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 - 20 / 24

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    GRASr2 Evaluation of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances used as flavoring ingredients
    Marnett, L.J. ; Cohen, S.M. ; Fukushima, S. ; Gooderham, N.J. ; Hecht, S.S. ; Rietjens, I. ; Smith, R.L. ; Adams, T.B. ; Bastaki, M. ; Harman, C.L. ; McGowen, M.M. ; Taylor, S.V. - \ 2014
    Journal of Food Science 79 (2014)4. - ISSN 0022-1147 - p. R428 - R441.
    food-additives amendment - recent progress - mutagenic properties - expert-panel - rat - alpha - hydroxylation - constituents - metabolism - chamomile
    This publication is the 1st in a series of publications by the Expert Panel of the Flavor and Extract Manufacturers Assoc. summarizing the Panel's 3rd re-evaluation of Generally Recognized as Safe (GRAS) status referred to as the GRASr2 program. In 2011, the Panel initiated a comprehensive program to re-evaluate the safety of more than 2700 flavor ingredients that have previously met the criteria for GRAS status under conditions of intended use as flavor ingredients. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, pharmacokinetics, and toxicology. Flavor ingredients are evaluated individually and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances as flavoring ingredients are evaluated. The group of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances was reaffirmed as GRAS (GRASr2) based, in part, on their rapid absorption, metabolic detoxication, and excretion in humans and other animals; their low level of flavor use; the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic studies and the lack of significant genotoxic and mutagenic potential.
    High loaded MBRs for organic matter recovery from sewage: Effect of solids retention time on bioflocculation and on the role of extracellular polymers
    Faust, L. ; Temmink, B.G. ; Zwijnenburg, A. ; Kemperman, A.J.B. ; Rijnaarts, H. - \ 2014
    Water Research 56 (2014). - ISSN 0043-1354 - p. 258 - 266.
    waterzuivering - membranen - biofilms - organische stof - water treatment - membranes - biofilms - organic matter - municipal waste-water - submerged membrane bioreactor - improved energy recovery - activated-sludge process - microbial community - surface-properties - substances eps - performance - extraction - constituents
    High loaded MBRs (HL-MBR) can concentrate sewage organic matter by aerobic bioflocculation for subsequent anaerobic conversion to methane or volatile fatty acids. In the range of very short solid retention times (SRT), the effect of SRT on bioflocculation and EPS production in HL-MBR was investigated. This short SRT range was selected to find an optimum SRT maximising recovery of organics by aerobic bioflocculation and minimizing losses of organics by aerobic mineralization. Bioflocculation was studied in five HL-MBRs operated at SRTs of 0.125, 0.25, 0.5, 1 and 5 d. The extent of flocculation, defined as the fraction of suspended COD in the concentrate, increased from 59% at an SRT of 0.125 d to 98% at an SRT of 5 d. The loss of sewage organic matter by biological oxidation was 1, 2, 4, 11 and 32% at SRT of 0.125–5 d. An SRT of 0.5–1 d gave best combination of bioflocculation and organic matter recovery. Bound extracellular polymeric substances (EPS) concentrations, in particular EPS-protein concentrations, increased when the SRT was prolonged from 0.125 to 1 d. This suggests that these EPS-proteins govern the bioflocculation process. A redistribution took place from free (supernatant) EPS to bound (floc associated) EPS when the SRT was prolonged from 0.125 to 1 d, further supporting the fact that the EPS play a dominant role in the flocculation process. Membrane fouling was most severe at the shortest SRTs of 0.125 d. No positive correlation was detected between the concentration of free EPS and membrane fouling, but the concentration of submicron (45–450 nm) particles proved to be a good indicator for this fouling.
    Potato and Mushroom Polyphenol Oxidase Activities Are Differently Modulated by Natural Plant Extracts
    Kuijpers, T.F.M. ; Herk, T. van; Vincken, J.P. ; Janssen, R.H. ; Narh, D.L. ; Berkel, W.J.H. van; Gruppen, H. - \ 2014
    Journal of Agricultural and Food Chemistry 62 (2014)1. - ISSN 0021-8561 - p. 214 - 221.
    tyrosinase inhibitors - chlorogenic acid - ilex-paraguariensis - constituents - activation - licorice - identification - mechanism - agents - sds
    Enzymatic browning is a major quality issue in fruit and vegetable processing and can be counteracted by different natural inhibitors. Often, model systems containing a single polyphenol oxidase (PPO) are used to screen for new inhibitors. To investigate the impact of the source of PPO on the outcome of such screening, this study compared the effect of 60 plant extracts on the activity of PPO from mushroom (Agaricus bisporus, AbPPO) and PPO from potato (Solanum tuberosum, StPPO). Some plant extracts had different effects on the two PPOs: an extract that inhibited one PPO could be an activator for the other. As an example of this, the mate (Ilex paraguariensis) extract was investigated in more detail. In the presence of mate extract, oxygen consumption by AbPPO was found to be reduced >5-fold compared to a control reaction, whereas that of StPPO was increased >9-fold. RP-UHPLC-MS analysis showed that the mate extract contained a mixture of phenolic compounds and saponins. Upon incubation of mate extract with StPPO, phenolic compounds disappeared completely and saponins remained. Flash chromatography was used to separate saponins and phenolic compounds. It was found that the phenolic fraction was mainly responsible for inhibition of AbPPO and activation of StPPO. Activation of StPPO was probably caused by activation of latent StPPO by chlorogenic acid quinones.
    Metabolomics in melon: A new opportunity for aroma analysis
    Allwood, J.W. ; Cheung, W.W.L. ; Xu, Y. ; Mumm, R. ; Vos, C.H. de; Deborde, C. ; Biais, B. ; Maucourt, M. ; Berger, Y. ; Schaffer, A. ; Rolin, D. ; Moing, A. ; Hall, R.D. ; Goodacre, R. - \ 2014
    Phytochemistry 99 (2014). - ISSN 0031-9422 - p. 61 - 72.
    charentais cantaloupe melons - volatile organic-compounds - oxidase antisense gene - cucumis-melo - gas-chromatography - flavor compounds - cv makdimon - fruit - constituents - sulfur
    Cucumis melo fruit is highly valued for its sweet and refreshing flesh, however the flavour and value are also highly influenced by aroma as dictated by volatile organic compounds (VOCs). A simple and robust method of sampling VOCs on polydimethylsiloxane (PDMS) has been developed. Contrasting cultivars of C. melo subspecies melo were investigated at commercial maturity: three cultivars of var. Cantalupensis group Charentais (cv. Cézanne, Escrito, and Dalton) known to exhibit differences in ripening behaviour and shelf-life, as well as one cultivar of var. Cantalupensis group Ha’Ogan (cv. Noy Yisre’el) and one non-climacteric cultivar of var. Inodorus (cv. Tam Dew). The melon cultivar selection was based upon fruits exhibiting clear differences (cv. Noy Yisre’el and Tam Dew) and similarities (cv. Cézanne, Escrito, and Dalton) in flavour. In total, 58 VOCs were detected by thermal desorption (TD)-GC–MS which permitted the discrimination of each cultivar via Principal component analysis (PCA). PCA indicated a reduction in VOCs in the non-climacteric cv. Tam Dew compared to the four Cantalupensis cultivars. Within the group Charentais melons, the differences between the short, mid and long shelf-life cultivars were considerable. 1H NMR analysis led to the quantification of 12 core amino acids, their levels were 3–10-fold greater in the Charentais melons, although they were reduced in the highly fragrant cv. Cézanne, indicating their role as VOC precursors. This study along with comparisons to more traditional labour intensive solid phase micro-extraction (SPME) GC–MS VOC profiling data has indicated that the high-throughput PDMS method is of great potential for the assessment of melon aroma and quality.
    Matrix-derived combination effect and risk assessment for estragole from basil-containing plant food supplements (PFS)
    Berg, S.J.P.L. van den; Klaus, V. ; Alhusainy, W. ; Rietjens, I. - \ 2013
    Food and Chemical Toxicology 62 (2013). - ISSN 0278-6915 - p. 32 - 40.
    in-vivo - trans-anethole - rat - 1'-hydroxyestragole - derivatives - mouse - bioactivation - constituents - metabolism - safrole
    Basil-containing plant food supplements (PFS) can contain estragole which can be metabolised into a genotoxic and carcinogenic 1'-sulfoxymetabolite. This study describes the inhibition of sulfotransferase (SULT)-mediated bioactivation of estragole by compounds present in basil-containing PFS. Results reveal that PFS consisting of powdered basil material contain other compounds with considerable in vitro SULT-inhibiting activity, whereas the presence of such compounds in PFS consisting of basil essential oil was limited. The inhibitor in powdered basil PFS was identified as nevadensin. Physiologically based kinetic (PBK) modeling was performed to elucidate if the observed inhibitory effects can occur in vivo. Subsequently, risk assessment was performed using the Margin of Exposure (MOE) approach. Results suggest that the consequences of the in vivo matrix-derived combination effect are significant when estragole would be tested in rodent bioassays with nevadensin at ratios detected in PFS, thereby increasing MOE values. However, matrix-derived combination effects may be limited at lower dose levels, indicating that the importance of matrix-derived combination effects for risk assessment of individual compounds should be done on a case-by-case basis considering dose-dependent effects. Furthermore, this study illustrates how PBK modeling can be used in risk assessment of PFS, contributing to further reduction in the use of experimental animals. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.
    MetIDB: A Publicly Accessible Database of Predicted and Experimental 1H NMR Spectra of Flavonoids
    Mihaleva, V.V. ; Beek, T.A. te; Zimmeren, F. van; Moco, S.I.A. ; Laatikainen, R. ; Niemitz, M. ; Korhonen, S.P. ; Driel, M.A. van; Vervoort, J. - \ 2013
    Analytical Chemistry 85 (2013)18. - ISSN 0003-2700 - p. 8700 - 8707.
    hplc-spe-nmr - structural elucidation - information-system - mass-spectrometry - identification - constituents - ms - products - extracts
    Identification of natural compounds, especially secondary metabolites, has been hampered by the lack of easy to use and accessible reference databases. Nuclear magnetic resonance (NMR) spectroscopy is the most selective technique for identification of unknown metabolites. High quality 1H NMR (proton nuclear magnetic resonance) spectra combined with elemental composition obtained from mass spectrometry (MS) are essential for the identification process. Here, we present MetIDB, a reference database of experimental and predicted 1H NMR spectra of 6000 flavonoids. By incorporating the stereochemistry, intramolecular interactions, and solvent effects into the prediction model, chemical shifts and couplings were predicted with great accuracy. A user-friendly web-based interface for MetIDB has been established providing various interfaces to the data and data-mining possibilities. For each compound, additional information is available comprising compound annotation, a 1H NMR spectrum, 2D and 3D structure with correct stereochemistry, and monoisotopic mass as well as links to other web resources. The combination of chemical formula and 1H NMR chemical shifts proved to be very efficient in metabolite identification, especially for isobaric compounds. Using this database, the process of flavonoid identification can then be significantly shortened by avoiding repetitive elucidation of already described compounds
    Four new depsides in Origanum dictamnus methanol extract
    Exarchou, V. ; Takis, P.G. ; Malouta, M. ; Vervoort, J. ; Karali, E. ; Troganis, A.N. - \ 2013
    Phytochemistry Letters 6 (2013)1. - ISSN 1874-3900 - p. 46 - 52.
    greek aromatic plants - antioxidant activities - salvia-officinalis - acid-derivatives - essential oils - caffeic acid - antimicrobial activity - constituents - l. - lamiaceae
    We herein describe the identification of four new depsides present in methanol extract of Origanum dictamnus. O. dictamnus’ (dittany) aerial parts methanol extract was subjected to semi-preparative RP-HPLC fractionation followed by identification of individual compounds in each fraction using 1D/2D NMR, MS approaches and DFT calculations. The structural data revealed that 4 of the compounds were novel hitherto unidentified molecules, whereas the other 6 corresponded to known structures belonging to the groups of monoterpenes, phenolic acids and depsides. We have additionally estimated the antioxidant capacity of the methanol extract and individual fractions using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) in vitro assay. Methanol extract exhibited significant scavenging activity, which was attributed predominantly to the depside group of phytochemicals. The scavenging activity of the new compounds is reported herein for first time. Moreover, the antimitotic activities of the methanol extract as well as that of rosmarinic acid were examined and appeared to be several fold weaker comparing to their scavenging capacity.
    Metabolomics and molecular marker analysis to explore pepper (Capsicum sp.) biodiversity
    Wahyuni, Y. ; Ballester, A.R. ; Tikunov, Y.M. ; Vos, C.H.R. de; Pelgrom, K.T.B. ; Maharijaya, A. ; Sudarmonowati, E. ; Bino, R.J. ; Bovy, A.G. - \ 2013
    Metabolomics 9 (2013)1. - ISSN 1573-3882 - p. 130 - 144.
    acyclic diterpene glycosides - annuum l. - capsaicinoid content - mass-spectrometry - volatile fraction - hs-spme - fruit - tomato - chinense - constituents
    An overview of the metabolic diversity in ripe fruits of a collection of 32 diverse pepper (Capsicum sp.) accessions was obtained by measuring the composition of both semi-polar and volatile metabolites in fruit pericarp, using untargeted LC–MS and headspace GC–MS platforms, respectively. Accessions represented C. annuum, C. chinense, C. frutescens and C. baccatum species, which were selected based on variation in morphological characters, pungency and geographic origin. Genotypic analysis using AFLP markers confirmed the phylogenetic clustering of accessions according to Capsicum species and separated C. baccatum from the C. annuum–C. chinense–C. frutescens complex. Species-specific clustering was also observed when accessions were grouped based on their semi-polar metabolite profiles. In total 88 semi-polar metabolites could be putatively identified. A large proportion of these metabolites represented conjugates of the main pepper flavonoids (quercetin, apigenin and luteolin) decorated with different sugar groups at different positions along the aglycone. In addition, a large group of acyclic diterpenoid glycosides, called capsianosides, was found to be highly abundant in all C. annuum genotypes. In contrast to the variation in semi-polar metabolites, the variation in volatiles corresponded well to the differences in pungency between the accessions. This was particularly true for branched fatty acid esters present in pungent accessions, which may reflect the activity through the acyl branch of the metabolic pathway leading to capsaicinoids. In addition, large genetic variation was observed for many well-established pepper aroma compounds. These profiling data can be used in breeding programs aimed at improving metabolite-based quality traits such as flavour and health-related metabolites in pepper fruits.
    A novel photocatalytic conversion of Tryptophan to Kynurenine using black light as a light source
    Hamdy Mohamed Saad, M.S. ; Scott, E.L. ; Carr, R.H. ; Sanders, J.P.M. - \ 2012
    Catalysis Letters 142 (2012)3. - ISSN 1011-372X - p. 338 - 344.
    amino-acids - human lens - photooxidation products - wool proteins - photochemistry - constituents - degradation - ozone - mass
    The photocatalytic conversion of an aqueous solution of l-tryptophan (Trp) to kynurenine (KN) was investigated under the illumination of different light sources. Results show that Trp converted to KN with a selectivity of 64% under the illumination of a medium pressure (MP) Hg lamp. KN selectivity was increased to >90% when black light (BL) was used a light source. The novel use of BL in the photocatalytic conversion of Trp to KN significantly reduces the energy consumption compared with MP light
    Effectiveness of unfertilized buffer strips for reducing nitrogen loads from agricultural lowland to surface waters
    Noij, I.G.A.M. ; Heinen, M. ; Heesmans, H.I.M. ; Thissen, J.T.N.M. ; Groenendijk, P. - \ 2012
    Journal of Environmental Quality 41 (2012)2. - ISSN 0047-2425 - p. 322 - 333.
    vegetative filter strips - stream riparian zones - nitrate removal - groundwater-flow - field-scale - retention - landscape - transport - constituents - attenuation
    Unfertilized buffer strips (BS) are widely accepted to reduce nitrogen (N) loads from agricultural land to surface water. However, the relative reduction of N load or concentration (BS effectiveness, BSE), varies with management and local conditions, especially hydrogeology. We present novel experimental evidence on BSE for 5-m-wide grass BS on intensively drained and managed plain agricultural lowland with varying hydrogeology. We selected characteristic sites for five major hydrogeological classes of the Netherlands and installed paired 5-m-wide unfertilized grass (BS) and reference (REF) treatments along the ditch. The REF was managed like the adjacent field, and BS was only harvested. Treatments were equipped with reservoirs in the ditch to collect and measure discharge and flow proportional N concentration for 3 or 4 yr. In addition, N concentration in upper groundwater was measured. We found a statistically significant BSE of 10% on the peat site. At the other sites, BSE for N was low and statistically insignificant. Low BSE was explained by denitrification between adjacent field and ditch, as well as by the site-specific hydrologic factors including low proportion of shallow groundwater flow, downward seepage, low residence time in the BS, and surface runoff away from the ditch. We emphasize that a REF treatment is needed to evaluate BSE in agriculture and recommend reservoirs if drainage patterns are unknown. Introduction of a 5-m-wide BS is ineffective for mitigating N loads from lowland agriculture to surface waters. We expect more from BS specifically designed to abate surface runoff.
    Role of Spectral Studies in Detection of Antibacterial Phytoelements and Phytchemicals of Moringa Oleifera
    Mehta, S. ; Rai, P.K. ; Rai, A.K. ; Bicanic, D.D. ; Watal, G. - \ 2011
    Food Biophysics 6 (2011)4. - ISSN 1557-1858 - p. 497 - 502.
    constituents - libs
    This paper reports, the Laser Induced Breakdown Spectroscopy (LIBS) studies and structure elucidation of compounds isolated from the fruit extract of Moringa oleifera and also deals with their possible effects on some bacterial strains viz. Staphylococcus aureus, Klebsiella pneumonia, Escherichia coli and Pseudomonas aeruginosa. The extract was found to be active against all four microorganisms used. Extent of inhibitory effect of extract was assessed at different concentrations of 25, 50, 75 mg/ml by measuring diameter of inhibition zone (DIZ). Our results clearly showed that the 75 mg/ml concentration of the extract had 14, 12 and 18 mm of the DIZ against Staphylococcus aureus, Klebsiella pneumonia and Pseudomonas aeruginosa and 14 mm with 50 mg/ml concentration against Escherichia coli. The results were compared with the standard antibiotic ‘ampicillin’ of 1 mg/ml concentration. LIBS was recorded with high power pulsed laser beam from Nd: YAG Laser (Continuum Surelite III-10), focused on the surface of the material, which was in liquid form, to generate plasma on the surface of the sample. LIBS data clearly demonstrate the presence of trace elements, magnesium and iron, in high concentration in the extract. Whereas, from the phytochemical profile reveals the presence of two new compounds, S-ethyl-N-{4-[(a-L-rhamnosyloxy) benzyl]} thiocarbamate and 2-acetoxy {4-[(2',3',4'-tri-O-acetyl-a-L-rhamnosyloxy) benzyl]} acetonitrile as the major constituents. This study is the first report on synergetic effect of the phytoconstituents and certain set of elements present in their defined role in bacterial management against different bacterial strains.
    The relationship between milking interval and somatic cell count in automatic milking systems
    Mollenhorst, H. ; Hidayat, M.M. ; Broek, J. van den; Neijenhuis, F. ; Hogeveen, H. - \ 2011
    Journal of Dairy Science 94 (2011)9. - ISSN 0022-0302 - p. 4531 - 4537.
    udder health - constituents - quarters
    The aim of this study was to explore whether, during automatic milking, milking interval or its variation is related to somatic cell count (SCC), even when corrected for effects of production, lactation stage, and parity. Data on milking interval and production level were available from the automatic milking systems of 151 farms. Data on SCC, parity, and lactation stage were derived from dairy herd improvement records of the same farms. Mainly due to incomplete records, data of 100 farms were used in the final analysis. For every cow, only 1 test day was used in the final analysis. Milking interval, the coefficient of variation of milking interval, production rate, the difference in production rate between short- and long-term, parity, days in milk, and some biologically relevant interactions were used in a linear mixed model with farm as random variable to assess their association with log10-transformed SCC. None of the interactions was significantly related to SCC, whereas all main effects were, and thus, stayed in the final model. The effect of milking interval was, although significant, not very strong, which shows that the effect of milking interval on SCC is marginal when corrected for the other variables. The variation in milking intervals was positively related with SCC, showing that the variation in milking interval is even more important than the milking interval itself. In the end, this study showed only a limited association between milking interval and SCC when milking with an automatic milking system
    Agonistic and antagonistic estrogens in licorice root (Glycyrrhiza glabra)
    Simons, R. ; Vincken, J.P. ; Mol, L.A.M. ; The, S.A.M. ; Bovee, T.F.H. ; Luijendijk, T.J.C. ; Verbruggen, M.A. ; Gruppen, H. - \ 2011
    Analytical and Bioanalytical Chemistry 401 (2011)1. - ISSN 1618-2642 - p. 305 - 313.
    breast-cancer cells - antiestrogenic activities - receptor-alpha - phenolic-compounds - in-vitro - constituents - mcf-7 - flavonoids - tissues - protein
    The roots of licorice (Glycyrrhiza glabra) are a rich source of flavonoids, in particular, prenylated flavonoids, such as the isoflavan glabridin and the isoflavene glabrene. Fractionation of an ethyl acetate extract from licorice root by centrifugal partitioning chromatography yielded 51 fractions, which were characterized by liquid chromatography–mass spectrometry and screened for activity in yeast estrogen bioassays. One third of the fractions displayed estrogenic activity towards either one or both estrogen receptors (ERs; ERa and ERß). Glabrene-rich fractions displayed an estrogenic response, predominantly to the ERa. Surprisingly, glabridin did not exert agonistic activity to both ER subtypes. Several fractions displayed higher responses than the maximum response obtained with the reference compound, the natural hormone 17ß-estradiol (E2). The estrogenic activities of all fractions, including this so-called superinduction, were clearly ER-mediated, as the estrogenic response was inhibited by 20–60% by known ER antagonists, and no activity was found in yeast cells that did not express the ERa or ERß subtype. Prolonged exposure of the yeast to the estrogenic fractions that showed superinduction did, contrary to E2, not result in a decrease of the fluorescent response. Therefore, the superinduction was most likely the result of stabilization of the ER, yeast-enhanced green fluorescent protein, or a combination of both. Most fractions displaying superinduction were rich in flavonoids with single prenylation. Glabridin displayed ERa-selective antagonism, similar to the ERa-selective antagonist RU 58668. Whereas glabridin was able to reduce the estrogenic response of E2 by approximately 80% at 6¿×¿10-6 M, glabrene-rich fractions only exhibited agonistic responses, preferentially on ERa.
    The potential of white-rot fungi to degrade phorbol esters of Jatropha curcas L. seed cake
    Barros, C.R.M. de; Ferreira, L.M.M. ; Nunes, F.M. ; Bezerra, R.M.F. ; Dias, A.A. ; Guedes, C. ; Cone, J.W. ; Marques, G.S.M. ; Rodrigues, M.A.M. - \ 2011
    Engineering in Life Sciences 11 (2011)1. - ISSN 1618-0240 - p. 107 - 110.
    chemical-composition - wheat-straw - provenances - diacylglycerols - bioremediation - constituents - mexico - state - water
    The potential of solid-state cultivation, with three white-rot fungi (Bjerkandera adusta, Ganoderma resinaceum and Phlebia rufa), to decrease phorbol esters concentration of Jatropha curcas L. was evaluated in this study. Incubation was conducted in 250¿mL Erlenmeyer flasks without agitation at 28°C for 30 days. Phorbol esters were analyzed by reverse-phase HPLC after an extraction procedure using dichloromethane. All fungi studied were able to decrease the concentration of phorbol esters, mainly B. adusta and P. rufa which significantly reduced (p
    Fungal Biotransormation Products of Dehydroabietic Acid
    Beek, T.A. van; Claassen, F.W. ; Dorado, J. ; Godejohann, M. ; Sierra-Alvarez, R. ; Wijnberg, J.B.P.A. - \ 2007
    Journal of Natural Products 70 (2007)2. - ISSN 0163-3864 - p. 154 - 159.
    pseudomonas-abietaniphila bkme-9 - mill effluent - kraft pulp - mortierella-isabellina - bacterial degradation - resin acids - paper-mill - hydroxylation - diterpenoids - constituents
    Dehydroabietic acid (DHA) (1) is one of the main compounds in Scots pine wood responsible for aquatic and microbial toxicity. The degradation of 1 by Trametes versicolor and Phlebiopsis gigantea in liquid stationary cultures was followed by HPLC-DAD-ELSD. Both fungi rapidly degraded DHA relative to a control. More breakdown products were observed for T. versicolor than for P. gigantea. After 13 days, four compounds were identified by means of spectroscopic methods in P. gigantea cultures: 1 beta-hydroxy-DHA (2), 1 beta,7 alpha-dihydroxy-DHA (3), 1 beta,16-dihydroxy-DHA (5), and tentatively 1 beta-hydroxy-7-oxo-DHA (4). In T. versicolor cultures, 1 beta,16-dihydroxy-DHA (5), 7 beta,16-dihydroxy-DHA (6), 1 beta,7 beta,16-trihydroxy-DHA (7), 1 beta,16-dihydroxy-7-oxo-DHA (8), 1 beta,15-dihydroxy-DHA (9), and 1 beta,7 alpha,16-trihydroxy-DHA (10) were identified after 9 days of incubation. Thus the biotransformation of 1 by the two fungi was different, with only 5 being produced by both strains. Compounds 3, 7, 8, and 10 are reported for the first time as natural products.
    Loss of essential oil of tarragon (Artemisia dranunculus L.) due to drying
    ArabHosseini, A. ; Padhye, S. ; Beek, T.A. van; Boxtel, A.J.B. van; Huisman, W. ; Posthumus, M.A. ; Müller, J. - \ 2006
    Journal of the Science of Food and Agriculture 86 (2006)15. - ISSN 0022-5142 - p. 2543 - 2550.
    aroma - constituents - volatiles - parsley
    The effect of hot air-drying on the essential oil constituents and yield in French and Russian tarragon (Artemisia dracunculus L.) leaves was studied. The tarragon leaves were dried at air temperatures ranging from 40 to 90 °C. The drying stopped when the moisture content of the samples reached 10% or for some of the treatments reached 7, 20 and 30%. The essential oil of the fresh and dried leaves was isolated by hydrodistillation and analysed by capillary gas chromatography and gas chromatography-mass spectrometry. The decrease of oil during the drying process was highest at 60 °C drying temperature. For French tarragon the decrease in the amount of oil was significantly lower at 90 °C. The effect of the relative humidity of the drying air at each temperature was not significant. The main compounds were estragole in French tarragon (69%) and sabinene in Russian tarragon (40%). The drying process changed the relative percentage of the constituents in the oil; for instance, the relative percentages of estragole decreased and sabinene increased in French tarragon
    Increased hippuric acid content of urine can reduce soil N2O fluxes
    Kool, D.M. ; Hoffland, E. ; Hummelink, E.W.J. ; Groenigen, J.W. van - \ 2006
    Soil Biology and Biochemistry 38 (2006)5. - ISSN 0038-0717 - p. 1021 - 1027.
    nitrous-oxide emissions - animal urine - ammonia - denitrification - nitrate - volatilization - constituents - grassland - pasture - methane
    Urine patches in grazed pastures are a major source of nitrous oxide (N2O) emission. It is well-documented that the relative concentration of the various nitrogenous urine constituents varies significantly with diet. The effect of these variations on NO emissions from urine patches, however, has never been reported. The aim of this study was to test whether variations in urine composition, consistent with different diets, lead to significant differences in N2O emission. Four varieties of artificial urine, all with similar total N concentrations, but varying in the relative contribution of the nitrogenous constituents, were applied to undisturbed cores from a sandy pasture soil. N2O fluxes were monitored for 65 days at two moisture treatments; 92% WFPS for the entire incubation, and 70% WFPS up to day 41 and 92% afterwards. Extra replicates were included for destructive analysis on mineral N concentrations and pH. Urine composition was a significant (P <0.001) factor determining N2O emissions. An increase in the relative hippuric acid concentration from 3 to 9% of total N resulted in a significant decline in average N2O fluxes, from 16.4 to 8.7 mu g N2O-N h(-1) kg(-1) soil (averaged over all treatments). Cumulative emission decreased from 8.4 to 4.4% of the applied urine-N (P <0.0 1). Soil mineral N showed a modest but significant decrease with an increase of hippuric acid content. pH did not show any significant relationship with urine composition. Increasing the urea concentration with 12% of applied urinary N did not significantly affect N2O emissions. Moisture content significantly affected N2O emissions (P <0.001), but no interaction between moisture and urine composition was found. As the inhibitory effect of hippuric acid could not be linked directly to mineral N concentrations in the soil, we hypothesize that the breakdown product benzoic acid either inhibits denitrification or decreases the N2O/N-2 ratio. We conclude that hippuric acid concentration in urine is an important factor influencing N2O emission, with a potential for reducing emissions with 50%. We suggest alternative rationing leading to higher hippuric acid concentrations in urine as a possible strategy to mitigate N2O emission from grazed pastures. (c) 2005 Elsevier Ltd. All fights reserved.
    Development of a triple hyphenated HPLC-radical scavenging detection-DAD-SPE-NMR system for the rapid identification of antioxidants in complex plant extracts
    Pukalskas, A. ; Beek, T.A. van; Waard, P. de - \ 2005
    Journal of Chromatography. A, Including electrophoresis and other separation methods 1074 (2005)1-2. - ISSN 0021-9673 - p. 81 - 88.
    rosmarinus-officinalis l - carnosic acid - phenolic diterpenes - salvia-officinalis - rosemary extracts - online detection - sage extracts - flow-probe - constituents - oil
    A rapid method for the simultaneous detection and identification of radical scavenging compounds in plant extracts was developed by combining an HPLC with on-line radical scavenging using DPPH as a model radical and an HPLC¿DAD¿SPE¿NMR system. Using this method a commercial rosemary extract was investigated. All major compounds present in the extract were collected on SPE cartridges after their separation. Advantages of on-line SPE peak trapping are the possibility to perform HPLC with non-deuterated solvents, a concentration effect and being able to record NMR spectra in pure 100% deuterated solvents. After comparing DAD and DPPH scavenging chromatograms, 1H NMR spectra of compounds having radical scavenging activities were recorded. Afterwards all compounds were collected and infused into an ESI-MS. The five main active compounds ¿ carnosol, carnosic acid carnosaldehyde, 12-methoxycarnosic acid and epiisorosmanol ¿ could be identified from the combined UV, NMR and mass spectral data without actually isolating them. It was possible to record on-line an HMBC spectrum of carnosic acid. Also one compound was tentatively identified as epirosmanol methyl ether
    Cockatiels (Nymphicus hollandicus) reject very low levels of plant secondary compounds
    Matson, K.D. ; Millam, J.R. ; Klasing, K.C. - \ 2004
    Applied Animal Behaviour Science 85 (2004)1. - ISSN 0168-1591 - p. 141 - 156.
    taste - constituents - performance - preferences - sunbirds - tannins - l.
    The rejection thresholds of caged cockatiels (Nymphicus hollandicus) were tested to determine their sensitivity to plant secondary compounds. Both alkaloids and tannins were tested using a two-bottle method in which purified water was always available in one bottle and an aqueous test solution was available in the other bottle. After each 3-day experimental period, three consumption parameters were recorded (test solution-side consumption, water-side consumption, and a ratio of test solution-side consumption to total consumption). Repeated test periods were conducted with increasingly concentrated test solutions of each compound until one or more consumption parameters were significantly (P
    Screening of radical scavenging activity of some medicinal and aromatic plant extracts
    Miliauskas, G. ; Venskutonis, R.P. ; Beek, T.A. van - \ 2004
    Food Chemistry 85 (2004)2. - ISSN 0308-8146 - p. 231 - 237.
    antioxidant activity - lipid-peroxidation - constituents - herbs
    Extracts of 12 medicinal and aromatic plants were investigated for their radical scavenging activity using DPPH and ABTS assays: Salvia sclarea, Salvia glutinosa, Salvia pratensis, Lavandula angustifolia, Calendula officinalis, Matricaria recutita, Echinacea purpurea, Rhaponticum carthamoides, Juglans regia, Melilotus officinalis, Geranium macrorrhizum and Potentilla fruticosa. Salvia officinalis was used as a reference plant with well documented antioxidant activity. G. macrorrhizum and P. fruticosa extracts possessed very high radical scavenging activity (RSA) in both assays, higher than that of S. officinalis extract. High RSA was also characteristic to other Salvia species and Rhaponticum carthamoides. The content of total phenolic compounds, flavonoids and flavonols was measured in plant extracts. A correlation between radical scavenging capacities of extracts with total phenolic compound content was observed. (C) 2003 Elsevier Ltd. All rights reserved.
    Check title to add to marked list
    << previous | next >>

    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.