the reactivity order of initial reactions. For Sy- and Sya- (anionic species of syringol and syringaldehyde), most initial reaction routes were more likely to occur than that of HSy and Hsya (neutral species of syringol and syringaldehyde). As the pH increased from 1 to 14, the overall rate constants (at 298 K) of syringol and syringaldehyde with ·OH in wastewater increased from 5.43 × 1010 to 9.87 × 1010 M-1 s-1 and from 3.70 × 1010 to 1.14 × 1011 M-1 s-1, respectively. In the NOx-rich environment, 4-nitrosyringol was the most favorable product, while ring-opening oxygenated chemicals were the most favorable products in the NOx-poor environment. On the whole, the NOx-poor environment could decrease the toxicities during the hydroxylation processes of syringol and syringaldehyde, which was the opposite in a NOx-rich environment. ·OH played an important role in the methoxyphenols degradation and its conversion into harmless compounds in the NOx-poor environment.


Assuntos
Benzaldeídos/química , Pirogalol/análogos & derivados , Atmosfera/química , Concentração de Íons de Hidrogênio , Cinética , Lignina/química , Oxirredução , Oxigênio , Pirogalol/química , Águas Residuárias , Água
7.
Phys Chem Chem Phys ; 22(15): 8006-8020, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32239002

RESUMO

4-Aminobenzoic acid (PABA) is one of the earliest patented and most commonly used sunscreen components. There is however a long-lasting controversy on its photo-protective efficacy owing to the lack of information on its protolytic equilibrium and photo-dynamics after absorption of ultraviolet radiation in physiologically relevant aqueous solution. The excitation dynamics in water also remains largely unknown for analogs of PABA such as 4-dimethylaminoacetophenone (DMAAP) and 4-dimethylaminobenzaldehyde (DMABA) which are recognized as prototypes for photo-induced twisted intramolecular charge transfer (TICT). Herein we report a combined application of femtosecond broadband time-resolved fluorescence and transient absorption coupled with density functional theoretical study for PABA, DMAAP, and DMABA under several solvent conditions with representative properties in terms of the pH, polarity and hydrogen bonding capacity. The results we gained demonstrate that, in a neutral aqueous solution, PABA taking the deprotonated anion form in the ground state undergoes rapid protonation after excitation, producing excited state species in the neutral form that may shift effectively by intersystem crossing (ISC) to the long-lasting triplet state capable of damaging nucleic acids. This provides evidence at the molecular level for the detrimental effect of PABA if used as a sunscreen ingredient. In contrast, our investigation on DMAAP and DMABA unveils an unusual solvent controlled deactivation dynamics rendered by the participation of the carbonyl oxygen associated nOπ* state featuring energy and structure strongly responsive to solvent properties. In particular, these molecules in water exhibit solute-solvent hydrogen bonding at the sites of the carbonyl oxygen and the amino nitrogen which is, respectively, weakened and strengthened after the excitation, leading to state reversal and formation of a nOπ* state with a peculiar non-planar structure. This quenches strongly the excitation, eliminates the TICT, suppresses the ISC and opens up the otherwise inaccessible internal conversion (IC) to account for ∼80% of the entire deactivation. The IC, observed to proceed at a rate of ∼2.5 ps, allows the effective recovery of the ground state, providing substantial protection against ultraviolet irradiation. Moreover, the revelation of highly solvent sensitive fluorescence emission from DMABA and DMAAP implies the potential application of these molecules as the functional element in the design of sensory materials for probing the polarity and hydrogen bonding character of the surrounding environment.


Assuntos
Ácido 4-Aminobenzoico/química , Benzaldeídos/química , Análise Espectral , Modelos Químicos , Protetores Solares/química
8.
Ecotoxicol Environ Saf ; 196: 110561, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32276163

RESUMO

A ternary catalysis system was investigated to evaluate the comparative degradation of toxic fungicide metabolite 3,5-dichloroaniline (3,5-DCA) by laccase and MnO2 with mediators. In this study, copper based fungal enzyme laccase (Trametes versicolor origin) and metal catalyst MnO2 with various combinations of phenolic mediators (catechol, syringaldehyde, syringic acid, caffeic acid and gallic acid) were monitored to optimize and screen the better one for 3,5-DCA degradation assay. Catechol showed better potentiality in reduction of 3,5-DCA among the studied mediators. Catechol (2mM) showed the highest reduction rate (99-100%) followed by syringaldehyde (40.51%) with 2U/mL of laccase at 25 °C within 24 h reaction time. Similarly, complete degradation of 3,5-DCA was obtained by catechol (2mM) with 2 mg/mL of MnO2 in MnO2-mediator assay. The notable finding of current study indicated the triggering of catechol for better 3,5-DCA degradation at higher pH condition but inertness in laccase-mediator assay due to laccase destabilization. The reaction pathways of optimized mediator-based catalysis for laccase and MnO2 were proposed. Finally, the optimized laccase-catechol based degradation was considered as a pioneer green catalysis approach to reduce the toxic metabolite 3,5-DCA concentrations in aqueous medium as compared to MnO2-catechol catalysis.


Assuntos
Compostos de Anilina/análise , Fungicidas Industriais/análise , Lacase/metabolismo , Compostos de Manganês/química , Óxidos/química , Trametes/enzimologia , Compostos de Anilina/metabolismo , Benzaldeídos/química , Catálise , Catecóis/química , Fungicidas Industriais/metabolismo , Fenóis/química
9.
Food Chem ; 319: 126545, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32169764

RESUMO

A sol-gel urea colorimetric method was developed for the determination of urea in feedstuffs. The sol-gel platform contained p-dimethylaminobenzaldehyde (p-DMAB) as the reagent entrapped within polymer network. The urea analysis relied on the formation of Schiff base under acidic conditions. The colorimetric product was imaged with a Smartphone. Under optimized conditions, the calibration curve for urea was linear over the concentration range of 2.5-100 and 100-1000 mg L-1 with a good coefficient of determination (r2 > 0.99). The limit of detection (LOD) and limit of quantification (LOQ) were 0.1 and 0.5 mg L-1, respectively. The intra-day and inter-day precisions were 0.83-3.01%RSD and 2.20-5.47%RSD, respectively. Accuracy of urea analysis ranged from -1.15 to 2.76%. The proposed method was stable for at least 90 days. The amount of urea in feedstuff sample was determined. The developed method is easy to use with small samples and reagent consumption in field conditions for monitoring the quality of feedstuff.


Assuntos
Ureia/análise , Benzaldeídos/química , Colorimetria/métodos , Limite de Detecção , Transição de Fase , Ureia/química
10.
Chem Asian J ; 15(7): 1018-1021, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32017396

RESUMO

Benzyl alcohol is a naturally occurring aromatic alcohol and has been widely used in the cosmetics and flavor/fragrance industries. The whole-cell biotransformation for synthesis of benzyl alcohol directly from bio-based L-phenylalanine (L-Phe) was herein explored using an artificial enzyme cascade in Escherichia coli. Benzaldehyde was first produced from L-Phe via four heterologous enzymatic steps that comprises L-amino acid deaminase (LAAD), hydroxymandelate synthase (HmaS), (S)-mandelate dehydrogenase (SMDH) and benzoylformate decarboxylase (BFD). The subsequent reduction of benzaldehyde to benzyl alcohol was achieved by a broad substrate specificity phenylacetaldehyde reductase (PAR) from Solanum lycopersicum. We found the designed enzyme cascade could efficiently convert L-Phe into benzyl alcohol with conversion above 99%. In addition, we also examined L-tyrosine (L-Tyr) and m-fluoro-phenylalanine (m-f-Phe) as substrates, the cascade biotransformation could also efficiently produce p-hydroxybenzyl alcohol and m-fluoro-benzyl alcohol. In summary, the developed biocatalytic pathway has great potential to produce various high-valued fine chemicals.


Assuntos
Álcoois Benzílicos/síntese química , Biotransformação , Benzaldeídos/química , Biocatálise , Vias Biossintéticas , Escherichia coli/metabolismo , Fenilalanina/química , Especificidade por Substrato
11.
Macromol Rapid Commun ; 41(6): e1900586, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32022359

RESUMO

Orthogonal dynamic covalent self-assembly is used as a facile method for constructing polymer hollow nanocapsules (NCs) and thin films. The bifunctional precursor 4-formylphenylboronic acid is symmetrically installed with a boronic acid group for the boroxine linkage, and an aldehyde group for the Schiff base reaction which can react with twofold symmetry linkers ethylenediamine and para phenylenediamine to attain polymer NCs and nanosheets. Owing to the reversibility of the imine linkages, the mutual morphological transformation between polymer NCs and thin films via an amine-imine-exchange strategy is successfully achieved. Multiple reversible covalent bonds allow the control the release of the load in polymer NCs using different techniques. This may be useful for designing stimulus-responsive smart materials.


Assuntos
Benzaldeídos/química , Ácidos Borônicos/química , Etilenodiaminas/química , Iminas/química , Nanocápsulas/química , Fenilenodiaminas/química , Polímeros/química , Polímeros/síntese química , Aldeídos/química , Aminas/química , Nanocápsulas/ultraestrutura , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Bases de Schiff/química , Propriedades de Superfície
13.
Mol Med Rep ; 21(3): 1107-1114, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31894337

RESUMO

Protocatechualdehyde (PCA) is considered to be the main phenolic component of Phellinus gilvus responsible for its anticancer properties. Previous studies have demonstrated that PCA can have an anticancer effect on multiple cancer types, but little is known about the effect of PCA on melanoma cells. The present study investigated the inhibitory abilities and potential anticancer mechanisms of PCA on B16­F10 cells using MTT assay. Cell apoptosis and cell cycle were assessed by flow cytometry using Annexin V­FITC and propidium iodide staining. Whole­transcriptome analysis was used to investigate the effects of PCA on gene expression. PCA significantly decreased cell viability, induced cell cycle arrest at G0/G1 phase and promoted apoptosis of B16­F10 cells, suggesting that PCA could have anticancer effects against melanoma cells. Whole­transcriptome analysis indicated that PCA treatment upregulated genes involved in histone modification and decreased the transcription of genes involved in DNA repair and replication. Kyoto Encyclopedia of Genes and Genomes analysis showed that PCA treatment enhanced the complement and coagulation cascades, and the p53 signaling pathway. The present results indicated that PCA could act as an antitumor agent in melanoma cells, which may provide experimental support for the development of novel therapies to treat melanoma.


Assuntos
Apoptose/efeitos dos fármacos , Basidiomycota/química , Benzaldeídos/farmacologia , Catecóis/farmacologia , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Fase G1/efeitos dos fármacos , Fase de Repouso do Ciclo Celular/efeitos dos fármacos , Animais , Benzaldeídos/química , Catecóis/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Biologia Computacional/métodos , Perfilação da Expressão Gênica , Humanos , Melanoma Experimental , Camundongos , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo
14.
Carbohydr Polym ; 231: 115745, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31888811

RESUMO

Hydrogels are promising carriers for the controlled drug delivery in response to the external stimuli such as pH and temperature. Here, a new hydrogel is designed and synthesized from the cross-linking of graphene, chitosan, and cellulose nanowhisker via Schiff base reaction by a synthetic dialdehyde. The hydrogel presented a flexible structure and responded to altering pH and adding the external stimuli such as benzaldehyde and amino acid cysteine. The synthesized hydrogel was stable under physiological conditions. In vivo test showed that the hydrogel is subcutaneously injectable. Three drug-loaded hydrogels were synthesized, and in vitro drug release study showed a pH-dependent release of drugs in PBS solution.


Assuntos
Curcumina/química , Doxorrubicina/química , Sistemas de Liberação de Medicamentos , Hidrogéis/química , Benzaldeídos/química , Celulose/química , Celulose/farmacologia , Quitosana/química , Curcumina/farmacologia , Cisteína/química , Doxorrubicina/farmacologia , Liberação Controlada de Fármacos , Grafite/química , Humanos , Concentração de Íons de Hidrogênio , Nanoestruturas/química , Temperatura
15.
Molecules ; 25(2)2020 Jan 19.
Artigo em Inglês | MEDLINE | ID: mdl-31963796

RESUMO

The optimization of sustainable protocols for reductive amination has been a lingering challenge in green synthesis. In this context, a comparative study of different metal-loaded cross-linked cyclodextrins (CDs) were examined for the microwave (MW)-assisted reductive amination of aldehydes and ketones using either H2 or formic acid as a hydrogen source. The Pd/Cu heterogeneous nanocatalyst based on Pd (II) and Cu (I) salts embedded in a ß-CD network was the most efficient in terms of yield and selectivity attained. In addition, the polymeric cross-linking avoided metal leaching, thus enhancing the process sustainability; good yields were realized using benzylamine under H2. These interesting findings were then applied to the MW-assisted one-pot synthesis of secondary amines via a tandem reductive amination of benzaldehyde with nitroaromatics under H2 pressure. The formation of a CuxPdy alloy under reaction conditions was discerned, and a synergic effect due to the cooperation between Cu and Pd has been hypothesized. During the reaction, the system worked as a bifunctional nanocatalyst wherein the Pd sites facilitate the reduction of nitro compounds, while the Cu species promote the subsequent imine hydrogenation affording structurally diverse secondary amines with high yields.


Assuntos
Reagentes para Ligações Cruzadas/química , Ciclodextrinas/química , Metais/química , Micro-Ondas , Nanopartículas/química , Aminação , Aminas/química , Benzaldeídos/química , Catálise , Cobre/química , Paládio/química , beta-Ciclodextrinas/química
16.
Food Chem ; 310: 125868, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31767484

RESUMO

The aim of this research was to investigate the effect of herring roe phospholipids (PLs) on the oxidative stability of cod liver oil during storage. The effect of PLs on the oxidative stability of cod liver oil was assessed in terms of peroxide value, free fatty acids, secondary oxidation products and pyrrolisation. The results show that the PV was lower in cod liver oil containing PLs (P < 0.05) than in the control without PLs. Benzaldehyde, 2,5-dimethylpyrazine, 2-methyl-2-pentenal, 1-penten-3-ol and 3-methylbutanal were the main volatiles. In addition, significant pyrrolisation was observed after 28 days when PLs were added to cod liver oil. The results suggested that cod liver oil with dispersed PLs was oxidized during storage followed by non-enzymatic browning reactions. The findings indicated that the ratio between pyrroles formed and α-tocopherol may influence the formation of new peroxides and secondary oxidation products.


Assuntos
Óleo de Fígado de Bacalhau/química , Fosfolipídeos/química , Aldeídos/química , Animais , Benzaldeídos/química , Peixes , Oxirredução , Peróxidos/química , alfa-Tocoferol/química
17.
Environ Sci Pollut Res Int ; 27(2): 1677-1685, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31755056

RESUMO

Several methods, such as pretreatment, membrane surface modification, feed water chlorination, and chemical cleaning, have recently been applied to control biofouling on reverse osmosis (RO) membranes-with limited success. As an alternative, compounds that inhibit bacterial quorum sensing can be used to disrupt formation of bacterial colonies. In this study, anti-biofouling using vanillin, which is a natural substance among quorum sensing inhibitor compounds, was trialed, by modifying RO membrane surfaces with vanillin, at various concentrations. We then reviewed consequential changes to membrane surface characteristics and vanillin anti-biofouling properties. A long-term RO membrane simulator was used to analyze permeability, contact angle was measured for hydrophilicity evaluation, and membrane surface morphology was analyzed, through atomic force microscopy and scanning electron microscopy. A quorum quenching effect was confirmed by utilizing Petrifilm to count bacteria on the surface of a modified membrane. As a result, the permeability of the surface modified membranes was slightly decreased compared to the pristine membrane, but the hydrophilicity was increased, and the number of colonies decreased remarkably, the membrane modified with 0.5 M vanillin outperforming that modified with 0.25 M vanillin.


Assuntos
Benzaldeídos/química , Incrustação Biológica , Purificação da Água , Biofilmes , Membranas Artificiais , Osmose
18.
J Colloid Interface Sci ; 559: 76-87, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31610307

RESUMO

Exploring and controlling chemical reactions in compartments opens new platforms for designing bioinspired catalysts and energy-autonomous systems. Aqueous polymer networks or hydrogels serve as a perfect model for biological tissues, allowing systematic investigations of chemical transformations in compartments. Herein, we report the synthesis of a versatile, colloidal microgel catalyst containing covalently bound l-proline as an organocatalyst. The key finding of our work is that the catalytic activity can be tuned by adjusting the distribution of the organocatalyst in the microgel network as well as the properties of the solvent. We demonstrate that l-proline groups integrated into microgels enable the reaction of 4-nitrobenzaldehyde and cyclohexanone in a heterogeneous reaction mixture in which free l-proline is not active. By controlling the localization of the l-proline groups within the microgel network (core or corona), the rate of the aldol reaction in homogenous and heterogeneous reaction mixtures can be modulated. Furthermore, microgels with covalently attached catalysts can be recycled and reused in sequential catalytic runs without deterioration of the catalyst performance in terms of activity and selectivity. The internal structure of the microgel in heterogeneous reaction mixtures was studied by computer simulations.


Assuntos
Materiais Biomiméticos/química , Coloides/química , Hidrogéis/química , Prolina/química , Aldeídos/química , Benzaldeídos/química , Catálise , Simulação por Computador , Reagentes para Ligações Cruzadas/química , Cicloexanonas/química , Cinética , Polimerização , Solventes/química , Água
19.
J Fluoresc ; 29(6): 1467-1474, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31786706

RESUMO

The condensation product (L) of 4,4'-methylenedianiline and p-anisaldehyde acts as colorimetric sensor for Cu2+ and Pb2+ ions. On interaction with Cu2+, ethanolic solution of L changes its color to brown while it becomes light pink on interaction with Pb2+. Interaction of Al3+ with L coated paper strip emits bright blue fluorescence. Metal ions like Mg2+, Cu2+, Li+, K+, Na+, Mn2+, Al3+, Hg2+, Co2+, Pb2+, Ni2+, Cd2+, Zn2+, Fe3+ do not interfere the paper strip sensor. The fluorescent intensity of L in ethanol is quenched 25 times by Pb2+ ion. The interaction between L and Pb2+ is reversible and the detection limit of Pb2+ is 10-6 M. The binding constant and stoichiometry of binding between L and Pb2+ was calculated to be 104.8 and 1:2. Theoretical calculations show that the binding of the metal ions to L are favorable and the fluorescence of L is due to π → π* transition.


Assuntos
Alumínio/análise , Colorimetria , Cobre/análise , Corantes Fluorescentes/química , Chumbo/análise , Papel , Compostos de Anilina/química , Benzaldeídos/química , Teoria da Densidade Funcional , Corantes Fluorescentes/síntese química , Estrutura Molecular , Bases de Schiff/síntese química , Bases de Schiff/química
20.
Molecules ; 25(1)2019 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-31861609

RESUMO

A library of 1,2-aminoalcohol derivatives with a neoisopulegol-based octahydrobenzofuran core was developed and applied as chiral catalysts in the addition of diethylzinc to benzaldehyde. The allylic chlorination of (+)-neoisopulegol, derived from natural (-)-isopulegol followed by cyclization, gave the key methyleneoctahydrobenzofuran intermediate. The stereoselective epoxidation of the key intermediate and subsequent oxirane ring opening with primary amines afforded the required 1,2-aminoalcohols. The ring closure of the secondary amine analogues with formaldehyde provided spiro-oxazolidine ring systems. The dihydroxylation of the methylenetetrahydrofuran moiety with OsO4/NMO (4-methylmorpholine N-oxide) resulted in the formation of a neoisopulegol-based diol in a highly stereoselective reaction. The antimicrobial activity of both the aminoalcohol derivatives and the diol was also explored.


Assuntos
Amino Álcoois/síntese química , Anti-Infecciosos/síntese química , Benzofuranos/química , Monoterpenos Cicloexânicos/química , Amino Álcoois/química , Amino Álcoois/farmacologia , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Bactérias/efeitos dos fármacos , Benzaldeídos/química , Catálise , Ciclização , Fungos/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Compostos Organometálicos/química
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