Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

    Current refinement(s):

    Records 1 - 13 / 13

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    Peroxidase Can Perform the Hydroxylation Step in the "oxidative Cascade" during Oxidation of Tea Catechins
    Verloop, Annewieke J.W. ; Vincken, Jean Paul ; Gruppen, Harry - \ 2016
    Journal of Agricultural and Food Chemistry 64 (2016)42. - ISSN 0021-8561 - p. 8002 - 8009.
    black tea - hydroxylation - peroxidase - theatridimensins - tyrosinase - UHPLCâMS/MS

    The formation of black tea thearubigins involves at least two of the following oxidation steps: (i) oligomerization, (ii) rearrangement, and (iii) hydroxylation. The first two are mainly catalyzed by polyphenol oxidase (PPO), whereas the enzyme responsible for hydroxylation has not yet been identified. Two main oxidative activities, peroxidase (POD) and PPO, occur in tea leaves. POD was hypothesized to be responsible for hydroxylation. Model systems with horseradish POD and mushroom tyrosinase were used investigating hydroxylation of theaflavins (TFs). POD was found capable of hydroxylation. TFs with up to five extra hydroxyl groups were annotated by their MS2 data. Hydroxylation by POD was also shown for theanaphtoquinones, theatridimensins, and dehydrodicatechins. The H2O2 concentration influenced the extent of hydroxylation, decreasing it at concentrations above 0.01 mM. TFs with up to five extra hydroxyl groups and traces of other hydroxylated oligomeric catechins could be annotated in black tea without any sample pretreatment, using a selective screening method with reversed-phase ultrahigh-performance liquid chromatography mass spectrometry.

    Annotation of Different Dehydrocatechin Oligomers by MS/MS and Their Occurrence in Black Tea
    Verloop, Annewieke J.W. ; Gruppen, Harry ; Vincken, Jean Paul - \ 2016
    Journal of Agricultural and Food Chemistry 64 (2016)30. - ISSN 0021-8561 - p. 6011 - 6023.
    black tea - catechins - dehydrocatechins - MALDI-TOF-MS - procyanidins - tyrosinase - UHPLC-MS/MS

    Dehydrocatechins (DhC's), oligomeric oxidation products of (epi)catechins, were formed in model incubations of epicatechin with mushroom tyrosinase. DhC oligomers up to tetramers were detected by reversed-phase ultrahigh-performance liquid chromatography mass spectrometry (RP-UHPLC-MS) analysis. Measurements with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) showed formation of oligomers up to at least 15 catechin subunits. Isomeric DhC's were obtained, and a method based on MS2 fragment ratios was set up to distinguish between the different interflavanic configurations of the isomers. In the model incubation, 8 dehydrodicatechins (DhC2's) and 22 dehydrotricatechins (DhC3's) were tentatively annotated by their MS2 signature fragments. Three different interflavanic configuration types were determined for the DhC2's. DhC2's and DhC3's were shown to occur in a black tea extract for the first time. For the DhC2's, at least two isomeric types, i.e., DhC β and DhC ϵ, could be annotated in black tea.

    Coffee and tea consumption, genotype-based CYP1A2 and NAT2 activity and colorectal cancer risk—Results from the EPIC cohort study
    Dik, V.K. ; Bueno-de-Mesquita, H.B. ; Oijen, M.G.C.T. van; Siersema, P.D. ; Uiterwaal, C.S.P.M. ; Gils, C.H. van; Duijnhoven, F.J.B. van - \ 2014
    International Journal of Cancer 135 (2014)2. - ISSN 0020-7136 - p. 401 - 412.
    colonic aberrant crypts - green tea - components kahweol - black tea - caffeine - cafestol - polyphenols - health - cells - rat
    Coffee and tea contain numerous antimutagenic and antioxidant components and high levels of caffeine that may protect against colorectal cancer (CRC). We investigated the association between coffee and tea consumption and CRC risk and studied potential effect modification by CYP1A2 and NAT2 genotypes, enzymes involved in the metabolization of caffeine. Data from 477,071 participants (70.2% female) of the European Investigation into Cancer and Nutrition (EPIC) cohort study were analyzed. At baseline (1992–2000) habitual (total, caffeinated and decaffeinated) coffee and tea consumption was assessed with dietary questionnaires. Cox proportional hazards models were used to estimate adjusted hazard ratio's (HR) and 95% confidence intervals (95% CI). Potential effect modification by genotype-based CYP1A2 and NAT2 activity was studied in a nested case–control set of 1,252 cases and 2,175 controls. After a median follow-up of 11.6 years, 4,234 participants developed CRC (mean age 64.7¿±¿8.3 years). Total coffee consumption (high vs. non/low) was not associated with CRC risk (HR 1.06, 95% CI 0.95–1.18) or subsite cancers, and no significant associations were found for caffeinated (HR 1.10, 95% CI 0.97–1.26) and decaffeinated coffee (HR 0.96, 95% CI 0.84–1.11) and tea (HR 0.97, 95% CI 0.86–1.09). High coffee and tea consuming subjects with slow CYP1A2 or NAT2 activity had a similar CRC risk compared to non/low coffee and tea consuming subjects with a fast CYP1A2 or NAT2 activity, which suggests that caffeine metabolism does not affect the link between coffee and tea consumption and CRC risk. This study shows that coffee and tea consumption is not likely to be associated with overall CRC.
    Consumption of both low and high (-)-epicatechin apple puree attenuates platelet reactivity and increases plasma concentrations of nitric oxide metabolites: A randomized controlled trial
    Gasper, A. ; Hollands, W. ; Casgrain, A. ; Saha, S. ; Teucher, B. ; Dainty, J.R. ; Venema, D.P. ; Hollman, P.C.H. - \ 2014
    Archives of Biochemistry and Biophysics 559 (2014). - ISSN 0003-9861 - p. 29 - 37.
    flavanol-rich cocoa - reduces blood-pressure - green tea catechins - black tea - grape juice - endothelial dysfunction - regular ingestion - food sources - red wine - in-vivo
    We hypothesised that consumption of flavanol-containing apple puree would modulate platelet activity and increase nitric oxide metabolite status, and that high flavanol apple puree would exert a greater effect than low flavanol apple puree. 25 subjects consumed 230 g of apple puree containing 25 and 100 mg epicatechin (low and high flavanol apple puree, respectively) and aspirin (75 mg) in random order. Measurements were made at baseline, acutely after treatment (2, 6 and 24 h), and after 14 d of treatment. Low flavanol apple puree significantly attenuated ADP and epinephrine-induced integrin-ß3 expression 2 h and 6 h after consumption and ADP and epinephrine-induced P-selectin expression within 2 h of consumption. High flavanol apple puree attenuated epinephrine and ADP-induced integrin-ß3 expression after 2 and 6 h. ADP and epinephrine-induced integrin-ß3 expression was significantly attenuated 2, 6 and 24 h after consumption of aspirin, whilst 14 d aspirin consumption attenuated collagen-induced P-selectin expression only. The plasma total nitric oxide metabolite conc. was significantly increased 6 h after consumption of both low and high flavanol apple purees. In conclusion, consumption of apple purees containing ¿25 or 100 mg flavanols transiently attenuated ex vivo integrin-ß3 and P-selectin expression and increased plasma nitric oxide metabolite conc. in healthy subjects, but the effect was not enhanced for the high flavanol apple puree.
    Population-based nutrikinetic modelling of phytochemical exposure
    Velzen, E.J.J. van; Westerhuis, J.A. ; Grün, C.H. ; Duynhoven, J.P.M. van; Jacobs, D.M. ; Eilers, P.H.C. ; Mulder, T.P. ; Foltz, M. ; Garczarek, U. ; Kemperman, R. ; Vaughan, E.E. ; Smilde, A.K. - \ 2014
    Metabolomics 10 (2014)6. - ISSN 1573-3882 - p. 1059 - 1073.
    red wine/grape juice - black tea - dietary polyphenols - phenolic metabolites - nutrition research - food sources - human plasma - green tea - gut model - pharmacokinetics
    The beneficial health effects of fruits and vegetables have been attributed to their polyphenol content. These compounds undergo many bioconversions in the body. Modeling polyphenol exposure of humans upon intake is a prerequisite for understanding the modulating effect of the food matrix and the colonic microbiome. This modeling is not a trivial task and requires a careful integration of measuring techniques, modeling methods and experimental design. Moreover, both at the population level as well as the individual level polyphenol exposure has to be quantified and assessed. We developed a strategy to quantify polyphenol exposure based on the concept of nutrikinetics in combination with population-based modeling. The key idea of the strategy is to derive nutrikinetic model parameters that summarize all information of the polyphenol exposure at both individual and population level. This is illustrated by a placebo-controlled crossover study in which an extract of wine/grapes and black tea solids was administered to twenty subjects. We show that urinary and plasma nutrikinetic time-response curves can be used for phenotyping the gut microbial bioconversion capacity of individuals. Each individual harbours an intrinsic microbiota composition converting similar polyphenols from both test products in the same manner and stable over time. We demonstrate that this is a novel approach for associating the production of two gut-mediated ¿-valerolactones to specific gut phylotypes. The large inter-individual variation in nutrikinetics and ¿-valerolactones production indicated that gut microbial metabolism is an essential factor in polyphenol exposure and related potential health benefits
    Solvent exchange module for LC-NMR hyphenation using machine vision-controlled droplet evaporation
    Schoonen, J.W. ; Vulto, P. ; Roo, N. de; Duynhoven, J.P.M. van; Linden, H. van der; Hankemeier, T. - \ 2013
    Analytical Chemistry 85 (2013)12. - ISSN 0003-2700 - p. 5734 - 5739.
    solid-phase extraction - nuclear-magnetic-resonance - red wine/grape juice - ms-spe-nmr - natural-products - liquid-chromatography - flow probe - black tea - identification - system
    We report the use of pendant droplet evaporation for exchange of eluents for 1H nuclear magnetic resonance (1H NMR) purposes. Analytes are fed and retained in 500 nL droplets, which are concentrated by evaporation and subsequently redissolved in deuterated solvent. Droplet size is monitored by machine vision (MV), and heating rates are adjusted concordingly to maintain a stable droplet volume. Evaporation control is independent of solvent properties, and the setup handles feed rates up to 7 µL min–1. The interface is capable of exchanging up to 90% of solvent for deuterated solvent, with a good recovery and repeatability for tomato extracts (Solanum lycopersicum). The system was capable of handling both polar and nonpolar analytes in one run. Volatiles such as formate, acetate, and lactate and the thermosensitive compound epigallocatechin gallate were recovered without significant losses. Ethanol and propionate were recovered with significant losses due to the formation of a minimum boiling azeotrope. The current setup is ideally suited for on- and off-line hyphenation of liquid chromatography and NMR, as it is comprehensive, fully automated, and easy to operate.
    Impact of Short-Term Intake of Red Wine and Grape Polyphenol Extract on the Human Metabolome
    Jacobs, D.M. ; Fuhrmann, J.C. ; Dorsten, F.A. van; Rein, D. ; Peters, S. ; Velzen, E.J.J. van; Hollebrands, B. ; Draijer, R. ; Duynhoven, J.P.M. van; Garczarek, U. - \ 2012
    Journal of Agricultural and Food Chemistry 60 (2012)12. - ISSN 0021-8561 - p. 3078 - 3085.
    black tea - phenolic-compounds - health - gut - microbiota - biomarkers - urine - acid - microflora - modulation
    Red wine and grape polyphenols are considered to promote cardiovascular health and are involved in multiple biological functions. Their overall impact on the human metabolome is not known. Therefore, exogenous and endogenous metabolic effects were determined in fasting plasma and 24 h urine from healthy male adults consuming a mix of red wine and grape juice extracts (WGM) for 4 days in a placebo-controlled, crossover study. Syringic acid, 3-hydroxyhippuric acid, pyrogallol, 3-hydroxyphenylacetic acid, and 3-hydroxyphenylpropionic acid were confirmed as the strongest urinary markers of WGM intake. Overall, WGM had a mild impact on the endogenous metabolism. Most noticeable were changes in several amino acids deriving from tyrosine and tryptophan. Reductions in the microbial metabolites p-cresol sulfate and 3-indoxylsulfuric acid and increases in indole-3-lactic acid and nicotinic acid were observed in urine. In plasma, tyrosine was reduced. The results suggest that short-term intake of WGM altered microbial protein fermentation and/or amino acid metabolism.
    Nutrikinetics: concept, technololgies applications and perspectives
    Duynhoven, J.P.M. van; Velzen, E.J.J. van; Westerhuis, J.A. ; Foltz, M. ; Jacobs, D.M. ; Smilde, A.K. - \ 2012
    Trends in Food Science and Technology 26 (2012)1. - ISSN 0924-2244 - p. 4 - 13.
    human metabolic phenotypes - nutrition research - systems biology - intestinal microbiota - phenolic-acids - dietary phytochemicals - tea polyphenols - food components - gut microbiome - black tea
    Exposure studies are the first step in predicting bioactivity of phytochemicals in humans. Due to the interaction between phytochemicals, their food matrix, the gut microbiome and the host, the resulting exogenous metabolites in systemic circulation vary largely between individuals. Nutrikinetics is an extension of the classical pharmacokinetic concept with explicit model adaptations. The concept relies on integrated deployment of metabolic profiling, multi-level data analysis and population-based single compartment modelling. Nutrikinetics is expected to make critical contributions in understanding how phenotypes and the food matrix modulate bioactivity of dietary phytochemicals, in particular when gut microbial bioconversions are involved.
    Tea consumption and incidence of type 2 diabetes in Europe: the EPIC-InterAct case-cohort study
    Feskens, E.J.M. ; Groenendijk-van Woudenbergh, G.J. ; Kuijsten, A. - \ 2012
    PLoS ONE 7 (2012)5. - ISSN 1932-6203 - 8 p.
    black tea - green tea - oolong tea - coffee - risk - obesity - plasma - cancer - milk - metaanalysis
    Background In previous meta-analyses, tea consumption has been associated with lower incidence of type 2 diabetes. It is unclear, however, if tea is associated inversely over the entire range of intake. Therefore, we investigated the association between tea consumption and incidence of type 2 diabetes in a European population. Methodology/Principal Findings The EPIC-InterAct case-cohort study was conducted in 26 centers in 8 European countries and consists of a total of 12,403 incident type 2 diabetes cases and a stratified subcohort of 16,835 individuals from a total cohort of 340,234 participants with 3.99 million person-years of follow-up. Country-specific Hazard Ratios (HR) for incidence of type 2 diabetes were obtained after adjustment for lifestyle and dietary factors using a Cox regression adapted for a case-cohort design. Subsequently, country-specific HR were combined using a random effects meta-analysis. Tea consumption was studied as categorical variable (0, >0-
    Structural elucidation and quantification of phenolic conjugates present in human urine after tea intake
    Hooft, J.J.J. van der; Vos, R.C.H. de; Mihaleva, V. ; Bino, R.J. ; Ridder, L.O. ; Roo, N. de; Jacobs, D.M. ; Duynhoven, J.P.M. van; Vervoort, J.J.M. - \ 2012
    Analytical Chemistry 84 (2012)16. - ISSN 0003-2700 - p. 7263 - 7271.
    tandem mass-spectrometry - green tea - black tea - metabolite identification - ellagic acid - metabolomics - polyphenols - nmr - ingestion - phytochemicals
    In dietary polyphenol exposure studies, annotation and identification of urinary metabolites present at low (micromolar) concentrations are major obstacles. In order to determine the biological activity of specific components, it is necessary to have the correct structures and the quantification of the polyphenol-derived conjugates present in the human body. We present a procedure for identification and quantification of metabolites and conjugates excreted in human urine after single bolus intake of black or green tea. A combination of a solid phase extraction (SPE) preparation step and two high pressure liquid chromatography (HPLC)-based analytical platforms was used; namely, accurate mass fragmentation (HPLC-FTMSn) and mass-guided SPE-trapping of selected compounds for nuclear magnetic resonance spectroscopy (NMR) measurements (HPLC-TOFMS-SPE-NMR). HPLC-FTMSn analysis led to the annotation of 138 urinary metabolites, including 48 valerolactone and valeric acid conjugates. By combining the results from MSn fragmentation with the one dimensional (1D)-1H-NMR spectra of HPLC-TOFMS-SPE trapped compounds, we elucidated the structures of 36 phenolic conjugates, including the glucuronides of 3’,4’-di, and 3’,4’,5’-trihydroxyphenyl-¿-valerolactone, three urolithin glucuronides, and indole-3-acetic acid glucuronide. We also obtained 26 hours of quantitative excretion profiles for specific valerolactone conjugates. The combination of the HPLC-FTMSn and HPLC-TOFMS-SPE-NMR platforms results in the efficient identification and quantification of low abundant phenolic conjugates down to nanomoles of trapped amounts of metabolite corresponding to micromolar metabolite concentrations in urine
    Productivity and nitrogen use of tea plantations in relation to age and genotype
    Kamau, D.M. ; Spiertz, J.H.J. ; Oenema, O. ; Owuor, P.O. - \ 2008
    Field Crops Research 108 (2008)1. - ISSN 0378-4290 - p. 60 - 70.
    dry-matter production - seasonal yield variation - camellia-sinensis l. - black tea - potential production - research-foundation - cuppa-tea - water-use - responses - kenya
    Lack of science-based knowledge on responses of tea bushes to nitrogen (N) in ageing tea plantations hampers the development of ecologically sound and economically profitable N-management strategies. It is hypothesized that ageing of tea plantations lowers productivity and weakens the yield response to N application. To establish insight into the relationship between ageing, productivity and N-use efficiency, seasonal and annual responses to N were studied in field experiments superimposed on a chronosequence of tea plantations (14, 29, 43, and 76 years). The two youngest plantations comprised of a clonal cultivar planted at a density of 10,766 and 13,448 plants ha(-1) and the two oldest plantations of seedlings at a density of 6730 and 7179 plants ha(-1), respectively. N was applied as urea at 0, 50,100,200, and 400 kg N ha(-1) year(-1). Mean annual made tea (mt) yields were higher for the clonal tea compared to the seedling tea and increased with age within genotypes. The clonal bushes out-yielded the seedlings by about 800 kg mt ha(-1) under favourable weather conditions in 2003/2004, while yield differences between the genotypes were minimal under stress conditions in 2002/2003. The yields of the clonal 29- and 14-year-old plantations responded positively to N fertilizer, whereas the 43- and 76-year-old plantations did not. Within the clonal cultivar made tea yield and N uptake were closely associated. Apparent shoot N-recovery (ASNR) based on N uptake by 'two leaves and a bud' was higher in clonal than in seedling tea plantations. A simple N-balance sheet showed that N excess was strongly associated with the rate of N application and N uptake. The effect of plant genotype on productivity was greater than the effect of age. The genotypes (seedlings or a clonal cultivar) to a great extent determined the yield response to N. In a well-managed mature tea plantation of up to 80 years, ageing did not lower the yielding ability within the same genotype. Thus, planting improved genotypes and implementing appropriate N-management strategies are key factors to avoid the risk on decline of productivity and profitability associated with ageing and bush degradation. N-management strategies should be based on the yielding potential of tea bushes in the target environment as defined by plant genotype and age of plantations. (C) 2008 Elsevier B.V. All rights reserved.
    Analysis of characteristic aroma of fungal fermented Fuzhuan brick-tea by gas chromatography/mass spectrophotometry
    Xu, X.Q. ; Mo, H.Z. ; Yan, M.C. ; Yang Zhu, Yang - \ 2007
    Journal of the Science of Food and Agriculture 87 (2007)8. - ISSN 0022-5142 - p. 1502 - 1504.
    thea-sinensis - black tea - puer tea
    Fuzhuan brick-tea is a popular fermented Chinese dark tea because of its typical fungal aroma. Fungal growth during the production process is the key step in achieving the unique colour, aroma and taste of Fuzhuan brick-tea. To further understand the generation of the characteristic aroma, changes in the main volatile compounds of Fuzhuan brick-tea during the fungal growth stage were studied by gas chromatography/mass spectrophotometry. The results showed that the content of volatile compounds, especially aldehyde compounds with stale aroma such as (E)-2-pentenal, (E)-2-hexenal, 1-penten-3-ol, (E, E)-2,4-heptadienal and (E, Z)-2,4-heptadienal, increased significantly in fermented tea samples. The concentration of terpene alcohols with flower aroma also increased notably during the fermentation process. The compounds with stale and flower aromas in combination with some volatile components of the raw material contributed to the characteristic fungal/flower aroma of Fuzhuan brick-tea. Microbial metabolism during the fermentation process probably played the key role in the generation of characteristic aromatic compounds of Fuzhuan brick-tea.
    Absorption, bioavailability and metabolism of flavonoids
    Hollman, P.C.H. - \ 2004
    Pharmaceutical biology 42 (2004)suppl.. - ISSN 1388-0209 - p. 74 - 83.
    lactase-phlorhizin hydrolase - human plasma - red wine - quercetin glycosides - cocoa procyanidins - urinary-excretion - mass-spectrometry - black tea - green tea - humans
    To unravel mechanisms of action of dietary flavonoids in their potential role in disease prevention, it is crucial to know the factors that determine their release from foods, their extent of absorption, and their fate in the organism. Research on absorption, metabolism, and bioavailability of flavonoids will answer these questions. The subclass, flavonols, with quercetin as the major dietary flavonol, was the first to be studied, and information on other subclasses of flavonoids is emerging. Most flavonoids, except for the subclass of catechins, are present in plants bound to sugars as ß-glycosides. This structural feature determines whether the flavonoid can be absorbed from the small intestine or has to go to the colon before absorption can occur. Generally, but exceptions have been described, glucosides are the only glycosides that can be absorbed from the small intestine. Absorption from the small intestine is more efficient than from the colon and will lead to higher plasma values. After absorption from the small intestine, flavonoids are conjugated with glucuronic acid or sulfate or O-methylation may occur. The conjugation reactions, which occur in the small intestine upon absorption, are very efficient. As a result, no free flavonoid aglycones can be found in plasma or urine, except for catechins. Plasma concentrations due to a normal diet will be less than 1 µM. Flavonoids that cannot be absorbed from the small intestine, and absorbed flavonoids secreted with bile, will be degraded in the colon by microorganisms, which will break down the flavonoid ring structure. The resulting phenolic acids have partly been characterised. These phenolic acids can be absorbed and have been measured in plasma and urine. Future research will need to address tissue distribution, cellular uptake, and cellular metabolism
    Check title to add to marked list

    Show 20 50 100 records per page

    Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.