@phdthesis{Schlichter2007,
  author    = {Schlichter, Susanne},
  title     = {Einfluss des Flavonoids Quercetin auf die epitheliale Barrierefunktion der humanen Kolonkarzinom-Zelllinie Caco-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-15269},
  school      = {Universit{\"a}t Potsdam},
  year      = {2007},
  abstract  = {Ein hoher Verzehr von Obst und Gem{\"u}se scheint das Risiko der Inzidenz verschiedener Erkrankungen zu reduzieren. Es wird vermutet, dass eine Gruppe sekund{\"a}rer Pflanzeninhaltsstoffe, die Flavonoide, hierf{\"u}r verantwortlich sind. M{\"o}gliche Effekte auf die intestinale Barrierefunktion dieser Substanzklasse sind jedoch weitgehend ungekl{\"a}rt. Parazellul{\"a}re Eigenschaften epithelialer Zellen werden haupts{\"a}chlich durch die Zell-Zell-Kontakte der Tight Junction (TJ) insbesondere durch die Proteine Occludin und die Claudine definiert. Ziel dieser Arbeit war es, die Effekte des am h{\"a}ufigsten vorkommenden Flavonoids Quercetin auf die Barrierefunktion der Kolonkarzinom-Zelllinie Caco-2 zu untersuchen. Hierbei zeigte sich, dass Quercetin konzentrationsabh{\"a}ngig (50-200 µM) den transepithelialen Widerstand erh{\"o}hte. Die Wirkung von 200 µM Quercetin war bereits nach 4 h Inkubation erkennbar und erreichte nach 48 h maximale Werte. Der Wirkverlust, welcher nach 72 h Inkubation eintrat, konnte durch eine t{\"a}gliche Gabe des Flavonoids verhindert werden. Weiterhin zeigte sich, dass der Quercetin-induzierte Widerstandsanstieg durch mukosale oder serosale Zugabe gleichermaßen ausl{\"o}sbar war. Western Blot-Analysen der TJ-Proteine Occludin, Claudin-1, -3, -4 und -7 ergaben, dass der durch Quercetin-induzierte Widerstandsanstieg insbesondere mit einer Zunahme der Expression des abdichtenden TJ-Proteins Claudin-4 einherging. Quercetin erh{\"o}hte ebenfalls die mRNA-Expression von Claudin-4 (quantitative RT-PCR) und bewirkte eine Aktivierung des Claudin-4-Promotors (Luciferase-Reportergen-Analysen). Mittels Immunfluoreszenz-F{\"a}rbungen und Laserscanning-Mikroskopie konnte ein vermehrter Einbau von Claudin-4 in die TJ nachgewiesen werden. Funktionelle Untersuchungen mittels radioaktiven Fluxmessungen zeigten, dass das Flavonoid die parazellul{\"a}re Permeabilit{\"a}t f{\"u}r Natrium und Chlorid reduzierte, aber die Durchl{\"a}ssigkeit von Mannitol als parazellul{\"a}rer Marker unver{\"a}ndert blieb. Wir konnten hiermit erstmals nachweisen, dass Quercetin die Expression des abdichtenden TJ-Proteins Claudin-4 in den TJ-Komplex verst{\"a}rkte, wodurch die Ionen-Durchl{\"a}ssigkeit f{\"u}r Natrium und Chlorid vermindert wurde. Das f{\"u}hrte zu einer Abdichtung der intestinalen Barriere. Dieser direkte Effekte von Quercetin k{\"o}nnte eine neue M{\"o}glichkeit f{\"u}r die Behandlung oder Pr{\"a}vention von Diarrh{\"o}e-bedingten intestinalen Barrieredefekten darstellen.},
  language  = {de}
}
@misc{KlopschBaldermannVossetal.2018,
  author    = {Klopsch, Rebecca and Baldermann, Susanne and Voss, Alexander and Rohn, Sascha and Schreiner, Monika and Neugart, Susanne},
  title     = {Bread enriched with legume microgreens and leaves},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1064},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-46870},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-468707},
  pages     = {21},
  year      = {2018},
  abstract  = {Flavonoids, carotenoids, and chlorophylls were characterized in microgreens and leaves of pea (Pisum sativum) and lupin (Lupinus angustifolius) as these metabolites change during ontogeny. All metabolites were higher in the leaves for both species. Acylated quercetin and kaempferol sophorotrioses were predominant in pea. Genistein and malonylated chrysoeriol were predominant in lupin. Further, the impact of breadmaking on these metabolites using pea and lupin material of two ontogenetic stages as an added ingredient in wheat-based bread was assessed. In "pea microgreen bread" no decrease of quercetin was found with regard to the non-processed plant material. However kaempferol glycosides showed slight decreases induced by the breadmaking process in "pea microgreen bread" and "pea leaf bread." In "lupin microgreen bread" no decrease of genistein compared to the non-processed plant material was found. Chrysoeriol glycosides showed slight decreases induced by the breadmaking process in "lupin microgreen bread" and "lupin leaf bread." In all breads, carotenoids and chlorophylls were depleted however pheophytin formation was caused. Thus, pea and lupin microgreens and leaves are suitable, natural ingredients for enhancing health-promoting secondary plant metabolites in bread and may even be used to tailor bread for specific consumer health needs.},
  language  = {en}
}
@article{KlopschBaldermannVossetal.2018,
  author    = {Klopsch, Rebecca and Baldermann, Susanne and Voss, Alexander and Rohn, Sascha and Schreiner, Monika and Neugart, Susanne},
  title     = {Bread enriched with legume microgreens and leaves},
  series = {Frontiers in chemistry},
  volume    = {6},
  journal   = {Frontiers in chemistry},
  publisher = {Frontiers Research Foundation},
  address   = {Lausanne},
  issn      = {2296-2646},
  doi       = {10.3389/fchem.2018.00322},
  pages     = {19},
  year      = {2018},
  abstract  = {Flavonoids, carotenoids, and chlorophylls were characterized in microgreens and leaves of pea (Pisum sativum) and lupin (Lupinus angustifolius) as these metabolites change during ontogeny. All metabolites were higher in the leaves for both species. Acylated quercetin and kaempferol sophorotrioses were predominant in pea. Genistein and malonylated chrysoeriol were predominant in lupin. Further, the impact of breadmaking on these metabolites using pea and lupin material of two ontogenetic stages as an added ingredient in wheat-based bread was assessed. In "pea microgreen bread" no decrease of quercetin was found with regard to the non-processed plant material. However kaempferol glycosides showed slight decreases induced by the breadmaking process in "pea microgreen bread" and "pea leaf bread." In "lupin microgreen bread" no decrease of genistein compared to the non-processed plant material was found. Chrysoeriol glycosides showed slight decreases induced by the breadmaking process in "lupin microgreen bread" and "lupin leaf bread." In all breads, carotenoids and chlorophylls were depleted however pheophytin formation was caused. Thus, pea and lupin microgreens and leaves are suitable, natural ingredients for enhancing health-promoting secondary plant metabolites in bread and may even be used to tailor bread for specific consumer health needs.},
  language  = {en}
}
@article{BrauneGuetschowBlaut2019,
  author    = {Braune, Annett and G{\"u}tschow, Michael and Blaut, Michael},
  title     = {An NADH-Dependent Reductase from Eubacterium ramulus Catalyzes the Stereospecific Heteroring Cleavage of Flavanones and Flavanonols},
  series = {Applied and environmental microbiology},
  volume    = {85},
  journal   = {Applied and environmental microbiology},
  number    = {19},
  publisher = {American Society for Microbiology},
  address   = {Washington},
  issn      = {0099-2240},
  doi       = {10.1128/AEM.01233-19},
  pages     = {15},
  year      = {2019},
  abstract  = {The human intestinal anaerobe Eubacterium ramulus is known for its ability to degrade various dietary flavonoids. In the present study, we demonstrate the cleavage of the heterocyclic C-ring of flavanones and flavanonols by an oxygen-sensitive NADH-dependent reductase, previously described as enoate reductase, from E. ramulus. This flavanone- and flavanonol-cleaving reductase (Fcr) was purified following its heterologous expression in Escherichia coli and further characterized. Fcr cleaved the flavanones naringenin, eriodictyol, liquiritigenin, and homoeriodictyol. Moreover, the flavanonols taxifolin and dihydrokaempferol served as substrates. The catalyzed reactions were stereospecific for the (2R)-enantiomers of the flavanone substrates and for the (25,35)-configured flavanonols. The enantioenrichment of the nonconverted stereoisomers allowed for the determination of hitherto unknown flavanone racemization rates. Fcr formed the corresponding dihydrochalcones and hydroxydihydrochalcones in the course of an unusual reductive cleavage of cyclic ether bonds. Fcr did not convert members of other flavonoid subclasses, including flavones, flavonols, and chalcones, the latter indicating that the reaction does not involve a chalcone intermediate. This view is strongly supported by the observed enantiospecificity of Fcr. Cinnamic acids, which are typical substrates of bacterial enoate reductases, were also not reduced by Fcr. Based on the presence of binding motifs for dinucleotide cofactors and a 4Fe-4S cluster in the amino acid sequence of Fcr, a cofactor-mediated hydride transfer from NADH onto C-2 of the respective substrate is proposed. IMPORTANCE Gut bacteria play a crucial role in the metabolism of dietary flavonoids, thereby contributing to their activation or inactivation after ingestion by the human host. Thus, bacterial activities in the intestine may influence the beneficial health effects of these polyphenolic plant compounds. While an increasing number of flavonoid-converting gut bacterial species have been identified, knowledge of the responsible enzymes is still limited. Here, we characterized Fcr as a key enzyme involved in the conversion of flavonoids of several subclasses by Eubacterium ramulus, a prevalent human gut bacterium. Sequence similarity of this enzyme to hypothetical proteins from other flavonoid-degrading intestinal bacteria in databases suggests a more widespread occurrence of this enzyme. Functional characterization of gene products of human intestinal microbiota enables the assignment of metagenomic sequences to specific bacteria and, more importantly, to certain activities, which is a prerequisite for targeted modulation of gut microbial functionality.},
  language  = {en}
}