The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform

Pierre Louis Teissedre - One of the best experts on this subject based on the ideXlab platform.

  • comparative evaluation of the phenolic content and antioxidant capacity of sun dried raisins
    Journal of the Science of Food and Agriculture, 2013
    Co-Authors: Hasim Kelebek, Michael Jourdes, Serkan Selli, Pierre Louis Teissedre
    Abstract:

    BACKGROUND Raisins are one of the favorite dried fruit because of their high healthful and nutrimental values. Three white (Besni beyazi-BBR, Hatun parmagi-HPR and Sultaniye-SR) and two red (Antep karasi-AKR and Besni karasi-BKR) grape varieties were used in the present study. The aim of this study was to determine and compare the phenolic composition and antioxidant properties of Turkish raisins. RESULTS Four flavan-3-ols, six phenolic acids, four Flavonols and 13 anthocyanins were identified and quantified in raisins. (+)-Catechin (range, 56.3–419 mg kg−1) was the mosst abundant flavanol, trans-caftaric acid (range, 20.48–114 mg kg−1) was the abundant dominannt phenol acid, quercetin-3-O-glucoside (range, 2.79–12.83 mg kg−1) was the dominant Flavonoll and malvidin-3-O-(6-O-p-coumaroyl)-glucoside (range, 16.75–22.59 mg kg−1) wass the major anthocyanin in all raisins. Antioxidant capacity were 22.69–63.66, 5.07–40.47, 7.00–17.69 and 40.d 40.74–77.41 mmol Trolox kg−1 as determined bby the ABTS, DPPH, FRAP and ORAC assays, respectively. CONCLUSIONS 27 phenolic compounds from four phenolic families (i.e. flavan-3-ols, phenolic acids, Flavonols and anthocyanins) have been characterised in the raisins of three white and two red grapes. The total phenolic and anthocyanins content vary widely among different raisins. Strong correlations between antioxidative capacity and phenolic content and between antioxidative capacity and Flavonol content were noticed. © 2013 Society of Chemical Industry

  • Comparative evaluation of the phenolic content and antioxidant capacity of sun-dried raisins
    Journal of the Science of Food and Agriculture, 2013
    Co-Authors: Hasim Kelebek, Michael Jourdes, Serkan Selli, Pierre Louis Teissedre
    Abstract:

    BACKGROUND Raisins are one of the favorite dried fruit because of their high healthful and nutrimental values. Three white (Besni beyazi-BBR, Hatun parmagi-HPR and Sultaniye-SR) and two red (Antep karasi-AKR and Besni karasi-BKR) grape varieties were used in the present study. The aim of this study was to determine and compare the phenolic composition and antioxidant properties of Turkish raisins. RESULTS Four flavan-3-ols, six phenolic acids, four Flavonols and 13 anthocyanins were identified and quantified in raisins. (+)-Catechin (range, 56.3-419 mg kg(-1)) was the mosst abundant flavanol, trans-caftaric acid (range, 20.48-114 mg kg(-1)) was the abundant dominannt phenol acid, quercetin-3-O-glucoside (range, 2.79-12.83 mg kg(-1)) was the dominant Flavonoll and malvidin-3-O-(6-O-p-coumaroyl)-glucoside (range, 16.75-22.59 mg kg(-1)) wass the major anthocyanin in all raisins. Antioxidant capacity were 22.69-63.66, 5.07-40.47, 7.00-17.69 and 40.d 40.74-77.41mmol Trolox kg(-1) as determined bby the ABTS, DPPH, FRAP and ORAC assays, respectively. CONCLUSIONS 27 phenolic compounds from four phenolic families (i.e. flavan-3-ols, phenolic acids, Flavonols and anthocyanins) have been characterised in the raisins of three white and two red grapes. The total phenolic and anthocyanins content vary widely among different raisins. Strong correlations between antioxidative capacity and phenolic content and between antioxidative capacity and Flavonol content were noticed.

  • Characterization of colored and colorless phenolic compounds in Öküzgözü wines from Denizli and Elazig regions using HPLC-DAD–MS
    Industrial Crops and Products, 2010
    Co-Authors: Hasim Kelebek, Michael Jourdes, Ahmet Canbas, Pierre Louis Teissedre
    Abstract:

    Characterization of colored and colorless phenolic compounds of wines from Öküzgözü, a native grape variety grown in Turkey and influence of different vineyard locations on these compounds were investigated. High performance liquid chromatography-diode array detector (HPLC-DAD) and mass spectrometry (MS) were used for the phenolic compounds analysis. Fourteen anthocyanins, six flavanols, twelve phenolic acids and six Flavonols were identified and quantified. It was observed that total phenolic content of Denizli region wines was clearly higher than Elazig wines. Malvidin-3-O-glucoside and its acylated esters was the most dominant anthocyanin, (+)-catechin was the most dominant flavanol, trans-caftaric acid was the most dominant phenol acid and myricetin-3-O-glucoside the most dominant Flavonol in both regions’ wines. Sensory analysis has also been used in investigating wines deriving from the two different vineyard locations. Based upon sensory analysis, wines from Denizli region was preferred due to better color, harmony, flavor and body attributes.

Jesus Simalgandara - One of the best experts on this subject based on the ideXlab platform.

  • pattern recognition of three vitis vinifera l red grapes varieties based on anthocyanin and Flavonol profiles with correlations between their biosynthesis pathways
    Food Chemistry, 2012
    Co-Authors: M Figueiredogonzalez, Elena Martinezcarballo, B Canchogrande, J L Santiago, M C Martinez, Jesus Simalgandara
    Abstract:

    The presence of anthocyanins and Flavonols in three selected red grape varieties was investigated, in order to use their polyphenolic characterisation as a fingerprint. Berry skins of Gran Negro grapes were characterised by the presence of high content of malvidin- and peonidin-3-O-glucoside; Mouraton grapes, by the presence of high content of petunidin- and delphinidin-3-O-glucoside; and Brancellao grapes, by the presence of high content of cyanidin-3-O-glucoside. The main Flavonols found included the 3-O-glucosides of quercetin, myricetin, kaempferol, laricitrin, isorhamnetin and syringetin. Using cluster analysis and principal components analysis, Gran Negro could be characterised by their content of isorhamnetin-3-O-glucoside and syringetin-3-O-glucoside and, along with Mouraton, by their myricetin conjugates. Flavonol profile could not provide a fingerprint of Brancellao variety. Stepwise discriminant analysis was performed in order to find the polyphenolic compounds, which characterised the selected grape varieties. Finally, anthocyanin and Flavonol profiles in red grapes were compared and results confirmed that biosynthesis of Flavonols is closely related to that of anthocyanins.

  • changes in antioxidant flavonoids during freeze drying of red onions and subsequent storage
    Food Control, 2011
    Co-Authors: M R Perezgregorio, Jorge Regueiro, C Gonzalezbarreiro, R Rialotero, Jesus Simalgandara
    Abstract:

    Abstract The aim of this study was to elucidate the effect of the freeze-drying process and storage on onion flavonoids content. Major Flavonols of a mature red onion bulb were confirmed as quercetin derivatives (3,4′-O-diglucoside (Qdg) and 4′-O-monoglucoside (Qmg)) using a combination of chromatographic comparisons, UV–visible spectra and scientific literature data. These two components account for about a 93% of the total Flavonols (334 ± 60 mg Q kg−1, fresh weight), and are the main responsible for the IC50 antioxidant activity of 15.84 ± 3.73 g/kg. The remaining Flavonol fraction (approx. 7%) comprises up to 8 different components of which quercetin-3-O-glucoside and isorhamnetin-4-glucoside are prominent members although each contribute less than 3% of the total Flavonol fraction; instead, quercetin represents less than 1% of total Flavonols. In this red onion, eight anthocyanins (which represent less than 1% of total Flavonols) were also found at a total level of 2.1 ± 0.05 mg C3g kg−1 (fresh weight). Anyway, 4 of them (cyanidin 3-glucoside (C3g) > cyanidin 3-(6′′-malonylglucoside) (C3,6mg) > cyanidin 3-(6′′- malonyl-laminaribioside) (C3,6mlmb) > cyanidin 3-laminaribioside (C3lmb)) account for the 95% of total anthocyanins. Freeze-drying process concludes in an increase in the extraction of flavonoids up to a 32% for Flavonols and 25% for anthocyanins. Freeze-dried onion powder storage at room temperature, in dark, in air- and water-tight glass bottles for up to 6 months was keeping rather stable all flavonoids.

  • identification and quantification of flavonoids in traditional cultivars of red and white onions at harvest
    Journal of Food Composition and Analysis, 2010
    Co-Authors: Rosa Perezgregorio, M S Garciafalcon, Jesus Simalgandara, Ana Sofia Rodrigues, Domingos P F Almeida
    Abstract:

    Abstract Onions are rich in different types of phenolics, mainly Flavonols, and in red varieties anthocyanins are also present. This is significant because these classes of phenolics are antioxidants and hence may impart important functional properties to onions. The aim of the present work was to simultaneously determine Flavonol and anthocyanin concentrations in different onion varieties, two white (Branca da Povoa and the hybrid SK409) and three red (landrace Vermelha da Povoa, a selected line of Vermelha da Povoa and Red Creole). Flavonols (quercetin 7,4-diglucoside, quercetin 3,4-diglucoside, isorhamnetin 3,4-diglucoside, quercetin 3-glucoside, quercetin 4-glucoside and isorhamnetin 4-glucoside) were the predominant polyphenolic compounds. White cultivars had the lowest total Flavonol content, with values of 89.3 ± 38.5 and 101.0 ± 18.9 mg quercetin/kg fresh weight for Branca da Povoa and the hybrid SK409, respectively. The red onions had the highest levels of Flavonols, especially the selected population of Vermelha da Povoa and Red Creole, with values of 280.2 ± 41.5 and 304.3 ± 81.2 mg quercetin/kg fresh weight, respectively. Red onions are not only richer in Flavonols, but also contain anthocyanins. Four anthocyanins (cyanidin 3-glucoside, cyanidin 3-laminaribioside, cyanidin 3-(6″-malonylglucoside), and cyanidin 3-malonylaminaribioside) were quantified in all red onions, with Red Creole presenting the highest concentration (28.6 ± 8 mg cyanidin/kg fresh weight). Red onions may be recommended for their major potential functional properties. A distinct gradient in total flavonoid content was found between the outer, central and inner edible scales and along the longitudinal axis of the bulb. Differences in Flavonol levels between small- and large-sized onions were also found. All of these factors are of paramount importance for sampling and characterizing onions with regard to flavonoids.

Alan Crozier - One of the best experts on this subject based on the ideXlab platform.

  • Antioxidant Flavonols from fruits, vegetables and beverages: measurements and bioavailability.
    Biological research, 2000
    Co-Authors: Alan Crozier, Azlina Abdul Aziz, Jennifer Burns, Amanda J. Stewart, Helena S Rabiasz, Gareth I. Jenkins, Christine A. Edwards, Michael E. J. Lean
    Abstract:

    Flavonols are polyphenolic secondary plant metabolites that are present in varying levels in commonly consumed fruits, vegetables and beverages. Flavonols have long held an interest for nutritionists, which has increased following a Dutch study in the early 1990’s showing that dietary intake of Flavonols was inversely correlated with the incidence of coronary heart disease. The main factors that have hindered workers in the field of Flavonol research are (i) the accurate measurement of these compounds in foods and biological samples, and (ii) a dearth of information on their absorption and metabolism. This review aims to highlight the work of the authors in attempting to clarify the situation. The sensitive and selective HPLC procedure to identify and quantify common Flavonols and their sugar conjugates is described. In addition, the results of an on-going screening program into the Flavonol content of common produce and beverages are presented. The bioavailability of dietary Flavonols is discussed with reference to an intervention study with onions, as well as pilot studies with tea, red wine and cherry tomatoes. It is concluded that Flavonols are absorbable and accumulate in plasma and that consuming high Flavonol-containing varieties of fruits and vegetables and particular types of beverages could increase their circulatory levels

  • Occurrence of Flavonols in tomatoes and tomato-based products
    Journal of agricultural and food chemistry, 2000
    Co-Authors: Amanda J. Stewart, Gareth I. Jenkins, Michael E. J. Lean, Sophie Bozonnet, William Mullen, Alan Crozier
    Abstract:

    The Flavonol contents of 20 varieties of tomato fruit were investigated in relation to variety, size, season, and country of origin. Ten commonly consumed tomato-based food products were also assessed. Free and conjugated Flavonols were identified and quantified using reversed-phase HPLC. Ninety-eight percent of Flavonols detected in tomatoes were found to occur in the skin. Tomatoes contained, primarily as conjugates, quercetin and kaempferol. The main quercetin conjugate was identified as rutin (quercetin 3-rhamnosylglucoside) by LC-MS. The total Flavonol content of the different varieties of tomato that were analyzed varied from 1.3 to 22.2 microgram/g of fresh weight (fw). Smaller cherry tomato fruits originating from warm sunny climates, such as Spain and Israel, were found to contain the highest concentration of Flavonols. Among the tomato-based products investigated, tomato juice and tomato puree were rich in Flavonols, containing 14-16 microgram/mL and 70 microgram/g fw, respectively. In contrast to fresh tomatoes, most tomato-based products contained significant amounts of free Flavonols.

Joseph M Awika - One of the best experts on this subject based on the ideXlab platform.

  • ultra performance liquid chromatography tandem quadrupole mass spectrometry profiling of anthocyanins and Flavonols in cowpea vigna unguiculata of varying genotypes
    Journal of Agricultural and Food Chemistry, 2012
    Co-Authors: Leonnard O Ojwang, Linda Dykes, Joseph M Awika
    Abstract:

    The structure of flavonoids in food plants affects bioactivity and important nutritional attributes, like micronutrient bioavailability. This study investigated Flavonol and anthocyanin compositions of cowpea (Vigna unguiculata) of varying genotypes. Black, red, green, white, light brown, and golden brown cowpea phenotypes were analyzed for anthocyanins and Flavonols using ultra performance liquid chromatography–tandem quadrupole mass spectrometry. Eight anthocyanins and 23 Flavonols (15 newly identified in cowpea) were characterized. Mono-, di-, and tri(acyl)glycosides of quercetin were predominant in most phenotypes; myricetin and kaempferol glycosides were present only in specific phenotypes. The red phenotypes had the highest Flavonol content (880–1060 μg/g), whereas green and white phenotypes had the lowest (270–350 μg/g). Only black (1676–2094 μg/g) and green (875 μg/g) phenotypes had anthocyanins, predominantly delphinidin and cyanidin 3-O-glucosides. Cowpea phenotype influenced the type and amount...

Ralf Stracke - One of the best experts on this subject based on the ideXlab platform.

  • natural variation in Flavonol accumulation in arabidopsis is determined by the Flavonol glucosyltransferase bglu6
    Journal of Experimental Botany, 2016
    Co-Authors: Hirofumi Ishihara, Bernd Weisshaar, Takayuki Tohge, Prisca Viehover, Alisdair R Fernie, Ralf Stracke
    Abstract:

    Flavonols are colourless secondary metabolites, primarily regarded as UV-protection pigments that are deposited in plants in their glycosylated forms. The glycosylation of Flavonols is mainly catalysed by UDP-sugar-dependent glycosyltransferases (UGTs). Although the structures of Flavonol glycosides accumulating in Arabidopsis thaliana are known, many genes involved in the flavonol glycosylation pathway are yet to be discovered. The Flavonol glycoside profiles of seedlings from 81 naturally occurring A. thaliana accessions were screened using high performance thin layer chromatography. A qualitative variation in Flavonol 3-O-gentiobioside 7-O-rhamnoside (F3GG7R) content was identified. Ler × Col-0 recombinant inbred line mapping and whole genome association mapping led to the identification of a glycoside hydrolase family 1-type gene, At1g60270/BGLU6, that encodes a homolog of acyl-glucose-dependent glucosyltransferases involved in the glycosylation of anthocyanins, possibly localized in the cytoplasm, and that is co-expressed with genes linked to phenylpropanoid biosynthesis. A causal single nucleotide polymorphism introducing a premature stop codon in non-producer accessions was found to be absent in the producers. Several other naturally occurring loss-of-function alleles were also identified. Two independent bglu6 T-DNA insertion mutants from the producer accessions showed loss of F3GG7R. Furthermore, bglu6 mutant lines complemented with the genomic Ler BGLU6 gene confirmed that BGLU6 is essential for production of F3GGR7. We have thus identified an accession-specific gene that causes a qualitative difference in Flavonol glycoside accumulation in A. thaliana strains. This gene encodes a Flavonol 3-O-glucoside: 6″-O-glucosyltransferase that does not belong to the large canonical family of Flavonol glycosyltransferases that use UDP-conjugates as the activated sugar donor substrate.

  • the grapevine r2r3 myb transcription factor vvmybf1 regulates Flavonol synthesis in developing grape berries
    Plant Physiology, 2009
    Co-Authors: Stefan Czemmel, Ralf Stracke, Bernd Weisshaar, Nicole Jane Cordon, Nilangani N Harris, Amanda R Walker, Simon P Robinson, Jochen Bogs
    Abstract:

    Flavonols are important ultraviolet light protectants in many plants and contribute substantially to the quality and health-promoting effects of fruits and derived plant products. To study the regulation of Flavonol synthesis in fruit, we isolated and characterized the grapevine (Vitis vinifera 'Shiraz') R2R3-MYB transcription factor VvMYBF1. Transient reporter assays established VvMYBF1 to be a specific activator of Flavonol synthase1 (VvFLS1) and several other promoters of grapevine and Arabidopsis (Arabidopsis thaliana) genes involved in Flavonol synthesis. Expression of VvMYBF1 in the Arabidopsis mutant myb12 resulted in complementation of its Flavonol-deficient phenotype and confirmed the function of VvMYBF1 as a transcriptional regulator of Flavonol synthesis. Transcript analysis of VvMYBF1 throughout grape berry development revealed its expression during flowering and in skins of ripening berries, which correlates with the accumulation of Flavonols and expression of VvFLS1. In addition to its developmental regulation, VvMYBF1 expression was light inducible, implicating VvMYBF1 in the control of VvFLS1 transcription. Sequence analysis of VvMYBF1 and VvFLS1 indicated conserved putative light regulatory units in promoters of both genes from different cultivars. By analysis of the VvMYBF1 amino acid sequence, we identified the previously described SG7 domain and an additional sequence motif conserved in several plant MYB factors. The described motifs have been used to identify MYB transcription factors from other plant species putatively involved in the regulation of Flavonol biosynthesis. To our knowledge, this is the first functional characterization of a light-inducible MYB transcription factor controlling Flavonol synthesis in fruit.

  • Arabidopsis thaliana expresses a second functional Flavonol synthase
    FEBS letters, 2009
    Co-Authors: Anja Preuss, Ulrich Matern, Ralf Stracke, Bernd Weisshaar, Alexander Hillebrecht, Stefan Martens
    Abstract:

    Arabidopsis thaliana L. produces flavonoid pigments, i.e. Flavonols, anthocyanidins and proanthocyanidins, from dihydroFlavonol substrates. A small family of putative Flavonol synthase (FLS) genes had been recognized in Arabidopsis, and functional activity was attributed only to FLS1. Nevertheless, other FLS activities must be present, because A. thalianafls1 mutants still accumulate significant amounts of Flavonols. The recombinant FLSs and leucoanthocyanidin dioxygenase (LDOX) proteins were therefore examined for their enzyme activities, which led to the identification of FLS3 as a second active FLS. This enzyme is therefore likely responsible for the formation of Flavonols in the ldox/fls1-2 double mutant. These double mutant and biochemical data demonstrate for the first time that LDOX is capable of catalyzing the in planta formation of Flavonols.