Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 306
Filtrar
1.
Biomed Chromatogr ; 34(1): e4712, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31633799

RESUMO

Coffee and tea are the most widely consumed beverages worldwide. However, the consumer may be unaware of the exact amount of methyl xanthine (MX, i.e. caffeine [C], theobromine [TB] and theophylline [TH]) consumed, as most of the products do not list the proper amounts. This may lead to serious risks including cardiovascular, kidney and stimulant effects. The aim of the study was to determine the MX amount in ready-to-use beverages (coffee and tea) collected from various outlets in the city of Al-Khobar, Saudi Arabia. Forty different samples of espresso, black coffee and red tea were collected. A fast, reliable and efficient UHPLC-DAD method was developed and validated for MX determination. Total lipids were extracted and fractionated in order to determine glycolipids, phospholipids and neutral lipids. The r2 value for the method was 0.980-0.988 in a linearity range of 0.5-200 ppm. The range for MX (C [0.02-2.39 mg/ml], TB [0.00-0.10 mg/ml] and TH [0.00-0.004 mg/ml]) and total lipids was 1-5 g. The amount of glycolipids (3.1 g) was higher among the lipid fractions followed by phospholipids (1.8 g) and neutral lipids (0.25 g). In general, espresso beverages (20-30 ml) contained high amounts of MX whereas black coffee beverages contained high amount of lipids. Most of the beverages expressed C, TB, TH, lipids or their fractions; however, the product with high amounts of MX and lipids at the same time was espresso (brands Chemistry and Wogard). Although the MX and lipid levels in these beverages well below the allowed limits, care must still be taken, especially when using the beverages with high serving volumes (200-250 ml) or coffee prepared via the filter method i.e. black coffee, using a high temperature for a longer time.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Café/química , Chá/química , Xantinas , Culinária , Temperatura Alta , Lipídeos/análise , Reprodutibilidade dos Testes , Arábia Saudita , Xantinas/análise , Xantinas/química , Xantinas/isolamento & purificação
2.
Food Chem ; 281: 222-230, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-30658751

RESUMO

Catechins and methylxanthines are natural molecules in guarana (Paullinia cupana) that are associated with antioxidant and stimulatory effects in the human body. There are few natural sources of these antioxidants. The most popular molecule used in foods and beverages is caffeine, which, most of the time, is derived from synthetic sources. In this work, cold hydroalcoholic (CHM), hot hydroalcoholic (HHM), and aqueous enzymatic maceration (AEM) were applied to crude (CG) and waste guarana seeds (WG) to process these materials into natural added-value products with enhanced levels of catechin, epicatechin, epicatechin gallate, caffeine, theobromine and theophylline. The highest level of catechins and methylxanthines was extracted with HHM. Nevertheless, AEM enhanced the global yield in the extract, probably due to the solubilization of other substances. The maceration procedures applied to guarana contributed to the valorization of this plant crop by providing antioxidant sources with clear applications in food and nonfood industries.


Assuntos
Catequina/análise , Paullinia/química , Sementes/química , Xantinas/análise , Antioxidantes/análise , Cafeína/análise , Catequina/análogos & derivados , Fenol/análise , Extratos Vegetais/análise , Teobromina/análise , Teofilina/análise
3.
Food Chem ; 273: 39-44, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30292372

RESUMO

This study deals with the development of a separation and quantification method by high performance liquid chromatography with a diode array detector (HPLC- DAD), for the determination of phenolic acids and methylxanthines in tea (Camellia Sinensis) samples. Six phenolic acids (Gallic, trans-cinnamic, caffeic, ferulic and p-coumaric acids) and two methylxanthines (caffeine, theobromine) were studied, according to the principles of green chemistry, with the goal of comparing teas with different processing level. After development and validation of separation and extraction methods was applied to 11 extracts obtained by infusions of green and black tea samples in commercial areas of the city of Salvador-BA, showing feasible and efficient. Was employed multivariate data analysis and the Tukey test to correlate the chromatographic profile with the different samples. Principal component and analysis and hierarchical cluster analysis were used for the chromatographic analysis, allowing the visualization of two groups, formed by green and black tea samples.


Assuntos
Camellia sinensis/química , Análise de Alimentos/estatística & dados numéricos , Hidroxibenzoatos/análise , Chá/química , Xantinas/análise , Cafeína/análise , Cromatografia Líquida de Alta Pressão/métodos , Análise por Conglomerados , Análise de Alimentos/métodos , Análise Multivariada , Análise de Componente Principal
4.
J Pharm Biomed Anal ; 162: 117-123, 2019 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-30236819

RESUMO

A novel polymer monolith based on the dicationic crosslinker 3,3'-(hexane-1,6-diyl)bis(1-vinylimidazolium) bromide, the monomer 1-vinylimidazole and a ternary porogen mixture (1-propanol, decan-1-ol and water) was developed and optimized for capillary electrochromatography. This aim was accomplished by adjusting the composition of individual constituents in the polymerization mixture and monitored based on several relevant parameters (e.g. pore structure by scanning electron microscopy, generation of electroosmotic flow, or permeability of material). The ultimately selected composition yielded a monolithic phase which excellently resolved six methylxanthines (including caffeine, theobromine and theophylline) in 15 min. Key requirements concerning the utilized buffer were an acidic pH of 3 and the addition of 50% acetonitrile; additionally, a negative voltage (-25 kV) had to be applied during analyses. The proposed separation mechanism was mixed mode, i.e. the combination of electrostatic repulsion and hydrophobic interaction. Monolith fabrication as well as separation efficiency were found to be highly repeatable, the material was mechanically stable and useable for at least 150 injections. Thus the presented stationary phase is definitely a very promising option for CEC.


Assuntos
Eletrocromatografia Capilar/métodos , Reagentes para Ligações Cruzadas/síntese química , Imidazóis/síntese química , Polivinil/síntese química , Xantinas/análise , Estrutura Molecular , Polimerização , Pressão , Solventes/química , Fatores de Tempo
5.
Food Res Int ; 114: 20-29, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30361017

RESUMO

Cocoa shell (CS) is a co-product of the cocoa industry used mainly as fuel for boilers but with secondary applications as fertilizer and in animal feed. Although it is known that this material is rich in flavanols and alkaloids, to date, a study has not been conducted that has quantitatively identified these compounds in CS. Thus, the aim of this work was to characterize CS in terms of its composition, regarding catechin, epicatechin, procyanidin B2, caffeine and theobromine, and to evaluate the extraction kinetics of the total flavanols using pressurized liquid extraction (PLE) with absolute ethanol. For the determination of the extraction kinetic data, the DMAC method was used, while each compound was quantified using a UPLC-MS/MS analysis. The major compounds found were theobromine and epicatechin (mean values of 9.89 and 3.5 mg/g CS, respectively). PLE proved to be quite effective; the flavanols extraction yield was enhanced by increasing the temperature and extraction time however, high extraction times and temperatures degraded the procyanidins B2. Peleg's model applied to extraction data description provided a reasonable agreement with the experimental results, which allows their application in modeling and optimization of solid-liquid extraction of the total flavanols from cocoa bean shell.


Assuntos
Antioxidantes/isolamento & purificação , Cacau/química , Flavonoides/isolamento & purificação , Extração Líquido-Líquido/métodos , Sementes/química , Xantinas/isolamento & purificação , Antioxidantes/análise , Antioxidantes/química , Cromatografia Líquida de Alta Pressão , Etanol/química , Flavonoides/análise , Flavonoides/química , Resíduos Industriais , Cinética , Espectrometria de Massas em Tandem , Termogravimetria , Xantinas/análise , Xantinas/química
6.
Anal Chim Acta ; 1036: 204-213, 2018 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-30253833

RESUMO

Proanthocyanidins as well as other secondary metabolites present in green cocoa beans were studied thanks to a new method involving the use of on-line comprehensive two-dimensional liquid chromatography coupled to tandem mass spectrometry (LC × LC-MS/MS). In order to enhance the performance of previously developed methodologies, the use of different modulation strategies were explored. Focusing modulation clearly allowed the attainment of higher resolving power and peak capacity compared to non-focusing modulation set-ups. Moreover, the use of active modulation by the addition of a make-up flow efficiently helped to compensate for the solvent strength mismatch produced between dimensions. The optimized method was useful to successfully describe the secondary metabolite composition of green cocoa that was characterized by the presence of 30 main compounds, including 3 xanthines, 2 flavan-3-ols and 24 oligomeric procyanidins with a degree of polymerization up to 12. The obtained results showed that the proanthocyanidins found in the cocoa beans were exclusively B-type procyanidins. The existence of (epi)catechin subunits linked to sugar or galloyl moieties was not observed. The developed method produced a good separation of secondary metabolites allowing an improvement with respect to the available methodologies for the analysis of a complex food sample such as cocoa metabolites in terms of speed of analysis, resolution and peak capacity.


Assuntos
Cacau/química , Flavonoides/análise , Proantocianidinas/análise , Xantinas/análise , Cacau/metabolismo , Cromatografia Líquida de Alta Pressão , Flavonoides/metabolismo , Estrutura Molecular , Proantocianidinas/metabolismo , Metabolismo Secundário , Espectrometria de Massas em Tandem , Xantinas/metabolismo
7.
Electrophoresis ; 39(19): 2446-2453, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30051931

RESUMO

Discovering hit compounds and optimization processes in medicinal chemistry nowadays could be improved by predictive tools, based on the relationship between structure of molecules and lipophilic properties. Lipophilicity of drug candidate can affect both the pharmacokinetic and pharmacodynamics properties, in particular, the ability of a molecule to cross the cell membrane. Among the new methods for determination of the lipophilicity of compounds, micellar electrokinetic chromatography (MEKC) is considered to be an appropriate one for bioactive molecules, as it closely mimics the physiological conditions. In this paper MEKC was used for the estimation of the lipophilicity of 24 derivatives of 8-alkoxy-7H-purine-2,6-dione, designed and synthesized as potential antidepressant/anxiolytic and antipsychotic agents. The results of experimental method were compared with calculated in silico parameters (AlogPs and milogP by Virtual Computational Laboratory website, log PPallas by Pallas 3.1, Mlog P by Marvin, log PChemS by ChemSketch, log PChemDraw by ChemBioUltra) using Principal Component Analysis (PCA) method. Finally, using estimated log P values for selected compounds ligand - lipophilicity efficiency (LLE), per cent efficiency index (PEI), and binding efficiency index (BEI) parameters were calculated. Applied MEKC procedure could be used for selection of potential lead structure in a group of 7H-purine-2,6-dione derivatives.


Assuntos
Cromatografia Capilar Eletrocinética Micelar/métodos , Psicotrópicos/química , Xantinas/química , Descoberta de Drogas , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Modelos Lineares , Psicotrópicos/análise , Psicotrópicos/farmacocinética , Xantinas/análise , Xantinas/farmacocinética
8.
Food Chem ; 246: 48-57, 2018 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-29291876

RESUMO

Oil extraction from green coffee seeds generates residual mass that is discarded by agribusiness and has not been previously studied. Bioactive secondary metabolites in coffee include antioxidant phenolic compounds, such as chlorogenic acids. Coffee seeds also contain caffeine, a pharmaceutically important methylxanthine. Here, we report the chemical profile, antioxidant activity, and cytotoxicity of hydroethanolic extracts of green Coffea arabica L. seed residue. The extracts of the green seeds and the residue have similar chemical profiles, containing the phenolic compounds chlorogenic acid and caffeine. Five monoacyl and three diacyl esters of trans-cinnamic acids and quinic acid were identified by ultra-performance liquid chromatography/electrospray ionization-quadruple time of flight mass spectrometry. The residue extract showed antioxidant potential in DPPH, ABTS, and pyranine assays and low cytotoxicity. Thus, coffee oil residue has great potential for use as a raw material in dietary supplements, cosmetic and pharmaceutical products, or as a source of bioactive compounds.


Assuntos
Antioxidantes/farmacologia , Coffea/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Sementes/química , Antioxidantes/química , Sulfonatos de Arila/química , Cafeína/análise , Linhagem Celular , Ácido Clorogênico/análise , Suplementos Nutricionais , Manipulação de Alimentos , Humanos , Fenóis/análise , Ácido Quínico/análise , Resíduos/análise , Xantinas/análise
9.
J Inorg Biochem ; 181: 104-110, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29150325

RESUMO

Ilex paraguariensis, yerba mate is a native plant from the southern region of Brazil. Studies showed that yerba mate has an antioxidant potential, which could help to reduce the risk of developing neurodegenerative diseases, as Alzheimer's Disease (AD). It's known that I. paraguariensis grows in acid soils with aluminium (Al), which is bioavailable in these soils. Al has a neurotoxic potential related with the progression of neurological disorders. This study aim was to evaluate the potential of I. paraguariensis in the etiology of AD using strains of Caenorhabditis elegans and the concentration of Al and antioxidants in the yerba mate extract. The results of the I. paraguariensis infusions made at 65°C and at 75° C show that there was no significant difference between both temperatures when preparing the tea infusion in relation to the presence of Al, methylxanthines, phenolic compounds and flavonoids. Additionally, in the case of Al, there was no difference between the extracts prepared at both temperatures. The behavioral parameters of C. elegans were altered after a long-term exposure to both factors: I. paraguariensis extract and Al. Through the antioxidant levels results along with the Al content on the Acetylcholinesterase (AChE) activity it is possible to observe that the acute and chronic exposure to Al and I. paraguariensis leaves extract are very similar to wild-type worms. Moreover, we can observe that the results in both the transgenic strains long-term exposed to I. paraguariensis leaves extract and to the Al concentrations presented an increase in the AChE activity.


Assuntos
Alumínio/toxicidade , Doença de Alzheimer/etiologia , Modelos Animais de Doenças , Contaminação de Alimentos , Ilex paraguariensis/química , Poluentes do Solo/toxicidade , Chás de Ervas/efeitos adversos , Acetilcolinesterase/química , Acetilcolinesterase/metabolismo , Alumínio/análise , Doença de Alzheimer/prevenção & controle , Animais , Animais Geneticamente Modificados , Antioxidantes/análise , Antioxidantes/uso terapêutico , Comportamento Animal/efeitos dos fármacos , Brasil , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/agonistas , Proteínas de Caenorhabditis elegans/metabolismo , Flavonoides/análise , Flavonoides/uso terapêutico , Ilex paraguariensis/crescimento & desenvolvimento , Síndromes Neurotóxicas/fisiopatologia , Fenóis/análise , Fenóis/uso terapêutico , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Poluentes do Solo/análise , Chás de Ervas/análise , Testes de Toxicidade Aguda , Testes de Toxicidade Crônica , Xantinas/análise , Xantinas/química , Xantinas/uso terapêutico
10.
J Agric Food Chem ; 65(46): 10093-10100, 2017 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-29056047

RESUMO

The main objective of this study was to investigate the daily intake of chlorogenic acids (CGAs) and methylxanthines by consumers of maté traditional beverages (MTBs), terere and chimarrão (Ilex paraguariensis A.St.-Hill). In the studied population (450 citizens from Toledo, PR, Brazil), 63% consume the chimarrão and 37% terere, with weighted mean daily intakes estimated at 648-2160 and 244-746 mL, respectively. For every 100 mL of beverage consumed, the average amount of total phenol compounds extracted was 673.6 mg for chimarrão and 1184.9 mg for terere. Regarding CGAs composition, caffeoylquinic acids (CQAs) constitute about 38.4% for chimarrão and 55.3% for terere, and dicaffeoylquinic acids (diCQAs) represent 61.6 and 44.7% of the extracted compounds, respectively. The daily intake of phenolic compounds by MTB consumers was estimated for chimarrão (512.5-1708.5 mg/day) and terere (583.0-1779.7 mg/day). These results allow us to conclude that MTBs are important dietary sources of CGAs, mainly CQAs and di-CQAs.


Assuntos
Bebidas/análise , Ácido Clorogênico/metabolismo , Ilex paraguariensis/metabolismo , Extratos Vegetais/metabolismo , Adolescente , Adulto , Brasil , Ácido Clorogênico/análise , Feminino , Humanos , Ilex paraguariensis/química , Masculino , Extratos Vegetais/análise , Xantinas/análise , Xantinas/metabolismo , Adulto Jovem
11.
Rocz Panstw Zakl Hig ; 68(3): 237-245, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28895389

RESUMO

Background: The processing of tea leaves determines the contents of bioactive ingredients, hence it should be expected that each variety of tea, black, red or green, will represent a different package of compounds of physiological importance. Taste and aroma, as well as price and brand are the main factors impacting consumers' preferences with regard to tea of their choice; on the other hand consumers less frequently pay attention to the chemical composition and nutritional value of tea. Objective: The purpose of the study was assessment of the nutritional value of black, green and white high-quality tea leaf from Chinese plantations based on the chemical composition of the dried leaves as well as minerals and caffeine content in tea infusions. Material and methods: The research material included 18 high-quality loose-leaf teas produced at Chinese plantations, imported to Poland, and purchased in an online store. The analyses included examination of the dried tea leaves for their chemical composition (contents of water, protein, volatile substances and ash) and assessment of selected minerals and caffeine contents in the tea infusions. Results: High-quality Chinese green teas were found with the most valuable composition of minerals, i.e. the highest contents of Zn, Mn, Mg, K, Ca and Al and the highest contents of protein in comparison to the other products. Chinese black teas had the highest contents of total ash and caffeine and white teas were characterized with high content of volatile substances, similar to the black teas, and the highest content of water and the lowest content of total ash. Conclusions: The three types of tea brews examined in the present study, in particular green tea beverages, significantly enhance the organism's mineral balance by providing valuable elements


Assuntos
Antioxidantes/análise , Camellia sinensis/química , Flavonoides/análise , Minerais/análise , Fenóis/análise , Chá/química , Fibras na Dieta/análise , Humanos , Valor Nutritivo , Extratos Vegetais/química , Folhas de Planta/química , Xantinas/análise
12.
PLoS One ; 12(2): e0171872, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28231253

RESUMO

Phytoplankton, with an estimated 30 000 to 1 000 000 species clustered in 12 phyla, presents a high taxonomic and ecophysiological diversity, reflected by the complex distribution of pigments among the different algal classes. High performance liquid chromatography is the gold standard method for qualitative and quantitative analysis of phytoplankton pigments in seawater and culture samples, but only a few pigments can be used as robust chemotaxonomic markers. A major challenge is thus to identify new ones, characteristic of a strain, species, class or taxon that cannot be currently identified on the basis of its pigment signature. Using an optimized extraction process coupled to a HPLC de-replication strategy, we examined the pigment composition of 37 microalgae strains, representative of the broad taxonomic diversity of marine and freshwater species (excluding cyanobacteria). For each species, the major pigments already described were unambiguously identified. We also observed the presence of several minor unidentified pigments in each chromatogram. The global analysis of pigment compositions revealed a total of 124 pigments, including 98 pigments or derivatives unidentified using the standards. Absorption spectra indicated that 35 corresponded to chlorophyll/porphyrin derivatives, 57 to carotenoids and six to derivatives having both spectral signatures. Sixty-one of these unidentified or new carotenoids and porphyrin derivatives were characteristic of particular strains or species, indicating their possible use as highly specific chemotaxonomic markers capable of identifying one strain out of the 37 selected. We developed a graphical analysis using Gephi software to give a clear representation of pigment communities among the various phytoplankton strains, and to reveal strain-characteristic and shared pigments. This made it possible to reconstruct the taxonomic evolution of microalgae classes, on the basis of the conservation, loss, and/or appearance of pigments.


Assuntos
Carotenoides/análise , Microalgas/química , Pigmentos Biológicos/análise , Porfirinas/análise , Carotenoides/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Água Doce/análise , Microalgas/classificação , Pigmentos Biológicos/isolamento & purificação , Porfirinas/isolamento & purificação , Água do Mar/análise , Xantinas/análise , Xantinas/isolamento & purificação
13.
Chem Biodivers ; 14(3)2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27701846

RESUMO

The aim of this study was to evaluate the phytochemical and genetic diversity, relationships and identification of mate (Ilex paraguariensis A.St.-Hil.) elite genetic resources belonging to the Brazilian germplasm collection and mate breeding program. Mate has been studied due to the presence of phytochemical compounds, especially methylxanthines and phenolic compounds. The samples were collected from the leaves of 76 mate elite genetic resources (16 progenies × 5 localities). Total DNA was extracted from mate leaves and 20 random primers were used for DNA amplification. Methylxanthines (caffeine and theobromine) and phenolic compounds (chlorogenic, neochlorogenic, and criptochlorogenic acids) were quantified by HPLC. The genetic divergence estimated was higher within (92%) than among (8%) the different populations. Analysis of genetic distance between origins provided the formation of two groups by UPGMA cluster analysis, with higher polymorphism (94.9%). The average content of caffeine ranged from 0.01 to 1.38% and theobromine of 0.10 - 0.85% (w/w). The caffeoylquinic acids concentrations (1.43 - 5.38%) showed a gradient 3-CQA > 5-CQA > 4-CQA. The coefficient of genetic variation (CVg) was of low magnitude for all mono-caffeoylquinics acids. Significant correlations (positive and negative) were observed between the phytochemical compounds. Genetic diversity analysis performed by RAPD markers showed a greater intra-populational diversity; genetic resources with low caffeine and higher theobromine content were identified and can be used in breeding programs; the correlation between methylxanthines and phenolic compounds can be used as a good predictor in future studies.


Assuntos
Variação Genética , Ilex paraguariensis/genética , Compostos Fitoquímicos/química , Brasil , Cromatografia Líquida de Alta Pressão , Análise por Conglomerados , DNA de Plantas/genética , DNA de Plantas/metabolismo , Ilex paraguariensis/química , Ilex paraguariensis/metabolismo , Compostos Fitoquímicos/análise , Extratos Vegetais/química , Folhas de Planta/química , Folhas de Planta/genética , Folhas de Planta/metabolismo , Reação em Cadeia da Polimerase , Ácido Quínico/análogos & derivados , Ácido Quínico/análise , Xantinas/análise
14.
Food Chem ; 220: 517-526, 2017 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-27855934

RESUMO

This is the first study to use chemometric methods to differentiate among 21 cultivars of Camellia sinensis from China and between leaves harvested at different times of the year using 30 compounds implicated in the taste and quality of tea. Unique patterns of catechin derivatives were observed among cultivars and across harvest seasons. C. sinensis var. pubilimba (You 510) differed from the cultivars of C. sinensis var. sinensis, with higher levels of theobromine, (+)-catechin, gallocatechin, gallocatechin gallate and theasinensin B, and lower levels of (-)-epicatechin, (-)-epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG), respectively. Three cultivars of C. sinensis var. sinensis, Fuyun 7, Qiancha 7 and Zijuan contained significantly more caffeoylquinic acids than others cultivars. A Linear Discriminant Analysis model based on the abundance of 12 compounds was able to discriminate amongst all 21 tea cultivars. Harvest time impacted the abundance of EGC, theanine and afzelechin gallate.


Assuntos
Camellia sinensis/metabolismo , Glutamatos/análise , Fenóis/análise , Extratos Vegetais/análise , Estações do Ano , Xantinas/análise , Camellia sinensis/crescimento & desenvolvimento , Catequina/análogos & derivados , Catequina/análise , China , Flavonoides/análise , Folhas de Planta/química
15.
Food Chem ; 211: 365-73, 2016 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-27283644

RESUMO

As the most abundant carotenoid in nature, fucoxanthin is susceptible to oxidation under some conditions, forming cleavage products that possibly exhibit both positive and negative health effects in vitro and in vivo. Thus, to produce relatively high amounts of cleavage products, chemical oxidation of fucoxanthin was performed. Kinetic models for oxidation were probed and reaction products were identified. The results indicated that both potassium permanganate (KMnO4) and hypochlorous acid/hypochlorite (HClO/ClO(-)) treatment fitted a first-order kinetic model, while oxidation promoted by hydroxyl radical (OH) followed second-order kinetics. With the help of liquid chromatography-tandem mass spectrometry, a total of 14 apo-fucoxanthins were detected as predominant cleavage products, with structural and geometric isomers identified among them. Three apo-fucoxanthinones and eleven apo-fucoxanthinals, of which five were cis-apo-fucoxanthinals, were detected upon oxidation by the three oxidizing agents (KMnO4, HClO/ClO(-), and OH).


Assuntos
Espectrometria de Massas em Tandem/métodos , Undaria , Xantinas/análise , Xantinas/química , Xantofilas/análise , Xantofilas/química , Pressão Atmosférica , Carotenoides/análise , Carotenoides/química , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida/métodos , Undaria/química
16.
Food Chem ; 208: 177-84, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27132838

RESUMO

Assessment of the flavanol composition of 41 commercial chocolates was by HPLC-DAD. Among individual flavonols ranged from 0.095 to 3.264mgg(-1), epicatechin was the predominant flavanol accounting for 32.9%. Contrary to catechin, epicatechin was a reliable predictive value of the polyphenol content. Conversely the percentage of theobromine used as a proxy measure for nonfat cocoa solids (NFCS) was not a good predictor of epicatechin or flavanol content. In a further chiral analysis, the naturally occurring forms of cocoa flavanols, (-)-epicatechin and (+)-catechin, was determined joint the occurrence of (+)-epicatechin and (-)-catechin due to the epimerization reactions produced in chocolate manufacture. (-)-Epicatechin, the most bioactive compound and predominant form accounted of 93%. However, no positive correlation was found with% cocoa solids, the most significant quality parameter.


Assuntos
Cafeína/análise , Chocolate/análise , Flavonoides/análise , Teobromina/análise , Biflavonoides/análise , Cacau/química , Catequina/análise , Cromatografia Líquida de Alta Pressão , Análise de Alimentos , Polifenóis/análise , Proantocianidinas/análise , Estereoisomerismo , Xantinas/análise
17.
Int J Food Sci Nutr ; 67(4): 422-30, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27055484

RESUMO

Analysis of the complex composition of cocoa beans provides fundamental information for evaluating the quality and nutritional aspects of cocoa-based food products, nutraceuticals and supplements. Cameroon, the world's fourth largest producer of cocoa, has been defined as "Africa in miniature" because of the variety it habitats. In order to evaluate the nutritional characteristics of cocoa beans from five different regions of Cameroon, we studied their polyphenolic content, volatile compounds and fatty acids composition. The High Performance Thin Layer Chromatography (HPTLC) analysis showed that the Mbalmayo sample had the highest content of theobromine (11.6 mg/g) and caffeic acid (2.1 mg/g), while the Sanchou sample had the highest level of (-)-epicatechin (142.9 mg/g). Concerning fatty acids, the lowest level of stearic acid was found in the Mbalmayo sample while the Bertoua sample showed the highest content of oleic acid. Thus, we confirmed that geographical origin influences the quality and nutritional characteristics of cocoa from these regions of Cameroon.


Assuntos
Antioxidantes/análise , Cacau/química , Cinamatos/análise , Flavonoides/análise , Sementes/química , Compostos Orgânicos Voláteis/análise , Xantinas/análise , Antioxidantes/metabolismo , Cacau/crescimento & desenvolvimento , Cacau/metabolismo , Ácidos Cafeicos/análise , Ácidos Cafeicos/metabolismo , Camarões , Catequina/análise , Catequina/biossíntese , Chocolate/análise , Cinamatos/metabolismo , Gorduras na Dieta/análise , Suplementos Nutricionais/análise , Ácidos Graxos/análise , Ácidos Graxos/biossíntese , Flavonoides/biossíntese , Qualidade dos Alimentos , Humanos , Valor Nutritivo , Proteínas de Vegetais Comestíveis/análise , Proteínas de Vegetais Comestíveis/biossíntese , Análise de Componente Principal , Sementes/crescimento & desenvolvimento , Sementes/metabolismo , Teobromina/análise , Teobromina/biossíntese , Compostos Orgânicos Voláteis/metabolismo , Xantinas/metabolismo
18.
Anal Biochem ; 496: 14-24, 2016 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-26717896

RESUMO

The current study describes the electrografting of 2,4-diamino-1,3,5-triazine (AT) groups at the surfaces of glassy carbon electrode (GCE) and indium tin oxide (ITO) through in situ diazotization of melamine. The presence of AT groups at the surface of the electrode was confirmed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Furthermore, graphene oxide (GO) was self-assembled on AT grafted GCE. The oxygen functional groups present on the surface of GO were electrochemically reduced to form an electrochemically reduced graphene oxide (ERGO) on AT grafted electrode surface. Raman spectra show the characteristic D and G bands at 1340 and 1605 cm(-1), respectively, which confirms the successful attachment of GO on AT grafted surface, and the ratio of D and G bands was increased after the electrochemical reduction of GO. EIS shows that the electron transfer reaction of [Fe(CN)6](3-/4-) was higher at the ERGO modified electrode than at bare, AT grafted, and GO modified GCEs. The electrocatalytic activity of ERGO was investigated toward the oxidation of methylxanthines. It shows excellent electrocatalytic activity toward these methylxanthines by not only shifting their oxidation potentials toward less positive potentials but also enhancing their oxidation currents.


Assuntos
Técnicas Eletroquímicas/métodos , Grafite/química , Triazinas/química , Xantinas/análise , Catálise , Microscopia Eletrônica de Varredura , Óxidos/química , Espectroscopia Fotoeletrônica , Análise Espectral Raman
19.
Water Res ; 74: 23-33, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25706221

RESUMO

The use of caffeine, nicotine and some major metabolites was investigated by wastewater analysis in 13 sewage treatment plants (STPs) across Italy, and their suitability was tested as qualitative and quantitative biomarkers for assessing population size and dynamics. A specific analytical method based on mass spectrometry was developed and validated in raw urban wastewater, and included two caffeine metabolites, 1-methylxanthine and 7-methylxanthine, never reported in wastewater before. All these compounds were found widely at the µg/L level. Mass loads, calculated by multiplying concentrations by the wastewater daily flow rate and normalized to the population served by each plant, were used to compare the profiles from different cities. Some regional differences were observed in the mass loads, especially for nicotine metabolites, which were significantly higher in the south than in the center and north of Italy, reflecting smoking prevalences from population surveys. There were no significant weekly trends, although the mean mass loads of caffeine and its metabolites were slightly lower during the weekend. Most caffeine and nicotine metabolites fulfilled the requirements for an ideal biomarker for the assessment of population size, i.e. being easily detectable in wastewater, stable in sewage and during sampling, and reflecting human metabolism. Nicotine metabolites were tested as quantitative biomarkers to estimate population size and the results agreed well with census data. Caffeine and its metabolites were confirmed as good qualitative biomarkers, but additional information is needed on the caffeine metabolism in relation to the multiple sources of its main metabolites. This exploratory study opens the way to the routine use of nicotine metabolites for estimating population size and dynamics.


Assuntos
Cafeína/análise , Nicotina/análise , Densidade Demográfica , Fumar/epidemiologia , Águas Residuárias/análise , Biomarcadores/análise , Cromatografia Líquida , Cidades , Humanos , Itália , Espectrometria de Massas em Tandem , Xantinas/análise
20.
Food Chem ; 174: 214-8, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25529672

RESUMO

Cocoa manufacturers are producing novel products increasing polyphenols, methylxanthines or dietary fibre to improve purported health benefits. We attempt to explain the contribution of cocoa bioactive compounds to cardiovascular effects observed in previous studies, placing particular emphasis on methylxanthines. We focused on a soluble cocoa product rich in dietary fibre (DFCP) and a product rich in polyphenols (PPCP). Effects of regularly consuming DFCP (providing daily 10.17 g, 43.8 mg and 168.6 mg of total-dietary-fibre, flavanols and methylxanthines, respectively) as well as PPCP (providing daily 3.74 g, 45.3 mg and 109.8 mg of total-dietary-fibre, flavanols and methylxanthines, respectively) on cardiovascular health were assessed in two controlled, cross-over studies in free-living normocholesterolemic and moderately hypercholesterolemic subjects. Both products increased HDL-cholesterol concentrations, whereas only DFCP decreased glucose and IL-1ß levels in all subjects. Flavanols appeared to be responsible for the increase in HDL-cholesterol, whereas insoluble-dietary-fibre and theobromine in DFCP were associated with the hypoglycemic and anti-inflammatory effects observed.


Assuntos
Cacau/química , Adolescente , Adulto , HDL-Colesterol/sangue , Estudos Cross-Over , Fibras na Dieta/análise , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polifenóis/análise , Xantinas/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA