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Phenolic profile of wild fruits of Rosa canina SL. from Northeast Portugal

Guimarães, Rafaela; Barros, Lillian; Reis, Filipa S.; Dueñas, Montserrat; Carvalho, Ana Maria; Santos-Buelga, Celestino; Queiroz, Maria João R.P.; Ferreira, Isabel C.F.R.
Fonte: Instituto Politécnico de Bragança Publicador: Instituto Politécnico de Bragança
Tipo: Conferência ou Objeto de Conferência
ENG
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Plant polyphenols are a wide group of secondary metabolites and are a common component of our diet. Flavonoids represent the most common and widely distributed group of plant phenolics, and can be further broken into classes including flavones, flavonols, flavanones, flavanols, anthocyanins and isoflavonoids. Different classes of bioactive constituents are present in Rosa canina, including phenolic compounds. Rosa canina fruits can be eaten raw as snacks and possess prophylactic and therapeutic activities against a wide range of ailments, including the inflammatory disorders arthritis, rheumatism, gout, colds and gastrointestinal disorders, which might be related with their phenolic composition. This study aimed to characterize the phenolic compounds present in the above mentioned wild fruits. The analysis of phenolic compounds was carried out by reversed-phase HPLC-DAD and the major phenolic compounds were identified by ESI-MS, in order to establish the specific phenolic profile. Rosa canina presented different classes of flavonoids. Flavones, flavonols and dihydroflavonols represented 5.50 mg/100 g dry weight, among which taxifolin, a dihydroflavonol, was prominent (1.18 mg/100 g). Flavan-3-ols (i.e., catechins and proanthocyanidins) were other relevant flavonoids found. (+)-Catechin was the most abundant flavan-3-ol found in the fruits (3.59 mg/100 g)...

In vitro evaluation of the antioxidant activity of liposomal flavonols by the HRP--H(2)O(2)--luminol system

LANDI-LIBRANDI, Ana Paula; OLIVEIRA, Carlos Alberto de; AZZOLINI, Ana Elisa Caleiro Seixas; KABEYA, Luciana Mariko; CIAMPO, Jose Orestes Del; BENTLEY, Maria Vitoria Lopes Badra; LUCISANO-VALIM, Yara Maria
Fonte: INFORMA HEALTHCARE Publicador: INFORMA HEALTHCARE
Tipo: Artigo de Revista Científica
ENG
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37.64%
Considering that antioxidant flavonols have been reported to be beneficial to human health, but that their low water solubility and bioavailability limit their administration through systemic route, the development of suitable flavonol-carriers is of great importance for clinical therapeutics. The aim of this study was to prepare liposomes containing flavonols or not and evaluate their antioxidant activity. Vesicles were obtained by ethanol injection method and characterized in terms of entrapment efficiency, size and zeta potential. Inhibitory activity of liposomal flavonols on reactive oxygen species generation was assessed in vitro using luminol--H(2)O(2)--horseradish peroxidase technique. Antioxidant activity of liposomal flavonols is dependent on concentration and chemical structure of active compound. Quercetin and myricetin are the most active flavonols (IC(50) == 0.6--0.9 mu A mu mol/L), followed by kaempferol (IC(50) == 3.0--4.5 mu A mu mol/L) and galangin (IC(50) == 4.0--7.0 mu A mu mol/L). Our results suggest that antioxidant-loaded liposomes may be promising tools for therapy of diseases where oxidative stress is involved.; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP, Brazil)[2006/04398-5]; Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP...

Flavonols from Pterogyne nitens and their evaluation as myeloperoxidase inhibitors

Regasini, Luis Octavio; Rebuglio Vellosa, Jose Carlos; Siqueira Silva, Dulce Helena; Furlan, Maysa; Mascarenhas de Oliveira, Olga Maria; Khalil, Najeh Maissar; Brunetti, Iguatemy Lourenço; Marx Young, Maria Claudia; Barreiro, Eliezer Jesus; Bolzani, Vand
Fonte: Pergamon-Elsevier B.V. Ltd Publicador: Pergamon-Elsevier B.V. Ltd
Tipo: Artigo de Revista Científica Formato: 1739-1744
ENG
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27.38%
A myeloperoxidase inhibitory kaempferol derivative, namely pterogynoside (1), was isolated from fruits of Pterogyne nitens, along with six known flavonols, kaempferol, afzelin, kaempferitrin, quercetin, isoquercetrin and rutin. The structures of all compounds were elucidated primarily from 1D and 2D NMR spectroscopic analyses, as well as by high resolution mass spectrometry. All flavonols were screened to identify secondary metabolites as potential myeloperoxidase (MPO) inhibitors, and at concentrations of 0.50-50 nM, quercetin (5), isoquercitrin (6) and rutin (7) exhibited strong inhibitory effects with IC(50) values of 1.22 +/- 0.01, 3.75 +/- 0.02 and 3.60 +/- 0.02, respectively. The MPO activity detected for the new derivative 1 was markedly decreased (IC(50) 10.3 +/- 0.03) when compared with known flavonols 5-7, and interestingly increased when tested against ABTS scavenging activity. (C) 2008 Published by Elsevier Ltd.

Antioxidant activity of flavonols

Ghiotto, R. C T; Lavarda, F. C.; Ferreira, F. J B
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 949-952
ENG
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In this work we use a single new electronic index to describe the antioxidant activity of the flavonols, a special class of flavonoids. We also try to predict theoretically the antioxidant activity of some yet nonisolated flavonols. © 2003 Wiley Periodicals, Inc.

Extraction and quantification of phenolic acids and flavonols from Eugenia pyriformis using different solvents

Haminiuk, Charles Windson Isidoro; Plata-Oviedo, Manuel Salvador Vicente; de Mattos, Gisely; Carpes, Solange Teresinha; Branco, Ivanise Guilherme
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1-5
ENG
Relevância na Pesquisa
37.21%
The recovery of phenolic compounds of Eugenia pyriformis using different solvents was investigated in this study. The compounds were identified and quantified by reverse-phase high-performance liquid chromatography coupled with ultraviolet-visible diode-array detector (RP-HPLC-DAD/UV-vis). Absolute methanol was the most effective extraction agent of phenolic acids and flavonols (588.31 mg/Kg) from Eugenia pyriformis, although similar results (p ≤ 0.05) were observed using methanol/water (1:1 ratio). Our results clearly showed that higher contents of phenolic compounds were not obtained either with the most or the least polar solvents used. Several phenolic compounds were identified in the samples whereas gallic acid and quercetin were the major compounds recovered. © 2012 Association of Food Scientists & Technologists (India).

Phenolic composition of the berry parts of hybrid grape cultivar BRS Violeta (BRS Rubea×IAC 1398-21) using HPLC-DAD-ESI-MS/MS

Rebello, Ligia Portugal Gomes; Lago-Vanzela, Ellen Silva; Barcia, Milene Teixeira; Ramos, Afonso Mota; Stringheta, Paulo César; Da-Silva, Roberto; Castillo-Muñoz, Noelia; Gómez-Alonso, Sergio; Hermosín-Gutiérrez, Isidro
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 354-366
ENG
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The grape is considered a major source of phenolic compounds when compared to other fruits and vegetables, however, there are many cultivars with distinct characteristics directly linked to phenolic profile. Thus, the present study aimed to identify and quantify, for the first time and in detail, the phenolic compounds present in the skin, flesh and seeds of BRS Violeta grape berry using combination of SPE methodologies and analytical HPLC-DAD-ESI-MS/MS. The study was extended to the different berry parts and the most important grape and wine phenolic families, and has revealed interesting features. Violeta grape has a very thick skin (46% of grape weight) that accumulated the most of grape phenolic compounds: great amount of anthocyanins (3930. mg/kg, as malvidin 3,5-diglucoside), together with also important amounts of flavonols (150. mg/kg, as quercetin 3-glucoside), hydroxycinnamic acid derivatives (HCAD; 120. mg/kg, as caftaric acid), and proanthocyanidins (670. mg/kg, as (+)-catechin); in contrast, it seems to be a low resveratrol producer. Violeta grape seeds accounted for similar proportions of low molecular weight flavan-3-ols (mainly monomers; 345. mg/kg, as (+)-catechin) and proanthocyanidins (480. mg/kg, as (+)-catechin). Violeta grape is a teinturier cultivar...

On-line LC/UV/MS analysis of flavonols in the three apple varieties most widely cultivated in Brazil

Tiberti,Luciana A.; Yariwake,Janete H.; Ndjoko,Karine; Hostettmann,Kurt
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
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This work describes the first detailed investigation into the chemical structures of flavonols present in the three apple varieties most commonly cultivated in Brazil: Gala, Golden and Fuji. The analyses were carried out by LC/UV/MS (high-performance liquid chromatography coupled to diode array UV detection and mass spectrometry), using post-column addition of UV shift reagents, as well as multiple stage mass spectrometry (MSn) with electrospray ionization in the negative ion mode. Rutin, hyperoside, isoquercitrin, quercitrin, quercetin and three other quercetin-3-pentoside derivatives were identified through the characterization of on-line-based LC/UV/MS data. LC/UV/MS analysis also revealed that the three apple cultivars have similar chromatographic profiles.

Hydrogen Peroxide-Dependent Oxidation of Flavonols by Intact Spinach Chloroplasts

Takahama, Umeo
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1984 EN
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27.21%
Externally added quercetin (100 micromolar) was oxidized by intact spinach chloroplasts at a rate of 30 micromoles per mg chlorophyll per hour in the presence of 100 micromolar H2O2. The oxidation rate was increased by about 20% in a hypotonic reaction mixture. The thylakoid fraction also oxidized the flavonol in the presence of H2O2, and the rate was about 25% of that by intact chloroplasts. The oxidation of quercetin was inhibited by KCN and NaN3. Ascorbate, which permeates slowly across chloroplast envelope, only slightly suppressed the initial rate of quercetin oxidation by intact chloroplasts, while the oxidation by ruptured chloroplasts was suppressed by ascorbate by about 60%. Quercetin glycosides, quercitrin and rutin, were also oxidized by chloroplasts in the presence of H2O2. These results suggest that flavonols are oxidized by peroxidase-like activity in chloroplasts and that externally added flavonols can permeate into the stroma through the envelope of intact chloroplasts.

Flavonols Stimulate Development, Germination, and Tube Growth of Tobacco Pollen 1

Ylstra, Bauke; Touraev, Alisher; Moreno, Rosa Maria Benito; Stöger, Eva; van Tunen, Arjen J.; Vicente, Oscar; Mol, Joseph N. M.; Heberle-Bors, Erwin
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1992 EN
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27.38%
The effect of anther-derived substances on pollen function was studied using pollen produced by in vitro culture of immature pollen of tobacco (Nicotiana tabacum L.) and petunia (Petunia hybrida). Addition of conditioned medium consisting of diffusates from in situ matured pollen strongly increased pollen germination frequency and pollen tube growth, as well as seed set after in situ pollination. Thin-layer chromatography and depletion of phenolic substances by Dowex treatment indicated that flavonols are present in the diffusate and may be the active compounds. When added to the germination medium, flavonols (quercetin, kaempferol, myricetin) but not other flavonoids strongly promoted pollen germination frequency and pollen tube growth in vitro. The best results were obtained at very low concentrations of the flavonols (0.15-1.5 μm), indicating a signaling function. The same compounds were also effective when added during pollen development in vitro.

Anthocyanidins and Flavonols, Major nod Gene Inducers from Seeds of a Black-Seeded Common Bean (Phaseolus vulgaris L.) 1

Hungria, Mariangela; Joseph, Cecillia M.; Phillips, Donald A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /10/1991 EN
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27.21%
Eleven compounds released from germinating seeds of a black-seeded bean (Phaseolus vulgaris L., cv PI165426CS) induce transcription of nod genes in Rhizobium leguminosarum biovar phaseoli. Aglycones from 10 of those compounds were identified by spectroscopic methods (ultraviolet/visible, proton nuclear magnetic resonance, and mass spectroscopy), and their biological activities were demonstrated by induction of β-galactosidase activity in R. leguminosarum strains containing nodA-lacZ or nodC-lacZ fusions controlled by R. leguminosarum biovar phaseoli nodD genes. By making comparisons with authentic standards, the chemical structures for aglycones from the 10 molecules were confirmed as being anthocyanidins (delphinidin, petunidin, and malvidin) and flavonols (myricetin, quercetin, and kaempferol). All anthocyanidins and flavonols had 3-O-glycosylation and free hydroxyl groups at the 4′, 5, and 7 positions. Hydrolysis experiments showed that the mean concentration required for half-maximum nod gene induction (I50) by the 10 glycosides was about half that of the corresponding aglycones. The mean I50 value for the three anthocyanidins (360 nanomolar) was less (P ≤ 0.05) than that of the three flavonol aglycones (980 nanomolar). Each seed released approximately 2500 nanomoles of anthocyanidin and 450 nanomoles of flavonol nod gene inducers in conjugated forms during the first 6 hours of imbibition. Based on amounts and activities of the compounds released...

Flavonols inhibit proinflammatory mediator release, intracellular calcium ion levels and protein kinase C theta phosphorylation in human mast cells

Kempuraj, Duraisamy; Madhappan, Bhuvaneshwari; Christodoulou, Spyridon; Boucher, William; Cao, Jing; Papadopoulou, Nikoletta; Cetrulo, Curtis L; Theoharides, Theoharis C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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Mast cells participate in allergies, and also in immunity and inflammation by secreting proinflammatory cytokines.Flavonoids are naturally occurring polyphenolic plant compounds, one group of which – the flavonols, inhibits histamine and some cytokine release from rodent basophils and mast cells. However, the effect of flavonols on proinflammatory mediator release and their possible mechanism of action in human mast cells is not well defined.Human umbilical cord blood-derived cultured mast cells (hCBMCs) grown in the presence of stem cell factor (SCF) and interleukin (IL)-6 were preincubated for 15 min with the flavonols quercetin, kaempferol, myricetin and morin (0.01, 0.1, 1, 10 or 100 μM), followed by activation with anti-IgE. Secretion was quantitated for IL-6, IL-8, tumor necrosis factor-alpha (TNF-α), histamine and tryptase levels.Release of IL-6, IL-8 and TNF-α was inhibited by 82–93% at 100 μM quercetin and kaempferol, and 31–70% by myricetin and morin. Tryptase release was inhibited by 79–96% at 100 μM quercetin, kampferol and myricetin, but only 39% by morin; histamine release was inhibited 52–77% by the first three flavonols, but only 28% by morin. These flavonols suppressed intracellular calcium ion elevations in a dose–response manner...

Interleukin-6 as a Potential Indicator for Prevention of High Risk Adenoma Recurrence by Dietary Flavonols in the Polyp Prevention Trial

Bobe, Gerd; Albert, Paul S.; Sansbury, Leah B.; Lanza, Elaine; Schatzkin, Arthur; Colburn, Nancy H.; Cross, Amanda J.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
27.49%
Serum interleukin (IL)-6, a pro-inflammatory cytokine, is considered an indicator of inflammation and may be an indicator of colorectal carcinogenesis given that inflammation can promote carcinogenesis. Flavonols, which can be found in fruits and vegetables, may inhibit colorectal carcinogenesis partly by inhibiting inflammation. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) to determine whether serum IL-6 was associated with colorectal adenoma recurrence and flavonol intake and, thus may serve as a risk indicator and as a response indicator to dietary flavonols. Serum IL-6 concentrations at baseline, year 1 and 3 were measured in 872 participants from the intervention arm of the Polyp Prevention Trial, a 4-year trial that examined the effectiveness of a low-fat, high-fiber, high-fruit and vegetable diet on adenoma recurrence. Intake of flavonols, especially of isorhamnetin, kaempferol, and quercetin, was inversely associated with serum IL-6 concentrations (highest vs. lowest flavonol intake quartile, 1.80 vs. 2.20 pg/mL) and high risk (OR = 0.51, 95% CI: 0.26–0.98) and advanced adenoma recurrence (OR = 0.17, 95% CI: 0.06–0.50). A decrease in IL-6 concentration during the trial was inversely associated with high risk (OR = 0.44...

SEPARATION OF THE MINOR FLAVONOLS FROM FLOS GOSSYPII BY HIGH-SPEED COUNTERCURRENT CHROMATOGRAPHY

Yang, Yi; Zhao, Yongxin; Gu, Dongyu; Ayupbek, Amatjan; Huang, Yun; Dou, Jun; Ito, Yoichiro; Zhang, Tianyou; Aisa, Haji Akber
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em 01/01/2010 EN
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27.58%
An effective high-speed countercurrent chromatography (HSCCC) method was established for further separation and purification of four minor flavonols in addition to five major flavonols which were reported by our previous study from extracts of Flos Gossypii. HSCCC was performed with three two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water (7.5:15:6:7, v/v), (2.5:15:2:7, v/v) and (0:1:0:1, v/v). The separation was repeated 3 times, and 3.8 mg of 8-methoxyl-kaempferol-7-O-β-D-rhamnoside (HPLC purity 98.27%), 6.7 mg of astragalin (HPLC purity 94.18%), 3.3 mg of 4′-methoxyl-quercetin-7-O-β-D-glucoside (HPLC purity 94.30%) and 8.2 mg of hyperoside (HPLC purity 93.48%) were separated from 150 mg of the crude sample. The chemical structures of the flavonols were confirmed by MS, 1H NMR and 13C NMR. Meanwhile, the results indicated that the target compound with smaller K value (<0.5) can be separated by increasing column length of HSCCC. And four separation rules of flavonols according to the present study and references were summarized, which can be used as a useful guide for separation of flavonols by HSCCC.

Three-Dimensional Quantitative Structure-Activity Relationship Studies on UGT1A9-Mediated 3-O-Glucuronidation of Natural Flavonols Using a Pharmacophore-Based Comparative Molecular Field Analysis ModelS⃞

Wu, Baojian; Morrow, John Kenneth; Singh, Rashim; Zhang, Shuxing; Hu, Ming
Fonte: The American Society for Pharmacology and Experimental Therapeutics Publicador: The American Society for Pharmacology and Experimental Therapeutics
Tipo: Artigo de Revista Científica
Publicado em /02/2011 EN
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27.76%
Glucuronidation is often recognized as one of the rate-determining factors that limit the bioavailability of flavonols. Hence, design and synthesis of more bioavailable flavonols would benefit from the establishment of predictive models of glucuronidation using kinetic parameters [e.g., Km, Vmax, intrinsic clearance (CLint) = Vmax/Km] derived for flavonols. This article aims to construct position (3-OH)-specific comparative molecular field analysis (CoMFA) models to describe UDP-glucuronosyltransferase (UGT) 1A9-mediated glucuronidation of flavonols, which can be used to design poor UGT1A9 substrates. The kinetics of recombinant UGT1A9-mediated 3-O-glucuronidation of 30 flavonols was characterized, and kinetic parameters (Km, Vmax, CLint) were obtained. The observed Km, Vmax, and CLint values of 3-O-glucuronidation ranged from 0.04 to 0.68 μM, 0.04 to 12.95 nmol/mg/min, and 0.06 to 109.60 ml/mg/min, respectively. To model UGT1A9-mediated glucuronidation, 30 flavonols were split into the training (23 compounds) and test (7 compounds) sets. These flavonols were then aligned by mapping the flavonols to specific common feature pharmacophores, which were used to construct CoMFA models of Vmax and CLint, respectively. The derived CoMFA models possessed good internal and external consistency and showed statistical significance and substantive predictive abilities (Vmax model: q2 = 0.738...

Flavonols Accumulate Asymmetrically and Affect Auxin Transport in Arabidopsis1[C][W][OA]

Kuhn, Benjamin M.; Geisler, Markus; Bigler, Laurent; Ringli, Christoph
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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Flavonoids represent a class of secondary metabolites with diverse functions in plants including ultraviolet protection, pathogen defense, and interspecies communication. They are also known as modulators of signaling processes in plant and animal systems and therefore are considered to have beneficial effects as nutraceuticals. The rol1-2 (for repressor of lrx1) mutation of Arabidopsis (Arabidopsis thaliana) induces aberrant accumulation of flavonols and a cell-growth phenotype in the shoot. The hyponastic cotyledons, aberrant shape of pavement cells, and deformed trichomes in rol1-2 mutants are suppressed by blocking flavonoid biosynthesis, suggesting that the altered flavonol accumulation in these plants induces the shoot phenotype. Indeed, the identification of several transparent testa, myb, and fls1 (for flavonol synthase1) alleles in a rol1-2 suppressor screen provides genetic evidence that flavonols interfere with shoot development in rol1-2 seedlings. The increased accumulation of auxin in rol1-2 seedlings appears to be caused by a flavonol-induced modification of auxin transport. Quantification of auxin export from mesophyll protoplasts revealed that naphthalene-1-acetic acid but not indole-3-acetic acid transport is affected by the rol1-2 mutation. Inhibition of flavonol biosynthesis in rol1-2 fls1-3 restores naphthalene-1-acetic acid transport to wild-type levels...

Probing 3-Hydroxyflavone for In Vitro Glycorandomization of Flavonols by YjiC

Pandey, Ramesh Prasad; Parajuli, Prakash; Koirala, Niranjan; Park, Je Won; Sohng, Jae Kyung
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /11/2013 EN
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27.38%
The glycosylation of five different flavonols, fisetin, quercetin, myricetin, kaempferol, and 3-hydroxyflavone, was achieved by applying YjiC. 3-Hydroxyflavone was selected as a probe for in vitro glycorandomization of all flavonols using diverse nucleotide diphosphate-d/l-sugars. This study unlocked the possibilities of the glycodiversification of flavonols and the generation of novel compounds as future therapeutics.

Flavonol composition of Australian red and white wines determined by high-performance liquid chromatography

Jeffery, D.; Parker, M.; Smith, P.
Fonte: Australian Society of Viticulture and Oenology Publicador: Australian Society of Viticulture and Oenology
Tipo: Artigo de Revista Científica
Publicado em //2008 EN
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Background and Aims: Flavonols are present in Vitis vinifera L. wine grapes as glycosides and are found in wines in both their glycosidic and aglycone forms. Flavonols and their glycosides are important components in wine because of their impact on colour, taste and health properties. An assessment of the flavonols and flavonol glycosides present in a wide selection of Australian red and white wines (n = 121 and 44, respectively) was undertaken. Methods and Results: Analyses were performed using HPLC, with compound identification being aided by HPLC-MS. In the red wines, quercetin and myricetin dominated the flavonol profile, and quercetin-3-glucuronide was by far the most abundant glycoside present. White wines had considerably lower levels of flavonols and their glycosides, in most cases, being below the detection limit of the HPLC method. Conclusions: There appeared to be no correlation between the flavonol profile and wine variety or region in either white or red wines. Contrary to literature reports of rutin in wine, rutin was not found in any of the wines we analysed, and spiking experiments showed rutin rapidly degraded to the aglycone quercetin. Furthermore, changes in elution order for some quercetin glycoside standards were observed depending upon the acid used in the mobile phase. Significance of the Study: This is the first time the flavonol contents of an extensive cross section of Australian wines have been reported. The concentrations are consistent with those reported in wines from other countries. In light of the instability of rutin in wine...

The leishmanicidal flavonols quercetin and quercitrin target Leishmania (Leishmania) amazonensis arginase

da Silva, Edson Roberto; Maquiaveli, Claudia do Carmo; Magalhaes, Prislaine Pupolin
Fonte: ACADEMIC PRESS INC ELSEVIER SCIENCE; SAN DIEGO Publicador: ACADEMIC PRESS INC ELSEVIER SCIENCE; SAN DIEGO
Tipo: Artigo de Revista Científica
ENG
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Polyamine biosynthesis enzymes are promising drug targets for the treatment of leishmaniasis, Chagas' disease and African sleeping sickness. Arginase, which is a metallohydrolase, is the first enzyme involved in polyamine biosynthesis and converts arginine into ornithine and urea. Ornithine is used in the polyamine pathway that is essential for cell proliferation and ROS detoxification by trypanothione. The flavonols quercetin and quercitrin have been described as antitrypanosomal and antileishmanial compounds, and their ability to inhibit arginase was tested in this work. We characterized the inhibition of recombinant arginase from Leishmania (Leishmania) amazonensis by quercetin, quercitrin and isoquercitrin. The IC50 values for quercetin, quercitrin and isoquercitrin were estimated to be 3.8, 10 and 4.3 mu M, respectively. Quercetin is a mixed inhibitor, whereas quercitrin and isoquercitrin are uncompetitive inhibitors of L. (L.) amazonensis arginase. Quercetin interacts with the substrate L-arginine and the cofactor Mn2+ at pH 9.6, whereas quercitrin and isoquercitrin do not interact with the enzyme's cofactor or substrate. Docking analysis of these flavonols suggests that the cathecol group of the three compounds interact with Asp129...

A sensitive microextraction by packed sorbent-based methodology combined with ultra-high pressure liquid chromatography as a powerful technique for analysis of biologically active flavonols in wines

Silva, Catarina L.; Gonçalves, João L.; Câmara, José S.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /08/2012 ENG
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A new approach based on microextraction by packed sorbent (MEPS) and reversed-phase high-throughput ultra high pressure liquid chromatography (UHPLC) method that uses a gradient elution and diode array detection to quantitate three biologically active flavonols in wines, myricetin, quercetin, and kaempferol, is described. In addition to performing routine experiments to establish the validity of the assay to internationally accepted criteria (selectivity, linearity, sensitivity, precision, accuracy), experiments are included to assess the effect of the important experimental parameters such as the type of sorbent material (C2, C8, C18, SIL, and C8/SCX), number of extraction cycles (extract-discard), elution volume, sample volume, and ethanol content, on the MEPS performance. The optimal conditions of MEPS extraction were obtained using C8 sorbent and small sample volumes (250 μL) in five extraction cycle and in a short time period (about 5 min for the entire sample preparation step). Under optimized conditions, excellent linearity View the MathML source(Rvalues2>0.9963), limits of detection of 0.006 μg mL−1 (quercetin) to 0.013 μg mL−1 (myricetin) and precision within 0.5–3.1% were observed for the target flavonols. The average recoveries of myricetin...

Tissue-specific accumulation of flavonoids in grape berries is related to transcriptional expression of VvF3'H and VvF3'5'H

Mu,L.; He,J.-J.; Pan,Q.-H.; He,F.; Duan,C.-Q.
Fonte: South African Journal of Enology and Viticulture Publicador: South African Journal of Enology and Viticulture
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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The products and the related gene expression of flavonoid metabolism were examined in the skin and pulp of Yan73 (Vtis vinifera L. cv.) grapes, a teinturier variety cultivated in China, and the data were compared with those in the skin and pulp of Cabernet Sauvignon (Vitis vinifera L. cv.) grapes, a well-known red variety. The results showed that, in comparison with the skins of Cabernet Sauvignon, the skins of Yan73 berries were characterised by fewer types of flavonols and anthocyanins, a higher level of flavonoids, and a much lower percentage of 3'-hydroxylated flavonols. Flavonoid metabolism was also present in the pulp of Yan73, and the percentages of 3'-hydroxylated flavonols and 3'-hydroxylated flavan-3-ols were significantly higher than the percentages of their corresponding 3',5'-hydroxylated forms. Only flavan-3-ols were found in the pulp of Cabernet Sauvignon. The expression of VvmybAl exhibited a co-ordination with the accumulation of anthocyanins in the pulp of the teinturier cultivar, which showed great similarity to that in the skin. A good correlation was found between the expression of VvF3'H and 3'-hydroxylated flavonoids, as well as between the expression of VvF3'5'H and 3',5'-hydroxylated flavonoids in the skin and pulp of the grape berries. It is suggested that tissue-specific accumulation of flavonoids in grape berries is related to the transcriptional expression of VvF3'H and VvF3'5'H.