546 research outputs found
Wolfender Jean-Luc. — Essai sur l'évolution du coût des grands barrages français, de 1900 à 1952
No full textC A. Wolfender Jean-Luc. — Essai sur l'évolution du coût des grands barrages français, de 1900 à 1952. In: Population, 9ᵉ année, n°1, 1954. pp. 150-151
Data for: Antiseizure compounds from the ancient Greek medicinal plant Helleborus odorus subsp. cyclophyllus and study of its chemical composition
No full textThe complete annotated molecular network with all the annotations, and in particular the first 6 levels, is available as an associated file in the Mendeley Data repository (Cytoscape file)
Screening of panamanian plant extracts for agricultural and cosmetic activities, and metabolomic study of "Isatis tinctoria" accessions
Get PDFThe FP7 project AGROCOS aimed at the discovery of new natural product scaffolds for possible uses in agrochemistry and as cosmetic ingredients. In addition, novel tools for metabolomics and multivariate statistics were applied to Isatis tinctoria as a model plant.
Nature provides compounds that are not only important for pharmaceutical industry, but also for agrochemistry and cosmetics. Extracts and pure natural compounds are widely used in cosmetics. For agrochemistry, natural products rather play a role for lead discovery, i.e. the discovery of a model compound that is further developed to a synthetic agrochemical. In the first part of the project, a library of 600 Panamanian plant extracts was screened for agrochemical and cosmetic properties. Selected extracts were submitted to HPLC-based activity profiling whereby five extracts showed activity in the agrochemistry screens, and two extracts in the cosmetic screens.
For the agrochemical part of the project, extracts and microfractions were screened for fungicidal, insecticidal, and herbicidal properties. Compounds from Bocconia frutescens, Miconia affinis, Myrcia splendens, Combretum affinis laxum, and Erythroxylum macrophyllum were isolated, identified, and submitted to screening for the corresponding indication. Benzophenanthridine alkaloids and arjunolic acid from B. frutescens and M. affinis, respectively, showed moderate to good fungicidal activity. Myricetin-3-O-(6''-O-galloyl)-beta-galactopyranoside from M. splendens showed moderate insecticidal activity. From the two plants selected for herbicidal activity of their extracts, no herbicidal compounds could be identified.
For the cosmetic part, phenolic compounds and flavonoids were isolated from methanolic extracts of leaves from Mosquitoxylum jamaicense and Combretum cacoucia. All isolated compounds showed either activity in the DPPH assay, in the UV-B protection assay, or in both. Gallic acid derivatives were the most active in the DPPH assay (IC50 < 0.01 mg/mL), while protocatechuic acid and isoquercitrin showed the best activity in the UV-B protection assay (< 10% UV-B-induced cell death).
Metabolomics of plant extracts combined with multivariate statistics is increasingly used for the differentiation of plant samples and assessment of quality traits. Metabolomics provides a metabolic fingerprint, in contrast to the classical quantitative analysis of single compounds, or a single class of compounds. The second part of the AGROCOS project comprised a metabolomic study on Isatis tinctoria of five different accessions, which were grown under identical and controlled conditions on experimental field plots. Leaves were harvested at six time points during the vegetation period, whereby sampling was done, on the one hand, by collection of single leaves from intact plants, and by repeated mowing of leaf rosettes, on the other hand. The latter regimen was to simulate repeated harvesting of annual plants. Extracts were prepared by PLE with ethyl acetate and 70% aqueous methanol, submitted to 1H NMR spectroscopy, and analyzed by the PCA/CA/k-NN classification method. PCA/CA/k-NN analysis of accessions and time points of harvesting showed differences in both cases. Using pairwise 1D-STOCSY, compounds such as unsaturated fatty acids, porphyrins, carbohydrates, indole derivatives, isoprenoids, phenylpropanoids, and minor aromatic compounds could be identified as metabolites contributing to differences of accessions and harvesting dates. In addition, an effect of repeated harvesting could be observed from the PCA/CA/k-NN plot, and the 1D-STOCSY plot revealed a decrease of 1,5-anhydroglucitol, sucrose, unsaturated fatty acids, porphyrins, isoprenoids, and a flavonoid upon repeated harvesting
Phospholipidosis effect of drugs by adsorption into lipid monolayers
No full textDrug-induced phospholipidosis indicates an accumulation of phospholipids within lysosomes, which can occur during therapeutic treatment. Whether or not phospholipidosis represents a toxicological phenomenon is still under investigation, and in the last decade the Food and Drug Administration has been raising concerns about the possible consequences of this adverse event. Cationic amphiphilic drugs represent the majority of phospholipidosis inducers, followed by aminoglycoside and macrolide antibiotics. Although the mechanism of phospholipidosis induction is still uncertain, the interaction of drugs with phospholipids in the lysosomal membrane represents a key step. Therefore, the study of the drug/lipid complex formation will provide valuable insight into the causation of phospholipidosis at the molecular level and to identify the potential phospholipidosis risk associated with drug. In this study, we investigated the insertion profile of eleven drugs with known phospholipidosis effect into preformed Langmuir monolayers of various lipid compositions, to evaluate for the first time the drug/lipid interaction for phospholipidosis inducers and non-inducers in a dynamic approach. We found that the addition of dipalmitoylphosphatidylserine (DPPS) to dipalmitoylphosphatidylcholine (DPPC) to form the lipid monolayer allowed a clear identification of the phospholipidosis effect of the selected drugs based on the variation of the surface pressure, not only for cationic amphiphilic drugs but also for the aminoglycoside and the macrolide antiobiotics tested. Compared to a standard PAMPA assay, the new method appears to be more effective for the study of poorly soluble drugs
Identification of novel anticonvulsant compounds in medicinal plants combining innovative in vivo zebrafish assays and efficient chromatographic methods
No full textNatural products (NPs) are known to possess a wide range of molecular variety and are found in extracts of complex composition providing a huge chemical diversity of secondary metabolites which is of great interest for drug discovery. The aim of this thesis is to develop strategies for the rapid discovery of natural products with antiepileptic activities by combining bioactivity-guided fractionation methods with in vivo zebrafish assays. Firstly a strategy for high throughput screening activity assessment at the microgram scale through bioactivity-guided fractionation combined to zebrafish in vivo assay has been developed and used to investigate the active principles isolated from plants. In order to obtain efficiently pure bioactive compounds at a large scale isolation platform containing a Medium Pressure Liquid Chromatography (MPLC) was developed and optimized to investigate several plants used in traditional medicine with claimed antiepileptic activities for the discovery of an active anticonvulsant compound from natural extracts
Medicinal Plants to Treat Epilepsy: Discovery of Antiseizure Compounds by In Vivo Zebrafish Bioactivity-Guided Isolation
No full textEpilepsy is a chronic neurological disorder characterized by recurrent epileptic seizures which affects 1% of the world's population, of whom 80% live in low- and middle-income countries. Antiseizure drugs (ASDs) and therapies are available for epilepsy management but despite these possibilities, a third of epileptic patients suffer from pharmaco-resistance. There is, therefore, an urgent need for new and cost-effective treatments to manage epilepsy. Herbs used in traditional medicine remain the first-line treatment for most people with limited access to ASDs. Thus, in this thesis, three plants traditionally used to treat epilepsy and CNS-related disorders were selected and studied using a bioactivity-guided isolation protocol combined to an in vivo zebrafish epilepsy model to effectively identify compounds with significant antiseizure activity. This work demonstrated the chemical diversity of antiseizure constituents and their mode of action which may help to provide evidence-based data for the management of epilepsy with well-selected medicinal herbs
Biotransformation du resvératrol halogéné par Botrytis cinerea
No full textL'émergence de souches de bactéries résistantes aux antibiotiques représente l'une des plus grandes menaces pour l'humanité. Il est urgent de rationaliser l'utilisation des antibiotiques et aussi de trouver de nouvelles molécules actives contre les bactéries résistantes. L'objectif de ce travail était d'explorer la biotransformation enzymatique afin d'obtenir des composés antibactériens. Cette technique basée sur l'utilisation d'un mélange d'enzymes (sécrétome fongique) obtenu à partir de champignons a été développée à l'Université de Genève. Récemment, des composés dérivés du resvératrol ayant une activité remarquable contre les souches résistantes de Staphylococcus aureus ont été obtenus grâce à cette approche. D'autre part, il a également été récemment démontré que l'ajout d'un atome d'halogène à la structure d'un composé peut améliorer considérablement son activité biologique
Recherche de biopesticides à base de plantes riches en saponines
No full textL’agriculture moderne est indissociable de l’utilisation des pesticides à grande échelle. En effet, plus de 40% des récoltes seraient perdues à cause des nombreux bioagresseurs sans leur utilisation. Le but de ces insecticides, fongicides, herbicides rodenticides ou encore régulateur de croissance est de prévenir ou d’atténuer tout dégât dus aux bioagresseurs en les repoussant ou en les détruisant. Depuis leur introduction dans les années 50, leur utilisation s’est largement répandue et de nombreux problèmes, notamment sanitaires, sont apparus avec certaines matières actives. Aujourd’hui, avec la prise de conscience de ces dangers, le défi est de concilier une production plus durable pour le consommateur et l’environnement avec une production végétale suffisante à grande échelle. Le développement de nouveaux biopesticides développés à base de plantes est un pas dans l’atteinte de cette agriculture durable. Ce travail a pour objectif de développer des méthodes de screening et de les employer pour tester l’activité d’extraits de plantes riches en saponines contre des ravageurs et des maladies de cultures
Mucilages de graines de lin (Linum usitatissimum L.) : extraction, séparation, purification et analyses structurales des différentes familles polysaccharidiques
No full textLes mucilages de graines de lin (Linum usitatissimum L.) ont de nombreuses applications à la fois dans l'industrie agroalimentaire, pharmaceutique et dans la filière textile. Ils représentent environ 8% du poids total de la graine de lin. Sa composition a été abondamment étudiée. Deux fractions polysaccharidiques caractérisent le mucilage, l'une neutre, les arabinoxylanes (AX), et la seconde à caractère acide, les rhamnogalacturonanes de type I (RG-I), faisant partie de la famille des pectines. Il semblerait qu'il existe en réalité un mélange plus complexe de polysaccharides dont les propriétés physicochimiques les différencieraient. Cet aspect a été le sujet central de ce travail de master. La séparation et l'analyse des différentes fractions de mucilage de graines de lin a été menée par HPAECPAD, HPSEC-MALLS et GC-MS. Ces travaux ont conduit à l'identification de 8 familles polysaccharidiques se différenciant par leur nature et leur compostions en polysaccharides
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