Effect of ambient levels of ozone on photosynthetic components and radical scavenging system in leaves of African cowpea varieties

Tropospheric ozone (O3), a main component of photochemical oxidants, adversely affects not only human health but also vegetation. To clarify the long-term effects of ambient levels of tropospheric ozone (O3) on photosynthetic components and radical scavenging system in the leaves of cowpea ( Vigna unguiculata L.), two African varieties, Blackeye and Asontem, were grown in open-top chambers and exposed to filtered air (FA), non-filtered air (NF) or non-filtered air with additional O3 of approximately 50 nl l-1. Ambient levels of O3 significantly reduced chlorophyll concentration, quantum yield and activity of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco), thus contributing to the reduction in net photosynthetic rate at the reproductive growth stage of both varieties; with no significant variety difference in the sensitivity to O3. The O3-induced significant reduction in catalase activity was observed in Blackeye at vegetative and reproductive growth stages; and in Asontem at reproductive growth stage. On the other hand, exposure to O3 significantly increased ascorbate peroxidase activity in Blackeye at reproductive stage and did not significantly affect that in Blackeye at vegetative growth stage and that in Asontem at both growth stages. At reproductive growth stage, activities of monodehydroascorbate reductase and glutathione reductase were significantly increased by the exposure to O3 in both varieties. The results obtained in this study suggest that, although ascorbate peroxidase, monodehydroascorbate reductase and glutathione reductase played important roles in scavenging O3-induced reactive oxygen species in the leaves, radical scavenging ability of these enzymes is not sufficient to avoid detrimental effects of ambient levels of O3 on photosynthesis in both African cowpea varieties.

Mate (Ilex paraguariensis) as a source of water extractable antioxidant for use in chicken meat

Aqueous extract of mate, made from dried leaves of Ilex paraguariensis, St. Hilaire, was shown to be effective during chilled storage for up to 10 days in protecting lipids and vitamin E against oxidation in pre-cooked meat balls made from chicken breast added 0.5% salt and packed in atmospheric air. Extracts made with water, methanol, ethanol or 70% aqueous acetone were evaluated by comparing (1) total phenolic content, (2) radical scavenging capacity, (3) effect on lipid oxidation in a food emulsion model, and in liposomes. Based on the three-step evaluation, aqueous mate extract was preferred for food use. Dried leaves were further compared to dried rosemary leaves in chicken meat balls, and mate (0.05 and 0.10%) found to yield equal or better protection than rosemary at the same concentration against formation of secondary lipid oxidation products.

Nutritional Aspects of Second Generation Soy Foods

Samples of 15 second generation soy-based products (n = 3), commercially available, were analyzed for their protein and isoflavone contents and in vitro antioxidant activity, by means of the Folin-Ciocalteu reducing ability, DPPH radical scavenging capacity, and oxygen radical absorbance capacity. Isoflavone identification and quantification were performed by high-performance liquid chromatography. Products containing soy and/or soy-based ingredients represent important sources of protein in addition to the low fat amounts. However, a large variation in isoflavone content and in vitro antioxidant capacity was observed. The isoflavone content varied from 2.4 to 18.1 mg/100 g (FW), and soy kibe and soy sausage presented the highest amounts. Chocolate had the highest antioxidant capacity, but this fact was probably associated with the addition of cocoa liquor, a well-known source of polyphenolics. This study showed that the soy-based foods do not present a significant content of isoflavones when compared with the grain, and their in vitro antioxidant capacity is not related with these compounds but rather to the presence of other phenolics and synthetic antioxidants, such as sodium erythorbate. However, they may represent alternative sources and provide soy protein, isoflavones, and vegetable fat for those who are not ready to eat traditional soy foods.

Assessing the association between phenolic compounds and the antioxidant activity of Brazilian red wines using chemometrics

The objective of this study was to evaluate the association among chemical parameters, the commercial value, and the antioxidant activity of Brazilian red wines using chemometric techniques. Twenty-nine samples from five different varieties were assessed. Samples were separated into three groups using hierarchical cluster analysis: cluster 1 presented the highest antioxidant activity towards DPPH (68.51% of inhibition) and ORAC (30,918.64 mu mol Trolox Equivalents/L), followed by cluster 3 (DPPH = 59.36% of inhibition: ORAC = 25,255.02 mu mol Trolox Equivalents/L) and then cluster 2 (DPPH = 46.67% of inhibition; ORAC = 19,395.74 gmol Trolox Equivalents/L). Although the correlation between the commercial value and the antioxidant activity on DPPH and ORAC was not statistically significant (P = 0.13 and P = 0.06, respectively), cluster 1 grouped the samples with higher commercial values. Cluster analysis applied to the variables suggested that non-anthocyanin flavonoids were the main phenolic class exerting antioxidant activity on Brazilian red wines. (C) 2010 Elsevier Ltd. All rights reserved.

Antioxidant Activity of Uruguayan Propolis. In Vitro and Cellular Assays

The antioxidant capacity of propolis from the southern region of Uruguay was evaluated using in vitro as well as cellular assays. Free radical scavenging capacity was assessed by ORAC, obtaining values significantly higher than those of other natural products (8000 mu mol Trolox equiv/g propolis). ORAC values correlated well with total polyphenol content (determined by Folin-Ciocalteu method) and UV absorption. Total polyphenol content (150 mg gallic acid equiv/g propolis) and flavonoids (45 mg quercetin equiv/g propolis) were similar to values reported for southern Brazilian (group 3) and Argentinean propolis. Flavonoid composition determined by RP-HPLC indicates a strong poplar-tree origin. Samples high in polyphenols efficiently inhibit low-density lipoprotein lipoperoxidation and tyrosine nitration. In addition, Uruguayan propolis was found to induce the expression of endothelial nitric oxide synthase and inhibit endothelial NADPH oxidase, suggesting a potential cardiovascular benefit by increasing nitric oxide bioavailability in the endothelium.

Effect of heating oxyhemoglobin and methemoglobin on microsomes oxidation.

Hemoglobin (Hb) has been proposed to be a major pro-oxidant in raw and cooked meats. To understand the mechanisms and differentiate between the pro-oxidant and antioxidant potential of oxyhemoglobin (OxyHb) and methemoglobin (MetHb), their pro-oxidant activity, protein solubility, radical scavenging capacity, iron content and contribution of non-chelatable iron on lipid oxidation were determined as a function of thermal treatments. The ability of native OxyHb and MetHb to promote lipid oxidation was similar and higher than their corresponding OxyHb or MetHb heated at 68 and 90 degrees C but not different from those at 45 degrees C. The pro-oxidant activity of MetHb heated at 68 and 90 degrees C were similar whereas the pro-oxidant activity of OxyHb heated at 68 degrees C was higher than that heated at 90 degrees C. The decreased pro-oxidant activity of heat-denatured Hb was associated with a decrease in the solubility of heme iron while free iron showed little impact on the lipid oxidation.

Elintarvikkeiden antioksidantit sekä antosyaniinien rakenteen vaikutus antioksidanttikapasiteettiin eri mittausmenetelmiä käyttäen

Kirjallisessa osassa tarkastellaan eri antioksidantteja ja niiden toimintamekanismeja, sekä luonnollisten kasviuutteiden mahdollisia käyttökohteita elintarviketeollisuudessa. Lisäksi perehdytään tarkemmin miten eri antosyaniinien rakenne vaikuttaa niiden antioksidanttikapasiteettiin neljällä eri mittausmenetelmällä. Valitut menetelmät ovat DPPH (Radical Scavenging Capacity Assay), ORAC (Oxygen radical absorbance capacity), TEAC (Trolox Equivalent Antioxidant Capacity) ja FRAP (The ferric reducing antioxidant power). Luonnollisiin antioksidantteihin kuuluvat C-, E-, ja A-vitamiinit, tietyt mineraalit ja esimerkiksi marjojen sisältämät polyfenoliset yhdisteet. Yleisimpiin synteettisiin antioksidantteihin kuuluvat butyylihydroksianisoli, butyylihydroksitolueeni, tertiäärinen butyylihydrokinoni ja propyyligallaatti. Antosyaniinien rakenteella, erityisesti B-renkaan hydroksyyliryhmillä, on suuri vaikutus antosyaniinien antioksidanttikapasiteettiin. Delfinidiini on yksi yleisimmistä antosyanidiineista ja sen B-renkaassa esiintyy kolme hydroksyyliryhmää. Hydroksyyliryhmiensä ansioista sillä on korkein kapasiteetti DPPH-, FRAP- ja TEAC-menetelmillä mitattuna, mutta kirjallisuuden perusteella ORAC-menetelmällä näin ei ole. Antosyanidiineihin sitoutuva sokeri vaikuttaa kapasiteettiin joko positiivisesti tai negatiivisesti. Sokeriyksiköiden lisääntyminen rakenteessa puolestaan alentaa kapasiteettia kaikilla mittausmenetelmillä. Kokeellisessa osassa tutkittiin eri menetelmillä uutettujen kasvi-, marja-, ja mausteuutteiden antioksidanttikapasiteettia muunneltua TRAP-menetelmää käyttäen (Total Radical-Trapping Antioxidant Parameter). Muunnellulle TRAP-menetelmälle optimoitiin sopivat Trolox-standardilaimennokset, mittausparametrit ja suoritustapa. Korkeimmat antioksidanttikapasiteetit määritettiin mustaherukan marjalle ja lehdelle, männyn petulle, puolukan lehdelle ja mausteneilikan kukalle. Näiden uutteiden korkeat antioksidanttikapasiteetit johtuvat niiden korkeista polyfenolipitoisuuksista, joiden on todettu aikaisemmissakin tutkimuksissa olevan yhteydessä korkeampiin antioksidanttikapasiteetteihin. Mausteneilikan kukalla oli ylivoimaisesti korkein antioksidanttikapasiteetti, jopa 20–100 kertaa korkeampi kuin muilla näytteillä. Mausteneilikan kukka sisältää paljon eugenolia ja fenolisia yhdisteitä. Eugenolin on todettu olevan jopa viisi kertaa aktiivisempi antioksidantti kuin α-tokoferoli. Monille muillekin marjoille, lehdille ja mausteille mitattiin korkeat antioksidanttikapasiteetit.

Extraction of polyphenols from processed black currant (Ribes nigrum L.) residues

The total phenol and anthocyanin contents of black currant pomace and black currant press residue (BPR) extracts, extracted with formic acid in methanol or with methanol/water/acetic acid, were studied. Anthocyanins and other phenols were identified by means of reversed phase HPLC, and differences between the two plant materials were monitored. In all BPR extracts, phenol levels, determined by the Folin-Ciocalteu method, were 8-9 times higher than in the pomace extracts. Acid hydrolysis liberated a much higher concentration of phenols from the pomace than from the black currant press residue. HPLC analysis revealed that delphinidin-3-O-glucoside, delphinidin-3-O-rutinoside, cyanidin-3-O-glucoside, and cyanidin-3-O-rutinoside were the major anthocyanins and constituted the main phenol class (approximate to 90%) in both types of black currant tissues tested. However, anthocyanins were present in considerably lower amounts in the pomace than in the BPR. In accordance with the total phenol content, the antioxidant activity determined by scavenging of 2,2'-azinobis(3-ethylbenzothiazoline-6- sulfonic acid) radical cation, the ABTS(center dot+) assay, showed that BPR extracts prepared by solvent extraction exhibited significantly higher (7-10 times) radical scavenging activity than the pomace extracts, and BPR anthocyanins contributed significantly (74 and 77%) to the observed high radical scavenging capacity of the corresponding extracts.

Atividades anticoagulante e antioxidante de extratos brutos ricos em polissacarídeos sulfatados das macroalgas marinhas marrons Canistrocarpus cervicornis, Dictyota mertensii e Dictyopteris delicatula e de Heterofucanas de Canistrocarpus cervicornis

In the present study, extracts rich-sulfated polysaccharides were obtained from three different species of Dictyotales (a class of brown macroalgae): Canistrocarpus cervicornis, Dictyota mertensii and Dictyopteris delicatula and their anticoagulant and antioxidant activities were evaluated. All extracts showed anticoagulant activity on aPTT assay, but not on PT assay. Extracts also exhibited total antioxidant activity, superoxide radical scavenging capacity and ferric chelating property. The extract from C. cervicornis showed the best results and was choose to have their sulfated polysaccharides fractioned and subsequently analysed. Thus, six fractions (CC-0.3, CC-0.5, CC-0.7, CC-1.0, CC-1.2 and CC-2.0) were obtained by proteolysis followed by sequential acetone precipitation. Agarose gel eletrophoresis stained with blue toluidine, confirmed the presence of sulfated polysaccharides in all fractions. Chemical analyses showed that all fractions presented heterofucans mainly constitued by fucose, galactose, glucuronic acid and sulfate. Any fraction changed the PT. However, all fractions were able to double the aPTT on a dose-dependent manner. CC- 0.3, CC-0.5, CC-0.7 and CC-1.0 needed only 0.100 mg/mL to double the aPTT, result only 1.25 times higher than the Clexane® (0.080 mg/mL), a commercial low molecular heparin. The heterofucans presented appreciable total antioxidant capacity, low capacity on scavenging hydroxyl radical and good efficiency on scavenging superoxide radicals (except CC-1.0). CC-1.2 showed 43.1 % on superoxide radical scavenging. This result was higher than that showed by the same concentration of gallic acid (41.8 %), a known antioxidant. Furthermore, the heterofucans showed excelent activity on ferrous chelating activity (except CC-0.3). CC-0.5, CC-0.7 and CC-1.0 showed the highest activities with 47.0 % of ferrous chelating activity, a result 2.0 times lesser than that exhibited by the same concentration of EDTA. These results clearly indicated the beneficial effects of heterofucans extracted from C. cervicornis as potential anticoagulant and antioxidant agents. However additional steps of purification, structural studies, besides in vivo experiments are needed for these fucans may be used as therapeutic agents

Atividade anticoagulante, antioxidante e antitumoral de heterofucanas da alga Dictyopteris delicatula (Lamouroux, 1809)

In the present study, six families of sulfated polysaccharides were obtained from seaweed Dictyopteris delicatula (Lamouroux, 1809) and their anticoagulant, antioxidant and antitumor activities were evaluated. All fractions showed anticoagulant activity on aPTT assay, but not on PT assay. Fractions also exhibited total antioxidant activity, superoxide radical scavenging capacity and ferric chelating property. Thus, six fractions (F0.5v, F0.7v, F1.0v, F1.3v, F1.5v e F2.0v) we obtained by proteolytic digestion, followed by acetone fractionation and molecular sieving on Sephadex G-100. Chemical analyses demonstrated that all polysaccharides contain heterofucans composed mainly of fucose, xylose, glucose, galactose, uronic acid, and sulfate. Any fractions changed the PT. However, all fractions were able on double the aPPT on a dose-dependent manner. The heterofucans F0.7v and F1.0v showed low anticoagulant activity while F1.5v presented the most prominent anticoagulant activity .When compared to Clexane®, a low molecular weight heparin, at same concentration F1.5v presented similar anticoagulant activity. The fucans F0.5v and F0.7v at 1.0 mg/mL showed high ferric chelating activity (~45%), whereas fucans F1.3v (0.5 mg/mL) showed considerable reducing power, about 53.2% of the activity of vitamin C. The fucan F1.5v presented the most prominent anticoagulant activity. The best antiproliferative activity was found with fucans F1.3v and F0.7v. However, F1.3v activity was much higher than F0.7v inhibiting almost 100% of HeLa cell proliferation. These fucans have been selected for further studies on structural characterization as well as in vivo experiments, which are already in progress

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

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relative antioxidant activity of Brazilian medicinal plants for gastrointestinal diseases

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

Avaliação do potencial alelopático, atividade antimicrobiana e antioxidante dos extratos orgânicos das folhas de Pyrostegia venusta (Ker Gawl.) Miers (Bignoniaceae)

Este trabalho apresenta os resultados de atividade alelopática, antimicrobiana e antioxidante dos extratos orgânicos (hexano, acetato de etila e metanol) das folhas de Pyrostegia venusta (Ker Gawl.) Miers (Bignoniaceae). Para alelopatia, foi estudado o desenvolvimento de Cucumis sativus (pepino), sendo avaliados o comprimento da raiz principal, o número de raízes secundárias e o comprimento do hipocótilo. Os dois primeiros parâmetros foram afetados por todos os três extratos testados enquanto o comprimento do hipocótilo só não foi afetado pelo extrato acetato de etila. Quanto à atividade antimicrobiana, avaliada pelo ensaio de CIM, o extrato hexânico apresentou inibição moderada frente ao Staphylococcus aureus (0,9 mg mL-1) e forte ao Enterococcus hirae (0,5 mg mL-1). O extrato acetato de etila apresentou forte atividade frente Candida albicans (0,3 mg mL-1) enquanto o extrato metanólico não mostrou-se ativo para os microrganismos testados. Por outro lado, o extrato metanólico apresentou a maior capacidade de seqüestrar radicais livres (Concentração Efetiva 50%-CE50 =102,0 ± 56,9 mg mL-1, com TCE50 = 30 min) no ensaio com DPPH (2,2-difenil-1-picril-hidrazila) e o maior teor de compostos fenólicos (116,2 ± 83,0 mg ácido gálico g amostra-1), avaliado pelo ensaio de Folin-Ciocalteau.

Phenylpropanoid glucosides from leaves of Coussarea hydrangeifolia (Rubiaceae)

Phenylpropanoid glycosides, 1 '-O-benzyl-alpha-(L)-rhamnopyranosyl-(1 ''-> 6 ')-beta-(D)-glucopyranoside (1) and alpha-(L)-Xylopyranosyl(4 '', 2 ')-(3-O-beta-(D)-glucopyranosyl)-1 '-O-E-caffeoyl-beta-(D)-glucopyranoside (2), together with the known derivatives, 1,6-di-O-caffeoyl- beta-(D)-glucopyrano side (3), 1-O-(E)-caffeoyl-beta-(D)-glucopyranoside (4) and 1-O-(E)-feruloyl-beta-(D)-glucopyranoside (5), were isolated from leaves of Coussarea hydrangeifolia. Their structures were determined by IR, HRESIMS, and I D and 2D NMR experiments, and their antioxidant activities, evaluated by assaying the free radical scavenging capacity using the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical as substrate. The antioxidant activities of 3 and 4 (IC50 values of 15.0 and 19.2 mu M, respectively) were comparable to that of the standard positive control caffeic acid, whilst 2 and 5 were only weakly active and 1 was inactive. (c) 2005 Elsevier Ltd. All rights reserved.

Bioprospecção de atividade antioxidante e antimicrobiana da casca de Stryphnodendron adstringens (Mart.) Coville (Leguminosae-Mimosoidae)

The aim of this work was to evaluate the class of secondary metabolites responsible for the antioxidant and antimicrobial activities of bark extracts of Stryphnodendron adstringens (Mart.) Coville (Leguminosae-Mimosoidae), a plant widely used in folk medicine in Brazil. Extracts of the bark were prepared with 50% ethanol, 70% ethanol, acetone:water (7:3, v/v) and chloroform. Antioxidant activity was prospected by spraying thin-layer chromatographs of the extracts with 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and measuring the DPPH radical scavenging capacity by spectrophotometry. Antibacterial activity was revealed by the agar diffusion method and bioautography. TLC spots assigned to tannins in the polar extracts showed antioxidant activity by DPPH radical scavenging and the chloroform extract showed the least scavenging activity. Antimicrobial activity was indicated by the bacterial growth inhibition haloes around polar extracts and bioautography showed activity in the TLC spots assigned to tannins. It was concluded that polar extracts of the bark of S. adstringens possessed antioxidant and antimicrobial activities which were due to secondary metabolite derived from the tannin class, which are the main constituent of these bark extracts, according to the literature.