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  • 1
    Language: English
    In: Inorganic chemistry, 07 April 2014, Vol.53(7), pp.3371-84
    Description: Bispidine (3,7-diazabicyclo[3.3.1]nonane, C7H14N2) analogues of cisplatin, carboplatin, and oxaliplatin have been prepared. (C7H14N2)PtCl2·DMF (1b), obtained from (1,5-hexadiene)PtCl2 and bispidine in DMF, is dimeric in the solid state. Dissolving 1b in hot N-methylformamide allows crystallization of the solvent-free polymeric (C7H14N2)PtCl2 (1a). Recrystallization of 1a,b from hot water yields the trihydrate (C7H14N2)PtCl2·3H2O (1c). Reaction of 1 with Ag2(cbdca) (cbdca = 1,1-cyclobutanedicarboxylate) in water affords the pentahydrate (C7H14N2)Pt{C4H6(CO2)2}·5H2O (2b), which loses water in vacuo to give (C7H14N2)Pt{C4H6(CO2)2} (2a). Reaction of 1 with AgNO3 in water, followed by addition of Na2C2O4, affords the water-free polymeric (C7H14N2)Pt(C2O4) (3). All complexes have been structurally characterized, revealing various patterns of N-H···Cl and N-H···O hydrogen bonds. In the hydrates 1c and 2b the complexes are embedded in intricate three-dimensional water networks. Complexes 1a, 2a, and 3 have been tested for their cytotoxicity against human cancer cell lines K562 (chronic myeloid leukemia), A2780 (ovarian cancer), and its platinum-resistant subline A2780 CisR and are compared to their parent analogues. The new complexes show significant cytotoxic activity along with a low platinum resistance factor.
    Keywords: Antineoplastic Agents -- Toxicity ; Bridged Bicyclo Compounds, Heterocyclic -- Chemistry ; Carboplatin -- Analogs & Derivatives ; Cisplatin -- Analogs & Derivatives ; Organoplatinum Compounds -- Toxicity
    ISSN: 00201669
    E-ISSN: 1520-510X
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  • 2
    Language: English
    In: Journal of the American Chemical Society, Nov 11, 2015, Vol.137(44), pp.11236-11246
    Keywords: Iron Oxides – Chemical Properties ; Nanoparticles – Research ; Activation Energy – Analysis
    ISSN: 0002-7863
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Bioorganic & Medicinal Chemistry Letters, 15 June 2012, Vol.22(12), pp.3866-3869
    Description: Fourteen tryptophan-containing cyclic dipeptides – , including all four stereoisomers of -Trp-Pro and -Trp-Ala, were converted to their C2-regularly prenylated derivatives – in the presence of dimethylallyl diphosphate by using the purified recombinant FtmPT1 as catalyst. The enzyme products were isolated on HPLC in preparative scales and their structures were elucidated by NMR and MS analyses. The cytotoxic effects of the prenylated products and their substrates were tested with human leukemia K562 and ovarian cancer A2780 sens and A2780 CisR cell lines. Preliminary results have been clearly shown that prenylation at C2 led to a significant increase of the cytotoxicity of the tested cyclic dipeptides in all the 14 cases. The second amino acid and the stereochemistry of tryptophan moiety of the cyclic dipeptides showed less influence on the cytotoxicity of the tested compounds.
    Keywords: Chemoenzymatic Synthesis ; Cyclic Dipeptides ; Cytotoxicity ; Prenyltransferase ; Prenylated Derivatives ; Medicine ; Chemistry ; Anatomy & Physiology
    ISSN: 0960-894X
    E-ISSN: 1464-3405
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  • 4
    Language: English
    In: Bioorganic & Medicinal Chemistry, 01 July 2013, Vol.21(13), pp.3667-3673
    Description: Falcipain-2 is a cysteine protease of the malaria parasite that plays a key role in the hydrolysis of hemoglobin, a process that is required by intraerythrocytic parasites to obtain amino acids. In this work we show that the polysulfonated napthylurea suramin is capable of binding to falcipain-2, inhibiting its catalytic activity at nanomolar concentrations against both synthetic substrates and the natural substrate hemoglobin. Kinetic measurements suggest that the inhibition occurs through an noncompetitive allosteric mechanism, eliciting substrate inhibition. Smaller suramin analogues and those with substituted methyl groups also showed inhibition within the nanomolar range. Our results identify the suramin family as a potential starting point for the design of falcipain-2 inhibitor antimalarials that act through a novel inhibition mechanism.
    Keywords: Malaria ; Falcipain-2 ; Suramin ; Inhibition ; Allostery ; Medicine ; Chemistry ; Anatomy & Physiology
    ISSN: 0968-0896
    E-ISSN: 1464-3391
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  • 5
    Language: English
    In: Inorganic Chemistry, March 21, 2016, Vol.55(6), pp.2986-2997
    Keywords: Chemical Synthesis – Usage ; Cisplatin – Chemical Properties ; Carboplatin – Chemical Properties
    ISSN: 0020-1669
    Source: Cengage Learning, Inc.
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  • 6
    Language: English
    In: Inorganic chemistry, 21 March 2016, Vol.55(6), pp.2986-97
    Description: 3,7-Diallyl-bispidin-9-one (6) (bispidin-9-one = 3,7-diazabicyclo[3.3.1]nonan-9-one) is converted to N-unsubstituted spiro[bispidin-9,2'-[1,3]dioxolane] (12; 35%). The ketal crystallizes in the forms of anhydrous 12a and the dihydrate 12b. The molecules in anhydrous 12a are linked to each other, forming N1-H1···N2-H2···N1* hydrogen-bond chiral helices of alternating chirality. In the dihydrate 12b, the ketal molecules are connected to a central string of water molecules by O3-H···O1 and O4-H···N1 hydrogen bonds, but not to themselves. Reaction of 12 with (1,5-hexadiene)PtCl2 affords almost quantitatively spiro[bispidin-9,2'-[1,3]dioxolane]PtCl2 (13). Cleavage of the ketal to retrieve the ketone produces the geminal diol (bispidin-9,9-diol)PtCl2 (14; 85%). Compound 14 reacts with Ag2cbdca (cbdca = 1,1-cyclobutanedicarboxylate) to give the dihydrate (bispidin-9,9-diol)Pt(cbdca)·2H2O (15b), which can be dehydrated to obtain anhydrous (bispidin-9,9-diol)Pt(cbdca) (15a). Similarly, anhydrous (bispidin-9,9-diol)Pt(oxalate) (16) is obtained. Crystal structures of 14 and 15b reveal association by various forms of O-H···O, O-H···Cl, N-H···Cl, and N-H···O hydrogen bonds. Biological studies showed a moderate cytotoxic activity of the bispidin-9,9-diol complexes 14-16, compared to the 9,9-unsubstituted bispidine complexes. No unspecific cytotoxicity of 14-16 up to 316 μM was found against the noncancer cell line HEK293.
    Keywords: Antineoplastic Agents -- Chemistry ; Bridged Bicyclo Compounds, Heterocyclic -- Chemical Synthesis ; Carboplatin -- Chemistry ; Cisplatin -- Chemistry ; Organoplatinum Compounds -- Chemistry
    ISSN: 00201669
    E-ISSN: 1520-510X
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  • 7
    Language: English
    In: Inorganic Chemistry, Dec 7, 2015, Vol.54(23), pp.11236-11246
    Keywords: Nanoparticles – Research ; Polymers – Research ; Iron Oxides – Chemical Properties
    ISSN: 0020-1669
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Inorganic chemistry, 07 December 2015, Vol.54(23), pp.11236-46
    Description: Maghemite (Fe2O3) iron oxide nanoparticles (IONPs) were synthesized, modified with covalent surface-bound CO-releasing molecules of a tri(carbonyl)-chlorido-phenylalaninato-ruthenium(II) complex (CORM), and coated with a dextran polymer. The time- and temperature-dependent CO release from this CORM-3 analogue was followed by a myoglobin assay. A new measurement method for the myoglobin assay was developed, based on confining "water-soluble" polymer-coated Dextran500k@CORM@IONP particles in hollow spheres of nontoxic and easily prepared calcium alginate. Dropping a mixture of Dextran500k@CORM@IONP and sodium alginate into a CaCl2 solution leads to stable hollow spheres of Ca(2+) cross-linked alginate which contain the Dextran500k@CORM@IONP particles. This "alginate-method" (i) protects CORM-3 analogues from rapid CO-displacement reactions with a protein, (ii) enables a spatial separation of the CORM from its surrounding myoglobin assay with the alginate acting as a CO-permeable membrane, and (iii) allows the use of substances with high absorptivity (such as iron oxide nanoparticles) in the myoglobin assay without interference in the optical path of the UV cell. Embedding the CORM@IONP nanoparticles in the alginate vessel represents a compartmentation of the reactive component and allows for close contact with, yet facile separation from, the surrounding myoglobin assay. The half-life of the CO release from Dextran500k@CORM@IONP particles surrounded by alginate was determined to be 890 ± 70 min at 20 °C. An acceleration of the CO release occurs at higher temperature with a half-life of 172 ± 27 min at 37 °C and 45 ± 7 min at 50 °C. The CO release can be triggered in an alternating current magnetic field (31.7 kA m(-1), 247 kHz, 39.9 mT) through local magnetic heating of the susceptible iron oxide nanoparticles. With magnetic heating at 20 °C in the bulk solution, the half-life of CO release from Dextran500k@CORM@IONP particles decreased to 155 ± 18 min without a noticeable temperature increase in the dispersion. At 37 and 50 °C, the half-life for the CO release triggered by local magnetic heating was 65 ± 5 min and 30 ± 3 min, respectively. Thus, at a physiological temperature of 37 °C, magnetic heating accelerates the CO release of the IONP-bound CORM by a factor of ∼ 2.6. The activation energy for CO release from a CORM-3 analogue was determined to be EA = 78 kJ/mol.
    Keywords: Carbon Monoxide -- Analysis ; Coordination Complexes -- Chemistry ; Ferric Compounds -- Chemistry ; Metal Nanoparticles -- Chemistry ; Phenylalanine -- Analogs & Derivatives
    ISSN: 00201669
    E-ISSN: 1520-510X
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  • 9
    Language: English
    In: Tetrahedron Letters, 11 June 2014, Vol.55(24), pp.3463-3468
    Description: Five new polyketide derivatives, 6′-hydroxypestalotiopsone C ( ), acropyrone ( ), bicytosporone D ( ), waol acid ( ), and pestalotiopene C ( ), together with seven known metabolites ( – ), were obtained from extracts of the endophytic fungus , isolated from the mangrove tree . The structures of the isolated compounds were elucidated on the basis of comprehensive NMR and MS analysis. Compounds , , and showed moderate cytotoxic activity against human cisplatin-sensitive (IC values 27.1, 76.2, and 8.3 μM, respectively) and resistant A2780 cell lines (IC values 12.6, 30.1, and 19.0 μM, respectively), whereas only exhibited antibacterial activity against (MIC value 14.3 μM).
    Keywords: Acremonium Strictum ; Cytotoxic Activity ; Endophytic Fungus ; Polyketides ; Rhizophora Apiculata ; Chemistry
    ISSN: 0040-4039
    E-ISSN: 1873-3581
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  • 10
    Language: English
    In: Tetrahedron Letters, 29 January 2014, Vol.55(5), pp.1020-1023
    Description: Neosartorin ( ) was isolated from the endophytic fungus . The absolute configuration of , including both axial and central chirality elements, was established as (a ,5 ,10 ,5′ ,6′ ,10′ ) for the first time on the basis of its electronic circular dichroism (ECD) spectra aided with TDDFT–ECD calculations. Neosartorin ( ) exhibited substantial antibacterial activity against a broad spectrum of Gram-positive bacterial species including staphylococci, streptococci, enterococci, and with minimal inhibitory concentrations in the range of 4–32 μg/mL. When the toxicity of against eukaryotic cells was measured using a panel of different cancer cell lines such as HELA and BALB/3T3, the average IC values exceeded 32 μg/mL.
    Keywords: Absolute Configuration ; Antibacterial Activity ; Aspergillus Fumigatiaffinis ; Neosartorin ; Chemistry
    ISSN: 0040-4039
    E-ISSN: 1873-3581
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