1H NMR- based metabolite profiling of tropane alkaloids in Duboisia spec.

Duboisia R.Br. (Solanaceae) is the main source of the tropane alkaloid scopolamine, which is an important precursor of various active pharmaceutical ingredients due to its anticholinergic properties. As only little is known about the metabolite composition among the different species, NMRbased metabolic profiling was done in order to elucidate primary and secondary metabolism in Duboisia especially focusing on the tropane alkaloid pathway. For this purpose, plants of five different genotypes (Duboisia myoporoides, D. leichardtii and hybrids of D. myoporoides and D. leichhardtii) were cultivated under strictly controlled conditions in climate chambers, leaf and root extracts were prepared and measured via 1H NMR. 14 different metabolites could be identified using 1D- and 2D-NMR techniques. Principal component analysis of the NMR data allowed a clear distinction between Duboisia hybrids and the wild types, which could be again subgrouped in D. myoporoides and D. leichhardtii, based on the metabolites identified

Endophytes as alternative paclitaxel sources : chemistry and genetics of Taxomyces andreanae and the endophytic flora of Wollemia nobilis

Whether suffering a pathogenic attack, basking in symbiotic comfort, or seemingly symptomless, plants constantly participate in molecular interplay with various classes of microbial organisms. One of the means of interorganismal communication in this dynamic continuum are secondary metabolites. The chemical diversity bearing pharmaceutical potential thus implied reaches beyond the plant kingdom and offers an expended view promising to transform glimpses of reductionist research of the past years to snapshots of an exuberant world of systems biology. Endophytes seem to fit perfectly into this natural ‘warehouse’, only a small part of which we have been able to tap into so far. The introductory section of the hereby presented thesis (chapter 2) provides an elaborate overview on the current state of knowledge about endophytic organisms – microbes colonizing internal tissues of all plant species, creating a huge biodiversity with yet unknown novel natural products presumed to push forward the frontiers of drug discovery (Staniek et al., 2008). Paclitaxel, the world’s first billion dollar anticancer blockbuster, was primarily obtained from Taxus brevifolia. While the search for alternative sources of the powerful antineoplastic agent brought an array of reports on paclitaxel producing endophytes, causing quite a controversy over the past two decades, the world’s market still relies on yew-derived supply of the valuable diterpene.

Least-Squares Methods for the Solution of Fluid-Structure Interaction Problems

Different numerical methods have been proposed for the solution of partial differential equations (PDE). Most of them are based on a variational principle which recasts the PDE into an equivalent integral equation. One of the most common principles is the Galerkin method, which has some specific disadvantages for some types of PDE. In this work an alternative variational principle, the least squares finite element method, will be tested with respect to its application for transient fluid-structure interaction problems. The accurracy of different formulations which were proposed for the Navier-Stokes equations in literature will be tested. In a next step these formulations will be coupled with a standard Galerkin approach for the structure. After that a new formulation for the linear equations of elastodynamics is developed and analysed with respect to its stability and accuracy. With this formulation it is possible do develop a pure least squares formulation for the strongly coupled fluid-structure problem. Finally the different formulations are tested with respect to their accuracy and efficiency.Zur Lösung von partiellen Differentialgleichungen (PDE) sind verschiedene numerische Verfahren vorgeschlagen worden. Die meisten basieren auf einem Variationsprinzip, das die PDE in eine äquivalente Integralgleichung überführt. Ein häufig verwendetes Variationsprinzip ist das Galerkin Verfahren, das jedoch für bestimmte Gleichungstypen Nachteile aufweist. In dieser Arbeit wird die Eignung eines alternativen Variationsprinzips, der Least-Squares Finite Elemente Methode, zur Lösung von instationären Fluid-Struktur Interaktionsproblemen untersucht. Dazu werden verschiedene Formulierungen für die Navier-Stokes Gleichungen, die in der Literatur vorgeschlagen wurden auf ihre Genauigkeit hin untersucht. Diese Formulierungen für die Navier-Stokes Gleichungen werden danach zunächst mit einer klassischen Galerkin Formulierung für die Struktur gekoppelt. Um eine reine Least-Squares Formlierung des gekoppelten Systems zu erhalten wird eine neue Formulierung für die instationären Gleichungen der linearen Elastizität entwickelt und analysiert. Hiermit wird dann eine stark gekoppelte reine Least-Squares Formulierung für Fluid-Struktur Probleme entworfen. Die verschiedenen entwickelten Formulierungen werden schließlich mit verschiedenen Beispielen auf ihre Genauigkeit und Effizienz hin untersucht

Five-Year Long-Term Followup of a Primary Lymph node Gastrinoma: Is a Pancreaticoduodenectomy Justified?

Background. Gastrinoma-positive lymph nodes and failed localization of the primary tumor during surgical exploration are described. Specialists suppose that these lymph nodes are metastases rather than a primary gastrinoma. Methods. Case report with a five-year long-term followup. A 60-year-old patient with an confirmed gastrinoma was treated in our department. All preoperative evaluations including somatostatin-receptor-scintigraphy and F-Dopa PET failed to localize the gastrinoma. Explorative laparotomy revealed a gastrinoma in two peripancreatic lymph nodes. Despite extensive intraoperative exploration, no primary gastrinoma could be detected in typical localization. Results. Over a period of 5 years, the patient's gastrin level stayed in the normal range and the patient seems to be completely cured. Conclusion. A prophylactic partial pancreatoduodenectomy is not indicated to avoid recurrence, since complete biochemical cure by local resection of the lymph node gastrinoma is possible

In vitro regeneration of wild chervil (Anthriscus sylvestris L.)

Anthriscus sylvestris (L.) Hoffm. (Apiaceae) is a common wild plant that accumulates the lignan deoxypodophyllotoxin. Deoxypodophyllotoxin can be hydroxylated at the C-7 position in recombinant organisms yielding podophyllotoxin, which is used as a semi-synthetic precursor for the anticancer drugs, etoposide phosphate and teniposide. As in vitro regeneration of A. sylvestris has not yet been reported, development of a regeneration protocol for A. sylvestris would be useful as a micropropagation tool and for metabolic engineering of the plant. Calli were induced from hypocotyl explants and transferred to shoot induction medium containing zeatin riboside. Regenerated shoots were obtained within 6 mo and were transferred onto growth regulator-free root induction medium containing 1% sucrose. Regenerated plants transferred to soil and acclimatized in a greenhouse. Plants were transferred to the field with a 100% survival rate. Regenerated plants flowered and were fully fertile. This is the first report of complete regeneration of A. sylvestris via shoot organogenesis from callus

Least-Squares FEM: Literature Review

During the last years the interest in least squares finite element methods (LSFEM) has grown continuously. Least squares finite element methods offer some advantages over the widely used Galerkin variational principle. One reason is the ability to cope with first order differential operators without special treatment as required by the Galerkin FEM. The other reason comes from the numerical point of view, where the LSFEM leads to symmetric positive definite matrices which can be solved very efficiently under some conditions. This report gives an overview about the recent literature which appeared in the field of least squares finite element methods and summarises the essential results and facts about the LSFEM.Während der letzten Jahre hat das Interesse an Least Squares Finite Element Methoden (LSFEM) stetig zugenommen. Least Squares Finite Element Methoden bieten einige Vorteile gegenüber dem etablierten Galerkin Variationsansatz. So können Differentialoperatoren erster Ordnung ohne besondere numerische Techniken, wie z.B. Stabilisierung, direkt behandelt werden. Ein anderer Grund für den Einsatz der LSFEM liegt in den entstehenden algebraischen Gleichungssystemen, die immer symmetrisch positiv definit sind und unter bestimmten Vorraussetzungen eine effiziente Lösung ermöglichen.Dieser Bericht gibt einen Überblick über die aktuelle Literatur zur LSFEM und faßt die entscheidenden Ergebnisse zusammen

Endophytes:Exploiting biodiversity for the improvement of natural product-based drug discovery

Endophytes, microorganisms that colonize internal tissues of all plant species, create a huge biodiversity with yet unknown novel natural products, presumed to push forward the frontiers of drug discovery. Next to the clinically acknowledged antineoplastic agent, paclitaxel, endophyte research has yielded potential drug lead compounds with antibacterial, antiviral, antioxidant, insulin mimetic, anti-neurodegenerative and immunosuppressant properties. Furthermore, while being implicated in livestock neurotoxicosis, some endophyte-produced alkaloids have been shown to display insecticidal activity. The endophyte-host relationship is postulated to be a 'balanced antagonism'. Moreover, the plausibility of horizontal gene transfer (HGT) hypothesis is taken into account. Knowledge of the genetic background of endophytic natural product biosynthesis is discussed on the basis of loline alkaloids, ergopeptines, lolitrems and maytansinoids. The current dynamic progress in genomics will contribute to a better understanding of endophytic microbes and to further exploiting them as a source of pharmaceutically relevant compounds

Einfluss von abiotischen Faktoren auf Wuchs und Scopolamin-Biosynthese in Duboisia myoporoides.

Duboisia ist eine in Australien beheimatete Pflanze aus der Familie der Nachtschattengewächse, die Tropanalkaloide als sekundäre Pflanzeninhaltsstoffe enthält, deren quantitativ und ökonomisch bedeutsamstes Scopolamin ist.Um neue Erkenntnisse hinsichtlich des Einflusses abiotischer Faktoren auf Wuchs und Scopolamin-Biosynthese zu gewinnen, wurden Pflanzen der Art Duboisia myoporoides in Hydrokultur in Klimakammern unter streng kontrollierten Bedingungen angebaut (kalibrierte Einstellungen für Beleuchtungsdauer, Lichtintensität und Temperatur). Wichtige Messgrößen stellten dabei Biomasse und Alkaloidgehalt dar, letzterer gemessen mittels UHPLC und LC-MS.Stichwörter: Duboisia, LC-MS, Scopolamin, TropanalkaloideInfluence of abiotic factors on growth and biosynthesis of scopolamine in Duboisia myoporoides.Duboisia, a native Australian plant belonging to the family of Solanaceae, contains tropane alkaloids as secondary plant components, thereof quantitatively as well as economically most important scopolamine. In order to obtain new findings regarding the effect of abiotic factors on biomass and biosynthesis of scopolamine, plants of the species Duboisia myoporoides were grown in climate chambers using hydroponics under strictly controlled conditions (calibrated settings regarding lighting period, light intensity and temperature). Essential measurement variables were biomass and alkaloid content, the latter analyzed via UHPLC and LC-MS. Keywords: Duboisia, LC-MS, scopolamine, tropane alkaloid