Kooperativer Bibliotheksverbund

Berlin Brandenburg


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  • 1
    Language: English
    In: European Journal of Inorganic Chemistry, November 2006, Vol.2006(22), pp.4600-4607
    Description: Neutral NCN‐pincer palladium bromide complex containing the monoanionic, enantiopure pincer ligand 2,6‐bis{[()‐2‐hydroxymethyl‐1‐pyrrolidinyl]methyl}phenyl bromide () with bis‐‐()‐prolinol substituents was synthesized and isolated as a mixture of three stereoisomers [(,,,), (,,,), and (,,,)] in a 1:1:1 ratio. Upon abstraction of the bromide ion from the unresolved mixture of , single diastereoisomers of the cationic complexes []BF and []PF, respectively, were formed with a uniqueη‐,,, coordination mode of ligand . X‐ray crystal structure determination established the intramolecularη‐,,, coordination of to palladium where the typical ‐η‐,, pincer coordination is accompanied by coordination of one of the hydroxy groups of the ()‐prolinol moieties. The water molecule that was cocrystallized in the crystal structure of []PF does not coordinate to palladium, but instead is involved in a hydrogen bonding network. The catalytic potential of both cationic complexes, []BF and []PF, was tested in an aldol reaction of aldehydes with methyl isocyanoacetate to yield the oxazoline products as racemic mixtures.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
    Keywords: Palladium ; Ncn‐Pincer ; Amino Acids ; Ligand Design ; Hydrogen Bonds
    ISSN: 1434-1948
    E-ISSN: 1099-0682
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  • 2
    In: Scientific Reports, 2015, Vol.5
    Description: Flubendazole was shown to exert anti-leukaemia and anti-myeloma activity through inhibition of microtubule function. Here, flubendazole was tested for its effects on the viability of in total 461 cancer cell lines. Neuroblastoma was identified as highly flubendazole-sensitive cancer entity in a screen of 321 cell lines from 26 cancer entities. Flubendazole also reduced the viability of five primary neuroblastoma samples in nanomolar concentrations thought to be achievable in humans and inhibited vessel formation and neuroblastoma tumour growth in the chick chorioallantoic membrane assay. Resistance acquisition is a major problem in high-risk neuroblastoma. 119 cell lines from a panel of 140 neuroblastoma cell lines with acquired resistance to various anti-cancer drugs were sensitive to flubendazole in nanomolar concentrations. Tubulin-binding agent-resistant cell lines displayed the highest flubendazole IC50 and IC90 values but differences between drug classes did not reach statistical significance. Flubendazole induced p53-mediated apoptosis. The siRNA-mediated depletion of the p53 targets p21, BAX, or PUMA reduced the neuroblastoma cell sensitivity to flubendazole with PUMA depletion resulting in the most pronounced effects. The MDM2 inhibitor and p53 activator nutlin-3 increased flubendazole efficacy while RNAi-mediated p53-depletion reduced its activity. In conclusion, flubendazole represents a potential treatment option for neuroblastoma including therapy-refractory cells.
    Keywords: Biology;
    ISSN: 20452322
    E-ISSN: 20452322
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  • 3
    Language: English
    In: Inorganica Chimica Acta, 2007, Vol.360(1), pp.405-417
    Description: The chiral prolinol-derived ligands Py(ProOH) and Py(ProPh OH) form diastereopure hexa-coordinated Fe(II) complexes with one labile coordination side. These complexes are able to oxidize alkenes to epoxides with modest product selectivities. In addition, sulfides are oxidized to sulfoxides with high product selectivities, but with low ee’s. Mononuclear iron(II) complexes of enantiopure Py(ProOH) ( ) and Py(ProPh OH) ( ) ligands have been prepared with FeCl and Fe(OTf) · 2MeCN. Both ligands coordinate to the metal in a pentadentate fashion. Next to the meridional , ′, -coordination of the ligand, additional coordination of the oxygen atoms of both hydroxyl groups to the metal is found in complexes – . Complex [FeCl( )](Cl) ( ) shows an octahedral geometry as determined by X-ray diffraction and is formed as a single diastereoisomer. The solution structures of complexes – were characterized by means of UV–Vis, IR, ESI-MS, conductivity and CD measurements. The catalytic potential of these complexes in the oxidation of alkenes and sulfides in the presence of H O is presented.
    Keywords: Amino Acids ; Iron ; Ligand Design ; Oxidation ; Peroxides ; Chemistry
    ISSN: 0020-1693
    E-ISSN: 1873-3255
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  • 4
    Language: English
    In: PLoS ONE, 2013, Vol.8(1), pp.urn:issn:1932-6203
    Description: Melanoma is one of the most aggressive skin cancers due to its high capacity to metastasize. Treatment of metastatic melanomas is challenging for clinicians, as most therapeutic agents have failed to demonstrate improved survival. Thus, new candidates with antimetastatic activity are much needed. Riboavin (RF) is a component of the vitamin B complex and a potent photosensitizer. Previously, our group showed that the RF photoproducts (iRF) have potential as an antitumoral agent. Hence, we investigated the capacity of iRF on modulating melanoma B16F10 cells aggressiveness in vitro and in vivo. iRF decreases B16F10 cells survival by inhibiting mTOR as well as Src kinase. Moreover, melanoma cell migration was disrupted after treatment with iRF, mainly by inhibition of metalloproteinase (MMP) activity and expression, and by increasing TIMP expression. Interestingly, we observed that the Hedgehog (HH) pathway was inhibited by iRF. Two mediators of HH signaling, GLI1 and PTCH, were downregulated, while SUFU expression (an inhibitor of this cascade) was enhanced. Furthermore, inhibition of HH pathway signaling by cyclopamine and Gant 61 potentiated the antiproliferative action of RF. Accordingly, when a HH ligand was applied, the effect of iRF was almost completely abrogated. Our findings indicate that Hedgehog pathway is involved on the modulation of melanoma cell aggressiveness by iRF. Moreover, iRF treatment decreased pulmonary tumor formation in a murine experimental metastasis model. Research to clarify the molecular action of flavins, in vivo, is currently in progress. Taken together, the present data provides evidence that riboflavin photoproducts may provide potential candidates for improving the efficiency of melanoma treatment
    Keywords: Research Article ; Biology ; Medicine;
    ISSN: 1932-6203
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  • 5
    Language: English
    In: Microbiology (Reading, England), June 2014, Vol.160(Pt 6), pp.1087-100
    Description: The DNA recombination and repair machineries of Mycoplasma pneumoniae and Mycoplasma genitalium were predicted to consist of a set of ~11 proteins. The function of one of these proteins was inferred from its homology with proteins belonging to the Endo IV enzyme family. The members of this family function in the repair of apyrimidinic/apurinic (AP) sites in DNA. As such activity may be crucial in the mycoplasmal life cycle, we set out to study the Endo IV-like proteins encoded by M. pneumoniae and M. genitalium. Both proteins, termed NfoMpn and NfoMge, respectively, were assessed for their ability to interact with damaged and undamaged DNA. In the absence of divalent cations, both proteins exhibited specific cleavage of AP sites. Surprisingly, the proteins also recognized and cleaved cholesteryl-bound deoxyribose moieties in DNA, showing that these Nfo proteins may also function in repair of large DNA adducts. In the presence of Mg(2+), NfoMpn and NfoMge also showed 3'→5' exonucleolytic activity. By introduction of 13 single point mutations at highly conserved positions within NfoMpn, two major types of mutants could be distinguished: (i) mutants that showed no, or limited, AP cleavage activity in the presence of EDTA, but displayed significant levels of AP cleavage activity in the presence of Mg(2+); these mutants displayed no, or very low, exonucleolytic activity; and (ii) mutants that only demonstrated marginal levels of AP site cleavage activity in the presence of Mg(2+) and did not show exonucleolytic activity. Together, these results indicated that the AP endonucleolytic activity of the NfoMpn protein can be uncoupled from its 3'→5' exonucleolytic activity.
    Keywords: Amino Acid Substitution ; Amino Acids -- Genetics ; DNA Repair Enzymes -- Genetics ; Deoxyribonucleases -- Genetics ; Mycoplasma Pneumoniae -- Enzymology
    ISSN: 13500872
    E-ISSN: 1465-2080
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  • 6
    Language: English
    In: Inorganic chemistry, 15 May 2006, Vol.45(10), pp.4214-27
    Description: A series of mononuclear iron(II) and zinc(II) complexes of the new chiral Py(ProMe)2 ligand (Py(ProMe)2 = 2,6-bis[[(S)-2-(methyloxycarbonyl)-1-pyrrolidinyl]methyl]pyridine) have been prepared. The molecular geometry in the solid state (X-ray crystal structures) of the complexes [FeCl2(Py(ProMe)2)] (1), [ZnCl2(Py(ProMe)2)] (2), [Fe(OTf)2(Py(ProMe)2)] (3), [Fe(Py(ProMe)2)(OH2)2](OTf)2 (4), and [Zn(OTf)(Py(ProMe)2)](OTf) (5) are reported. They all show a meridional NN'N coordination of the Py(ProMe)2 ligand. The bis-chloride derivatives 1 and 2 represent neutral isostructural five-coordinated complexes with a distorted geometry around the metal center. Unusual seven-coordinate iron(II) complexes 3 and 4 having a pentagonal bipyramidal geometry were obtained using weakly coordinating triflate anions. The reaction of Zn(OTf)2 with the Py(ProMe)2 ligand afforded complex 5 with a distorted octahedral geometry around the zinc center. All complexes were formed as single diastereoisomers. In the case of complexes 3-5, the oxygen atoms of both carbonyl groups of the ligand are also coordinated to the metal. The stereochemistry of the coordinated tertiary amine donors in complexes 3-5 is of opposite configuration as in complexes 1 and 2 as a result of the planar penta-coordination of the ligand Py(ProMe)2. Complexes 1, 2, and 5 have an overall -configuration at their metal center, while the Fe(II) ion in complexes 3 and 4 has the opposite delta-configuration (crystal structures and CD measurements). The magnetic moments of iron complexes 1, 3, and 4 correspond to that of high-spin d6 Fe(II) complexes. The solution structures of complexes 1-5 were characterized by means of UV-vis, IR, conductivity, and CD measurements and their electrochemical behavior. These studies showed that the coordination environment of 1 and 2 observed in the solid state is maintained in solution. In coordinating solvents, the triflate anion (3, 5) or water (4) co-ligands of complexes 3-5 are replaced by solvent molecules with retention of the original pentagonal bipyramidal and octahedral geometry, respectively.
    Keywords: Ferrous Compounds -- Chemistry ; Organometallic Compounds -- Chemistry ; Proline -- Analogs & Derivatives ; Pyridines -- Chemistry ; Zinc Compounds -- Chemistry
    ISSN: 0020-1669
    E-ISSN: 1520510X
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  • 7
    In: BioMed Research International, 2017, Vol.2017, 6 pages
    Description: With the introduction of three-dimensional (3D) ultrasound it has become possible to measure volumes. The relative increase in embryonic volume (EV) is much larger than that of the crown-rump length (CRL) over the same time period. We examined whether EV is a better parameter to determine growth restriction in fetuses with structural congenital abnormalities. CRL and EV were measured using a Virtual Reality (VR) system in prospectively collected 3D ultrasound volumes of 56 fetuses diagnosed with structural congenital abnormalities in the first trimester of pregnancy (gestational age 7 to 14 weeks). Measured CRL and EV were converted to -scores and to percentages of the expected mean using previously published reference curves of euploid fetuses. The one-sample -test was performed to test significance. The EV was smaller than expected for GA in fetuses with structural congenital abnormalities (−35%  , -score −1.44  ), whereas CRL was not (−6.43%  , -score −0.43  ). CRL is a less reliable parameter to determine growth restriction in fetuses with structural congenital abnormalities as compared with EV. By measuring EV, growth restriction in first-trimester fetuses with structural congenital abnormalities becomes more evident and enables an earlier detection of these cases.
    Keywords: Research Article
    ISSN: 2314-6133
    E-ISSN: 2314-6141
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  • 8
    Language: English
    In: Chemistry – A European Journal, 28 January 2008, Vol.14(4), pp.1228-1237
    Description: The Rieske dioxygenases are a group of non‐heme iron enzymes, which catalyze the stereospecific ‐dihydroxylation of its substrates. Herein, we report the iron(II) coordination chemistry of the ligands 3,3‐bis(1‐methylimidazol‐2‐yl)propionate () and its neutral propyl ester analogue propyl 3,3‐bis(1‐methylimidazol‐2‐yl)propionate (). The molecular structures of two iron(II) complexes with were determined and two different coordination modes of the ligand were observed. In [Fe()](BPh) () the ligand is facially coordinated to the metal with an N,N,O donor set, whereas in [Fe()(MeOH)](OTf) () a bidentate N,N binding mode is found. In , the solvent molecules are in a arrangement with respect to each other. Complex is a close structural mimic of the crystallographically characterized non‐heme iron() enzyme apocarotenoid‐15–15′‐oxygenase (APO). The mechanistic features of APO are thought to be similar to those of the Rieske oxygenases, the original inspiration for this work. The non‐heme iron complexes [Fe()](OTf) () and [Fe()](BPh) () were tested in olefin oxidation reactions with HO as the terminal oxidant. Whereas was an active catalyst and both epoxide and ‐dihydroxylation products were observed, showed negligible activity under the same conditions, illustrating the importance of the anion in the reaction. : Biomimetic non‐heme iron complexes with a neutral, tridentate N,N,O ligand such as (illustrated) catalyze the epoxidation and ‐dihydroxylation of olefins with HO as the oxidant. The complexes thus mimic the reactivity of the Rieske dioxygenases. The anion has a remarkable influence on their catalytic activity.
    Keywords: Hydrogen Bonds ; Iron ; N ; N ; O Ligands ; Olefins ; Oxidation
    ISSN: 0947-6539
    E-ISSN: 1521-3765
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  • 9
    Language: English
    In: Organometallics, 06/2008, Vol.27(11), pp.2549-2559
    Description: New chiral NCN-pincer palladium complexes containing bulky diphenylhydroxymethyl pyrrolidinyl moieties as chiral auxiliaries have been synthesized. Oxidative palladium addition to ligand 2 (2 = 2,6-bis{[(S)-2-(diphenylhydroxymethyl)-1-pyrrolidinyl]methyl}-1-bromobenzene) initially yielded neutral arylpalladium bromide complex 3 in a moderate yield as a consequence of the bulky pyrrolidinyl functional groups. Performing the palladation reaction under microwave irradiation for only 5 min gave 3 in 79% yield. Abstraction of the bromide ion from 3 subsequently yielded the cationic complexes [4]PF6 and [4]BF4. Palladium complexes 3, [4]PF6, and [4]BF4 are all formed as single diastereoisomers with an RNRNSCSC configuration. X-ray crystal structure determinations of [4]PF6 and [4]BF4 revealed an unusual κ5-N,C,N,O,O coordination around palladium, in which the normal meridional κ3-coordination mode of the pincer framework is complemented by two rather long Pd−O interactions (2.622(2)–2.649(2) Å). Theoretical cal...
    Keywords: Chemistry;
    ISSN: 0276-7333
    E-ISSN: 1520-6041
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  • 10
    Language: English
    In: Journal of Medical Genetics, 22 September 2018, Vol.55(9), p.607
    Description: Rolandic epilepsy (RE) is the most common genetic childhood epilepsy, consisting of focal, nocturnal seizures and frequent neurodevelopmental impairments in speech, language, literacy and attention. A complex genetic aetiology is presumed in most, with monogenic mutations in accounting for 〉5% of cases.
    Keywords: Copy-Number ; Developmental ; Genome-Wide ; Epilepsy and Seizures
    ISSN: 0022-2593
    ISSN: 00222593
    E-ISSN: 1468-6244
    E-ISSN: 14686244
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