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[en] Combretastatin A-4 is a highly potent natural stilbene that can inhibit cancer cell proliferation. Numerous analogues of combretastatin A-4 have been proposed for clinical applications. However, structural studies of combretastatin A-2, a methylenedioxy derivative of combretastain A-4, are not available. In this study, various analogues of combretastatin A-2 with polymethylenedioxy spacer were prepared and their antiproliferative activities to four human cancer cell lines (HeLa, SK-OV-3, A549, and HT-29) and two normal cells (HaCaT and MDCK) were evaluated. Binding characteristics were evaluated based on computational docking and previously reported experimental data. Results suggest that their binding conformations are highly dependent on steric volume and electrostatic properties of substituents.
Journal
Applied Biological Chemistry (Online); ISSN 2468-0842; 
; v. 62(1); p. 1-7
; v. 62(1); p. 1-7
No abstract available
Source
Madura, I. (ed.); Department of Chemistry, Warsaw Technical University, Warsaw (Poland); Warsaw Branch of the Polish Chemical Society (Poland); [170 p.]; ISBN 978-83-60988-06-0; ; 2011; p. 38; ChemSession'11: 8. Warsaw Seminar of the PhD Students in Chemistry; 8. Warszawskie Seminarium Doktorantow Chemikow ChemSession'11; Warsaw (Poland); 13 May 2011; PROJECT VENTURES; INNOVATIVE ECONOMY OPERATIONAL PROGRAMME; Also available from the Polish Chemical Society, ul. Freta 16, 00-227 Warsaw, Poland; 3 refs., 1 fig.
; 2011; p. 38; ChemSession'11: 8. Warsaw Seminar of the PhD Students in Chemistry; 8. Warszawskie Seminarium Doktorantow Chemikow ChemSession'11; Warsaw (Poland); 13 May 2011; PROJECT VENTURES; INNOVATIVE ECONOMY OPERATIONAL PROGRAMME; Also available from the Polish Chemical Society, ul. Freta 16, 00-227 Warsaw, Poland; 3 refs., 1 fig.
[en] The dimerisation of 3,4-dimethoxy-12-benzyloxy stilbene 1 with 15 equivalent of ferric chloride (FeCl3) 60% w/v for 12 hours afforded unnatural products, a pallidol-like compound 2 and an ampelopsin F analogue, 3 (molecular formula 2, 3 = C46H42O6). By using High Resolution-Electron Impact Mass Spectrometer (HR-EIMS) technique, we found that the mass spectrum of 2 showed significant mass peaks. This allows us to suggest several fragmentations, compatible to the peaks. The mass spectrum of 2 exhibited molecular ion peak as 713.2869, compatible with the presence of pallidol analogue (690) associated with sodium adduct (23). The loss of methyl group gave single oxygen which presumed unstable, followed by deformation with new bonding with proton thus giving m/z 676. M/z 508 was resulted from the loss of benzyl oxybenzene. The base peak was indicated by the m/z 294, where bis cyclopentane transformed to cyclo octa-1,5-diene having two aromatic rings attached with methoxy and single oxygen. The presence of 1 during fragmentation was remarked as the fragment molecular formula compatible with m/z 242. Meanwhile, the protonated molecular ion peak of 3 was observed to give compatible molecular formula 690. The fragmentation of 3 exhibited the occurrence of highly stabilized tropylium cation (C7H7+). The loss of benzyl oxybenzene and benzyloxy led to fragment having m/z 417. It was followed by the cleavage of the benzyloxy to present fragment with m/z 401. We concluded that the spectra were more informative than those published from previous study. (author)
Journal
Malaysian Journal of Analytical Sciences; ISSN 1394-2506; ; v. 12(3); p. 633-637
; v. 12(3); p. 633-637
[en] Highlights: • A unitary mechanism for the cyclization of tetraketides in stilbene and chalcone synthase. • The identification of an active water that functions as a “Claisen switch” in chalcone synthase. • QM-MM and FMO analysis of model tetraketide ligands highlighting common and disparate components of binding pockets and cyclization sites in stilbene and chalcone synthase. The polyketide synthases found in a variety of plants and fungi provide a varied source of biologically active compounds of pharmacological and medicinal interest. Stilbene synthase and chalcone synthase catalyze the formation of a common tetraketide intermediate, but use different cyclization mechanisms to produce distinct and separate natural products. While key structural differences have been identified to explain this functional diversity, a fuller explication of the factors responsible for this mechanistic disparity is required. Based on the energetics of our models of the bound tetraketides, and our structural analysis of the active sites we propose that a key tautomeric conversion provides a mechanistic framework common to both cyclizations. A previously unidentified active water molecule facilitates cyclization in chalcone synthase through a Claisen mechanism. Such a “Claisen switch” is comparable to the previously characterized “aldol switch” mechanism proposed for the biosynthesis of resveratrol in stilbene synthase.
Journal
Biochemical and Biophysical Research Communications; ISSN 0006-291X; ; CODEN BBRCA9; v. 497(4); p. 1123-1128
; CODEN BBRCA9; v. 497(4); p. 1123-1128
No abstract available
Journal
Ciencia e Cultura; ISSN 0009-6725; ; v. 33(7); p. 382-383
; v. 33(7); p. 382-383
[en] Stilbene compounds, well known for their biological activities, have been widely investigated as short subunits of poly(p-phenylenevinylene), the first light-emitting polymer, to understand the emission mechanism and relationship between the molecular structure and emitted light. Distyrylarylene derivatives are also well known as blue fluorescent materials and hole-transport materials. As part of our program directed toward the development of novel blue electroluminescent materials with unsymmetrical stilbene or distyrylarylene skeletons, we have prepared various bromostilbene intermediates by the Horner. Wadsworth.Emmons reaction of bromobenzophenone derivatives with benzyl phosphonates. However, great difficulties arise when isolating and identifying pure products from these reactions because of the generation of chromatographically inseparable mixtures of (E)- and (Z)-geometric isomers. Therefore, an efficient process for separating the two isomers is quite necessary for the systematic development of electroluminescent π-conjugated hydrocarbons
Journal
Bulletin of the Korean Chemical Society; ISSN 0253-2964; ; v. 35(6); p. 1871-1874
; v. 35(6); p. 1871-1874
[en] Using a femtosecond pump-probe laser system, the excited-state lifetimes of cis-stilbene in n-hexane, tetradecane, methanol, 1,4-dioxane, and cyclohexane are measured and correlated with solvent bulk viscosity. The measured lifetimes in n-hexane and tetradecane correlate well to solvent bulk viscosity, but methanol, 1,4-dioxane, and cyclohexane do not. Polarity-influenced solvent-solute interactions occur in methanol and 1,4-dioxane and a slow isomerization rate in cyclohexane occurs with cis-stilbene. 39 refs., 7 figs., 2 tabs
Journal
[en] Based on the extraction procedures described for tissue of veal calves and following the introduction of reversed-phase-column chromatography as an alternative purification step, a radioimmuno-assay is described for the determination of DES in pork-tissue. When using the DES-specific antiserum AS 254 and depending on the tissue examined, the lower limits of detection were between 29-69 pg. A mean enor of 10.8% (CV between 13-17%) for the ecovery added to tissue samples and a CV between 3.6 and 10.5% for the reproducibility demonstrate a good reliability. Testing the 'stilbene-specific' antiserum AS 6139 by using 3H-DES as tracer revealed, the DES - and to a lesser extent also HEX - could be quantified with an acceptable degree of reliability when using the homologous RIA-system (use of DES and HEX resp. as calibration-standard), differently to DIEN; the possibility of a transformation of DIEN during the extraction into a compound exhibiting a higher cross reactivity is discussed. Application of the heterologous test system (quantification of the 'sample-stilbene' by using each of the other two stilbenes for calibration) yielded the expected over- and underestimations. Furtheron, in respect to total stilbenes, i.e. not knowing whether DES, HEX or DIEN are present in the sample, it has been shown, that the assay - though qualitative - is highly sensitive (59-86 pg lower level of detection) when DES is used as tracer and for calibration purposes. (orig.)
[de]
Basierend auf dem fuer Gewebe von Kalb beschriebenen Extraktionsverfahren sowie unter Einfuehrung einer Reversed-Phase-Saeulenchromatographie als alternativem Reinigungsschritt, wird ein Radioimmunotest mit Rueckstandsnachweis von DES beim Schwein beschrieben. Bei Verwendung des DES-spezifischen Antiserums AS 254 ergaben sich fuer diese Methodik in Abhaengigkeit vom Gewebe untere Nachweisgrenzen zwischen 29 und 69 pg. Ein mittlerer Fehler von 10,8%, Variationskoeffizienten zwischen 13 und 17% fuer die Wiederfindung abgestufter DES-Zusaetze sowie Variationskoeffizienten zwischen 3,6 und 10,5% fuer die Reproduzierbarkeit charakterisieren die Zuverlaessigkeit des Verfahrens. Untersuchungen zur Ueberpruefung des polyvalenten Antiserums AS 6139 zur Erfassung der Gesamtstilbenrueckstaende zeigten, dass bei Verwendung von 3H-DES als radioaktiv markiertem Ligand DES und - in einem geringen Ausmass auch Hexoestrol (HEX) - bei Messung im homologen Testsystem (Verwendung von DES bzw. HEX zur Erstellung der Standardkurve) relativ genau gemessen werden konnten, waehrend dies unter den gleichen Bedingungen bei Dienoestrol (DIEN) nicht der Fall war; auf die Moeglichkeit einer Umwandlung von DIEN in eine staerker kreuzreagierende Substanz waehrend des Extraktionsganges wird hingewiesen. In den heterologen Testsystemen (Messung des Probenstilbens gegen das jeweils andere zur Erstellung der Eichkurve verwendete Stilben) zeigten sich die erwarteten Ueber- oder Unterschaetzungen im Rahmen von Zusatzversuchen. Hinsichtlich der Erfassung der Gesamtstilbenrueckstaende, d.h. in Unkenntnis der Tatsache, ob DES, HEX oder DIEN angewandt wurden, ergibt sich aus vorliegenden Versuchen, dass bei Verwendung von DES sowohl als Tracer als auch als Standardsubstanz ein empfindlicher qualitativer Rueckstandsnachweis moeglich ist (Nachweisgrenze zwischen 59 und 86 pg). (orig.)Journal
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