Avaliação do potencial fotoprotetor de extratos de musgos e investigação de seus riscos toxicológicos

A radiação ultravioleta (UV) induz diversos efeitos nocivos nos organismos e a quantidade desta radiação que atinge a biosfera é afetada pela concentração de ozônio, latitude, altitude, clima e reflexão especular. As respostas de briófitas em relação aos efeitos da radiação UV e a presença de compostos que absorvem esta radiação têm sido estudadas. Sanionia uncinata, Holomitriopsis laevifolia e Leucobryum laevifolium são espécies de musgos encontrados em locais expostos a alta incidência de radiação UV e com habitats distintos. Considerando que as respostas de musgos contra os efeitos da radiação UV e seus mecanismos de proteção ainda são pouco caracterizados, o objetivo deste estudo foi investigar o potencial fotoprotetor e possíveis riscos toxicológicos associados aos extratos dos musgos S. uncinata, proveniente da Antártica e H. laevifolia e L. laevifolium, proveniente do Amazonas. Seus extratos metanólico (EM), aquoso (EA), hidroalcoólico (EH) e etanólico (EE) foram estudados com a caracterização química por absorção ao UV e visível e pela cromatografia líquida de alta eficiência; quantificação do índice total de compostos fenólicos; determinação da capacidade captadora do radical 2,2-difenil-1-picril-hidrazila a fim de avaliar as atividades antioxidantes; avaliação do potencial de fotoproteção cutânea pela determinação do fator de proteção solar; avaliações do potencial mutagênico e citototóxico, através do ensaio de Salmonella/microssoma, utilizando as cepas TA97, TA98, TA100, TA102 e TA104; do potencial fotomutagênico através do ensaio de fotomutagenicidade, usando as cepas TA102 e TA104; e investigação dos efeitos genotóxicos e fotogenotóxicos, pelo ensaio de micronúcleo e fotomicronúcleo, respectivamente, usando diferentes linhagens celulares estabelecidas. Foram encontradas atividades fotoprotetoras e antioxidantes e observou-se que os extratos se apresentaram singulares devido a sua composição química. Os resultados fotoprotetores, além dos mutagênicos/fotomutagênicos, genotóxicos/fotogenotóxicos e suas respectivas avaliações citotóxicas também permitiram selecionar extratos e suas concentrações, como promissores candidatos em fotoproteção Assim, os EA e EH de H. laevifolia e L. laevifolium apresentam, no geral, os resultados mais significativos, tornando-se potenciais para avaliações refinadas em fotoproteção e na separação de componentes que possam levar a futuras aplicações como antioxidantes e protetores solares ou como adjuvantes.

On the antioxidant properties of erythropoietin and its association with the oxidative-nitrosative stress response to hypoxia in humans

Aim: The aim of this study was to examine if erythropoietin (EPO) has the potential to act as a biological antioxidant and determine the underlying mechanisms.

Methods: The rate at which its recombinant form (rHuEPO) reacts with hydroxyl (HO center dot), 2,2-diphenyl-1-picrylhydrazyl (DPPH center dot) and peroxyl (ROO center dot) radicals was evaluated in-vitro. The relationship between the erythopoietic and oxidative-nitrosative stress response to poikilocapneic hypoxia was determined separately in-vivo by sampling arterial blood from eleven males in normoxia and following 12 h exposure to 13% oxygen. Electron paramagnetic resonance spectroscopy, ELISA and ozone-based chemiluminescence were employed for direct detection of ascorbate (A(center dot-)) and N-tert-butyl-a-phenylnitrone spin-trapped alkoxyl (PBN-OR) radicals, 3-nitrotyrosine (3-NT) and nitrite (NO2-).

Results: We found rHuEPO to be a potent scavenger of HO center dot (k(r) = 1.03-1.66 x 10(11) M-1 s(-1)) with the capacity to inhibit Fenton chemistry through catalytic iron chelation. Its ability to scavenge DPPH. and ROO center dot was also superior compared to other more conventional antioxidants. Hypoxia was associated with a rise in arterial EPO and free radical-mediated reduction in nitric oxide, indicative of oxidative-nitrosative stress. The latter was confirmed by an increased systemic formation of A(center dot-), PBN-OR, 3-NT and corresponding loss of NO2- (P <0.05 vs. normoxia). The erythropoietic and oxidative-nitrosative stress responses were consistently related (r =-0.52 to 0.68, P <0.05).

Conclusion: These findings demonstrate that EPO has the capacity to act as a biological antioxidant and provide a mechanistic basis for its reported cytoprotective benefits within the clinical setting.

Phenolic compounds from forest industrial by-products

Em Portugal, as indústrias corticeira e de pasta de papel constituem um importante sector económico, contudo, gerando elevadas quantidades de subprodutos. Estes subprodutos poderiam ser explorados em aplicações de alto valor acrescentado, como fonte de compostos fenólicos, por exemplo, em vez de serem apenas queimados para produção de energia. Estes compostos são conhecidos pelas suas inúmeras propriedades, entre as quais, antioxidante, anti-inflamatória e anti-trombótica. Neste estudo as frações fenólicas da maior parte dos subprodutos gerados nas indústrias corticeira e de pasta de papel foram caracterizados em detalhe, com vista à sua valorização. A fração fenólica das cascas de Eucalyptus globulus, E. grandis, E. urograndis e E. maidenii, bem como da cortiça de Quercus suber e resíduos provenientes da sua exploração, nomeadamente, o pó de cortiça e os condensados negros, foi obtida por processos convencionais de extração sólido-líquido. No caso da casca de E. globulus, foi ainda avaliado o potencial de metodologias “verdes” no processo de extração de compostos fenólicos, usando extração com CO2 supercrítico. Esta técnica foi otimizada com recurso a metodologias de superfície de resposta. Na identificação e quantificação dos compostos fenólicos foi usada cromatografia líquida de alta resolução aliada a técnicas de espectrometria de massa. O teor de fenólicos totais foi ainda determinado pelo método de Folin- Ciocalteu, essencialmente para efeitos comparativos. A caracterização da fração fenólica de cada extrato foi ainda complementada com a análise da atividade antioxidante, usando o radical 2,2-difenil-1-picrilhidrazilo (DPPH). Foram identificados trinta compostos fenólicos na casca de E. globulus, 17 deles referenciados pela primeira vez como seus constituintes, nomeadamente os ácidos quínico, di-hidroxifenilacétic, cafeico e metil-elágico, bis-hexahidroxidifenoil( HHDP)-glucose, galoil- bis-HHDP-glucose, galoil-HHDPglucose, isoramnetina—hexosídeo, quercetina-hexosídeo, ácido metil-elágicopentosídeo, miricetina-ramnosídeo, isoramnetina-ramnosídeo, mearnsetina, floridzina, mearnsetina-hexosídeo, luteolina e uma proantocianidina B. Neste trabalho, foi estudada pela primeira vez a composição fenólica das cascas de E. grandis, E. urograndis e E. maidenii. Treze, doze e vinte e quatro compostos fenólicos foram identificados nas cascas de E. grandis, E. urograndis e E. maidenii, respetivamente. Entre estes compostos encontram-se os ácidos quínico, gálico, metilgálico, protocatequínico, clorogénico e elágico, catequina, galoil-bis-HHDP-glucose, digaloilglucose, epicatequina, quercetina-glucoronídeo, di-hidroxiisopropilcromona- hexosídeo, isoramnetina-hexosídeo, ácido elágicoramnosídeo, taxifolina, quercetina-hexosídeo, di-hidroxi- (metilpropil)isopropilcromona-hexosídeo, ácido metil-elágico-pentosídeo, miricetina-ramnosídeo, isoramnetina-ramnosídeo, aromadendrina-ramnosídeo, mearnsetina, mearnsetina-hexosídeo, eriodictiol, quercetina, isoramnetina e naringenina. A análise da fração fenólica da cortiça permitiu identificar vinte e dois compostos fenólicos, dez deles referenciados pela primeira vez como seus constituintes, nomeadamente, os ácidos quínico, salicílico, p-hidroxifenillático e metilgálico, ácido carboxílico da brevifolina, eriodictiol, naringenina, um éster isoprenílico do ácido cafeico, isoramnetina-ramnosídeo e isoramnetina. No pó de cortiça industrial foram identificados dezasseis compostos fenólicos, nomeadamente os ácidos quínico, gálico, protocatequínico, cafeico, ferúlico, elágico e metilgálico, esculetina, ácido carboxílico da brevifolina, coniferaldeído, um éster isoprenílico do ácido cafeico, uma dilactona do ácido valoneico, ácido elágico-pentosídeo, ácido elágico-ramnosídeo, isoramnetinaramnosídeo e isoramnetina. Destes, apenas o ácido elágico foi previamente referenciado como componente do pó de cortiça. Do mesmo modo, treze compostos fenólicos foram identificados no condensado negro, doze deles referenciados pela primeira vez como seus constituintes. São eles os ácidos quínico, gálico, p-hidroxifenil-láctico, protocatequínico, p-coumarico, cafeico e elágico, vanilina, esculetina, coniferaldeído, um éster isoprenílico do ácido cafeico e o eriodictiol. A extração supercrítica de compostos fenólicos da casca de eucalipto permitiu não só verificar os parâmetros que afetam a qualidade e quantidade finais dos extratos, como também obter os valores ótimos para estes parâmetros. Esta extração mostrou ainda ser bastante seletiva para determinados grupos de compostos fenólicos, como as flavanonas eriodictiol e naringenina e para o flavonol O-metilado isoramnetina. Este é também o primeiro estudo envolvendo a determinação da atividade antioxidante de extratos da cortiça e dos resíduos da sua exploração, bem como da casca de E. grandis, E. urograndis e E. maidenii. A vasta gama de compostos fenólicos identificados em cada extrato analisado, assim como as prominentes atividades antioxidantes, todas na mesma gama de valores do bem conhecido antioxidante comercial, ácido ascórbico, são claramente um grande contributo para a valorização destes subprodutos industriais.

Brewer's spent grain from different types of malt: Evaluation of the antioxidant activity and identification of the major phenolic compounds

The antioxidant activity and phenolic composition of brewer's spent grain (BSG) extracts obtained by microwave-assisted extraction from twomalt types (light and darkmalts) were investigated. The total phenolic content (TPC) and antioxidant activity among the light BSG extracts (pilsen, melano, melano 80 and carared)were significantly different (p b 0.05) compared to dark extracts (chocolate and black types), with the pilsen BSG showing higher TPC (20 ± 1 mgGAE/g dry BSG). In addition, the antioxidant activity assessed by 2,2-diphenyl- 1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and deoxyribose assays decreased as a result of increasing kilning temperatures in the following order: pilsen N melano N melano 80 N carared N chocolate N black. HPLC-DAD/ESI-MS/MS analysis indicated the presence of phenolic acids, such as ferulic, p-coumaric and syringic acids, as well as several isomeric ferulate dehydrodimers and one dehydrotrimer. Chocolate and black extracts, obtained frommalts submitted to the highest kilning temperatures, showed the lowest levels of ferulic and p-coumaric acids. These results suggested that BSG extracts from pilsen malt might be used as an inexpensive and good natural source of antioxidants with potential interest for the food, pharmaceutical and/or cosmetic industries after purification.

Teor mineral e capacidade antioxidante em chás e infusões

Mestrado em Engenharia Química – Ramo Optimização Energética na Indústria Química

Characterization of the phytochemicals and antioxidant properties of extracts from Teaw (Cratoxylum formosum Dyer)

The leaves of the Thai vegetable, Teaw (Cratoxylum formosum Dyer) were extracted with ethanol to provide an extract that had antioxidant properties. The composition of the extract was studied by high-performance liquid chromatography with a diode array detector, and by electrospray ionization mass spectrometry. The main antioxidant component (peak 1) was chlorogenic acid, which was present at 60% of the extract. Three minor components were present at 7%, 3% and 2%, and other components that were present at lower concentrations were also observed. Treatment of the Teaw extract with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH center dot) caused a similar reduction in peak area of 55.2-58.1% for chlorogenic acid and the three minor components, indicating that these components had common structural features. Component 2 was identified as dicaffeoylquinic acid, and compounds 3 and 4 were identified as ferulic acid derivatives. The radical-scavenging activity of the Teaw extract was compared with alpha-tocopherol, BHT and chlorogenic acid, using the DPPH center dot and 2,2'-azinobis (3-ethylbenzothialozinesulfonic acid) radical cation (ABTS(center dot+)) assays. The Teaw extract scavenged both free radicals more strongly than did a-tocopherol and BHT, and the activity of the extract was consistent with the concentration of chlorogenic acid that was present, confirming that this component is a major contributor to the antioxidant activity. The acute toxicity of the Teaw leaf extract was investigated in mice, and it was found that the LD50 of the extract was > 32 g/kg. Consequently, this plant is a promising source of a natural food antioxidant. (c) 2006 Elsevier Ltd. All rights reserved.

In vitro antioxidant activity and antigenotoxicity of 5-n-alkylresorcinols

Incubation with 5-n-alkylresorcinols (chain lengths C15:0, C17:0, C19:0, C21:0, and C23:0) increased the self-protection capacity of HT29 human colon cancer cells against DNA damage induced by hydrogen peroxide and genotoxic fecal water samples using comet assay (single-cell gel electrophoresis assay). The alkylresorcinols did not exert potent antioxidant activity in the FRAP (ferric reduction ability of plasma) and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical assays. However they were able to significantly inhibit copper-mediated oxidation of human LDL (low-density lipoprotein) in vitro, and pentadecylresorcinol at 25 micromol/L increased lag time by 65 min. The results show that alkylresorcinols have antigenotoxic and antioxidant activity under in vitro conditions.

Brazilian red propolis: unreported substances, antioxidant and antimicrobial activities

BACKGROUND: Chloroform, ethyl acetate and methanol extracts of a sample of red propolis from the state of Alagoas (northeast Brazil) were analyzed by gas chromatography-mass spectrometry and high-performance liquid chromatography-diode array detection-electrospray ionization-mass spectrometry. Antimicrobial and antioxidant activities were also obtained. RESULTS: The propolis sample contained low content of narigenin-8-C-hexoside, this being the first report of a C-glycoside in propolis. The main constituent found was characterized as 3,4,2`,3`-tetrahydroxychalcone. Other important constituents were the chalcone isoliquiritigenin, the isoflavans (3S)-vestitol, (3S)-7-O-methylvestitol, the pterocarpan medicarpin, the phenylpropenes trans-anethol, methyl eugenol, elimicin, methoxyeugenol and cis-asarone, and the triterpenic alcohols lupeol and alpha- and beta- amyrins. The methanol extract exhibited high antioxidant activities by 2,2-diphenyl-1-picrylhydrazyl and beta-carotene/linoleic acid assay methods, and antimicrobial activity toward Gram-positive and Gram-negative bacteria. CONCLUSION: Structures are suggested for new substances never before seen in any kind of propolis. This is the first report of 3,4,2`,3`-tetrahydroxychalcone and a flavone C-glycoside in a propolis sample. (C) 2011 Society of Chemical Industry

Sugarcane spirit extracts of oak and Brazilian woods: antioxidant capacity and activity

Sugarcane spirit extracts of six different Brazilian woods for potential use in manufacturing aging casks were compared with similar extracts of five oak samples from different geographic origin and heat treatment regarding: (1) content of phenolics and copper; (2) radical reducing capacity and reactivity toward 2,2-diphenyl-1-picrylhydrazyl radical (DPPH center dot); and (3) effect on the rate of oxygen depletion rate in a peroxidating lipid model system. Total phenolic contents of the Brazilian wood extracts ranged from 0.65 (canela-sassafras) to 6.4 (jatoba) mmol(GAE) L(-1) and from 1.39 to 2.87 mmol(GAE) L(-1) for oak extracts. Flavonoids ranged from 1.54 x 10(-4) (ipe) to 6.5 x 10(-2) (oak) mmol(rutin) L(-1), and tannins from below the detection limit to 0.22 (jatoba) mmol(tannic acid) L(-1). Correlation was observed for the antioxidant capacity versus phenolics/flavonoids/tannins content, where oak extracts exhibit the highest radical scavenging capacity compared to Brazilian woods. Rate constant for radical scavenging by the extracts ranged from 4.9 x 10(3) M(-1) s(-1)(canela-sassafras) to 9.7 x 10(4) M(-1) s(-1) (oak). The oxygen consumption index showed the Brazilian woods amendoim and jatoba to be more efficient inhibitors than the oak extracts for lipid autoxidation initiated by metmyoglobin, despite that the oak extracts seem to be more efficient to scavenge DPPH center dot. No simple correlation with phenolics or copper content could be established, and a prooxidative tendency was observed for the extracts of canela-sassafras, castanheira, and louro-canela.

Hypolipemic and antioxidant activities from Tamarindus indica L. pulp fruit extract in hypercholesterolemic hamsters

Dietary modifications may significantly reduce cardiovascular disease (CVD) risk factors, including cholesterol and atherosclerosis. The present study addressed the effects of the crude extract from the pulp fruit of Tamarindus indica L. on lipid serum levels and early atherosclerotic lesions in hypercholesterolemic hamsters in vivo, and the extract's antioxidant action, in vitro. Animals were fed on either chow or atherogenic diet during 10 weeks and concomitantly received either water or T indica L. extract for drinking. Treatment of hypercholesterolemic hamsters with the T. indica pulp fruit extract (5%) led to a decrease in the levels of serum total cholesterol (50%), non-HDL cholesterol (73%) and triglyceride (60%), and to an increase of high-density lipoprotein (HDL) cholesterol levels (61%). In vitro, the extract presented radical scavenging ability, as assessed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide radicals assays, and led to decreased lipid peroxidation in serum, as assessed by the thiobarbituric acid reactive substances (TBARS) assay. In vivo, the extract improved the efficiency of the antioxidant defense system, as assessed by the superoxide dismutase, catalase and glutathione peroxidase activities. Together these results indicate the potential of tamarind extracts in diminishing the risk of atherosclerosis development in humans. (c) 2005 Elsevier Ltd. All rights reserved.

Chemical Composition and Antioxidant and Antimycobacterial Activities of Bromelia balansae (Bromeliaceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Antimicrobial, Cytotoxic and Antioxidant Activities and Determination of the Total Tannin Content of Bark Extracts Endopleura uchi

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Interconverting flavanone glucosides and other phenolic compounds in Lippia salviaefolia Cham. ethanol extracts

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

ANTIOXIDANT PROPERTIES of LENTINUS EDODES and AGARICUS BLAZEI EXTRACTS

This work aimed to evaluate the antioxidant activity of Lentinus edodes and Agaricus blazei mushrooms, as well as to measure the content of total phenolic compounds of mushroom extracts and verify the oxidative stability of soybean oil added with mushroom extracts that showed higher antioxidant activity according to the methods of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and the beta-carotene/linoleic acid system. According to the DPPH method, the maximum antioxidant activity for L. edodes and A. blazei methanol extracts was 92.84 and 95.10%, respectively. For the beta-carotene/linoleic acid system, the highest values of antioxidant activity were 93.06% for L. edodes and 78.96% for A. blazei. The content of total phenolic compounds ranged from 7.21 to 128.44 and 26.67 to 134.67 mg gallic acid equivalent/g for L. edodes and A. blazei, respectively. The oxidative stability values provided by the Rancimat method indicated that the two varieties presented similar induction period of 19.85 h.

Evaluation of the use of Syzygium cumini fruit extract as an antioxidant additive in orange juice and its sensorial impact

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)