Search results for "Ether"
showing 10 items of 986 documents
Higher aggression is related to poorer academic performance in compulsory education
2019
Background To conduct a comprehensive assessment of the association between aggression and academic performance in compulsory education. Method We studied aggression and academic performance in over 27,000 individuals from four European twin cohorts participating in the ACTION consortium (Aggression in Children: Unraveling gene‐environment interplay to inform Treatment and InterventiON strategies). Individual level data on aggression at ages 7–16 were assessed by three instruments (Achenbach System of Empirically Based Assessment, Multidimensional Peer Nomination Inventory, Strengths and Difficulties Questionnaire) including parental, teacher and self‐reports. Academic performance was measu…
An in vitro model to study cellular photosensitizer uptake and photodynamic dose-response relationships of tumor cells
1993
Cellular fluorescence intensity (CFI) after incubation with varying concentrations of the photosensitizer Photofrin and the photodynamically induced dose-response relationships of hamster melanoma cells (A-MEL-3) were studied in a recently developed in vitro model. After administration of Photofrin to the extracellular serum-free medium, CFI was evaluated by flow cytometry together with constantly fluorescing latex particles used as a reference. After 5 min, 50% of maximal CFI was found, and after 60 min CFI was maximal. No further increase was obtained during the exposure to Photofrin over the incubation period of 4 h. During this plateau phase, CFI was significantly related to the concent…
Mumijo traditional medicine: fossil deposits from Antarctica (chemical composition and beneficial bioactivity)
2008
Mumijo is a widely used traditional medicine, especially in Russia, Altai Mountains, Mongolia, Iran Kasachstan and in Kirgistan. Mumijo preparations have been successfully used for the prevention and treatment of infectious diseases; they display immune-stimulating and antiallergic activity as well. In the present study, we investigate the chemical composition and the biomedical potential of a Mumijo(-related) product collected from the Antarctica. The yellow material originates from the snow petrels,Pagodroma nivea. Extensive purification and chemical analysis revealed that the fossil samples are a mixture of glycerol derivatives.In vitroexperiments showed that the Mumijo extract caused in…
Brominated Azaphilones from the Sponge-Associated Fungus Penicillium canescens Strain 4.14.6a
2019
The fungus Penicillium canescens was isolated from the inner tissue of the Mediterranian sponge Agelas oroides. Fermentation of the fungus on solid rice medium yielded one new chlorinated diphenyl ether (1) and 13 known compounds (2-14). Addition of 5% NaBr to the rice medium increased the amounts of 4-6, while lowering the amounts of 8, 12, and 14. Furthermore, it induced the accumulation of 17 and two new brominated azaphilones, bromophilones A and B (15 and 16). Compounds 15 and 16 are the first example of azaphilones with the connection of a benzene moiety and the pyranoquinone core through a methylene group. The structures of the new compounds were elucidated based on the 1D and 2D NMR…
Diastereoselective synthesis of substituted 2-phenyltetrahydropyrans as useful precursors of aryl C-glycosides via selenoetherification
2004
The cyclization of several substituted 5-phenyl-pent-4-en-1-ols with selenium electrophiles along some mechanistic considerations is discussed. In particular, an efficient diastereoselective synthesis of a 2,3,5,6-tetrasubstitued tetrahydropyran is reported. These findings open an interesting approach: the use of chiral selenium electrophiles for cyclization of chiral substrates. The cyclized products are useful starting material for the synthesis of D- or L-aryl C-glycosides.
Synthesis and biological evaluation of lipid-like 5-(2-hydroxyethyl)-4-methyl-1,3-thiazole derivatives as potential anticancer and antimicrobial agen…
2015
A series of new lipid-like thiazole derivatives have been synthesized in good yields by O-alkylation of 5-(2-hydroxyethyl)-4-methyl-1,3-thiazole, a thiamine metabolite, under phase transfer catalysis conditions followed by N-alkylation with the aim to obtain potential anticancer and antimicrobial agents. The synthesized cationic amphiphiles and their ether precursors were subjected to in vitro cytotoxic evaluation against monolayer human fibrosarcoma HT-1080 and mouse hepatoma MG-22A tumour cell lines and normal mouse NIH 3T3 fibroblasts and were screened for antimicrobial activity concerning gram-positive and gram-negative bacterial and fungal strains. The synthesized compounds possessed s…
Eine Methode zur Beurteilung des Nierengef��tonus bei M�usen
1955
Durch den Vergleich von in vivo unterbundenen und nichtunter-bundenen Nieren last sich mit Hilfe der Benzidinfarbung von Slonimski u. Cunge der Tonuszustand von Nierengefasen feststellen. Im Excitations-und Toleranzstadium der Athernarkose findet eine Tonuserhohung der Rindengefase statt, im Asphyxiestadium eine allgemeine renale Gefasdilatation. Methodik und Ergebnisse werden mit den Befunden von Still u. Whitcomb vor allem in bezug auf einen Trueta-Shunt diskutiert.
The Chemistry of [1,2,3]Triazolo[1,5- a] pyridines
2003
The reactivity of [1,2,3]triazolo[1,5-a]pyridines 1 is described. Triazolopyridines react with electrophiles in two contrasting ways, giving 3-substituted triazolopyridines 2, or products 3, resulting from triazolo ring opening with loss of molecular nitrogen. The triazolopyridines can be lithiated at -40 degrees C by lithium diisopropylamide in ether giving regiospecifically the 7-lithio derivative. Bromotriazolopyridines have activation towards nucleophilic substitution at position 5 and 7, and benzenoid inertness at position 6. The parent compound 1a is easily hydrogenated giving tetrahydrotriazolopyridine 11a in high yield; when the triazolopyridines have substituents, the hydrogenation…
Intramolecular Interactions in the Triplet Excited States of Benzophenone–Thymine Dyads
2005
Time-resolved and product studies on the synthesized dyads 1 and 2 have provided evidence that the benzophenone-to-thymine orientation strongly influences intramolecular photophysical and photochemical processes. The prevailing reaction mechanism has been established as a Paterno-Büchi cycloaddition to give oxetanes 3-6; however, the ability of benzophenone to achieve a formal hydrogen abstraction from the methyl group of thymidine has also been evidenced by the formation of photoproducts 7 and 8. These processes have been observed only in the case of the cisoid dyad 1. Adiabatic photochemical cycloreversion of the oxetane ring is achieved upon direct photolysis to give the starting dyad 1 …
Selective Derivatization of Calix[4]arenes via Amino Groups Attached to the Wide Rim
2004
A new strategy is proposed for the synthesis of tetraether derivatives of calix[4]arenes bearing at the wide rim nitro and phthalimido groups in well defined positions. Since both groups are precursors of amino functions, calix[4]arenes substituted by different N-acylamino residues are easily available in four steps. The essential steps during the synthesis of the precursor consist in the protection of amino groups by the formation of their phthalimides followed by ipso-nitration of the remaining tert-butylphenol ether units. This nitration occurs without side reactions at the phthalimido substituted units, in contrast to simple N-acyl derivatives.