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OLEANANE GLYCOSIDES FROM HYDROCOTYLE RANUNCULOIDES
No full textSix new oleanane glycosides, ranuncosides I-VI, have been isolated from Hydrocotyle ranunculoides. Their structures have been determined on the basis of chemical and spectroscopic studies. © 1994
Prednisolone biotransformation by the green alga T76 Scenedesmus quadricauda
No full textExogenus prednisolone is biotransformed in cultures of the green alga T76 Scenedesmus quadricauda in two main bioproducts, which have been purified by chromatographic processes and identified by spectroscopic means. The first compound is the 5α-hydroxyderivative of prednisolone and might be formed by a simple hydration of the Δ4 double bond. The latter rises from a complex rearrangement. It is rather unstable and undergoes oxidation by atmospheric oxygen to a hydroperoxide which slowly decays to the corresponding hydroxyderivative
Toxicity evaluation of natural and synthetic phenanthrenes in aquatic systems
No full textSeven natural 9,10-dihydrophenanthrenes were isolated from the common reed Juncus effusus by means of chromatographic processes and identified by spectroscopic means. Furthermore, mimics of natural isolated compounds were synthesized to try to evaluate the influence of functional groups on the dihydrophenanthrene skeleton. Syntheses of compounds were based on the cross-coupling of 1-(2-iodo-5-methoxy)phenyl-ethanol with variously substituted iodobenzenes by zerovalent nickel. All the chemicals were tested to evaluate their effects on freshwater organisms from different trophic levels. Toxicity tests were performed on reducers (the bacterium Escherichia coli); producers (the alga Raphidocelis subcapitata, previously known as Selenastrum capricornutum); and consumers including a rotifer (Brachionus calyciflorus), a cladoceran (Daphnia pulex), and an anostracan (Thamnocephalus platyurus). Results suggested no one organism was uniquely sensitive to the chemicals tested. Toxicity depended on the kind and position of substituents on the aromatic skeleton
TETRAHYDROPYRENE GLUCOSIDES FROM JUNCUS-EFFUSUS
No full textTwo tetrahydropyrene glucosides have been isolated from Juncus effuses and their structures determined by spectroscopic analysis and hemisynthesis. © 1995, Taylor & Francis Group, LLC. All rights reserved
Juncoside I,A New Cycloartanelactone Glucoside From Juncus Effusus
No full textA new cycloartanelactone glucoside, Juncoside I, has been isolated from Juncus effusus anM its structure has been determined by chemical and spectroscopic studies.Key Words. Juncus effusus,Juncaceae, cycloartane glucoside, 3j3-hydroxy-cycloart-24Z-ene-22(S)—»26 lactone, Juncoside I. © 1994 Harwood Academic Publishers GmbH
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Absolute stereochemistry of stratioside I - A C13 norterpene glucoside from pistia stratiotes
No full textThe structure (3S,5R,6S,7E,9R)-3-hydroxy-5,6-epoxy-β-ionyl-3–0-β-D-glucopyranoside has been attributed to stratioside I, the major component of the methanolic extract of Pistia stratiotes on the basis of its spectroscopic features and by analysis using the Mosher method. © 1995, Taylor & Francis Group, LLC. All rights reserved
Photochemical fate and eco-genotoxicity assessment of the drug etodolac
No full textThe photochemical behavior of etodolac was investigated under various irradiation conditions. Kinetic data were obtained after irradiation of 10-4M aqueous solutions by UVB, UVA and direct exposure to sunlight. The Xenon lamp irradiation was used in order to determine the photodegradation quantum yield under sun-simulated condition (φsun). The value was determined to be=0.10±0.01. In order to obtain photoproducts and for mechanistic purposes, experiments were carried out on more concentrated solutions by exposure to sunlight and to UVA and UVB lamps. The drug underwent photooxidative processes following an initial oxygen addition to the double bond of the five membered ring and was mainly converted into a spiro compound and a macrolactam. Ecotoxicity tests were performed on etodolac, its photostable spiro derivative and its sunlight irradiation mixture on two different aquatic trophic levels, plants (algae) and invertebrates (rotifers and crustaceans). Mutagenesis and genotoxicity were detected on bacterial strains. The results showed that only etodolac had long term effects on rotifers although at concentrations far from environmental detection values. A mutagenic and genotoxic potential was found for its derivative
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