Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 8 de 8
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Sensors (Basel) ; 17(8)2017 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-28788082

RESUMO

This work deals with a portable device system applied to detect and classify different metallic ions as proposed and developed, aiming its application for hydrological monitoring systems such as rivers, lakes and groundwater. Considering the system features, a portable colorimetric system was developed by using a multispectral optoelectronic sensor. All the technology of quantification and classification of metallic ions using optoelectronic multispectral sensors was fully integrated in the embedded hardware FPGA ( Field Programmable Gate Array) technology and software based on virtual instrumentation (NI LabView®). The system draws on an indicative colorimeter by using the chromogen reagent of 1-(2-pyridylazo)-2-naphthol (PAN). The results obtained with the signal processing and pattern analysis using the method of the linear discriminant analysis, allows excellent results during detection and classification of Pb(II), Cd(II), Zn(II), Cu(II), Fe(III) and Ni(II) ions, with almost the same level of performance as for those obtained from the Ultravioled and visible (UV-VIS) spectrophotometers of high spectral resolution.

2.
An Acad Bras Cienc ; 85(4): 1235-47, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24141413

RESUMO

Coconut water contains several uncharacterized substances and is widely used in the human consumption. In this paper we detected and quantified ascorbic acid and caffeic acid and total phenolics in several varieties of coconut using HPLS/MS/MS (25.8 ± 0.6 µg/mL and 1.078 ± 0.013 µg/mL and 99.7 µg/mL, respectively, in the green dwarf coconut water, or 10 mg and 539 µg and 39.8 mg for units of coconut consumed, 500 ± 50 mL). The antioxidant potential of four coconut varieties (green dwarf, yellow dwarf, red dwarf and yellow Malaysian) was compared with two industrialized coconut waters and the lyophilized water of the green dwarf variety. All varieties were effective in scavenging the DPPH radical (IC50=73 µL) and oxide nitric (0.1 mL with an IP of 29.9%) as well as in inhibiting the in vitro production of thiobarbituric acid reactive substances (1 mL with an IP of 34.4%), highlighting the antioxidant properties of the green dwarf which it is the most common used. In cell culture, the green dwarf water was efficient in protecting against oxidative damages induced by hydrogen peroxide.


Assuntos
Antioxidantes/análise , Ácido Ascórbico/análise , Ácidos Cafeicos/análise , Cocos/química , Fenóis/análise , Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Ácidos Cafeicos/farmacologia , Células Cultivadas , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Humanos , Peroxidação de Lipídeos/efeitos dos fármacos , Pulmão/citologia , Fenóis/farmacologia , Espectrometria de Massas em Tandem
3.
J Am Chem Soc ; 133(24): 9140-3, 2011 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-21604744

RESUMO

Acetaldehyde is an environmentally widespread genotoxic aldehyde present in tobacco smoke, vehicle exhaust and several food products. Endogenously, acetaldehyde is produced by the metabolic oxidation of ethanol by hepatic NAD-dependent alcohol dehydrogenase and during threonine catabolism. The formation of DNA adducts has been regarded as a critical factor in the mechanisms of acetaldehyde mutagenicity and carcinogenesis. Acetaldehyde reacts with 2'-deoxyguanosine in DNA to form primarily N(2)-ethylidene-2'-deoxyguanosine. The subsequent reaction of N(2)-ethylidenedGuo with another molecule of acetaldehyde gives rise to 1,N(2)-propano-2'-deoxyguanosine (1,N(2)-propanodGuo), an adduct also found as a product of the crotonaldehyde reaction with dGuo. However, adducts resulting from the reaction of more than one molecule of acetaldehyde in vivo are still controversial. In this study, the unequivocal formation of 1,N(2)-propanodGuo by acetaldehyde was assessed in human cells via treatment with [(13)C(2)]-acetaldehyde. Detection of labeled 1,N(2)-propanodGuo was performed by HPLC/MS/MS. Upon acetaldehyde exposure (703 µM), increased levels of both 1,N(2)-etheno-2'-deoxyguanosine (1,N(2)-εdGuo), which is produced from α,ß-unsaturated aldehydes formed during the lipid peroxidation process, and 1,N(2)-propanodGuo were observed. The unequivocal formation of 1,N(2)-propanodGuo in cells exposed to this aldehyde can be used to elucidate the mechanisms associated with acetaldehyde exposure and cancer risk.


Assuntos
Acetaldeído/farmacologia , Adutos de DNA/metabolismo , Desoxiguanosina/análogos & derivados , Linhagem Celular , Desoxiguanosina/metabolismo , Humanos , Fenil-Hidrazinas/química , Volatilização
4.
J Inorg Biochem ; 101(5): 866-75, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17383005

RESUMO

S(IV) (SO(2),HSO(3)(-)andSO(3)(2-)) autoxidation catalyzed by Cu(II)/tetraglycine complexes in the presence of DNA or 2'-deoxyguanosine (dGuo) resulted in DNA strand breaks and formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo), respectively. Ni(II), Co(II) or Mn(II) (1.0x10(-4)M) complexes had much smaller effects. Cu(II)/tetraglycine (1.0x10(-4)M) in the presence of Ni(II) or Mn(II) (10(-7)-10(-6)M) and S(IV) showed remarkable synergistic effect with these metal ions producing a higher yield of 8-oxodGuo. Oxidation of dGuo and DNA damage were attributed to oxysulfur radicals formed as intermediates in S(IV) autoxidation catalyzed by transition metal ions. SO*(3)(-) and HO* radicals were detected by EPR-spin trapping experiments with DMPO (5,5-dimethyl-1-pyrroline-N-oxide).


Assuntos
Cobre/química , Dano ao DNA , Desoxiguanosina/química , Oligopeptídeos/química , Compostos Organometálicos/química , Dióxido de Enxofre/química , Espectroscopia de Ressonância de Spin Eletrônica , Eletroforese em Gel de Ágar , Oxirredução , Espectrofotometria
5.
Chem Res Toxicol ; 19(7): 927-36, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16841961

RESUMO

A recent study showed that tetrahydrofuran (THF), a widely used solvent, is carcinogenic in experimental animals. Despite its carcinogenic activity, there is a paucity of information regarding cellular toxicity, biomolecular damage, and genotoxicity induced by THF. We describe here the structural characterization of adducts produced by the reaction of oxidized THF with 2'-deoxyguanosine (dGuo-THF 1 and dGuo-THF 2), 2'-deoxyadenosine (dAdo-THF), and 2'-deoxycytidine (dCyd-THF). Adducts were isolated from in vitro reactions by reverse-phase HPLC and fully characterized on the basis of spectroscopic measurements. The stable derivatives obtained by the reduction of adducts with NaBH(4) (the case of dGuo-THF 1, dCyd-THF, and dAdo-THF) and the stable adduct dGuo-THF 2 were used as standards for optimization of chromatographic separations for adduct detection in DNA through HPLC/ESI/MS-MS. Using this methodology, we successfully detected the four adducts in calf thymus DNA reacted with oxidized THF. The present study also provides evidence that rat liver microsomal monooxigenases oxidize THF to the reactive electrophilic compounds that are able to damage the DNA molecule, as indicated by a significant increase in adduct dGuo-THF 1 level when NADPH was added to the THF/microsomes/dGuo incubation mixtures. Our data point to DNA-THF adducts as possible contributing factors to the toxicological effects of THF exposure.


Assuntos
Adutos de DNA/química , Desoxiadenosinas/química , Desoxicitidina/química , Desoxiguanosina/química , Furanos/química , Animais , Carcinógenos/química , Carcinógenos/toxicidade , Cromatografia Líquida de Alta Pressão , Adutos de DNA/efeitos dos fármacos , Desoxicitidina/análogos & derivados , Desoxiguanosina/análogos & derivados , Furanos/farmacologia , Furanos/toxicidade , Microssomos Hepáticos/enzimologia , Estrutura Molecular , Oxirredução , Ratos , Espectrometria de Massas por Ionização por Electrospray
6.
Chem Res Toxicol ; 18(2): 290-9, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15720135

RESUMO

The reaction of 2'-deoxyguanosine with the alpha,beta-unsaturated aldehydes trans-2-octenal, trans-2-nonenal, trans-2-decenal, trans,trans-2,4-nonadienal, and trans,trans-2,4-decadienal in THF gives rise to three novel adducts: 3-(2'-deoxy-beta-D-erythro-pentafuranosyl)-7-[3-hydroxy-1-(3-(2'-deoxy-beta-D-erythro-pentafuranosyl)-3,5-dihydro-imidazo[1,2-a]purin-9-one-7-yl)-propyl]-3,5-dihydro-imidazo[1,2-a]purin-9-one (A7) and 3-(2'-deoxy-beta-D-erythro-pentafuranosyl)-7-(tetrahydrofuran-2-yl)-3,5-dihydro-imidazo[1,2-a]purin-9-one (A8 and A9), which are not observed in the absence of THF. These adducts were isolated from in vitro reactions by reversed-phase HPLC and fully characterized on the basis of spectroscopic measurements. Adduct A7 consists of two 1,N2-etheno-2'-deoxyguanosine (1,N2-epsilon dGuo) residues linked to a hydroxy-carbon side chain; adducts A8 and A9 are interconvertible 1,N2-epsilon dGuo derivatives bearing a THF moiety. The proposed reaction mechanism involves the electrophilic attack on 1,N2-epsilon dGuo by the carbonyl of 4-hydroxy-butanal, generated via ring opening of alpha-hydroxy-THF (THF-OH), yielding adducts A8 and A9. A further combination of these adducts with another 1,N2-epsilon dGuo produces the double adduct A7. These findings demonstrate that reactions of unsaturated aldehydes in the presence of THF produce novel condensation 1,N2-epsilon dGuo-THF adducts. Further studies would indicate the relevance of these adducts in THF toxicity.


Assuntos
Desoxiguanosina/análogos & derivados , Desoxiguanosina/química , Furanos/química , Desoxiguanosina/síntese química , Concentração de Íons de Hidrogênio , Estrutura Molecular
7.
Chem Res Toxicol ; 17(5): 641-9, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15144221

RESUMO

Background levels of exocyclic DNA adducts have been detected in rodent and human tissues. Several studies have focused on bifunctional electrophiles generated from lipid peroxidation as one of the endogenous sources of these lesions. We have previously shown that the reaction of 2'-deoxyguanosine (dGuo) with trans,trans-2,4-decadienal (DDE), a highly cytotoxic aldehyde generated as a product of lipid peroxidation in cell membranes, results in the formation of a number of different base derivatives. Three of these derivatives have been fully characterized as 1,N(2)-etheno-2'-deoxyguanosine adducts. In the present work, four additional adducts, designated A3-A6, were isolated from in vitro reactions by reversed-phase HPLC and fully characterized on the basis of spectroscopic measurements. Adducts A3-A6 are four diastereoisomeric 1,N(2)-hydroxyethano-2'-deoxyguanosine derivatives possessing a carbon side chain with a double bond and a hydroxyl group. The systematic name of these adducts is 6-hydroxy-3-(2'-deoxy-beta-D-erythro-pentafuranosyl)-7-((E)-1-hydroxy-oct-2-enyl)-3,5,6,7-tetrahydro-imidazo[1,2-a]purin-9-one. The proposed reaction mechanism yielding adducts A3-A6 involves DDE epoxidation at C2, followed by nucleophilic addition of the exocyclic amino group of dGuo to the C1 of the aldehyde and cyclization, via nucleophilic attack, on the C2 epoxy group by N-1. The formation of adducts A1-A6 has been investigated in acidic, neutral, and basic pH in the presence of H(2)O(2) or tert-butyl hydroperoxide. Neutral conditions, in the presence of H(2)O(2), have favored the formation of adducts A1 and A2, with minor amounts of A3-A6, which were prevalent under basic conditions. These data indicate that DDE can modify DNA bases through different oxidative pathways involving its two double bonds. It is important to structurally characterize DNA base derivatives induced by alpha,beta-unsaturated aldehydes so that the genotoxic risks associated with the lipid peroxidation process can be assessed.


Assuntos
Aldeídos/química , Adutos de DNA/química , Desoxiadenosinas/química , Membrana Celular/metabolismo , Cromatografia Líquida de Alta Pressão , Ciclização , Dano ao DNA , Desoxiadenosinas/metabolismo , Compostos de Epóxi/química , Humanos , Peróxido de Hidrogênio/química , Concentração de Íons de Hidrogênio , Peroxidação de Lipídeos/fisiologia , Espectroscopia de Ressonância Magnética , Oxirredução , Estereoisomerismo
8.
FEBS Lett ; 560(1-3): 125-30, 2004 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-14988010

RESUMO

Epidemiological studies testing the effect of beta-carotene in humans have found a relative risk for lung cancer in smokers supplemented with beta-carotene. We investigated the reactions of retinal and beta-apo-8'-carotenal, two beta-carotene oxidation products, with 2'-deoxyguanosine to evaluate their DNA damaging potential. A known mutagenic adduct, 1,N(2)-etheno-2'-deoxyguanosine, was isolated and characterized on the basis of its spectroscopic features. After treatment of calf thymus DNA with beta-carotene or beta-carotene oxidation products, significantly increased levels of 1,N(2)-etheno-2'-deoxyguanosine and 8-oxo-7,8-dihydro-2'-deoxyguanosine were quantified in DNA. These lesions are believed to be important in the development of human cancers. The results reported here may contribute toward an understanding of the biological effects of beta-carotene oxidation products.


Assuntos
Antioxidantes/metabolismo , Adutos de DNA/análise , Dano ao DNA , Desoxiguanosina/análogos & derivados , Desoxiguanosina/análise , beta Caroteno/metabolismo , Animais , Carotenoides/metabolismo , Bovinos , Cromatografia Líquida de Alta Pressão , DNA/análise , Desoxiguanosina/isolamento & purificação , Espectrometria de Massas , Estrutura Molecular , Oxirredução , Retinaldeído/metabolismo , Espectrometria de Massas por Ionização por Electrospray
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...