Gyroscopic Instability of a Drop Trapped Inside an Inclined Circular Hydraulic Jump

International audienceA drop of moderate size deposited inside a circular hydraulic jump remains trapped at the shock front and does not coalesce with the liquid flowing across the jump. For a small inclination of the plate on which the liquid is impacting, the drop does not always stay at the lowest position and oscillates around it with a sometimes large amplitude, and a frequency that slightly decreases with flow rate. We suggest that this striking behavior is linked to a gyroscopic instability in which the drop tries to keep constant its angular momentum while sliding along the jump

STUDY OF CRUDE EXTRACTS FROM CASSIA SIEBERIANA ROOT BARK AND KHAYA GRANDIFOLIOLA TRUNK BARK: PHYTOCHEMICAL SCREENING, QUANTITATIVE ANALYSIS AND RADICAL SCAVENGING ACTIVITY

Objective: Cassia sieberiana and Khaya grandifoliola are two plants commonly used in traditional medicine in Côte d’Ivoire. Photochemical screening of crud extract obtained from C. sieberiana root bark and K. grandifoliola trunk bark revealed the presence of alkaloids, sterols, terpenes, polyphenols, flavonoids, coumarins, tannins, reducing sugars, glycosides, carbohydrates, cardiac glycosides and saponins. Methods: Quantitative analysis was screened in C. sieberiana root bark and K. grandifoliola trunk bark. Results: The results respectively showed high concentrations of total phenols (225.57±7.57 and 186.75±12.76 μgGAE/mg), total flavonoids (64.70±5.25 and 117.88±8, 68 μgQE/mg) and total tannins (170.60±5.85 and 39.96±1, 58 μgTAE/mg). The antioxidant activity of the glycosides extracts CS1, KG1 and their corresponding aglycones CS2, KG2 of these plants has been studied by scavenging free radicals by DPPH and that, compared with L-ascorbic acid (vitamin C, IC50 = 0.07 µg/ml). IC50 values of CS1 (2.69 µg/ml), KG1 (3.16 µg/ml) and CS2 (1.30 µg/ml), KG2 (0.726 µg/ml) showed that the aglycones are clearly more effective than the glycosides. Conclusion: Qualitative analysis of Cassia sieberiana root bark and Khaya grandifoliola trunk bark showed a presence of a variety of secondary metabolites in these plants, when the quantitative analysis concludes that they contain phenolic compounds, flavonoids and tannins to varied contents

Preparation of gem-difluorinated retrohydroxamic-fosmidomycin

International audienceFrom several decades, some organophosphorus compounds specifically designed to alterbiological systems were introduced on market as agrochemicals (ie glyphosate and glufosinate asherbicides). Nevertheless, it becomes necessary to find new compounds in order to counter plantresistances already observed with glyphosate. Fosmidomicyn and its N-acetyl analogues FR-900098 were perceived as starting points for elaboration of new herbicide candidates, targetingthe second enzyme of the non-mevalonate pathway in plants, the 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DOXP reductoisomerase or DXR). It is expected that theenhancement of bioactivity compared to the parent compounds, might be reached by insertion oftwo fluorine atoms close to the phosphonate function. Indeed, the presence of both fluorineatoms could improve the lipophilicity, affect the pKa of the phosphonic acid function and theninduce better activities. Herein, the synthesis of gem-difluorinated analogues of retrohydroxamicfosmidomycin and FR-900098-ester is reported using a radical addition mediated by acobaloxime comple

Caractérisation Phytochimique et Activité Larvicide d’extraits Bruts de Plantes Issues de la Pharmacopée Traditionnelle du Niger sur les Larves d’Anopheles gambiae S.L.

In the preventive fight against malaria, natural products are considered better because they are biodegradable and therefore more respectful of the environment and the ecosystem. In the framework of the research of new insecticidal molecules, the present study concerns, the phytochemical screening and the evaluation of the larvicidal activity of the extracts (aqueous and methanolic) of 26 plants on the larvae of Anopheles gambiae sl. been carried out according to a WHO protocol (1985). The phytochemical profile of the plants was determined according to the standard methods of characterization (color reactions). High larvicidal activity against Anopheles gambiae larvae after 24 h and then 48 h exposure was observed. Crotalaria podocarpa, Momordica balsamina, Xeromphis nilotica and Senna occidentalis showed a 100% mortality rate after 24 hours of exposure. The larvicidal activity is much more important after 48 hours. A 100% mortality was observed with Senna occidentalis, Momordica balsamina, Ocimum basilicum, Citrus sinensis, Striga hermontheca, Xeromphis. nilotica, Crotalaria podocarpa, Diospyros mespiliformis, Cymbopogon citratus, Cleome viscosa and Combretum micrantum. Poor larvicidal activity was observed on the one hand with the methanolic extracts of Crotalaria podocarpa and Aloe vera and on the other with the aqueous extracts of Citrus sinensis, Ocimum basilicum and Aloe vera. Phytochemicalscreening revealed the presence of five major groups of compounds, including saponosides, terpenes sterols, flavonoids, tannins and alkaloids, which are also present in the aqueous and methanolic extracts of the various plant samples. These chemical groups could justify the traditional use of these plants.Dans la lutte préventive contre le paludisme, les produits naturels sont considérés comme meilleurs car biodégradables et donc plus respectueux de l’environnement et de le écosystème. Dans le cadre de la recherche des nouvelles molécules insecticides, la présente étude concerne, le screening phytochimique et l’évaluation de l’activité larvicide des extraits (aqueux et méthanoliques) de 26 plantes sur les larves d’Anophèles gambiae s.l. Les tests larvicides ont été réalisés selon un protocole de l’OMS(1985). Le profil phytochimique des plantes a été déterminé suivant les méthodes standards de caractérisation (réactions colorées). Une forte activité larvicide vis-à-vis des larves d’Anophèles gambiae après 24h puis 48h d’exposition a été observée. Crotalaria podocarpa, Momordica balsamina, Xeromphis nilotica et Senna occidentalis ont montré un taux de mortalité de 100% après 24h d’exposition. L’activité larvicide est beaucoup plus importante après 48h. Une mortalité de 100% a été observée avec Senna occidentalis, Momordica balsamina, Ocimum basilicum, Citrus sinensis, Striga hermontheca, Xeromphis. nilotica, Crotalaria podocarpa, Diospyros mespiliformis, Cymbopogon citratus, Cleome viscosa et Combretum micrantum. De faibles activités larvicides ont été constatées d’une part avec les extraits méthanoliques de Crotalaria podocarpa et Aloe vera et d’autre part avec les extraits aqueux de Citrus sinensis, Ocimum basilicum et Aloe vera. Le screening phytochimique a mis en évidence la présence de cinq (5) grands groupes de composés parmi lesquels les saponosides, les terpènes stérols, les flavonoïdes, les tanins et les alcaloïdes aussi bien présents dans les extraits aqueux et méthanoliques des différents échantillons des plantes. Ces groupes chimiques pourraient justifier l’utilisation traditionnelle de ces plantes

NMDA receptor channels: Labeling of MK-801 with iodine-125 and fluorine-18

Methods for labeling the glutamate channel blocking agent MK-801 with iodine-125 (125I) and fluorine-18 (18F) are described. Radioiodine was incorporated in the 1- or 3-positions of the aromatic ring of (+/-)MK-801 by solid-state halogen exchange techniques. Attachment of the [18F]fluoromethyl group to the bridgehead methyl position was achieved by reaction of [18F]fluoride with the triflamide alcohol 8 or the novel cyclic sulfamate 9 recently reported by Merck chemists. Radiochemical yields of (+/-)13-[18F]- fluoromethyl-MK-801 were >72%, EOB; radiochemical purity >99%. In competitive binding studies using rat brain homogenates, (+/-)3-bromo-MK-801 showed greater affinity than (+/-)MK-801 for the glutamate-linked channel. The experimental log P (2.1 +/- 0.1) of MK-801 is optimal for transit of the blood-brain barrier. These preliminary findings support further testing of 3-[123I]iodo-MK-801 and (+/-)13-[18F]fluoromethyl-MK-801 as possible agents for in vivo mapping of the glutamate receptor complex.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27605/1/0000649.pd

Vers la recherche de structures antagonistes de l'action de la phencyclidine

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Product Class 12: Alkylphosphonium Salts

International audienc

Acyclic to cyclic aminophosphonic and phosphinic acids

International audienceThe results presented in this account deal with the synthesis of acyclic α- or β-aminophosphonates or phosphinates and with the synthesis of heterocyclic compounds, where the phosphorus and/or the nitrogen atoms can be embedded in the heterocyclic core, showing new perspectives in bioactive molecules

The 1-Deoxy-D-Xylulose-5-Phosphate Reductoisomerase, a target metalloenzyme for the elaboration of chelation-based inhibitors

La voie non-mévalonate est fortement présente chez les plantes et les bactéries mais est absente chez les mammifères. C'est pourquoi inhiber la synthèse des isoprénoïdes et identifier un inhibiteur de cette voie enzymatique contribuera grandement à la recherche de nouveaux antibiotiques, antifongiques et herbicides. Les propriétés uniques de la 1-deoxy-D-xylulose 5-phosphate reductoisomérase (DXR), l'enzyme centrale de cette voie enzymatique, en font une cible très intéressante pour la synthèse de nouveaux composés. La Fosmidomycine agit comme un inhibiteur de la DXR et reste aujourd'hui, avec son homologue acétylé FR90098, la référence en termes d'inhibiteur même si de nombreux efforts ont été faits pour la synthèse d'analogues depuis plusieurs années comme expliqué dans le premier chapitre avec la mise en relation de la structure des composés et leur activité. L'analyse de la diffraction des rayons X de la DXR avec la Fosmidomycine où le substrat naturel montre que la fonction phosphonate ou phosphate interagit avec une poche polaire hautement spécifique dans le site actif de l'enzyme permettant peu de modifications. Par comparaison, la fonction acide hydroxamique qui chélate le cation de l'enzyme offre la possibilité de modifications par l'introduction d'autres fonctions complexantes. Dans ce contexte, de nombreuses modifications comme l'introduction de fonctions carbamoylphosphinate, amidoxime, N-hydroxyurée et dérivées d'uraciles comme unités complexantes ont été synthétisées pour trouver des nouvelles familles d'inhibiteurs de la DXR. Toutes ces fonctions possèdent des propriétés de chélation intéressantes. En effet, elles ont déjà conduit à de puissants inhibiteurs de différentes métalloenzymes.The non-mevalonate pathway is highly present in higher plants, protozoa and bacteria but as no equivalent in mammals. That is why shut down isoprenoid biosynthesis and identify a non-mevalonate pathway inhibitor would greatly contribute to the search for safer antibiotics, antimalarials and for our concern herbicides. The unique properties of the 1-deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), the central enzyme of this pathway, make it a remarkable and attractive target for drug design. Fosmidomycin acts as an inhibitor of DXR and still remains, along with its N-acetyl homologue FR90098, one of the most potent inhibitor ever known even if extensive work on the development of Fosmidomycin analogue derivatives have been developed since the last decade as demonstrated in the first chapter with the development of a structure activity relationship of all the potential inhibitors of this enzyme already reported in the literature. The X-ray diffraction analysis of the co-crystals of DXR and Fosmidomycin or substrate shows that the phosphonic/phosphate group interacts with a highly specific polar pocket in the enzyme site, allowing only few structural modifications. By contrast, the cation chelating subunit represented by the hydroxamic acid function offers fine tuning possibilities for the complexation abilities as well as potential secondary interactions with the NADPH cofactor or directly with the enzyme. In this context, several modifications such as the introduction of carbamoylphosphinate, amidoxime, N-hydroxyurea and uracil complexing subunits have been made in order to find new families of DXR inhibitors. All of these functions show promising chelation capabilities as they already led to potent inhibitors of different metalloenzymes.MONTPELLIER-Ecole Nat.Chimie (341722204) / SudocSudocFranceF