Change search
Refine search result
31323334 1651 - 1668 of 1668
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1651. Zovko, Ana
    et al.
    Novak, Metka
    Hååg, Petra
    Kovalerchick, Dimitry
    Holmlund, Teresa
    Färnegårdh, Katarina
    Stockholm University, Faculty of Science, Department of Organic Chemistry. Stockholm University, Science for Life Laboratory (SciLifeLab).
    Ilan, Micha
    Carmeli, Shmuel
    Lewensohn, Rolf
    Viktorsson, Kristina
    Compounds from the marine sponge Cribrochalina vasculum offer a way to target IGF-1R mediated signaling in tumor cells2016In: OncoTarget, ISSN 1949-2553, E-ISSN 1949-2553, Vol. 7, no 31, p. 50258-50276Article in journal (Refereed)
    Abstract [en]

    In this work two acetylene alcohols, compound 1 and compound 2, which were isolated and identified from the sponge Cribrochalina vasculum, and which showed antitumor effects were further studied with respect to targets and action mechanisms. Gene expression analyses suggested insulin like growth factor receptor (IGF-1R) signaling to be instrumental in controlling anti-tumor efficacy of these compounds in non-small cell lung cancer (NSCLC). Indeed compounds 1 and 2 inhibited phosphorylation of IGF-1R beta as well as reduced its target signaling molecules IRS-1 and PDK1 allowing inhibition of pro-survival signaling. In silico docking indicated that compound 1 binds to the kinase domain of IGF-1R at the same binding site as the well known tyrosine kinase inhibitor AG1024. Indeed, cellular thermal shift assay (CETSA) confirmed that C. vasculum compound 1 binds to IGF-1R but not to the membrane localized tyrosine kinase receptor EGFR. Importantly, we demonstrate that compound 1 causes IGF-1R beta but not Insulin Receptor degradation specifically in tumor cells with no effects seen in normal diploid fibroblasts. Thus, these compounds hold potential as novel therapeutic agents targeting IGF-1R signaling for anti-tumor treatment.

  • 1652. Zovko, Ana
    et al.
    Viktorsson, Kristina
    Haag, Petra
    Kovalerchick, Dimitry
    Farnegardh, Katarina
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Alimonti, Andrea
    Ilan, Micha
    Carmeli, Shmuel
    Lewensohn, Rolf
    Marine Sponge Cribrochalina vasculum Compounds Activate Intrinsic Apoptotic Signaling and Inhibit Growth Factor Signaling Cascades in Non-Small Cell Lung Carcinoma2014In: Molecular Cancer Therapeutics, ISSN 1535-7163, E-ISSN 1538-8514, Vol. 13, no 12, p. 2941-2954Article in journal (Refereed)
    Abstract [en]

    Marine-derived compounds have been explored and considered as possible antitumor agents. In this study, we analyzed extracts of the sponge Cribrochalina vasculum for their ability to inhibit tumor cell proliferation. Screening identified two acetylenic compounds of similar structure that showed strong tumor-specific toxicity in non-small cell lung carcinoma (NSCLC) cells and small-cell lung carcinoma cells, and less prominent toxicity in ovarian carcinoma, while having no effect on normal cells. These acetylenic compounds were found to cause a time-dependent increase in activation of apoptotic signaling involving cleavage of caspase-9, caspase-3, and PARP, as well as apoptotic cell morphology in NSCLC cells, but not in normal fibroblasts. Further analysis demonstrated that these compounds caused conformational change in Bak and Bax, and resulted in loss of mitochondrial potential and cytochrome c release in NSCLC cells. Moreover, a decreased phosphorylation of the growth factor signaling kinases Akt, mTOR, and ERK was evident and an increased phosphorylation of JNK was observed. Thus, these acetylenic compounds hold potential as novel therapeutic agents that should be further explored for NSCLC and other tumor malignancies.

  • 1653.
    Åberg, Jenny B.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanistic Studies on Ruthenium-Catalyzed Hydrogen Transfer Reactions2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Mechanistic studies on three different ruthenium-based catalysts have been performed. The catalysts have in common that they have been employed in hydrogen transfer reactions involving alcohols and ketones, amines and imines or both.

    Bäckvall’s catalyst, η5-(Ph5C5)Ru(CO)2Cl, finds its application as racemization catalyst in dynamic kinetic resolution, where racemic alcohols are converted to enantiopure acetates in high yields. The mechanism of the racemization has been investigated and both alkoxide and alkoxyacyl intermediates have been characterized by NMR spectroscopy and in situ FT-IR measurements. The presence of acyl intermediates supports a mechanism via CO assistance. Substantial support for coordination of the substrate during the racemization cycle is provided, including exchange studies with both external and internal potential ketone traps. We also detected an unexpected alkoxycarbonyl complex from 5-hydroxy-1-hexene, which has the double bond coordinated to ruthenium.

    Shvo’s catalyst, [Ru2(CO)4(μ-H)(C4Ph4COHOCC4Ph4)] is a powerful catalyst for transfer hydrogenation as well as for dynamic kinetic resolution. The mechanism of this catalyst is still under debate, even though a great number of studies have been published during the past decade. In the present work, the mechanism of the reaction with imines has been investigated. Exchange studies with both an external and an internal amine as potential traps have been performed and the results can be explained by a stepwise inner-sphere mechanism. However, if there is e.g. a solvent cage effect, the results can also be explained by an outer-sphere mechanism. We have found that there is no cage effect in the reduction of a ketone containing a potential internal amine trap. If the mechanism is outer-sphere, an explanation as to why the solvent cage effect is much stronger in the case of imines than ketones is needed.

    Noyori’s catalyst, [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3), has successfully been used to produce chiral alcohols and amines via transfer hydrogenation. The present study shows that the mechanism for the reduction of imines is different from that of ketones and aldehydes. Acidic activation of the imine was found necessary and an ionic mechanism was proposed.

  • 1654.
    Åberg, Jenny B.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanistic studies on three different ruthenium based hydrogen transfer catalysts2006Licentiate thesis, comprehensive summary (Other academic)
  • 1655.
    Åberg, Jenny B.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Investigation of a possible solvent cage effect in the reduction of 4-aminocyclohexanone by a hydroxycyclopentadienyl ruthenium hydride2008In: Chemistry: a European Journal, ISSN 0947-6539, Vol. 14, no 30, p. 9169-9174Article in journal (Refereed)
  • 1656.
    Åberg, Jenny B.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Nyhlén, Jonas
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Martín-Matute, Belén
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Privalov, Timofei
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    CO Assistance in ligand exchange of a ruthenium racemization catalyst: identification of an acyl intermediate2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 27, p. 9500-9501Article in journal (Refereed)
    Abstract [en]

    An acyl intermediate in the activation of eta(5)-(Ph(5)Cp)Ru(CO)(2)Cl by t-BuOK was identified by means of in situ FT-IR measurements and NMR spectroscopy. This strongly supports the conclusion that the ligand exchange takes place via CO assistance, i.e., that the activation occurs via nucleophilic attack by tert-butoxide on one of the CO ligands. The tert-butoxycarbonyl intermediate shows stretching vibrations at 1933 and 1596 cm(-1), corresponding to the CO and COOt-Bu groups, respectively. In the (13)C NMR spectrum, the CO group appears at 209.5 ppm and the COOt-Bu group at 208.7 ppm. The NMR assignments were confirmed by density functional theory calculations. The subsequent alcohol-alkoxide exchange is also thought to take place via CO assistance. However, no intermediate in that step could be detected.

  • 1657.
    Åberg, Jenny B.
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Warner, Madeleine C.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Unexpected formation of a cyclopentadienylruthenium alkoxycarbonyl complex with a coordinated C=C bond2009In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 131, no 38, p. 13622-13624Article in journal (Refereed)
  • 1658.
    Åberg, Jenny
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Samec, Joseph S. M.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Mechanistic Investigation on the Hydrogenation of Imines by [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3). Experimental support for an  Ionic Pathway2006In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, no 26, p. 2771-2773Article in journal (Refereed)
    Abstract [en]

    The need for acidic activation in the stoichiometric hydrogenation of benzyl-[1-phenyl-ethylidene]-amine ( 6a) or [1-(4-methoxy-phenyl)-ethylidene]-methyl-amine ( 6b) by Noyori's catalyst [p-(Me2CH)C6H4Me]RuH(NH2CHPhCHPhNSO2C6H4-p-CH3)( 2) is inconsistent with the proposed concerted mechanism and supports an ionic mechanism.

  • 1659.
    Åkermark, Björn
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Vätgas från solljus och vatten, en dröm som närmar sig sin uppfyllelse2008In: Sveriges Energiting, 13-14 mars 2008, 2008, p. xxxx-Conference paper (Other academic)
  • 1660.
    Åkermark, Björn
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Sjögren, Magnus P.T.
    Iron-catalyzed nucleophilic substitution of allylic acetate2007In: Advanced Synthesis & Catalysis, ISSN 1615-4150, Vol. 349, no 17-18, p. 2641-2646Article in journal (Refereed)
  • 1661.
    Éll, Alida H
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Csjernyik, Gábor
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Slagt, Vincent F
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Bäckvall, Jan-Erling
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Berner, Simon
    Puglia, Carla
    Greger, Ledung
    Oscarsson, Sven
    Synthesis os S-Thioacetate Functionalized Cobalt(II) Porphyrins and Heterogenization on gold Surface2006In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 5, p. 1193-1199Article in journal (Refereed)
    Abstract [en]

    Cobalt tetraarylporphyrins 1-Co and 2-Co with thioacetate-functionalized carbon chains on the aryl groups were synthesized. The cobalt porphyrin 2-Co was immobilized on a gold surface after deprotection of the S-acetyl group. The immobilized porphyrin was studied by X-ray Photoelectron Spectroscopy (XPS) and the results suggest that a complete monolayer of porphyrins is formed.

  • 1662. Éll, Alida H
    et al.
    Samec, Joseph S M
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Brasse, Claudia
    Bäckvall, Jan-E
    Dehydrogenation of aromatic amines to imines via ruthenium-catalyzed hydrogen transfer2002In: Chemical Communications, ISSN 1359-7345, no 10, p. 1144 - 1145Article in journal (Refereed)
  • 1663. Öksnes Dalheim, Marianne
    et al.
    Björk Arnfinnsdottir, Nina
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Christensen, Björn E.
    The size and shape of three water-soluble, non-ionic polysaccharides produced by lactic acid bacteria: A comparative study2016In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 142, p. 91-97Article in journal (Refereed)
    Abstract [en]

    Three water-soluble, non-ionic extracellular polysaccharides (EPS) obtained from lactic acid bacteria (S. thermophilus THS, L. helveticus K16 and S. thermophilus ST1) were subjected to a comparative study by means of multidetector size-exclusion chromatography, providing distributions and averages of molar masses, radii of gyration and intrinsic viscosities. All polysaccharides displayed random coil character. Further analysis of the data reveals differences in chain stiffness and extension that could be well correlated to structural features. The calculated persistence lengths ranged from 5 to 10 nm and fall within the range typical for many single-stranded bacterial or plant polysaccharides. The ST1 polysaccharide had the highest molar mass but the lowest persistence length, which is attributed to the presence of the flexible (1→6)-linkage in the main chain.

  • 1664.
    Östervall, Jennie
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Conformational Dynamics of Carbohydrates Studied by NMR Spectroscopy and Molecular Simulations2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Carbohydrates play important roles in biological processes. Their function is closely related to their conformation. In this thesis, conformational studies of carbohydrates by NMR spectroscopy and molecular dynamics computer simulations are described.

    The first two papers discuss the anomalous solubility of β-cyclodextrin compared to other cyclodextrins. Time correlation functions revealed flexibility in all cyclodextrins. Molecular dynamics computer simulations showed that the glycosidic linkages were rather rigid and the flexibility was suggested to be macrocyclic. From spatial distribution functions β-cyclodextrin was found to have greater ability to order the surrounding water than the other cyclodextrins. Paper III deals with some of the difficulties of conformational studies. In Paper IV, a new method, Additative Potential Maximum Entropy, APME, is applied to a disaccharide. Conformational distribution functions are derived from NOEs, J-couplings and residual dipolar couplings and calculated from computer simulations. All distribution functions were found to be in good agreement. In papers V and VI oligosaccharides from human milk are studied. Residual dipolar coupling, J-couplings and cross relaxation rates were measured by NMR spectroscopy and molecular dynamics computer simulations were carried out. Both oligosaccharides showed high flexibility for the β-D-GlcpNAc-(1→3)-β-D-Galp linkage.

  • 1665.
    Östervall, Jennie
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Maliniak, Arnold
    Widmalm, Göran
    Conformational dynamics of the pentasaccharide LNF-1 from NMR spectroscopy and molecular dynamics simulationsManuscript (Other academic)
  • 1666.
    Östervall, Jennie
    et al.
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Naidoo, Kevin J.
    Chen, Jeff Yu-Jen
    Widmalm, Göran
    Maliniak, Arnold
    Molecular structure and dynamics of α, β and γ-cyclodextrinsManuscript (Other academic)
  • 1667. Číhalová, Sylva
    et al.
    Dziedzic, Pawel
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Córdova, Armando
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Veselý, Jan
    Asymmetric Aza-Morita–Baylis–Hillman-type reactions: The highly enantioselective reaction between unmodified α,β-unsaturated aldehydes and N-acylimines by organo-co-catal2011In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 353, no 7, p. 1096-1108Article in journal (Refereed)
    Abstract [en]

    The highly enantioselective organo-co-catalytic aza-Morita–Baylis–Hillman (MBH)-type reaction between N-carbamate-protected imines and α,β-unsaturated aldehydes has been developed. The organic co-catalytic system of proline and 1,4-diazabicyclo[2.2.2]octane (DABCO) enables the asymmetric synthesis of the corresponding N-Boc- and N-Cbz-protected β-amino-α-alkylidene-aldehydes in good to high yields and up to 99% ee. In the case of aza-MBH-type addition of enals to phenylprop-2-ene-1-imines, the co-catalytic reaction exhibits excellent 1,2-selectivity. The organo-co-catalytic aza-MBH-type reaction can also be performed by the direct highly enantioselective addition of α,β-unsaturated aldehydes to bench-stableN-carbamate-protected α-amidosulfones to give the corresponding β-amino-α-alkylidene-aldehydes with up to 99% ee.The organo-co-catalytic aza-MBH-type reaction is also an expeditious entry to nearly enantiomerically pure β-amino-α-alkylidene-amino acids and β-amino-α-alkylidene-lactams (99% ee). The mechanism and stereochemistry of the chiral amine and DABCO co-catalyzed aza-MBH-type reaction arealso discussed.

  • 1668.
    Šoltésová, Mária
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK). Charles University in Prague.
    Kowalewski, Jozef
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK).
    Widmalm, Göran
    Stockholm University, Faculty of Science, Department of Organic Chemistry.
    Dynamics of exocyclic groups in the Escherichia coli O91 O-antigen polysaccharide in solution studied by carbon-13 NMR relaxation2013In: Journal of Biomolecular NMR, ISSN 0925-2738, E-ISSN 1573-5001, Vol. 57, no 1, p. 37-45Article in journal (Refereed)
    Abstract [en]

    Carbon-13 relaxation data are reported for exocyclic groups of hexopyranosyl sugar residues in the repeating unit within the Escherichia coli O91 O-antigen polysaccharide in a dilute D2O solution. The measurements of T 1, T 2 and heteronuclear nuclear Overhauser enhancements were carried out at 310 K at two magnetic fields (16.4 T, 21.1 T). The data were analyzed using the standard and extended Lipari–Szabo models, as well as a conformational jump model. The extended version of the Lipari–Szabo and the two-site jump models were most successful for the hydroxymethyl groups of Gal and GlcNAc sugar residues. Different dynamics was found for the hydroxymethyl groups associated with different configurations (d-gluco, d-galacto) of the sugar residues, the latter being faster than the former.

31323334 1651 - 1668 of 1668
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf