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1.
Yakugaku Zasshi ; 140(10): 1225-1233, 2020.
Artigo em Japonês | MEDLINE | ID: mdl-32999201

RESUMO

This article describes our stereoselective and site-selective chemical methods for exploiting cationic heterocycles as electron-withdrawing groups (EWGs). We envisioned that the phosphoramide N-H proton of a pyridyl phosphoramide 3 would be activated by the cationic pyridinium moiety that is formed upon protonation. The resulting imide-like N-H proton and the acidic pyridinium proton of the pyridinium phosphoramide 3⋅HX cooperate together, making 3⋅HX a highly acidic dual Brønsted acid. The catalytic ability of 3⋅HX was demonstrated in the development of the first asymmetric Diels-Alder reaction between 1-amide dienes and maleimides. Focusing on the activation of N-bromosuccinimide (NBS) because of its structural similarity to maleimides, the enantioselective bromolactonization of trisubstituted olefinic acids was accomplished utilizing pyridyl phosphoramide 3f as a Brønsted base catalyst bearing an acidic N-H proton. Lastly, our strategy for the site-selective acylation of polyol compounds is described. In our system, a pyridine aldoxime ester 10, used as a mild acylating reagent, was activated by a catalytic amount of Lewis acid via the inductive effect of the cationic pyridinium moiety. The resulting metal complex preferentially attracted the alcohol with a Lewis basic site, thereby facilitating selective acylation via a template effect. This metal-template-driven strategy allowed for the site-selective acylation of diverse α-hydroxyamides, including unprotected N-glycolyl aminosugars.


Assuntos
Cátions/química , Cátions/síntese química , Química Orgânica/métodos , Desenvolvimento de Medicamentos/métodos , Elétrons , Compostos Heterocíclicos/química , Compostos Heterocíclicos/síntese química , Acilação , Amidas/química , Catálise , Complexos de Coordenação/química , Reação de Cicloadição , Ésteres/química , Compostos de Pralidoxima/química , Estereoisomerismo
2.
J Chromatogr A ; 1626: 461347, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797827

RESUMO

Phthalate diesters are a group of plasticizers extensively used in the manufacturing and processing of plastics. Phthalate monoesters are the primary degradation products of the diesters. Accumulation of endocrine disruptive diesters and monoesters in soil is of great concern because of the extensive use of plastic mulching and misdisposal of plastics. Accurate determination of their levels in soil is critical to assess the occurrence, exposure, and risks of phthalate diesters and monoesters. In this study, we aimed to develop a robust and environmentally friendly method for the simultaneous determination of phthalate diesters and monoesters in soil. Ultra-performance liquid chromatography coupled with electrospray tandem mass spectrometry was used for quantification, combined with accelerated solvent extraction and in-line cleanup for sample preparation. The method detection limits for the 14 diesters and 11 monoesters were in the range of 0.59 to 10.08 ng g-1 d.w. Acceptable recoveries (69%-131%) for these analytes were obtained when four deuterated analogs were used for internal calibration, and intra- and inter-day variations were less than 15%. This method was later successfully applied to five soil samples, and 8 diesters and 7 monoesters were detected with the maximum concentration up to 1142.2 ng g-1 d.w. The method developed in this study can be used for screening and accurate quantification of phthalate diesters and monoesters in soil and possibly in other environmental matrices.


Assuntos
Ácidos Ftálicos/análise , Plastificantes/análise , Solo/química , Calibragem , Cromatografia Líquida de Alta Pressão/normas , Disruptores Endócrinos/análise , Disruptores Endócrinos/normas , Ésteres/química , Limite de Detecção , Ácidos Ftálicos/química , Ácidos Ftálicos/normas , Plastificantes/normas , Espectrometria de Massas em Tandem/normas , Temperatura
3.
PLoS One ; 15(6): e0234215, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32502195

RESUMO

Bacterial histidine kinases (HKs) are considered attractive drug targets because of their ability to govern adaptive responses coupled with their ubiquity. There are several classes of HK inhibitors; however, they suffer from drug resistance, poor bioavailability, and a lack of selectivity. The 3D structure of Staphylococcus aureus HK was not isolated in high-resolution coordinates, precluding further disclosure of structure-dependent binding to the specific antibiotics. To elucidate structure-dependent binding, the 3D structure of the catalytic domain WalK of S. aureus HK was constructed using homology modeling to investigate the WalK-ligand binding mechanisms through molecular docking studies and molecular dynamics simulations. The binding free energies of the waldiomycin and its methyl ester analog were calculated using molecular mechanics/generalized born surface area scoring. The key residues for protein-ligand binding were postulated. The structural divergence responsible for the 7.4-fold higher potency of waldiomycin than that of its ester analog was clearly observed. The optimized 3D macromolecule-ligand binding modes shed light on the S. aureus HK/WalK-ligand interactions that afford a means to assess binding affinity to design new HK/WalK inhibitors.


Assuntos
Ésteres/química , Histidina Quinase/química , Histidina Quinase/metabolismo , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Quinonas/química , Quinonas/metabolismo , Staphylococcus aureus/enzimologia , Sequência de Aminoácidos , Conformação Proteica , Termodinâmica
4.
Nat Commun ; 11(1): 2424, 2020 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-32415122

RESUMO

Lipid-like nanoparticles (LNPs) have potential as non-viral delivery systems for mRNA therapies. However, repeated administrations of LNPs may lead to accumulation of delivery materials and associated toxicity. To address this challenge, we have developed biodegradable lipids which improve LNPs clearance and reduce toxicity. We modify the backbone structure of Dlin-MC3-DMA by introducing alkyne and ester groups into the lipid tails. We evaluate the performance of these lipids when co-formulated with other amine containing lipid-like materials. We demonstrate that these formulations synergistically facilitate robust mRNA delivery with improved tolerability after single and repeated administrations. We further identify albumin-associated macropinocytosis and endocytosis as an ApoE-independent LNP cellular uptake pathway in the liver. Separately, the inclusion of alkyne lipids significantly increases membrane fusion to enhance mRNA release, leading to synergistic improvement of mRNA delivery. We believe that the rational design of LNPs with multiple amine-lipids increases the material space for mRNA delivery.


Assuntos
Sistemas de Liberação de Medicamentos , Lipídeos/química , Fígado/metabolismo , Nanopartículas/química , RNA Mensageiro/metabolismo , Receptores de Albumina/metabolismo , Alquinos/química , Aminas/química , Animais , Apolipoproteínas E/metabolismo , Materiais Biocompatíveis/química , Endossomos/metabolismo , Eritrócitos/metabolismo , Eritropoetina/química , Ésteres/química , Hepatócitos/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Simulação de Dinâmica Molecular , RNA Interferente Pequeno/metabolismo
5.
J Food Sci ; 85(5): 1548-1564, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32249935

RESUMO

Mandarins (or tangerines) are mainly consumed as fresh fruits due to the ease of peeling and desirable flavor. Sweetness, acidity, and flavor of mandarin are the most important criteria for consumer preference. The objective of this study was to evaluate the effects of harvest date on sensory and chemical components of four mandarin cultivars (Murcott, 411, Temple, and 'LB8-9' Sugar Belle®). Volatiles were extracted from the headspace of juice samples with solid phase microextraction (SPME) and analyzed using gas chromatography-mass spectrometry (GC-MS). The optimum harvest window for eating quality of 411 was late January to mid-February (soluble solids content [SSC]/titratable acidity [TA]: 11.3 to 14.0), Sugar Belle® fruits were best tasted when harvested from mid- to end of January (SSC/TA: 14.1 to 16.1), and February was the best month for harvesting Murcott (SSC/TA: 13.10 to 18.0) and Temple (SSC/TA:10.3 to 12.50). Sensory perception of sweetness, ripeness, and juiciness increased as SSC/TA increased while sourness and bitterness decreased. Pumpkin flavor, an indicator of overripe fruit, was mainly noticed late in the season. Tangerine flavor tended to decrease, whereas fruity-noncitrus flavor tended to increase with fruit maturity. Monoterpenes were the most abundant volatiles and tended to decrease with fruit maturity, whereas alcohols, esters, and aldehydes increase. Aldehydes, esters, and alcohols were positively correlated with sweetness, ripeness, juiciness, and fruity characteristics, and negatively with sourness and bitterness. On the other hand, monoterpenes were positively correlated with bitterness and tangerine flavor, and negatively correlated with sweetness and fruity-noncitrus flavor. The highest number of esters was found in Temple, whereas Murcott and 411 were high in aldehydes.


Assuntos
Citrus/genética , Aromatizantes/química , Frutas/crescimento & desenvolvimento , Aldeídos/química , Aldeídos/isolamento & purificação , Cruzamento , Citrus/química , Citrus/classificação , Citrus/crescimento & desenvolvimento , Comportamento do Consumidor , Ésteres/química , Ésteres/isolamento & purificação , Aromatizantes/isolamento & purificação , Frutas/química , Frutas/classificação , Frutas/genética , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Monoterpenos/química , Monoterpenos/isolamento & purificação , Microextração em Fase Sólida , Paladar , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/isolamento & purificação
6.
Food Chem ; 318: 126507, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32145544

RESUMO

Vegetables are easily contaminated by phthalate esters (PAEs) from the environment, agricultural films and fertilizers, affecting human health. In this paper, titanium dioxide (TiO2) nanotube arrays were prepared by electrochemical anodic oxidation on the surface of titanium wire. Covalent organic framework of TpBD was in situ bonded to the titanium wire via TiO2 nanotube arrays using monomers of 1,3,5-trimethylphloroglucinol (Tp) and benzidine (BD). The fabricated TpBD-TiO2 coated titanium wire was used as the solid-phase microextraction fiber to extract 11 PAEs in vegetable samples. Coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS), the limits of detection for PAEs were from 0.001 (di-n-butyl phthalate) to 0.430 (butyl benzyl phthalate) µg/L (S/N = 3) and enrichment factors were between 226 (dimethyl phthalate) and 2154 (di-n-butyl phthalate). Our fabricated TpBD-TiO2 fiber can be used at least 150 times without significant loss of extraction efficiency (<4.8%). Quantitative determination of PAEs in vegetable samples (tomato, lettuce, cucumber) was achieved by standard addition.


Assuntos
Ésteres/isolamento & purificação , Contaminação de Alimentos/análise , Ácidos Ftálicos/isolamento & purificação , Microextração em Fase Sólida/métodos , Titânio/análise , Verduras/química , Ésteres/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Limite de Detecção , Estruturas Metalorgânicas/química , Ácidos Ftálicos/química , Microextração em Fase Sólida/instrumentação , Espectrometria de Massas em Tandem/métodos , Titânio/química
7.
J Food Sci ; 85(4): 1098-1104, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32147835

RESUMO

Newly developed magnetic carbon particles prepared from coffee grounds were used as the sorbent for the magnetic solid-phase extraction of eight phthalic acid esters (PAEs) from plastic bottled water prior to their analysis by GC-MS. The method, which uses coffee-ground particles coated with iron oxide, was validated, and exhibited linearities for the eight PAEs, with coefficients of determination above 0.998 in the 0.005 to 0.1 mg/L concentration range. Limits of detection and limits of quantification of 0.00003 to 0.002 mg/L and 0.0001 to 0.005 mg/L, respectively, were achieved, with recoveries (%) ranging between 77% and 120%, and relative standard deviations for intra- and interday precisions below 16.3% at three fortification levels. No PAE residues were detected when the developed and validated method was applied to 10 real plastic bottled water samples. Taken together, the developed magnetic solid-phase extraction method is a useful tool for monitoring phthalate esters in aqueous samples. PRACTICAL APPLICATION: The development of a new, inexpensive, and efficient magnetic sorption material derived from spent coffee grounds, and its ability to determine phthalate esters in aqueous solutions was described by GC-MS/MS. The developed magnetic solid-phase extraction method is a useful tool for monitoring phthalate esters in aqueous samples.


Assuntos
Coffea/química , Água Potável/análise , Ésteres/isolamento & purificação , Magnetismo/métodos , Ácidos Ftálicos/isolamento & purificação , Plásticos/isolamento & purificação , Extração em Fase Sólida/métodos , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Carbono/química , Ésteres/química , Cromatografia Gasosa-Espectrometria de Massas , Limite de Detecção , Magnetismo/instrumentação , Ácidos Ftálicos/análise , Plásticos/química , Sementes/química , Extração em Fase Sólida/instrumentação , Poluentes Químicos da Água/química
8.
J Oleo Sci ; 69(2): 93-103, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32023581

RESUMO

In this study, the antioxidative capacity of caffeic acid (CA), ascorbyl palmitate (AP), α-tocopherol (α-TO), and caffeic acid phenethyl ester (CAPE) was evaluated under the thermal oxidation model, in which 200 ppm of each compound was added to soybean oil, followed by thermal oxidation at 180°C for 32 h. Change of viscosity, acid value (AV), conjugated dienoic acid value (CDAV), p-anisidine value (p-AV), total polar materials (TPM), and the ratio of C18:2 to C16:0 (LA/PA) were evaluated during the reaction. All antioxidants showed significantly lower viscosity, TPM, and p-AV, and higher LA/PA, than the control (without antioxidant, CON), indicating that thermal oxidation was delayed. Among them, CAPE showed significantly lower viscosity, TPM, and p-AV, and higher LA/PA, than the other antioxidants (p < 0.05). In the correlation between the oxidation parameters measured from CON and CAPE, the correlation coefficient between p-AV and viscosity was rather low at r = 0.7603 (in CON) and r = 0.7338 (in CAPE), respectively.


Assuntos
Ácido Ascórbico/análogos & derivados , Ácidos Cafeicos/química , Ésteres/química , alfa-Tocoferol/química , Ácido Ascórbico/química , Oxirredução
9.
World J Microbiol Biotechnol ; 36(3): 41, 2020 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-32107645

RESUMO

This study presents a new microbial lipolytic enzyme GD-95RM designed via random mutagenesis using previously characterized GD-95 lipase as a template. The improvement in activity of GD-95 lipase was caused by E100K, F154V and V174I mutations. Compared with GD-95 lipase, the GD-95RM lipase had 1.3-fold increased specific activity (2000 U/mg), demonstrated resistance to higher temperatures (75-85 °C), had fourfold increased Vmax towards p-NP dodecanoate and showed 2.5-fold lower KM for p-NP butyrate. It retained > 50% of its lipolytic activity when hydrolyzing short, medium and long acyl chain substrates at 30 °C and 55 °C reaction temperatures after 20 days' incubation with 25% of ethanol. GD-95RM also displayed long-term tolerance (40 d) to 5% NaCl, trisodium citrate, sodium perborate, urea, 0.1% boric acid, citric acid and Triton X-100. Moreover, oil hydrolysis and transesterification results revealed the capability of GD-95RM lipase to produce fatty acids or fatty acid esters through eco-friendly hydrolysis and transesterification reactions using a broad range of vegetable and fish oils, animal fat and different alcohols as substrates. GD-95RM lipase was successfully applied in synthesis reactions for ethyl oleate, octyl oleate and isoamyl oleate without giving to use additional reaction compounds or special reaction conditions.


Assuntos
Geobacillus/enzimologia , Lipase/genética , Lipase/metabolismo , Mutação , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Butiratos/química , Ésteres/química , Geobacillus/genética , Temperatura Alta , Produtos Domésticos , Lauratos/química , Lipase/química , Modelos Moleculares , Engenharia de Proteínas , Termodinâmica
10.
Biochim Biophys Acta Bioenerg ; 1861(5-6): 148173, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32059842

RESUMO

Infrared absorption bands associated with the neutral state of quinones in the A1 binding site in photosystem I (PSI) have been difficult to identify in the past. This problem is addressed here, where time-resolved step-scan FTIR difference spectroscopy at 77 K has been used to study PSI with six different quinones incorporated into the A1 binding site. (P700+A1- - P700A1) and (A1- - A1) FTIR difference spectra (DS) were obtained for PSI with the different quinones incorporated, and several double-difference spectra (DDS) were constructed from the DS. From analysis of the DS and DDS, in combination with density functional theory based vibrational frequency calculations of the quinones, the neutral state bands of the incorporated quinones are identified and assigned. For neutral PhQ in the A1 binding site, infrared absorption bands were identified near 1665 and 1635 cm-1, that are due to the C1O and C4O stretching vibrations of the incorporated PhQ, respectively. These assignments indicate a 30 cm-1 separation between the C1O and C4O modes, considerably less than the ~80 cm-1 found for similar modes of PhQ-. The C4O mode downshifts due to hydrogen bonding, so the suggestion is that hydrogen bonding is weaker for the neutral state compared to the anion state, indicating radical-induced proton dynamics associated with the quinone in the A1 binding site in PSI.


Assuntos
Complexo de Proteína do Fotossistema I/química , Quinonas/química , Amidas/química , Ânions , Sítios de Ligação , Isótopos de Carbono , Transporte de Elétrons , Ésteres/química , Modelos Moleculares , Fotossíntese , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , Vibração
11.
Int J Biol Macromol ; 148: 1109-1117, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32004608

RESUMO

In this work, cellulose nanofibres (CNFs) were extracted from sawdust, which is an underutilized by-product from the wood and timber industry. The extracted CNFs by chemical and mechanical treatments had a web-like structure with diameters ranging between 2 nm and 27 nm and lengths reaching a few microns. The obtained CNFs were further chemically modified with vegetable canola oil using two different esterification processes. In order to compare the effect of the surface modification of CNFs, the nanopapers were prepared from their prospective suspensions through solvent evaporation method, and then characterize with Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis spectroscopy and tensile tester. FTIR results indicated that both methods led to a successful grafting of the long chain hydrocarbon structure onto the CNFs, and became more hydrophobic when compared to unmodified CNFs-based nanopapers. The crystallinity, mechanical, light transmittance and thermal properties were significantly affected primarily by the esterification method employed, thus the degree of substitution. It was found that high degree of substitution adversely affected the crystallinity, light transmittance, mechanical and thermal properties. The crystallinity decreased from 70% to <40% when the degree of substation was about 0.8.


Assuntos
Celulose/química , Ésteres/química , Nanofibras/química , Óleo de Brassica napus/química , Madeira/química , Cristalização , Esterificação , Hidrocarbonetos/química , Interações Hidrofóbicas e Hidrofílicas , Fenômenos Mecânicos , Estrutura Molecular , Solventes/química , Relação Estrutura-Atividade , Condutividade Térmica
12.
Chemosphere ; 249: 126153, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32058129

RESUMO

In this study, we determined DNA damage and chromosome breakage (indicators of genotoxicity) and cell viability (an indicator of cytotoxicity) in human lymphoblastoid TK6 and Chinese hamster ovary (CHO) cells treated with 33 e-liquids using in vitro single cell gel (comet), micronucleus (MN), and trypan blue assays, respectively. We also measured the contents of nicotine, five phthalate esters, and DL-menthol in the e-liquids to examine their effects on DNA damage, chromosome breakage, and cell viability. Our chemical analyses showed that: (1) six e-liquids had nicotine ≥2-fold higher than the manufacture's label claim (2-3.5 mg); (2) both dimethyl- and dibutyl-phthalate levels were >0.1 µg/g, i.e., their threshold limits as additives in cosmetics; and (3) the DL-menthol contents ranged from 0.0003 to 85757.2 µg/g, with those of two e-liquids being >1 mg/g, the threshold limit for trigging sensory irritation. Though all the e-liquids induced DNA damage in TK6 cells, 20 resulted in cell viabilities ≤75%, indicating cytotoxicity, yet the inverse relationship between cell viability and DNA damage (r = -0.628, p = 0.003) might reflect their role as pro-apoptotic and DNA damage inducers. Fifteen e-liquids induced MN% in TK6 cells ≥3-fold that of untreated cells. Some of the increase in %MN might be false due to high cytotoxicity, yet six brands showed acceptable cell viabilities (59-71%), indicating chromosome damage. DNA damage and %MN increased when the TK6 cells were exposed to metabolic activation. The CHO cells were less sensitive to the genotoxic effects of the e-liquids than the TK6 cells. DL-menthol was found to be associated with decreased cell viability and increased DNA damage, even at low levels. We cannot dismiss the presence of other ingredients in e-liquids with cytotoxic/genotoxic properties since out of the 63 different flavors, 47 induced DNA damage (≥3-folds), and 26 reduced cell viability (≤75%) in TK6 cells.


Assuntos
Vapor do Cigarro Eletrônico/química , Ácidos Ftálicos/química , Animais , Células CHO , Sobrevivência Celular/efeitos dos fármacos , Cricetinae , Cricetulus , Dano ao DNA , Dibutilftalato/farmacologia , Vapor do Cigarro Eletrônico/análise , Vapor do Cigarro Eletrônico/toxicidade , Ésteres/química , Humanos , Mentol/química , Mentol/toxicidade , Testes para Micronúcleos/métodos , Nicotina/química , Nicotina/toxicidade
13.
Chem Commun (Camb) ; 56(9): 1353-1356, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31904054

RESUMO

A novel cyclodextrin molecular tube with one fully modified and one unmodified end was facilely synthesized by selective desilylation of a 6-O-tert-butyldimethylsilylated ß-cyclodextrin dimer possessing multiple linkers. This molecular tube showed a selective inclusion ability toward cis-unsaturated fatty acid esters by utilizing the asymmetric cylindrical nanocavity.


Assuntos
Ésteres/química , Ácidos Graxos Insaturados/química , beta-Ciclodextrinas/química , Estrutura Molecular , Estereoisomerismo , beta-Ciclodextrinas/síntese química
14.
Chem Asian J ; 15(4): 450-462, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-31895493

RESUMO

Carbohydrates contain numerous hydroxyl groups and sometimes amine functionalities which lead to a variety of complex structures. In order to discriminate each hydroxyl group for the synthesis of complex oligosaccharides, protecting group manipulations are essential. Although the primary role of a protecting group is to temporarily mask a particular hydroxyl/amino group, it plays a greater role in tuning the reactivity of coupling partners as well as regioselectivity and stereoselectivity of glycosylations. Several protecting groups offer anchimeric assistance in glycosylation. They also alter the solubility of substrates and thereby influence the reaction outcome. Since oligosaccharides comprise branched structures, the glycosyl donors and acceptors need to be protected with orthogonal protected groups that can be selectively removed one at a time without affecting other groups. This minireview is therefore intended to provide a discussion on new protecting groups for amino and hydroxyl groups, which have been introduced over last ten years in the field of carbohydrate synthesis. These protecting groups are also useful for synthesizing non-carbohydrate target molecules as well.


Assuntos
Oligossacarídeos/química , Benzoatos/química , Compostos de Benzilideno/química , Ésteres/química , Éter/química , Glicosídeos/química , Glicosilação , Oligossacarídeos/síntese química , Estereoisomerismo
15.
J Photochem Photobiol B ; 203: 111771, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31911399

RESUMO

Ultraviolet B (UVB) radiation triggers the activation of many reactive oxygen species (ROS)-sensitive signaling pathways, resulting in the induction of skin damage that can progress to premature skin aging with long-term exposure. Even after the cessation of UVB radiation, the activated photosensitizers can still cause cellular injury. Thus, the use of photoprotectors that inhibit or prevent intracellular ROS production during or after UV exposure is one alternative to counteract UV-induced oxidative damage. The present study investigated the photoprotective activity of protocatechuic acid (P0) and its alkyl esters ethyl protocatechuate (P2) and heptyl protocatechuate (P7) against UVB-induced damage in L929 fibroblasts by evaluating biomarkers of oxidative stress and photoaging. P0, P2 and P7 markedly increased cell viability after UVB exposure. This protective effect was related to the ability of these compounds to absorb UVB and restore cellular redox balance even 24 h after UVB exposure. P0, P2 and P7 also decreased oxidative damage to membrane lipids, mitochondrial membrane potential, and DNA. They also inhibited the nuclear translocation of NF-κB p65 and downregulated the expression of the photoaging-related proteins matrix metalloproteinases-1 and -9 and cyclooxygenase-2. As the lipophilicity of the P0 derivatives increased, their antioxidant potency increased, but more pronounced cytotoxic effects were also detected. In summary, P0 and P2 may be promising candidates for the prevention and treatment of UVB-induced skin photodamage and photoaging.


Assuntos
Senescência Celular/efeitos dos fármacos , Ésteres/química , Hidroxibenzoatos/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Raios Ultravioleta , Animais , Antioxidantes/química , Antioxidantes/metabolismo , Linhagem Celular , Senescência Celular/efeitos da radiação , Ciclo-Oxigenase 2/metabolismo , Regulação para Baixo/efeitos dos fármacos , Fibroblastos/citologia , Hidroxibenzoatos/química , Peroxidação de Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos da radiação , Metaloproteinase 1 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , NADPH Oxidases/metabolismo , Oxirredução , Estresse Oxidativo/efeitos da radiação , Substâncias Protetoras/química , Substâncias Protetoras/farmacologia , Espécies Reativas de Oxigênio/metabolismo
16.
Ecotoxicol Environ Saf ; 190: 110148, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31911388

RESUMO

Phthalate esters have raised public concerns owing to their effects on the environment and human health. We identified a novel phthalate-degrading hydrolase, EstJ6, from a metagenomic library using function-driven screening. Phylogenetic analysis indicated that EstJ6 is a member of family IV esterases. EstJ6 hydrolyzed various dialkyl and monoalkyl phthalate esters, and exhibited high hydrolytic activity (128 U/mg) toward dibutyl phthalate at 40 °C and pH 7.5. EstJ6 hydrolyzed not only common phthalate esters with simple side chains but also diethylhexyl phthalate and monoethylhexyl phthalate, which have complex and long side chains. Site-directed mutagenesis indicated that the catalytic triad residues of EstJ6 consists of Ser146, Glu240, and His270. EstJ6 is therefore a promising biodegradation enzyme, and our study illustrates the advantages of a metagenomic approach in identifying enzyme-coding genes for agricultural, food, and biotechnological applications.


Assuntos
Biodegradação Ambiental , Hidrolases/metabolismo , Ácidos Ftálicos/metabolismo , Dibutilftalato/metabolismo , Dietilexilftalato/metabolismo , Esterases/metabolismo , Ésteres/química , Biblioteca Gênica , Hidrolases/genética , Hidrólise , Metagenoma , Filogenia , Solo
17.
Food Chem ; 313: 125926, 2020 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31945703

RESUMO

This study investigates whether the formation of monochloropropane diol fatty acid esters (MCPDE) can be mitigated by removing the residual sediments from vegetable oils. Settling and centrifugation were conducted in crude sunflower and palm oil and the purified oils and their sediment-rich fractions were heated and analyzed for their MCPDE content. Increased MCPDE levels by factors of x2 to x6 were found in the sediment-rich fractions of settled sunflower oils compared to the sediment-free oil. The sediment-containing fraction could be however purified by ultracentrifugation resulting in the mitigation of MCPDE levels by a factor of 10. The effect of residual sediment on the MCPDE formation was also confirmed in the case of palm oil showing x2 to x10 more MCPDE formation in the sediment containing fractions compared to the purified oil. These results confirm that the mechanical removal of the trace sediments from crude vegetable oils results in reduced MCPDE levels.


Assuntos
Ésteres/análise , Óleos Vegetais/química , Propilenoglicóis/química , Cromatografia Líquida de Alta Pressão , Ésteres/química , Espectrometria de Massas , Óleo de Palmeira/química , Óleo de Girassol/química , Temperatura , Ultracentrifugação
18.
J Agric Food Chem ; 68(5): 1248-1256, 2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-31927921

RESUMO

Lipophenols are regarded as an emerging source of functional food ingredients. However, little is known about their in vivo digestion, absorption, and metabolism. Thus, the pharmacokinetic characteristics in rat and the gut microbial degradation of tyrosol acyl esters (TYr-Es) with fatty acids of C12:0, C18:0, and C18:2 were investigated for the first time. Major metabolites including tyrosol sulfate and tyrosol glucuronide, rather than the parent compounds, were detected in rat plasma after oral administration of TYr-Es. The increased plasma half-life (T1/2) and mean residence time demonstrated that TYr-Es display a longer duration of action in vivo than TYr, potentially leading to higher oral bioavailability. TYr-Es could be hydrolyzed by the gut microbiota to free TYr, which may result in the appearance of the second absorption peak in pharmacokinetic profiles. Therefore, TYr-Es exhibit improved bioavailability compared to that of TYr because of their prolonged duration of action.


Assuntos
Ésteres/farmacocinética , Álcool Feniletílico/análogos & derivados , Animais , Disponibilidade Biológica , Ésteres/química , Ácidos Graxos/sangue , Ácidos Graxos/química , Cinética , Masculino , Álcool Feniletílico/química , Álcool Feniletílico/farmacocinética , Plasma/química , Ratos , Ratos Sprague-Dawley
19.
Chemistry ; 26(14): 3049-3053, 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-31961029

RESUMO

A general and powerful method for the stereo-controlled Pd-catalyzed N-allylation of amino acid esters is reported, as a previously largely unsolved synthetic challenge. Employing a new class of tartaric acid-derived C2 -symmetric chiral diphosphane ligands the developed asymmetric amination protocol allows the conversion of various amino acid esters to the N-allylated products with highest levels of enantio- or diastereoselectivity in a fully catalyst-controlled fashion and predictable configuration. Remarkably, the in situ generated catalysts also exhibit outstanding levels of activity (ligand acceleration). The usefulness of the method was demonstrated in the stereo-divergent synthesis of a set of new conformationally defined dipeptide mimetics, which represent new modular building blocks for the development of peptide-inspired bioactive compounds.


Assuntos
Aminoácidos/química , Dipeptídeos/síntese química , Ésteres/química , Paládio/química , Alanina/química , Catálise , Cristalografia por Raios X , Reação de Cicloadição , Ligantes , Modelos Moleculares , Estrutura Molecular , Oxirredução , Prolina/química , Estereoisomerismo
20.
Food Chem ; 314: 126179, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31968292

RESUMO

In this study, for the first time, hollow fiber and monolithic fiber were fabricated based on metal-organic framework deep eutectic solvents/molecularly imprinted polymers (MOF- DES/MIPs) and were used for microextraction of phthalate esters under termed hollow fiber liquid membrane-protected solid-phase microextraction (HFLMP-SPME) followed by gas chromatography- flame ionization detection. Several parameters influencing extraction recoveries of phthalate esters including adsorption and desorption parameters were investigated and optimized using fabricated MOF- DES/MIPs monolithic fiber. Under optimal conditions, detection limits (S/N = 3) of the method were in a range of 0.008-0.03 µg L-1 and limits of quantification (S/N = 10) were between 0.028 and 0.12 µg L-1. RSD (%) for intra-day and inter-day precisions were between 2.4-4.7% and 2.6-3.4%, respectively. Subsequently, this procedure was successfully applied with satisfactory results in the determination of phthalate esters in yogurt, water, and soybean oil samples. The R (%) ranged from 95.5 to 100.0% in different samples.


Assuntos
Estruturas Metalorgânicas/química , Impressão Molecular/métodos , Microextração em Fase Sólida/métodos , Óleo de Soja/química , Água/química , Iogurte/análise , Adsorção , Cromatografia Gasosa , Ésteres/química , Limite de Detecção , Impressão Molecular/instrumentação , Ácidos Ftálicos/química , Polímeros/química , Microextração em Fase Sólida/instrumentação , Solventes/química
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