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1.
Food Chem ; 305: 125479, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31505418

RESUMO

1-o-Galloylglycerol (GG) was synthesized by the enzymatic glycerolysis of propyl gallate (PG) using a food-grade lipase (Lipozyme® 435). The reaction conditions affecting the yield of GG were optimized and a yield of 76.9% ±â€¯1.2% was obtained. GG was characterized by various techniques after being separated from the reaction mixture using liquid-liquid extraction. The water solubility and hydrophilicity of GG were significantly higher than those of gallic acid (GA) and PG. The antioxidant properties, measured by the ferric reducing antioxidant power (FRAP) and hydrogen peroxide (H2O2) scavenging assays, showed that GG exhibited the highest scavenging capacity (GG > GA > PG). From the results of the 1,1-diphenyl-2-picrylhydrazyl (DPPH•) and 2,2'-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS•+) assays, GG and GA exhibited greater scavenging capacity than PG (GG = GA > PG). These results suggest that GG may be used as a water-soluble antioxidant alternative to GA for food and cosmetic applications.


Assuntos
Antioxidantes/metabolismo , Antioxidantes/farmacologia , Ácido Gálico/análogos & derivados , Glicerol/análogos & derivados , Antioxidantes/química , Ácido Gálico/química , Ácido Gálico/metabolismo , Ácido Gálico/farmacologia , Glicerol/química , Glicerol/metabolismo , Glicerol/farmacologia , Peróxido de Hidrogênio/química , Lipase/metabolismo , Extração Líquido-Líquido , Espectroscopia de Ressonância Magnética , Galato de Propila/química , Solubilidade , Temperatura
2.
Molecules ; 24(22)2019 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-31744244

RESUMO

Biodegradable polyesters gain significant attention because of their wide potential biomedical applications. The ring-opening polymerization method is widely used to obtain such polymers, due to high yields and advantageous properties of the obtained material. The preparation of new, effective, and bio-safe catalytic systems for the synthesis of biomedical polymers is one of the main directions of the research in modern medical chemistry. The new diethylzinc/propyl gallate catalytic system was first used in the copolymerization of ε-caprolactone and rac-lactide. In this paper, the activity of the new zinc-based catalytic system in the copolymerization of cyclic esters depending on the reaction conditions was described. The microstructure analysis of the obtained copolyesters and their toxicity studies were performed. Resulted copolyesters were characterized by low toxicity, moderate dispersity (1.19-1.71), varying randomness degree (0.18-0.83), and average molar mass (5300-9800 Da).


Assuntos
Caproatos/química , Dioxanos/química , Lactonas/química , Compostos Organometálicos/química , Galato de Propila/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Peso Molecular , Polimerização , Polímeros/química
3.
J Agric Food Chem ; 67(31): 8520-8526, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31310120

RESUMO

Reactive carbonyl species (RCS), such as acrolein (ACR), glyoxal (GO), and methylglyoxal (MGO), have received extensive attention recently as a result of their high activity and toxicity in vitro and in vivo. In the present study, propyl gallate (PG), a common food antioxidant, was found to effectively trap more ACR than butylated hydroxytoluene and butylated hydroxyanisole through the formation of mono-ACR adducts (PG-ACR) and di-ACR adducts (PG-2ACR). The two adducts were successfully purified, and their structures were elucidated on the basis of their high-resolution mass spectrometry and 1H, 13C, and two-dimensional nuclear magnetic resonance data. We further identified that PG-ACR had the ability to continue to trap GO and MGO to form PG-ACR-GO and PG-ACR-MGO, respectively, by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Furthermore, we verified that PG could inhibit the production of ACR, GO, and MGO via trapping these RCS simultaneously to form the corresponding adducts in pound cakes using LC-MS/MS.


Assuntos
Acroleína/química , Antioxidantes/química , Galato de Propila/química , Culinária , Temperatura Alta , Espectroscopia de Ressonância Magnética , Modelos Biológicos , Estrutura Molecular , Espectrometria de Massas em Tandem
4.
Food Chem ; 297: 124972, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253320

RESUMO

The aim of the present study was to evaluate Paralichthys olivaceus parvalbumin (PV) following treatment by laccase (LAC) in the presence of propyl gallate (PG) on the structure and potential allergenicity. The structure of LAC + PG treated PV was analyzed through SDS-PAGE, CD, fluorescence, and allergenicity was analyzed by immunological and cell model. Our results showed that LAC + PG treatment can induce structural changes through PV cross-linking. Western blotting and indirect ELISA analysis revealed the decrease in IgG binding capacity of PV, corresponding with the structural changes. The results of in vitro digestion illustrate that LAC + PG treated PV showed more resistance to gastrointestinal digestion compared to untreated PV. The release rate of ß-hexosaminidase and histamine decreased by 35.6% and 66.9%, respectively, with LAC + PG treatment by RBL-2H3 cell assay. Considering the wide utilization of LAC in food industry, our treatment reveals its potential for creation of hypoallergenic fish products under mild reaction conditions.


Assuntos
Alérgenos/imunologia , Proteínas de Peixes/imunologia , Linguados/imunologia , Lacase/metabolismo , Parvalbuminas/imunologia , Galato de Propila/química , Animais , Catálise , Reagentes para Ligações Cruzadas/química , Digestão , Ensaio de Imunoadsorção Enzimática , Proteínas de Peixes/química , Indústria Alimentícia , Histamina/metabolismo , Parvalbuminas/química , beta-N-Acetil-Hexosaminidases/metabolismo
5.
Food Chem ; 278: 692-699, 2019 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-30583431

RESUMO

Studies of 54 antioxidants revealed that 27 of them, mainly polyphenols, generated hydrogen peroxide (H2O2) when added to Dulbecco's modified Eagle's medium (DMEM), other media used for culture of mammalian and yeast cells and phosphate-buffered saline. The most active antioxidants were: propyl gallate (PG), (-)-epigallocatechin gallate (EGCG) and quercetin (Q). Chelex treatment and iron chelators decreased H2O2 generation suggesting that transition metal ions catalyze antioxidant autoxidation and H2O2 production. Green tea also generated H2O2; tea prepared on tap water generated significantly more H2O2 than tea prepared on deionized water. Ascorbic acid decreased H2O2 production although it generated H2O2 itself, in the absence of other additives. Lemon added to the tea significantly reduced generation of H2O2. Hydrogen peroxide generated in the medium contributed to the cytotoxicity of PG, EGCG and Q to human prostate carcinoma DU-145 cells, since catalase increased the survival of the cells subjected to these compounds in vitro.


Assuntos
Antioxidantes/química , Peróxido de Hidrogênio/química , Catalase/metabolismo , Catequina/análogos & derivados , Catequina/química , Catequina/farmacologia , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Humanos , Peróxido de Hidrogênio/metabolismo , Oxirredução , Polifenóis/química , Galato de Propila/química , Galato de Propila/farmacologia , Quercetina/química , Quercetina/farmacologia , Chá/química , Chá/metabolismo , Elementos de Transição/química
6.
Food Chem ; 265: 227-232, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29884377

RESUMO

In the present study, we investigated the trapping of methylglyoxal (MGO) by propyl gallate (PG), a known food grade antioxidant, and the anti-carbonyl and anti-oxidative properties of the mono-MGO adduct of PG (MM-PG). Our result indicated that more than 77.5% MGO was suppressed by PG after a 30 min incubation of PG with MGO, which was much more effective than gallic acid (15.2%). For the first time, MM-PG was purified, and its structure was elucidated based on the analysis of its 1H, 13C, and 2D-NMR data. We also demonstrated that MM-PG had strong anti-oxidative and anti-carbonyl activities. Furthermore, PG could trap the MGO generated during the preparation of roasted pork, and both mono- and di- MGO adducts of PG were detected in the roasted pork system using LC/MS technique. Thus, PG could be widely applied in the food system for inhibiting the formation of both carbonyl species and oxidative species.


Assuntos
Estresse Oxidativo/efeitos dos fármacos , Galato de Propila/química , Aldeído Pirúvico/química , Antioxidantes/química , Cromatografia Líquida , Produtos Finais de Glicação Avançada/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Galato de Propila/farmacologia , Carne Vermelha , Espectrometria de Massas em Tandem
7.
Food Chem ; 245: 1062-1069, 2018 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-29287323

RESUMO

This study prepared and investigated the inclusion complexes of propyl gallate (PG) with beta-cyclodextrin (ß-CD) and its water-soluble derivatives dimethyl-beta-cyclodextrin (DM-ß-CD), hydroxypropyl-beta-cyclodextrin (HP-ß-CD), and sulfobutylether-beta-cyclodextrin (SBE-ß-CD). Phase solubility studies indicated that the formed complexes were in 1:1 stoichiometry. FT-IR, PXRD, DSC, 1H-NMR, ROESY-NMR, and SEM analysis results confirmed the formation of the complexes. The NMR results indicated that the aromatic ring of PG was embedded into the CD cavity. The aqueous solubility of PG was markedly improved, and that of the PG/DM-ß-CD complex increased by 365.3 times. In addition, the results of the antioxidant activity assay showed that the hydroxyl radical and superoxide radical scavenging capacities of the complexes increased by 3-11 times and 1-6.5 times, respectively, compared with those of PG under the same concentration. Therefore, CD/PG inclusion complexes with improved solubility and radical scavenging capacity can be used as water-soluble antioxidants in the food industry.


Assuntos
Ciclodextrinas/química , Depuradores de Radicais Livres/química , Galato de Propila/química , Indústria Alimentícia , Solubilidade , Água/química
8.
Redox Rep ; 22(6): 572-581, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28812524

RESUMO

OBJECTIVES: Two important classes of hydrazide-containing fused azaisocytosines were evaluated as possible antioxidants and characterised by UV spectroscopy. METHODS: 2,2-Diphenyl-1-picrylhydazyl (DPPH), nitric oxide (NO), hydrogen peroxide (H2O2) scavenging potencies and reducing power of molecules were evaluated. RESULTS: The strongest DPPH scavengers were found to be 9, showing the potency superior to that of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) and comparable to that of ascorbic acid (AA), and 6, revealing the antioxidant potency superior to that of BHA, BHT, PG and Trolox. In turn, 3 and 9 were the most promising NO scavengers, exhibiting the potency superior to that of BHA, BHT (3 and 9) and AA (3). The most potent H2O2 scavengers proved to be 10 and 9 showing similar or even better neutralising potency than that of Trolox, BHT and BHA. Simultaneously, the majority of hydrazides revealed higher ferric reducing abilities than that of AA and BHT. Some structure-activity relationships were explored. A possible mechanism for the DPPH radical scavenging ability of hydrazide-containing molecules was proposed. DISCUSSION: Hydrazides 3, 6 and 9 with an antioxidant potential better or comparable to that of the well-known antioxidants are proposed as new antioxidant candidates.


Assuntos
Antioxidantes/química , Ácido Ascórbico/química , Hidroxitolueno Butilado/química , Cromanos/química , Depuradores de Radicais Livres/química , Peróxido de Hidrogênio/química , Peroxidação de Lipídeos , Galato de Propila/química , alfa-Tocoferol/química
9.
Biosens Bioelectron ; 86: 741-747, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27476055

RESUMO

A new strategy based on sign-on and sign-off was proposed for propyl gallate (PG) determination by an electrochemical sensor. The successively modified poly(thionine) (PTH) and molecular imprinted polymer (MIP) showed an obvious electrocatalysis and a good recognition toward PG, respectively. Furthermore, the rebound PG molecules in imprinted cavities not only were oxidized but also blocked the electron transmission channels for PTH redox. Thus, a sign-on from PG current and a sign-off from PTH current were combined as a dual-sign for PG detection. Meanwhile, the modified MIP endowed the sensor with recognition capacity. The electrochemical experimental results demonstrated that the prepared sensor possessed good selectivity and high sensitivity. A linear ranging from 5.0×10(-8) to 1.0×10(-4)mol/L for PG detection was obtained with a limit of detection of 2.4×10(-8)mol/L. And the sensor has been applied to analyze PG in real samples with satisfactory results. The simple, low cost, and effective strategy reported here can be further used to prepare electrochemical sensors for other compounds selective recognition and sensitive detection.


Assuntos
Condutometria/instrumentação , Impressão Molecular/métodos , Polímeros/química , Galato de Propila/análise , Tiofenos/química , Eletrodos , Desenho de Equipamento , Análise de Falha de Equipamento , Aditivos Alimentares/análise , Análise de Alimentos/instrumentação , Galato de Propila/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
10.
Food Chem ; 213: 19-25, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27451150

RESUMO

This study investigated a method for the validation and determination of measurement uncertainty for the simultaneous determination of synthetic phenolic antioxidants (SPAs) such as propyl gallate (PG), octyl gallate (OG), dodecyl gallate (DG), 2,4,5-trihydroxy butyrophenone (THBP), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) in edible oils commonly consumed in Korea. The validated method was able to extract SPA residues under the optimized HPLC-UV and LC-MS/MS conditions. Furthermore, the measurement of uncertainty was evaluated based on the precision study. For HPLC-UV analysis, the recoveries of SPAs ranged from 91.4% to 115.9% with relative standard deviations between 0.3% and 11.4%. In addition, the expanded uncertainties of the SPAs ranged from 0.15 to 5.91. These results indicate that the validated method is appropriate for the extraction and determination of SPAs and can be used to verify the safety of edible oil products containing SPAs residues.


Assuntos
Antioxidantes/química , Análise de Alimentos/métodos , Fenóis/química , Óleos Vegetais/química , Hidroxianisol Butilado/química , Hidroxitolueno Butilado/química , Calibragem , Cromatografia Líquida de Alta Pressão , Cromatografia Líquida , Ácido Gálico/análogos & derivados , Ácido Gálico/química , Hidroquinonas/química , Galato de Propila/química , Reprodutibilidade dos Testes , República da Coreia , Espectrofotometria Ultravioleta , Espectrometria de Massas em Tandem , Incerteza
11.
Int J Biol Macromol ; 91: 471-6, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27234496

RESUMO

Arginine is widely used in biotechnological application, but mostly with chloride counter ion. Here, we examined the effects of various anions on solubilization of aromatic compounds and reduced lysozyme and on refolding of the lysozyme. All arginine salts tested increased the solubility of propyl gallate with acetate much more effectively than chloride. The effects of arginine salts were compared with those of sodium or guanidine salts, indicating that the ability of anions to modulate the propyl gallate solubility is independent of the cation. Comparison of transfer free energy of propyl gallate between sodium and arginine salts indicates that the interaction of propyl gallate is more favorable with arginine than sodium. On the contrary, the solubility of aromatic amino acids is only slightly modulated by anions, implying that there is specific interaction between acetic acid and propyl gallate. Unlike their effects on the solubility of small aromatic compounds, the solubility of reduced lysozyme was much higher in arginine chloride than in arginine acetate or sulfate. Consistent with high solubility, refolding of reduced lysozyme was most effective in arginine chloride. These results suggest potential broader applications of arginine modulated by different anions.


Assuntos
Aminoácidos Aromáticos/química , Arginina/química , Guanidina/química , Muramidase/química , Redobramento de Proteína , Galato de Propila/química , Solubilidade
12.
J Agric Food Chem ; 63(46): 10131-9, 2015 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-26540621

RESUMO

Although numerous biologically active molecules exist as glycosides in nature, information on the activity, stability, and solubility of glycosylated antioxidants is rather limited to date. In this work, a wide variety of antioxidants were glycosylated using different phosphorylase enzymes. The resulting antioxidant library, containing α/ß-glucosides, different regioisomers, cellobiosides, and cellotriosides, was then characterized. Glycosylation was found to significantly increase the solubility and stability of all evaluated compounds. Despite decreased radical-scavenging abilities, most glycosides were identified to be potent antioxidants, outperforming the commonly used 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT). Moreover, the point of attachment, the anomeric configuration, and the glycosidic chain length were found to influence the properties of these phenolic glycosides.


Assuntos
Antioxidantes/metabolismo , Fenóis/metabolismo , Fosforilases/metabolismo , Antioxidantes/química , Estabilidade de Medicamentos , Depuradores de Radicais Livres , Glicosídeos/química , Glicosídeos/metabolismo , Glicosilação , Fenóis/química , Galato de Propila/química , Galato de Propila/metabolismo , Solubilidade
13.
Biosens Bioelectron ; 68: 563-569, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25638798

RESUMO

A novel molecularly imprinted electrochemical sensor for propyl gallate (PG) determination was developed via electropolymerization of an o-phenylenediamine membrane in the presence of template molecules on glassy carbon electrode surface modified by PtAu bimetallic nanoparticles-capped graphene-carbon nanotubes composites (PtAu-GrCNTs). The modified electrodes were characterized by cyclic voltammetry, scanning electron microscope, x-ray diffraction and chronoamperometry. Moreover, experimental parameters such as scan cycles, incubation time, molar ratios of template molecules to functional monomers and extraction time were optimized. It was found that the PtAu-GrCNTs composite could effectively enhance the electron transfer efficiency and remarkably improve the sensitivity of the sensor. The results revealed the sensor displayed superb resistance to no-specific binding, very attractive detection limit as low as 2.51×10(-8) mol/L, and a wide linear range from 7×10(-8) mol/L to 1×10(-5) mol/L towards PG. Furthermore, the MIPs sensor was also successfully used for the detection of PG in food samples. Therefore, the MIPs-based electrochemical sensing strategy might provide a sensitive, rapid, and cost-effective method for PG determination and related food safety analysis.


Assuntos
Técnicas Biossensoriais , Técnicas Eletroquímicas , Galato de Propila/isolamento & purificação , Ouro/química , Grafite/química , Limite de Detecção , Impressão Molecular , Nanotubos de Carbono/química , Platina/química , Polímeros/química , Galato de Propila/química
14.
Food Chem ; 177: 37-42, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25660855

RESUMO

A novel imprinted sol-gel electrochemical sensor for the determination of propyl gallate (PG) was developed based on a composite of graphene and single walled carbon nanotubes (GR-SWCNTs). It was fabricated by stepwise modifying GR-SWCNTs and molecularly imprinted polymers and stored in 0.10 mol L(-1) phosphate buffer solution pH 6.0, which endowed the sensor good sensitivity and selective recognition towards template molecules. The morphology and specific adsorption capacity of the sensor was characterized by scanning electron microscope and electrochemical methods, respectively. Under the optimized conditions, a linear range of the sensor to PG was 8.0 × 10(-8)-2.6 × 10(-3)mo lL(-1) with a limit of detection of 5.0 × 10(-8)mol L(-1) (S/N=3). The sensor exhibited specificity and selectivity towards template molecules as well as excellent reproducibility, regeneration and stability. Furthermore, the sensor could be applied to determine PG in edible oils, instant noodles and cookies with satisfactory results.


Assuntos
Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas/métodos , Grafite/química , Nanotubos de Carbono/química , Galato de Propila/química , Inocuidade dos Alimentos , Polímeros/química
15.
Biotechnol Prog ; 31(1): 70-7, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25311237

RESUMO

The comparative evaluation of distinct types of ionic liquid-based aqueous biphasic systems (IL-ABS) and more conventional polymer/salt-based ABS to the extraction of two antioxidants, eugenol and propyl gallate, is focused. In a first approach, IL-ABS composed of ILs and potassium citrate (C6H5K3O7/C6H8O7) buffer at pH 7 were applied to the extraction of two antioxidants, enabling the assessment of the impact of IL cation core on the extraction. The second approach uses ABS composed of polyethylene glycol (PEG) and potassium phosphate (K2HPO4/KH2PO4) buffer at pH 7 with imidazolium-based ILs as adjuvants. Their application to the extraction of the compounds allowed the investigation of the impact of the presence/absence of IL, the PEG molecular weight, and the alkyl side chain length of the imidazolium cation on the partition. It is possible to maximize the extractive performance of both antioxidants up to 100% using both types of IL-ABS. The IL enhances the performance of ABS technology. The data puts in evidence the pivotal role of the appropriate selection of the ABS components and design to develop a successful extractive process, from both environmental and performance points of view.


Assuntos
Antioxidantes/isolamento & purificação , Fracionamento Químico/métodos , Eugenol/isolamento & purificação , Imidazóis/química , Líquidos Iônicos/química , Galato de Propila/isolamento & purificação , Antioxidantes/análise , Antioxidantes/química , Eugenol/análise , Eugenol/química , Galato de Propila/análise , Galato de Propila/química
16.
Chem Pharm Bull (Tokyo) ; 62(10): 1013-8, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25273060

RESUMO

Three new compounds were isolated from a MeOH extract of the leaves of Syzygium samarangense, one new cyanogenic glucoside, taxiphyllin 6'-O-gallate (1), one new megastigmane glucoside, actinidioionoside 6'-O-gallate (2), and one new sulfated flavonoid rhamnoside, myricetrin 2″-O-sulfate (3), together with 14 known compounds, lupeol (4), demethoxymatteucinol (5), cryptostrobin (6), betulinic acid (7), ß-sitosterol glucoside (8), 2R-prunasin (9), myrciaphenone A (10), 1-feruloyl-ß-D-glucopyranoside (11), (3S,5R,6R,7E,9S)-3,5,6,9-tetrahydroxymegastigman-7-ene (12), guaijaverin (13), myricetin 4'-methyl ether 3-O-α-L-rhamnopyranoside (14), myricetrin (15), gallic acid (16) and actinidioionoside (17). The structures of the new compounds were determined through a combination of spectroscopic, HPLC and chemical analyses.


Assuntos
Anti-Infecciosos/química , Antineoplásicos/química , Flavonoides/química , Nitrilos/química , Galato de Propila/análogos & derivados , Syzygium/química , Anti-Infecciosos/isolamento & purificação , Anti-Infecciosos/farmacologia , Antineoplásicos/isolamento & purificação , Antineoplásicos/toxicidade , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Flavonoides/isolamento & purificação , Flavonoides/farmacologia , Depuradores de Radicais Livres/química , Humanos , Leishmania/efeitos dos fármacos , Espectroscopia de Ressonância Magnética , Metanol/química , Testes de Sensibilidade Microbiana , Conformação Molecular , Nitrilos/isolamento & purificação , Nitrilos/farmacologia , Folhas de Planta/química , Folhas de Planta/metabolismo , Galato de Propila/química , Galato de Propila/isolamento & purificação , Galato de Propila/farmacologia , Syzygium/metabolismo
17.
Food Chem ; 159: 445-50, 2014 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-24767080

RESUMO

In this paper, a novel chemiluminescence (CL) method has been developed for the determination of propyl gallate (PG). The proposed method was based on the enhancing effect of PG on the CL signal of 2-phenyl-4,5-di(2-furyl)-1H-imidazole (PDFI) and K3Fe(CN)6 reaction in an alkaline solution. Under the optimum conditions, the enhanced CL intensity was linearly related to the concentration of PG. The linear range of the calibration curve was 0.05-8 µg/mL, and the corresponding detection limit (3σ) was 0.036 µg/mL. The relative standard deviation for determining 1.0 µg/mL PG was 2.8% (n=11). The proposed method has been successfully applied to the determination of PG in edible oil. The edible oil samples were prepared by the solid-phase extraction (SPE) with a C18 column served as the stationary phase. Furthermore, the possible CL mechanism was also discussed briefly based on the photoluminescence (PL) and CL spectra.


Assuntos
Antioxidantes/química , Análise de Alimentos/métodos , Imidazóis/química , Luminescência , Óleos Vegetais/análise , Galato de Propila/química , Extração em Fase Sólida , Calibragem , Técnicas de Química Analítica , Ferricianetos , Ferro/química , Limite de Detecção , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Soluções
18.
Phys Chem Chem Phys ; 15(31): 13137-46, 2013 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-23824251

RESUMO

In this work, we have carried out a quantum chemistry and computational kinetics study on the reactivity of propyl gallate towards ˙OOH, ˙OOCH3 and ˙OOCHCH2 radicals, in aqueous and lipid media. We have considered three reaction mechanisms: hydrogen transfer (HT), radical adduct formation (RAF) and single electron transfer (SET). Rate constants and relative branching ratios for the different paths contributing to the overall reaction, at 298.15 K, are reported. Our results show that propyl gallate reacts mainly through the HT mechanism, independently of the solvent or the peroxyl radical, contrary to other phenols such as catechols and guayacols previously studied, which react mainly via the SET mechanism. In aqueous media at physiological pH, the calculated rate constants towards the ˙OOH, ˙OOCH3 and ˙OOCHCH2 radicals are 4.56 × 10(8), 1.59 × 10(6) and 4.05 × 10(8) M(-1) s(-1), while in lipid media the rate constants are 2.94 × 10(4), 7.73 × 10(3) and 9.94 × 10(5) M(-1) s(-1). Thus, a propyl gallate molecule acts as a very efficient peroxyl radical scavenger, both in aqueous and lipid media. Since the gallate moiety is a part of other naturally occurring polyphenols such as aflavine gallates and epigallocatechin gallates, the results of this study could be extrapolated to these compounds. Even if these compounds have other antioxidant structures or enhancers, the activity of the gallate moiety could be considered as a lower limit to their antioxidant activity.


Assuntos
Antioxidantes/química , Galato de Propila/química , Teoria Quântica , Concentração de Íons de Hidrogênio , Cinética , Estrutura Molecular , Água/química
19.
Prep Biochem Biotechnol ; 43(5): 445-55, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23581780

RESUMO

Enzymatic synthesis of propyl gallate in organic solvent was studied using cell-associated tannase (EC 3.1.1.20) of Bacillus massiliensis. Lyophilized biomass showing tannase activity was used as the biocatalyst. The effects of solvent, surfactant treatment, and bioimprinting on the propyl gallate synthesis were studied and subsequently optimized. Among various solvents, benzene followed by hexane was found to be the most favorable. Treatment of the biocatalyst with Triton X-100 at a lower concentration (0.2% w/v), before lyophilization, increased the propyl gallate yield by 24.5% compared to the untreated biocatalyst. The biocatalyst was imprinted with various concentrations of gallic acid and tannic acid. Biocatalyst imprinted with tannic acid showed 50% enhancement in the propyl gallate yield compared to the non-imprinted biocatalyst.


Assuntos
Bacillus/enzimologia , Hidrolases de Éster Carboxílico/química , Galato de Propila/síntese química , Biocatálise , Meios de Cultura/química , Ativação Enzimática , Esterificação , Liofilização , Ácido Gálico/química , Octoxinol/química , Galato de Propila/química , Solventes/química , Taninos/química
20.
Lab Chip ; 13(10): 1955-62, 2013 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-23546540

RESUMO

The kinetic activity of individual enzyme molecules was determined in aqueous droplets generated in a nano- and microfluidic device. To avoid high background noise, the enzyme and substrate solution was confined into femtoliter carriers, achieving high product concentrations from single-molecule encapsulation. The tiny droplets (φ ~ 2.5-3 µm) generated from this fluidic system were highly monodisperse, beneficial for an analysis of single enzyme activity. The method presented here allows to follow large numbers of individual droplets over time. The instrumental requirements are furthermore modest, since the small droplet size allows to use of standard microscope and standard Pyrex glass chips as well as the use of relatively high enzyme concentrations (nM range) for single molecule encapsulation.


Assuntos
Técnicas Analíticas Microfluídicas/métodos , Nanotecnologia/métodos , beta-Galactosidase/análise , Fluoresceína/química , Cinética , Técnicas Analíticas Microfluídicas/instrumentação , Nanotecnologia/instrumentação , Galato de Propila/química , Espectrometria de Fluorescência , Especificidade por Substrato
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