973 resultados para Umpolung, heterocycles, natural products
Resumo:
Terrestrial radioactivity for most individual is the major contributor to the total dose and is mostly provided by 238U, 232Th and 40K radionuclides. In particular indoor radioactivity is principally due to 222Rn, a radioactive noble gas descendent of 238U, second cause of lung cancer after cigarettes smoking. Vulsini Volcanic District is a well known quaternary volcanic area located between the northern Latium and southern Tuscany (Central Italy). It is characterized by an high natural radiation background resulting from the high concentrations of 238U, 232Th and 40K in the volcanic products. In this context, subduction-related metasomatic enrichment of incompatible elements in the mantle source coupled with magma differentiation within the upper crust has given rise to U, Th and K enriched melts. Almost every ancient village and town located in this part of Italy has been built with volcanic rocks pertaining to the Vulsini Volcanic District. The radiological risk of living in this area has been estimated considering separately: a. the risk associated with buildings made of volcanic products and built on volcanic rock substrates b. the risk associated to soil characteristics. The former has been evaluated both using direct 222Rn indoor measurements and simulations of “standard rooms” built with the tuffs and lavas from the Vulsini Volcanic District investigated in this work. The latter has been carried out by using in situ measurements of 222Rn activity in the soil gases. A radon risk map for the Bolsena village has been developed using soil radon measurements integrating geological information. Data of airborne radioactivity in ambient aerosol at two elevated stations in Emilia Romagna (North Italy) under the influence of Fukushima plume have been collected, effective doses have been calculated and an extensive comparison between doses associated with artificial and natural sources in different area have been described and discussed.
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The main topic of my Ph.D. thesis is the study of nucleophilic and electrophilic aromatic substitution reaction, in particular from a mechanistic point of view. The research was mainly focused on the reactivity of superactivated aromatic systems. In spite of their high reactivity (hence the high reaction’s rate), we were able to identify and in some case to isolate -complexes until now only hypothesized. For example, interesting results comes from the study of the protonation of the supernucleophiles tris(dialkylamino)benzenes. However, the best result obtained in this field was the isolation and structural characterization of the first stables zwitterionic Wheland-Meisenheimer complexes by using 2,4-dipyrrolidine-1,3-thiazole as supernucleophile and 4,6-dinitrobenzofuroxan or 4,6-dinitrotetrazolepyridine as superelectrophile. These reactions were also studied by means of computational chemistry, which allowed us to better investigate on the energetic and properties of the reactions and reactants studied. We also discovered, in some case fortuitously, some relevant properties and application of the compounds we synthesized, such as fluorescence in solid state and nanoparticles, or textile dyeing. We decided to investigate all these findings also by collaborating with other research groups. During a period in the “Laboratoire de Structure et Réactivité des Systèmes Moléculaires Complexes-SRSMC, Université de Lorraine et CNRS, France, I carried out computational studies on new iron complexes for the use as dyes in Dye Sensitized Solar Cells (DSSC). Furthermore, thanks to this new expertise, I was involved in a collaboration for the study of the ligands’ interaction in biological systems. A collaboration with University of Urbino allowed us to investigate on the reactivity of 1,2-diaza-1,3-dienes toward nucleophiles such as amino and phosphine derivatives, which led to the synthesis of new products some of which are 6 or 7 member heterocycles containing both phosphorus and nitrogen atoms.
Resumo:
The demand of minimally processed fruits and vegetables has increased in the last years. However, their intrinsic characteristics may favor the growth of pathogens and spoilage microbiota. The negative effects on human health reported for some traditional chemical sanitizers have justified the search for substitutes to guarantee food safety and quality. In this work we have evaluate the potential of some essential oils and their components to improve the safety and the shelf life of Lamb’s lettuce (Valerianella locusta) and apples (Golden delicious). Moreover, the effects of selected lactic acid bacteria alone or in combination with essential oils or their components, on the shelf-life and safety as well as organoleptic properties of minimally processed products, were evaluated. Since the lack of knowledge of microbial cell targets of essential oils represent one of the most important limit to the use of these molecules at industrial level, another aim of this thesis was the study of the action mechanisms of essential oils and their components. The results obtained showed the beneficial effects of the natural antimicrobials as well as the selected lactic acid bacteria on minimally processed fruit and vegetable safety and shelf-life, without detrimental effects on the quality parameters. The beneficial effects obtained by the use of the selected biocontrol agents were further increased combining them with selected natural antimicrobials. The natural antimicrobial employed induced noticeable modifications of membrane fatty acid profiles and volatile compounds produced by microbial cells during the growth. The modification of the expression in genes involved in fatty acid biosynthesis suggesting that the cytoplasmic membrane of microbial cells is one of the major cellular target of essential oils and their components. The comprehension of microbial stress response mechanisms can contribute to the scaling up of natural antimicrobials and bio-control agents at industrial level.
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The overall objective of this PhD was to investigate the possibility to increase the nutritional value of confectionary products by the use of natural ingredients with healthy functions. The first part of the thesis focused on the possible substitution of the most characteristic component of confectionary products, i.e. refined sugar. Many natural whole sweetening alternatives are available, though not widely used; the use of molasses, the byproduct of sugar beet and cane production, still rich in healthy components as minerals and phytochemicals is hereby discussed; after having verified molasses effectiveness in oxidative stress counteraction on liver cultured cells, the higher antioxidant capacity of a sweet food prepared with molasses instead of refined sugar was confirmed. A second step of the project dealt with another main ingredient of various sweet products, namely wheat. Particularly, the exploitation of soft and durum wheat byproducts could be another sustainable strategy to improve the healthy value of confectionery. The isolation of oligosaccharides with bioactive functions form different fractions of the wheat milling stream was studied and the new ingredients were shown to have a high dietary fiber and antioxidants content. As valid alternative, product developers should consider the appealing and healthy addition of ancient grains flour to sweet baked goods. The possibility of substituting the modern whole durum wheat with the ancient Kamut® khorasan was considered, and the antioxidant and anti-inflammatory effects of these grains were evaluated and compared both in vitro and in vivo on rats. Finally, since high consumption of confectionery is a risk factor for obesity, a possible strategy for the counteraction of this disease was investigated. The ability of three bioactives in inhibiting adipocytes differentiation was investigated. In fact, theoretically, compounds able to influence adipogenesis could be used in the formulation of functional sweet products and contribute to prevent obesity.
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Introduction: Among all cancer types leukemia represents the leading cause of cancer death in man younger than 40 years. Single-target drug therapy has generally been highly ineffective in treating complex diseases such as cancer. A growing interest has been directed toward multi-target drugs able to hit multiple targets. In this context, plant products, based on their intrinsic complexity, could represent an interesting and promising approach. Aim of the research followed during my PhD was to indentify and study novel natural compounds for the treatment of acute leukemias. Two potential multi-target drugs were identified in Hemidesmus indicus and piperlongumine. Methodology/Principal Findings: A variety of cellular assays and flow cytometry were performed on different cell lines. We demonstrated that Hemidesmus modulates many components of intracellular signaling pathways involved in cell viability and proliferation and alters gene and protein expression, eventually leading to tumor cell death, mediated by a loss of mitochondrial transmembrane potential, raise of [Ca2+]i, inhibition of Mcl-1, increasing Bax/Bcl-2 ratio, and ROS formation. Moreover, we proved that the decoction causes differentiation of HL-60 and regulates angiogenesis of HUVECs in hypoxia and normoxia, by the inhibition of new vessel formation and the processes of migration/invasion. Clinically relevant observations are that its cytotoxic activity was also recorded in primary cells from acute myeloid leukemia (AML) patients. Moreover, both Hemidesmus and piperlongumine showed a selective action toward leukemic stem cell (LSC). Conclusions: Our results indicate the molecular basis of the anti-leukemic effects of Hemidesmus indicus and indentify the mitochondrial pathways, [Ca2+]i, cytodifferentiation and angiogenesis inhibition as crucial actors in its anticancer activity. The ability to selectively hit LSC showed by Hemidesmus and piperlongumine enriched the knowledge of their anti-leukemic activity. On these bases, we conclude that Hemidesmus and piperlongumine can represent a valuable strategy in the anticancer pharmacology.
Resumo:
Definiert konfigurierte mittelgroße ungesättigte Heterocyclen sind wertvolle Zwischenstufen in der Naturstoff- und Wirkstoffsynthese. Es konnte gezeigt werden, dass 2-alkinyl-substituierte Piperidine und Azepane in einer Aza-Keten-Claisen-Reaktion zu 10- und 11-gliedrigen Allenyllactamen umgelagert werden können. Ein 9-gliedriges Allenyllactam konnte nicht dargestellt werden (Ringspannung). Über eine sechs- bis sieben-stufige Reaktionssequenz konnten optisch aktive, geschützte Piperidinole aufgebaut werden. Es wurden Auxiliar kontrollierte Hetero-Diels-Alder-Reaktionen, diastereoselektive Reduktionen, Bestmann-Ohira Umlagerungen zu Alkinen und verschiedene Alkin-Funktionalisierungen erarbeitet. Eine Aza-Claisen-Umlagerung liefert schließlich optisch aktive Lactame deren absolute Konfiguration des Allensystems mittels NOE-NMR-Spektroskopie untersucht werden kann. Limitierungen und Möglichkeiten der Synthese werden eingehend diskutiert. Sowohl der stereochemische Verlauf der Reaktion als auch die Konformation der Produkte ermöglichen eine Fokussierung auf nachfolgende Naturstoffsynthesen vorzunehmen.
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In der vorliegenden Studie wurden verschiedene Techniken eingesetzt um drei Proben (4, 7, and 8) die aus denrnKorrosionsprodukten von aus dem Kosovo Krieg stammenden Munitionskugeln, bestehend aus abgereichertem Uranrn(Depleted Uranium - DU), zu untersuchen. Als erstes Verfahren wurde die Raman-Spektroskopie eingesetzt. Hierbeirnzeigte sichin den Proben, charakterisiert durch einen Doppelpeak, die Anwesenheit von Schoepitrn(UO2)8O2(OH)12(H2O)12. Der erste und zweite Peakzeigte sich im Spektralbereich von 840,3-842,5 cm-1rnbeziehungsweise 853,6-855,8 cm-1. Diese Werte stimmen mit den Literaturwerten für Raman-Peaks für Schoepitrnüberein. Des Weiteren wurde bei dieser Untersuchungsmethode Becquerelite Ca(UO2)6O4(OH)6(H2O)8 mit einemrnPeak im Bereich zwischen 829 to 836 cm-1 gefunden. Aufgrund des Fehlens des Becquerelitespektrums in derrnSpektralbibliothek wurde eine in der Natur vorkommende Variante analysiert und deren Peak bei 829 cm-1 bestimmt,rnwas mit den Ergebnissen in den Proben korrespondiert. Mittels Röntgenbeugung (X-Ray Diffraction, XRD) zeigtenrnsich in allen Proben ähnliche Spektren. Das lässt darauf schließen, dass das pulverisierte Material in allen Probenrndas gleiche ist. Hierbei zeigte sich eine sehr gute Übereinstimmung mit Schoepit und/oder meta-rnSchoepit(UO2)8O2(OH)12(H2O)10, sowie Becquerelite. Weiterhin war weder Autunit, Sabugalit noch Uranylphosphatrnanwesend, was die Ergebnisse einer anderen Studie, durchgeführt an denselben Proben, wiederlegt. DiernAnwesenheit von P, C oder Ca im Probenmaterial konnte ausgeschlossen werden. Im Falle von Calciumkann diesrnmit der Anwesenheit von Uran erklärt werden, welches aufgrund seines Atomradius bevorzugt in Becquerelite (1:6)rneingebaut wird. Die beiden Hauptpeaks für Uran lagen im Falle von U 4f 7/2 bei 382.0 eV und im Falle von U 4f 5/2rnbei 392 eV. Diese Werte mit den Literaturwerten für Schoepit und meta-Schoepitüberein. Die Ergebnissernelektronenmikroskopischen Untersuchung zeigen U, O, Ca, Ti als dominante Komponenten in allen Messungen.rnElemente wie Si, Al, Fe, S, Na, und C wurden ebenfalls detektiert; allerdings kann nicht ausgeschlossen werden,rndass diese Elemente aus dem Boden in der unmittelbaren Umgebung der Munitionsgeschosse stammen. Gold wurdernebenfalls gemessen, was aber auf die Goldarmierung in den Probenaufbereitungsbehältern zurückgeführt werdenrnkann. Die Elektronenmikroskopie zeigte außerdem einige Stellen in denen elementares Uran und Bodenmineralernsowie sekundäre Uranminerale auftraten. Die Elementübersicht zeigt einen direkten Zusammenhang zwischen U andrnCa und gleichzeitig keine Korrelation zwischen U und Si, oder Mg. Auf der anderen Seite zeigte sich aber einrnZusammenhang zwischen Si und Al da beide Konstituenten von Bodenmineralen darstellen. Eine mit Hilfe derrnElektronenstrahlmikroanalyse durchgeführte quantitative Analyse zeigte den Massenanteil von Uran bei ca. 78 - 80%,rnwas mit den 78,2% and 79,47% für Becquerelite beziehungsweise Schoepit aufgrund ihrer Summenformelrnkorrespondiert. Zusätzlich zeigt sich für Calcium ein Massenanteil von 2% was mit dem Wert in Becquerelite (2.19%)rnrecht gut übereinstimmt. Der Massenanteil von Ti lag in einigen Fällen bei 0,77%, was auf eine noch nicht korrodierternDU-Legierung zurückzuführen ist. Ein Lösungsexperiment wurde weiterhin durchgeführt, wobei eine 0,01 M NaClO4-rnLösung zum Einsatz kam in der die verbliebene Probensubstanz der Korrosionsprodukte gelöst wurde;rnNatriumperchlorate wurde hierbei genutzt um die Ionenstärke bei 0,01 zu halten. Um Verunreinigungen durchrnatmosphärisches CO2 zu vermeiden wurden die im Versuch für die drei Hauptproben genutzten 15 Probenbehälterrnmit Stickstoffgas gespült. Eine Modelkalkulation für den beschriebenen Versuchsaufbau wurde mit Visual MINTEQrnv.3.0 für die mittels vorgenannten Analysemethoden beschriebenen Mineralphasen im pH-Bereich von 6 – 10 imrnFalle von Becquerelite, und Schoepit berechnet. Die modellierten Lösungskurven wurden unter An- und Abwesenheitrnvon atmosphärischem CO2 kalkuliert. Nach dem Ende des Lösungsexperiments (Dauer ca. 6 Monate) zeigten diernKonzentrationen des gelösten Urans, gemessen mittels ICP-OES, gute Übereinstimmung mit den modelliertenrnSchoepit und Becquerelite Kurven. Auf Grund des ähnlichen Löslichkeitverhaltens war es nicht möglich zwichen denrnbeiden Mineralen zu unterscheiden. Schoepit kontrolliert im sauren Bereich die Löslichkeit des Urans, währendrnbecquerelit im basichen am wenigsten gelöst wird. Des Weiteren bleibt festzuhalten, dass ein Anteil an CO2 in diernverschlossenen Probenbehälter eingedrungen ist, was sich mit der Vorhersage der Modeldaten deckt. Die Löslichkeitrnvon Uran in der Lösung als Funktion des pH-Wertes zeigte die niedrigsten Konzentrationen im Falle einer Zunahmerndes pH-Wertes von 5 auf 7 (ungefähr 5,1 x 10-6 mol/l) und einer Zunahme des pH-Wertes auf 8 (ungefähr 1,5 x 10-6rnmol/l bei). Oberhalb dieses Bereichs resultiert jeder weitere Anstieg des pH-Wertes in einer Zunahme gelösten Uransrnin der Lösung. Der ph-Wert der Lösung wie auch deren pCO2-Wert kontrollieren hier die Menge des gelösten Urans.rnAuf der anderen Seite zeigten im Falle von Becquerelite die Ca-Konzentrationen höhere Werte als erwartet, wobeirnwahrscheinlich auf eine Vermischung der Proben mit Bodensubstanz zurückgeführt werden kann. Abschließendrnwurde, unter Berücksichtigung der oben genannten Ergebnisse, eine Fallstudie aus Basrah (Irak) diskutiert, wo inrnzwei militärischen Konflikten Uranmunition in zwei Regionen unter verschiedenen Umweltbedingungen eingesetztrnwurden.
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In the Peruvian Andes, a long history of interaction between the local populations and their natural environment has led to extraordinary levels of agrobiodiversity. However, in sharp contrast with this biological wealth, Andean indigenous populations live under most precarious conditions. Moreover, natural resources are undergoing severe degradation processes and local knowledge about biodiversity management is under serious pressure. Against this background, the BioAndes Programme is developing initiatives based on a biocultural approach that aim at fostering biodiversity through the enhancement of cultural processes. On the basis of intercultural dialogue, joint learning and capacity development, and transdisciplinary action-research, indigenous communities, development practitioners, and researchers strive for the creation of innovative ways to contribute to more sustainable economic, socio-cultural, and political valorization of Andean biodiversity. Project activities are diverse and range from the cultivation, transformation, and commercialization of organic Andean fruits in San Marcos, Cajamarca Department, to the recuperation of natural dying techniques for alpaca wool and traditional weaving in Pitumarca, Cusco Department, and the promotion of responsible ecotourism in both regions. Based on the projects’ first two-years of experience, the following lessons learnt will be presented and discussed: 1. The economic valorization and commercialization of local products can be a powerful tool for the revival and innovation of eroded know-how; at the same time it contributes to the strengthening of local identities, in parallel with the empowerment of marginalized groups such as smallholders and women. 2. Such initiatives are only successful when they are embedded within activities that go beyond the focus on local products and seek the valorization of the entire natural and cultural landscape (e.g. through the promotion of agrotourism and local gastronomy, more sustainable management of local resources including the restoration of ecosystems, and the realization of inventories of local agrobiodiversity and the knowledge related to it). 3. The sustainability of these initiatives, which are often externally induced, is conditioned by the ability of local actors to acquire ownership of projects and access to the knowledge required to carry them out, which also means developing the personal and institutional capacities for handling the whole chain from production to commercialization. 4. The confrontation of different economic rationalities and their underlying worldviews that occur when local or indigenous people integrate into the market economy implies the need for a dialogical co-production of knowledge and collective action by local people, experts from NGOs, and political authorities in order to better control the conditions relating to the market economy. The valorization of local agrobiodiversity shows much potential for enhancing natural and cultural diversity in Southern countries, but only when local communities can participate in the shaping of the conditions under which this happens. Such activities should be designed in the mid- to long-term as part of social learning processes that are carefully embedded in the local context. Supporting institutions play a crucial role in these processes, but should see themselves only as facilitators, while ensuring that control and ownership remain with the local actors.
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OBJECTIVES The application of an enamel matrix derivative (EMD) for regenerative periodontal surgery has been shown to promote formation of new cementum, periodontal ligament, and alveolar bone. In intrabony defects with a complicated anatomy, the combination of EMD with various bone grafting materials has resulted in additional clinical improvements, but the initial cellular response of osteoblasts coming in contact with these particles have not yet been fully elucidated. The objective of the present study was to evaluate the in vitro effects of EMD combined with a natural bone mineral (NBM) on a wide variety of genes, cytokines, and transcription factors and extracellular matrix proteins on primary human osteoblasts. MATERIAL AND METHODS Primary human osteoblasts were seeded on NBM particles pre-coated with versus without EMD and analyzed for gene differences using a human osteogenesis gene super-array (Applied Biosystems). Osteoblast-related genes include those transcribed during bone mineralization, ossification, bone metabolism, cell growth and differentiation, as well as gene products representing extracellular matrix molecules, transcription factors, and cell adhesion molecules. RESULTS EMD promoted gene expression of various osteoblast differentiation markers including a number of collagen types and isoforms, SMAD intracellular proteins, osteopontin, cadherin, alkaline phosphatase, and bone sialoprotein. EMD also upregulated a variety of growth factors including bone morphogenetic proteins, vascular endothelial growth factors, insulin-like growth factor, transforming growth factor, and their associated receptor proteins. CONCLUSION The results from the present study demonstrate that EMD is capable of activating a wide variety of genes, growth factors, and cytokines when pre-coated onto NBM particles. CLINICAL RELEVANCE The described in vitro effects of EMD on human primary osteoblasts provide further biologic support for the clinical application of a combination of EMD with NBM particles in periodontal and oral regenerative surgery.
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Stress response pathways allow cells to sense and respond to environmental changes and adverse pathophysiological states. Pharmacological modulation of cellular stress pathways has implications in the treatment of human diseases, including neurodegenerative disorders, cardiovascular disease, and cancer. The quinone methide triterpene celastrol, derived from a traditional Chinese medicinal herb, has numerous pharmacological properties, and it is a potent activator of the mammalian heat shock transcription factor HSF1. However, its mode of action and spectrum of cellular targets are poorly understood. We show here that celastrol activates Hsf1 in Saccharomyces cerevisiae at a similar effective concentration seen in mammalian cells. Transcriptional profiling revealed that celastrol treatment induces a battery of oxidant defense genes in addition to heat shock genes. Celastrol activated the yeast Yap1 oxidant defense transcription factor via the carboxy-terminal redox center that responds to electrophilic compounds. Antioxidant response genes were likewise induced in mammalian cells, demonstrating that the activation of two major cell stress pathways by celastrol is conserved. We report that celastrol's biological effects, including inhibition of glucocorticoid receptor activity, can be blocked by the addition of excess free thiol, suggesting a chemical mechanism for biological activity based on modification of key reactive thiols by this natural product.
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The State of Connecticut owns a LIght Detection and Ranging (LIDAR) data set that was collected in 2000 as part of the State’s periodic aerial reconnaissance missions. Although collected eight years ago, these data are just now becoming ready to be made available to the public. These data constitute a massive “point cloud”, being a long list of east-north-up triplets in the State Plane Coordinate System Zone 0600 (SPCS83 0600), orthometric heights (NAVD 88) in US Survey feet. Unfortunately, point clouds have no structure or organization, and consequently they are not as useful as Triangulated Irregular Networks (TINs), digital elevation models (DEMs), contour maps, slope and aspect layers, curvature layers, among others. The goal of this project was to provide the computational infrastructure to create a first cut of these products and to serve them to the public via the World Wide Web. The products are available at http://clear.uconn.edu/data/ct_lidar/index.htm.