Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Metabolomics as a Potential Chemotaxonomical Tool: Application in the Genus Vernonia Schreb
Martucci, M.E.P. ; Vos, R.C.H. de; Carollo, C.A. - \ 2014
PLoS ONE 9 (2014)4. - ISSN 1932-6203 - 8 p.
ericoides mart. asteraceae - mass-spectrometry - sesquiterpene lactones - chlorogenic acids - flavonoids - identification - compositae - amygdalina - saponins - leaves
The taxonomic classification of the genus Vernonia Schreb is complex and, as yet, unclear. We here report the use of untargeted metabolomics approaches, followed by multivariate analyses methods and a phytochemical characterization of ten Vernonia species. Metabolic fingerprints were obtained by accurate mass measurements and used to determine the phytochemical similarities and differences between species through multivariate analyses approaches. Principal component analysis based on the relative levels of 528 metabolites, indicated that the ten species could be clustered into four groups. Thereby, V. polyanthes was the only species with presence of flavones chrysoeriol-7-O-glycuronyl, acacetin-7-O-glycuronyl and sesquiterpenes lactones piptocarphin A and piptocarphin B, while glaucolide A was detected in both V. brasiliana and V. polyanthes, separating these species from the two other species of the Vernonanthura group. Species from the Lessingianthus group were unique in showing a positive response in the foam test, suggesting the presence of saponins, which could be confirmed by metabolite annotation. V. rufogrisea showed a great variety of sesquiterpene lactones, placing this species into a separate group. Species within the Chrysolaena group were unique in accumulating clovamide. Our results of LC-MS-based profiling combined with multivariate analyses suggest that metabolomics approaches, such as untargeted LC-MS, may be potentially used as a large-scale chemotaxonomical tool, in addition to classical morphological and cytotaxonomical approaches, in order to facilitate taxonomical classifications.
Structural annotation and elucidation of conjugated phenolic compounds in black, green, and white tea extracts
Hooft, J.J.J. van der; Akermi, M. ; Yelda Ünlü, F. ; Mihaleva, V. ; Gomez Roldan, V. ; Bino, R.J. ; Vos, R.C.H. de; Vervoort, J.J.M. - \ 2012
Journal of Agricultural and Food Chemistry 60 (2012)36. - ISSN 0021-8561 - p. 8841 - 8850.
pu-erh tea - mass-spectrometry - oolong tea - hplc-dad - lc-msn - liquid-chromatography - chlorogenic acids - camellia-sinensis - purine alkaloids - ellagic acid
Advanced analytical approaches consisting of both LC-LTQ-Orbitrap Fourier transformed (FT)-MS and LC-time-of-flight-(TOF)-MS coupled to solid-phase extraction (SPE) NMR were used to obtain more insight into the complex phenolic composition of tea. On the basis of the combined structural information from (i) accurate mass fragmentation spectra, derived by using LC-Orbitrap FTMS(n), and (ii) proton NMR spectra, derived after LC-TOFMS triggered SPE trapping of selected compounds, 177 phenolic compounds were annotated. Most of these phenolics were glycosylated and acetylated derivatives of flavan-3-ols and flavonols. Principal component analysis based on the relative abundance of the annotated phenolic compounds in 17 commercially available black, green, and white tea products separated the black teas from the green and white teas, with epicatechin-3,5-di-O-gallate and prodelphinidin-O-gallate being among the main discriminators. The results indicate that the combined use of LC-LTQ-Orbitrap FTMS and LC-TOFMS-SPE-NMR leads to a more comprehensive metabolite description and comparison of tea and other plant samples
Identification and quantification of (dihydro) hydroxycinnamic acids and their conjugates in potato by UHPLC–DAD–ESI-MSn
Narvaez Cuenca, C.E. ; Vincken, J.P. ; Gruppen, H. - \ 2012
Food Chemistry 130 (2012)3. - ISSN 0308-8146 - p. 730 - 738.
phenolic-compounds - hplc-dad - lc-msn - liquid-chromatography - chlorogenic acids - mass-spectrometry - brassica-rapa - ascorbic-acid - l. - glycoalkaloids
Hydroxycinnamic acid conjugates (HCAcs) and dihydrohydroxycinamic acid conjugates (DHCAcs) were identified and quantified in potato tuber extracts by UHPLC–DAD–ESI-MSn. The HCAcs and DHCAcs identification took place by screening for product ions and neutral losses in combination with UV spectra. Thirty-nine HCAcs/DHCAcs were detected, including 17 previously reported in potato. HCAs were found unconjugated, linked to hydroxyl-containing compounds including hexose, quinic acid and malic acid, to amino-containing compounds, such as putrescine and octopamine, and to unknown compounds. DHCAs were present linked to spermine, spermidine and to still unidentified compounds. Chlorogenic acid was the most abundant compound (25.43 ± 0.49 mg/g DW) followed by cryptochlorogenic acid (7.31 ± 0.38 mg/g DW), a non-hydrolyzable sinapic acid conjugate (2.80 ± 0.06 mg/g DW) and neochlorogenic acid (2.41 ± 0.10 mg/g DW), in total accounting for 83% (w/w) of the total concentration of HCAs/DHCAs-containing compounds. Quantifications of HCAs released after alkaline hydrolysis matched well with the quantification of the unhydrolyzed molecules. The UHPLC–DAD–ESI-MSn method showed a larger diversity of HCAcs and DHCAcs in potato than described before.
Antimicrobial and efflux pump inhibitory activity of caffeoylquinic acids from Artemisia absinthium against gram-positive pathogenic bacteria.
Fiamegos, Y.C. ; Kastritis, P.L. ; Exarchou, V. ; Han, H. ; Bonvin, A.M. ; Vervoort, J.J.M. ; Lewis, K. ; Hamblin, M.R. ; Tegos, G.P. - \ 2011
PLoS ONE 6 (2011)4. - ISSN 1932-6203 - 12 p.
staphylococcus-aureus - multidrug-resistance - antibiotic-activity - chlorogenic acids - nora - transporter - derivatives - berberine - analogs - protein
Background Traditional antibiotics are increasingly suffering from the emergence of multidrug resistance amongst pathogenic bacteria leading to a range of novel approaches to control microbial infections being investigated as potential alternative treatments. One plausible antimicrobial alternative could be the combination of conventional antimicrobial agents/antibiotics with small molecules which block multidrug efflux systems known as efflux pump inhibitors. Bioassay-driven purification and structural determination of compounds from plant sources have yielded a number of pump inhibitors which acted against gram positive bacteria. Methodology/Principal Findings In this study we report the identification and characterization of 4',5'-O-dicaffeoylquinic acid (4',5'-ODCQA) from Artemisia absinthium as a pump inhibitor with a potential of targeting efflux systems in a wide panel of Gram-positive human pathogenic bacteria. Separation and identification of phenolic compounds (chlorogenic acid, 3',5'-ODCQA, 4',5'-ODCQA) was based on hyphenated chromatographic techniques such as liquid chromatography with post column solid-phase extraction coupled with nuclear magnetic resonance spectroscopy and mass spectroscopy. Microbial susceptibility testing and potentiation of well know pump substrates revealed at least two active compounds; chlorogenic acid with weak antimicrobial activity and 4',5'-ODCQA with pump inhibitory activity whereas 3',5'-ODCQA was ineffective. These intitial findings were further validated with checkerboard, berberine accumulation efflux assays using efflux-related phenotypes and clinical isolates as well as molecular modeling methodology. Conclusions/Significance These techniques facilitated the direct analysis of the active components from plant extracts, as well as dramatically reduced the time needed to analyze the compounds, without the need for prior isolation. The calculated energetics of the docking poses supported the biological information for the inhibitory capabilities of 4',5'-ODCQA and furthermore contributed evidence that CQAs show a preferential binding to Major Facilitator Super family efflux systems, a key multidrug resistance determinant in gram-positive bacteria.
Stress -induced biosynthesis of dicaffeoylquinic acids in globe artichoke
Moglia, A. ; Lanteri, S. ; Comino, C. ; Acquadro, A. ; Vos, C.H. de; Beekwilder, M.J. - \ 2008
Journal of Agricultural and Food Chemistry 56 (2008)18. - ISSN 0021-8561 - p. 8641 - 8649.
cynara-scolymus l. - leaf extract - lc-msn - antioxidant activity - phenolic-compounds - chlorogenic acids - mass-spectrometry - rat hepatocytes - b radiation - metabolism
Leaf extracts from globe artichoke (Cynara cardunculus L. var. scolymus) have been widely used in medicine as hepatoprotectant and choleretic agents. Globe artichoke leaves represent a natural source of phenolic acids with dicaffeoylquinic acids, such as cynarin (1,3-dicaffeoylquinic acid), along with its biosynthetic precursor chlorogenic acid (5-caffeoylquinic acid) as the most abundant molecules. This paper reports the development of an experimental system to induce caffeoylquinic acids. This system may serve to study the regulation of the biosynthesis of (poly)phenolic compounds in globe artichoke and the genetic basis of this metabolic regulation. By means of HPLC-PDA and accurate mass LC-QTOF MS and MS/MS analyses, the major phenolic compounds in globe artichoke leaves were identified: four isomers of dicaffeoylquinic acid, three isomers of caffeoylquinic acid, and the flavone luteolin 7-glucoside. Next, plant material was identified in which the concentration of phenolic compounds was comparable in the absence of particular treatments, with the aim to use this material to test the effect of stress application on the regulation of biosynthesis of caffeoylquinic acids. Using this material, the effect of UV-C, methyl jasmonate, and salicylic acid treatments on (poly)phenolic compounds was tested in different globe artichoke genotypes. UV-C exposure consistently increased the levels of dicaffeoylquinic acids in all genotypes, whereas the effect on compounds from the same biosynthetic pathway, for example, chlorogenic acid and luteolin-7-glucoside, was much less pronounced and was not statistically significant. No effect of methyl jasmonate or salicylic acid was found. Time-response experiments indicated that the level of dicaffeoylquinic acids reached a maximum at 24 h after UV radiation. On the basis of these results a role of dicaffeoylquinic acids in UV protection in globe artichoke is hypothesized.
Electron Spin Resonance (ESR) Studies on the Formation of Roasting-Induced Antioxidative Structures in Coffee Brews at Different Degrees of Roast
Bekedam, E.K. ; Schols, H.A. ; Cämmerer, B. ; Kroh, L.W. ; Boekel, M.A.J.S. van; Smit, G. - \ 2008
Journal of Agricultural and Food Chemistry 56 (2008)12. - ISSN 0021-8561 - p. 4597 - 4604.
chemical-characterization - thermal-degradation - chlorogenic acids - model systems - melanoidins - capacity - foods - beverages - green
The antioxidative properties of coffee brew fractions were studied using electron spin resonance spectroscopy using 2,2,6,6-tetramethyl-1-piperidin-1-oxyl (TEMPO) and Fremy¿s salt (nitrosodisulfonate) as stabilized radicals. TEMPO was scavenged by antioxidants formed during roasting and not by chlorogenic acid, whereas Fremy¿s salt was scavenged by all antioxidants tested including chlorogenic acid. The stabilized radical TEMPO allowed the exclusive measurement of roasting-induced antioxidants. The roasting-induced antioxidant activity of coffee brews increased with increasing degree of roast, and most of these antioxidants were formed during the initial roasting stage. The majority of these roasting-induced antioxidants were present in the high molecular weight fractions, indicating that the formation of these antioxidants preferably occurs at specific high molecular weight structures, likely being arabinogalactan and/or protein moieties which might be part of the melanoidin complex. It was found that chlorogenic acids most probably do not lose their antioxidant activity and phenolic characteristics upon incorporation in coffee melanoidins. The parameter fast reacting antioxidants (FRA) was introduced as an alternative for the antioxidative potential. FRA levels showed that coffee fractions rich in roasting-induced antioxidants exposed their antioxidant activity relatively slowly, which must be a consequence of its complex structure. Finally, the melanoidin content and the roasting-induced antioxidant activity showed a positive and linear correlation for the coffee brew fractions, showing that roasting-induced antioxidants are present within melanoidins. This is the first time that the formation of roasting-induced antioxidants could be directly correlated with the extent of Maillard reaction and melanoidin formation in a complex product such as coffee.
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