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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    An automated modular microsystem for enzymatic digestion with gut-on-a-chip applications
    Haan, P. de; Ianovska, M.A. ; Mathwig, K. ; Bouwmeester, H. ; Verpoorte, E. - \ 2020
    In: 21st International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2017. - Chemical and Biological Microsystems Society (21st International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2017 ) - ISBN 9780692941836 - p. 1593 - 1594.
    Digestion - Enzyme kinetics - Gut-on-a-chip - Organ-on-a-chip

    Gut-on-a-chip models have gained attention as replacements for other cell-based assays or animal studies in drug development or toxicological studies. These models aim to provide a more accurate representation of the in vivo situation in form and function; however, no digestive processes have been included in these systems so far. This work describes a miniaturized digestive system based on artificial digestive juices that digest liquid samples in a series of three microreactors. After optimization of the pH value of juices and mixtures, samples leading to fluorescent products were digested to demonstrate enzyme functionality and to determine kinetic parameters.

    Inbreeding, Allee effects and stochasticity might be sufficient to account for Neanderthal extinction
    Vaesen, Krist ; Scherjon, Fulco ; Hemerik, Lia ; Verpoorte, Alexander - \ 2019
    PLoS ONE 14 (2019)11. - ISSN 1932-6203

    The replacement of Neanderthals by Anatomically Modern Humans has typically been attributed to environmental pressure or a superiority of modern humans with respect to competition for resources. Here we present two independent models that suggest that no such heatedly debated factors might be needed to account for the demise of Neanderthals. Starting from the observation that Neanderthal populations already were small before the arrival of modern humans, the models implement three factors that conservation biology identifies as critical for a small population’s persistence, namely inbreeding, Allee effects and stochasticity. Our results indicate that the disappearance of Neanderthals might have resided in the smallness of their population(s) alone: even if they had been identical to modern humans in their cognitive, social and cultural traits, and even in the absence of inter-specific competition, Neanderthals faced a considerable risk of extinction. Furthermore, we suggest that if modern humans contributed to the demise of Neanderthals, that contribution might have had nothing to do with resource competition, but rather with how the incoming populations geographically restructured the resident populations, in a way that reinforced Allee effects, and the effects of inbreeding and stochasticity.

    Digestion-on-a-chip: A continuous-flow modular microsystem recreating enzymatic digestion in the gastrointestinal tract
    Haan, Pim De; Ianovska, Margaryta A. ; Mathwig, Klaus ; Lieshout, Glenn A.A. Van; Triantis, Vassilis ; Bouwmeester, Hans ; Verpoorte, Elisabeth - \ 2019
    Lab on a Chip 19 (2019)9. - ISSN 1473-0197 - p. 1599 - 1609.

    In vitro digestions are essential for determining the bioavailability of compounds, such as nutrients. We have developed a cell-free, miniaturized enzymatic digestive system, employing three micromixers connected in series to mimic the digestive functions of the mouth, stomach and small intestine. This system continuously processes samples, e.g. containing nutrients, to provide a constant flow of digested materials which may be presented to a subsequent gut-on-a-chip absorption module, containing living human intestinal cells. Our system incorporates three-compartment enzymatic digestion, one of the key functions of the gastrointestinal tract. In each of these compartments, we modify the chemical environment, including pH, buffer, and mineral composition, to closely mimic the local physiological environment and create optimal conditions for digestive processes to take place. It will therefore provide an excellent addition to existing gut-on-a-chip systems, providing the next step in determining the bio-availability of orally administered compounds in a fast and continuous-flow ex vivo system. In this paper, we demonstrate enzymatic digestion in each separate compartment using compounds, starch and casein, as model nutrients. The use of transparent, microfluidic micromixers based on chaotic advection, which can be probed directly with a microscope, enabled enzyme kinetics to be monitored from the very start of a reaction. Furthermore, we have digested lactoferrin in our system, demonstrating complete digestion of this milk protein in much shorter times than achievable with standard in vitro digestions using batch reactors.

    Micro magnetic resonance imaging of murine liver tissue slices on a microfluidic perfusion device
    Sharma, Manvendra ; Patra, Bishnubrata ; Hale, William ; Karsten, Ruby E.H. ; Salentijn, Gert I.J. ; Grajewski, Maciej ; Fuhrer, Erwin ; Zakhurdaeva, Anna ; Mager, Dario ; Korvink, Jan ; Olinga, Peter ; Verpoorte, Elisabeth ; Utz, Marcel - \ 2018
    In: 22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018. - Chemical and Biological Microsystems Society (22nd International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2018 ) - ISBN 9781510897571 - p. 1722 - 1724.
    Micro-MRI - NMR - PCLS

    Micro-MRI (Magnetic Resonance Imaging) and NMR (Nuclear Magnetic Resonance) spectroscopy are used to image and study metabolic activity of precision-cut liver slices (PCLS) on a microfluidic perfusion device. The imaging experiments were performed under static medium conditions while metabolic activity was monitored under continuous flow of medium. LDH (Lactate dehydrogenase) leakage assay was performed to assess the tissue viability on different days. MR images having ~30 (μm)2 in-plane resolution are recorded. This method could be used to culture and monitor PCLS non-invasively.

    Reinventing (Bio)chemical Analysis with Paper
    Salentijn, G.I.J. ; Grajewski, M. ; Verpoorte, E. - \ 2018
    Analytical Chemistry 90 (2018)23. - ISSN 0003-2700 - p. 13815 - 13825.

    This paper focuses on one of the most commonly encountered materials in our society, namely paper. Paper is an inherently complex material, yet its use provides for chemical analysis approaches that are elegant in their simplicity of execution. In the first half of the previous century, paper in scientific research was used mainly for filtration and chromatographic separation. While its use decreased with the rise of modern elution chromatography, paper remains a versatile substrate for low-cost analytical tests. Recently, we have seen renewed interest to work with paper in (bio)analytical science, a result of the growing demand for inexpensive, portable analysis. Dried blood spotting, paper microfluidics, and paper spray ionization are areas in which paper is (re)establishing itself as an important material. These research areas all exploit several properties of paper, including stable sample storage, passive fluid movement and manipulation, chromatographic separation/extraction, modifiable surface and/or volume, easily altered shape, easy transport, and low cost. We propose that the real, and to date underexploited, potential of paper lies in utilizing its combined characteristics to add new dimensions to paper-based (bio)chemical analysis, expanding its applicability. This article provides the reader with a short historical perspective on the scientific use of paper and the developments that led to the establishment of the aforementioned research areas. We review important characteristics of paper and place them in a scientific context in this descriptive, yet critical, assessment of the achieved and the achievable in paper-based analysis. The ultimate goal is the exploration of integrative approaches at the interface between the different fields in which paper is or can be used.

    Metabolomic variation of brassica rapa var. rapa (var. raapstelen) and raphanus sativus l. at different developmental stages
    Jahangir, M. ; Abdel-Farid, I.B. ; Vos, C.H.R. de; Jonker, H.H. ; Choi, Y.H. ; Verpoorte, R. - \ 2014
    Pakistan Journal of Botany 46 (2014)4. - ISSN 0556-3321 - p. 1445 - 1452.
    antioxidant activity - plant metabolomics - growth - vegetables - phenolics - genomics - radish
    Brassica rapa (var. raapstelen) and Raphanus sativus (red radish) are being used as food and fodder while also known as model in recent plant research due to the diversity of metabolites as well as genetic resemblance to Arabidopsis. This study explains the change in metabolites (amino acids, organic acids, chlorophyll, carotenoids, tocopherols, ascorbic acid, sucrose, phenylpropanoids and glucosinolates) during plant development. In present study the metabolomic variation in relation to plant growth has been evaluated, for Brassica rapa (var. raapstelen) and red radish (Raphanus sativus) at three different developmental stages. A non-targeted and targeted metabolomic approach by NMR and HPLC in combination with Principal component analysis (PCA) of the data was used to identify phytochemicals being influenced by plant growth. The results lead to the better understanding of metabolic changes during plant development and show the importance of plant age with respect to the metabolomic profile of vegetables.
    The seco-iridoid pathway from Catharanthus roseus
    Miettinen, K. ; Dong, L. ; Navrot, N. ; Burlat, V. ; Schneider, T. ; Pollier, J. ; Woittiez, L.S. ; Krol, A.R. van der; Lugan, R. ; Llc, T. ; Verpoorte, R. ; Oksman-Caldentey, K.M. ; Martinoia, E. ; Bouwmeester, H.J. - \ 2014
    Nature Communications 5 (2014). - ISSN 2041-1723 - 12 p.
    indole alkaloid biosynthesis - subcellular organization - rauwolfia-serpentina - statistical-model - plants - expression - proteins - synthase - enzyme - cytochrome-p450
    The (seco)iridoids and their derivatives, the monoterpenoid indole alkaloids (MIAs), form two large families of plant-derived bioactive compounds with a wide spectrum of high-value pharmacological and insect-repellent activities. Vinblastine and vincristine, MIAs used as anticancer drugs, are produced by Catharanthus roseus in extremely low levels, leading to high market prices and poor availability. Their biotechnological production is hampered by the fragmentary knowledge of their biosynthesis. Here we report the discovery of the last four missing steps of the (seco)iridoid biosynthesis pathway. Expression of the eight genes encoding this pathway, together with two genes boosting precursor formation and two downstream alkaloid biosynthesis genes, in an alternative plant host, allows the heterologous production of the complex MIA strictosidine. This confirms the functionality of all enzymes of the pathway and highlights their utility for synthetic biology programmes towards a sustainable biotechnological production of valuable (seco)iridoids and alkaloids with pharmaceutical and agricultural applications.
    Toxicity of Pyrrolizidine Alkaloids to Spodoptera exigua Using Insect Cell Lines and Injection Bioassays
    Nuringtyas, T.R. ; Verpoorte, R. ; Klinkhamer, P.G.L. ; Oers, M.M. van; Leiss, K.A. - \ 2014
    Journal of Chemical Ecology 40 (2014)6. - ISSN 0098-0331 - p. 609 - 616.
    tertiary amine - n-oxides - performance - herbivores - resistance - asteraceae - vulgaris - hybrids - plants
    Pyrrolizidine alkaloids (PAs) are feeding deterrents and toxic compounds to generalist herbivores. Among the PAs of Jacobaea vulgaris Gaertn, jacobine and erucifoline are the most effective against insect herbivores as indicated by correlative studies. Because little is known about the effect of jacobine and erucifoline as individual PAs, we isolated these compounds from their respective Jacobaea chemotypes. These PAs and other commercially available senecionine-like PAs, including senecionine, seneciphylline, retrorsine, and senkirkine, were tested as free base and N-oxide forms at a range of 0–70 ppm. Feeding bioassays using live insects are closer to the natural pattern but require relatively large amounts of test compounds. We, therefore, compared the toxicity of PAs using both Spodoptera exigua cell line and larval injection bioassays. Both bioassays led to similar results in the order of PA toxicity, indicating that the cell lines are a valuable tool for a first toxicity screen. Testing individual PAs, jacobine and erucifoline were the most toxic PAs, suggesting their major role in plant defense against generalist herbivores. Senkirkine and seneciphylline were less toxic than jacobine and erucifoline but more toxic than retrorsine. Senecionine was not toxic at the tested concentrations. For all toxic PAs, the free base form was more toxic than the N-oxide form. Our results demonstrate that structural variation of PAs influences their effectiveness in plant defense.
    Tuliposides and tulipalins in tulip Gum
    Lubbe, A. ; Verpoorte, R. ; Gude, H. ; Dijkema, M.H.G.E. - \ 2013
    In: Proceedings of the XIth International Symposium on Flowerbulbs and Herbaceous Perennials (ISHS), Antalya, Turkey, 28-04-2012. - - p. 333 - 338.
    Gummosis in tulip bulbs is one of the negative effects of ethylene gas that is produced during storage by Fusarium-infected bulbs on the healthy bulbs. Several aspects of the gummosis process, like the factors inducing it, the underlying carbohydrate metabolism and the composition of the gum have been described in detail in a review by Saniewski et al. (2007). The composition of tulip gum has mostly been studied in terms of large macromolecules. The gum polysaccharides have been analyzed to determine sugar composition and molecular mass. Up to now relatively little was known about the gum in terms of small (low molecular weight) metabolite content. Gummosis was induced in tulip bulbs of the cultivar ‘Apeldoorn’ by exposing the bulbs to air containing 30 ppm ethylene for 24, 48 or 72 h. Gum was collected after 3 to 4 days. A maximum amount of approximately 5 g per 100 g bulbs was obtained. Extracts of the gum were analyzed by 1H Nuclear Magnetic Resonance (1H NMR) and were found to contain tuliposides, in concentrations up to around 25% (DW). Tuliposides are glycosides consisting of glucose with one or more a-methylene-¿-butyrolactone side chains. The side chains, when separated from the glucose, form ring structures known as tulipalins. Six different tuliposides and two tulipalins have been reported in various parts of the tulip plant. However, this is the first time they are reported in the gum from tulip bulbs. Isolated tulipalins and tuliposides have previously been tested for various bioactivities, and have been reported to possess antibacterial, antifungal and insecticidal properties. The presence of these bioactive molecules in tulip gum may suggest a protective role for this physiological response
    Seasonal accumulation of major alkaloids in organs of pharmaceutical crop Narcissus Carlton
    Lubbe, A. ; Gude, H. ; Verpoorte, R. ; Choi, C.Y. - \ 2013
    Phytochemistry 88 (2013). - ISSN 0031-9422 - p. 43 - 53.
    amaryllidaceae alkaloids - chlorogenic acid - metabolomic analysis - cancer-cells - galanthamine - apoptosis - root - nmr
    Narcissus pseudonarcissus (L.) cv. Carlton is being cultivated as a main source of galanthamine from the bulbs. After galanthamine, haemanthamine and narciclasine are the next most abundant alkaloids in this cultivar. Both these compounds are promising chemical scaffolds for potential anticancer drugs. For further research and drug development, a reliable supply of these compounds will be needed. In this study a field experiment was conducted to investigate the levels of galanthamine, haemanthamine and narciclasine in plants of N. pseudonarcissus cv. Carlton. In a field experiment alkaloids in the bulbs, leaves and roots were analyzed by quantitative 1H NMR to monitor the variations during the growing season. Major primary and secondary metabolites were identified in the various plant parts. Multivariate data analysis was performed on the 1H NMR spectra to investigate how metabolites changed in the plant organs over time. The results show that the leaves have relatively high concentrations of the alkaloids before flowering. The bulbs had lower concentrations of the compounds of interest but would have a higher total yield of alkaloids due to bigger biomass. Narcissus pseudonarcissus cv. Carlton represents a good source of galanthamine, and can potentially be a source of the other major alkaloids depending on choice of organ and harvest time
    Activation of antioxidant response element in mouse primary cortical cultures with sesquiterpene lactones isolated from Tanacetum parthenium
    Fischedick, J.T. ; Standiford, M. ; Johnson, D.A. ; Vos, R.C.H. de; Todorovic, S. ; Banjanac, T. ; Verpoorte, R. ; Johnson, J.A. - \ 2012
    Planta Medica 78 (2012)16. - ISSN 0032-0943 - p. 1725 - 1730.
    biomimetic transformations - neurodegenerative disease - parthenolide - santamarine - anticancer - compositae - feverfew - pathway - target - cells
    Tanacetum parthenium produces biologically active sesquiterpene lactones (SL). Nuclear factor E2-related factor 2 (Nrf2) is a transcription factor known to activate a series of genes termed the antioxidant response element (ARE). Activation of Nrf2/ARE may be useful for the treatment of neurodegenerative disease. In this study we isolated 11 SL from T. parthenium with centrifugal partition chromatography and semipreparative HPLC. Compounds were screened in vitro for their ability to activate the ARE on primary mouse cortical cultures as well as for their toxicity towards the cultures. All SL containing the a-methylene-¿-lactone moiety were able to activate the ARE and cause cellular toxicity. The structure-activity relationship among the SL isolated indicates that the guaianolides were more active and when lacking the endoperoxide functionality less toxic then the germacranolides.
    Effect of fertilizers on galanthamine and metabolite profiles in narcissus bulbs by 1H NMR
    Lubbe, A. ; Choi, Y.H. ; Vreeburg, P.J.M. ; Verpoorte, R. - \ 2011
    Journal of Agricultural and Food Chemistry 59 (2011)7. - ISSN 0021-8561 - p. 3155 - 3161.
    amaryllidaceae alkaloids - nitrogen-fertilizer - gas-chromatography - nmr - growth - metabolomics - leaves
    Narcissus bulbs contain the biologically active alkaloid galanthamine, and Narcissus is being developed as a natural source of the molecule for the pharmaceutical industry. The effect of fertilizer on galanthamine production was investigated in a field study using a 1H nuclear magnetic resonance (NMR) metabolite profiling approach. Galanthamine was quantitated and major metabolites in the bulbs were identified. The application of standard fertilization levels of nitrogen and potassium caused a significant increase in galanthamine as compared to a control. Multivariate data analysis of the 1H NMR data revealed that applying double the standard level of nitrogen fertilizer resulted in production of more amino acids and citric acid cycle intermediates, but not more galanthamine. The results indicated that standard levels of fertilizer currently applied in The Netherlands are sufficient for optimal galanthamine accumulation in the bulbs. This study shows how 1H NMR-based metabolic profiling can provide insight into the response of plant metabolism to agricultural practices.
    Commentary: "A systems view on the future of medicine: Inspiration from Chinese medicine?"
    Verpoorte, R. ; Crommelin, D. ; Danhof, M. ; Gilissen, L.J.W.J. ; Schuitmaker, H. ; Greef, J. de; Witkamp, R.F. - \ 2009
    Journal of Ethnopharmacology 121 (2009)3. - ISSN 0378-8741 - p. 479 - 481.
    Chinese medicine could serve as a source of inspiration for drug development. Using systems biology in combination with reverse pharmacology is a novel way for the discovery of novel biological active compounds and targets as well as for proving the occurrence of synergy and prodrugs. A key factor for coming to evidence-based Chinese medicine will be the quality control. Metabolomics is a very promising tool for this purpose.
    Metabolic engineering of terpenoid biosynthesis in plants
    Lücker, J. ; Bouwmeester, H.J. ; Aharoni, A. - \ 2007
    In: Applications of plant metabolic engineering / Verpoorte, R., Alferman, W., Johnson, T.S., Berlin : Springer Verlag - ISBN 9781402060304 - p. 211 - 218.
    Analysis of taxines in Taxus plant material and cell cultures by hplc photodiode array and hplc-electrospray mass spectrometry
    Theodoridis, G. ; Laskaris, G. ; Rozendaal, E.L.M. ; Verpoorte, R. - \ 2001
    Journal of liquid chromatography & related technologies 24 (2001)15. - ISSN 1082-6076 - p. 2267 - 2282.
    A semi-purified Taxus baccata needles extract was analysed by RP-HPLC. More than 18 taxines and cinnamates were detected by photodiode array detection and LC-MS, 10 of them being positively identified. Furthermore, 10-deacetyl baccatin III (paclitaxel's main precursor) and other taxanes were also found in the extract. Taxines were also detected in numerous extracts of plant and cell culture extracts of various origins. The identification of the taxines in the extracts was made by correlation of retention and spectral data. LC-electrospray MS verified the identification of the known taxines in T. baccata seeds, needles, and pollen
    Purification and characterisation of strictosidine ß-D-glucosidase from Catharanthus roseus cell suspension cultures
    Luijendijk, T.J.C. ; Stevens, L.H. ; Verpoorte, R. - \ 1998
    Plant Physiology and Biochemistry 36 (1998). - ISSN 0981-9428 - p. 419 - 425.
    Distribution of ginkgolides and terpenoid biosynthetic activity in Ginkgo biloba.
    Carrier, D.J. ; Beek, T.A. van; Heijden, R. van der; Verpoorte, R. - \ 1998
    Phytochemistry 48 (1998). - ISSN 0031-9422 - p. 89 - 92.
    Reaction for the localization of strictosidine glucosidase activity on polyacrylamide gels
    Luijendijk, T.J.C. ; Stevens, L.H. ; Verpoorte, R. - \ 1996
    Phytochemical Analysis 7 (1996). - ISSN 0958-0344 - p. 16 - 19.
    Capillary gas chromatography analysis of indole alkaloids: investigation of the indole alkaloids present in Tabernaemontana divaricata cell suspension culture.
    Dagnino, D. ; Schripsema, J. ; Peltenburg, A. ; Verpoorte, R. ; Teunis, K. - \ 1991
    Journal of Natural Products 54 (1991). - ISSN 0163-3864 - p. 1558 - 1563.
    A reinvestigation of the stereochemistry of tubotaiwine using NMR spectroscopy.
    Schripsema, J. ; Beek, T.A. van; Verpoorte, R. ; Erkelens, C. ; Perera, P. ; Tibell, C. - \ 1987
    Journal of Natural Products 50 (1987). - ISSN 0163-3864 - p. 89 - 101.
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