37612
2014
2014
eng
67
73
7
9
article
Elsevier
Amsterdam
1
--
--
--
A xanthone and a phenylanthraquinone from the roots of Bulbine frutescens, and the revision of six seco-anthraquinones into xanthones
Phytochemical investigation of the dichloromethane/methanol (1:1) extract of the roots of Bulbine frutescens led to the isolation of a new xanthone, 8-hydroxy-6-methylxanthone-1-carboxylic acid (1) and a new phenylanthraquinone, 6',8-O-dimethylknipholone (2) along with six known compounds. The structures were elucidated on the basis of NMR and MS spectral data analyses. The structure of compound 1 was confirmed through X-ray crystallography which was then used as a reference to propose the revision of the structures of six seco-anthraquinones into xanthones. The isolated compounds were evaluated for cytotoxicity against human cervix carcinoma KB-3-1 cells with the phenylanthraquinone knipholone being the most active (IC50 = 0.43 mu M). Two semi-synthetic knipholone derivatives, knipholone Mannich base and knipholone-1,3-oxazine, were prepared and tested for cytotoxic activity; both showed moderate activities (IC50 value of 1.89 and 2.50 mu M, respectively). (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
Phytochemistry letters
10.1016/j.phytol.2014.04.004
1874-3900
1876-7486
wos:2014
WOS:000340884100013
Yenesew, A (reprint author), Univ Nairobi, Dept Chem, POB 30197-00100, Nairobi, Kenya., ayenesew@uonbi.ac.ke
German Academic Exchange Service (DAAD) for the scholarship through
Natural Product Research Network of Eastern and Central Africa
(NAPRECA); ISP (Sweden) [KEN-02]
Negera Abdissa
Matthias Heydenreich
Jacob O. Midiwo
Albert Ndakala
Zsuzsanna Majer
Beate Neumann
Hans-Georg Stammler
Norbert Sewald
Abiy Yenesew
eng
uncontrolled
Bulbine frutescens
eng
uncontrolled
Xanthone
eng
uncontrolled
seco-Anthraquinone
eng
uncontrolled
Phenylanthraquinone
eng
uncontrolled
Cytotoxicity
eng
uncontrolled
Structure revision
Institut für Chemie
Referiert
38129
2014
2014
eng
S91
S91
1
387
conferenceobject
Springer
New York
1
--
--
--
Dynamic interaction between sphingolipid enzymes, S1P and inflammatory cytokine regulation in dendritic cells
NAUNYN-SCHMIEDEBERGS ARCHIVES OF PHARMACOLOGY
0028-1298
1432-1912
wos:2014
80th Annual Meeting of the Deutsche-Gesellschaft-fur-Experimentelle-und-Klinische-Pharmakologie-und -Toxikologie-e-V
APR 01-03, 2014
WOS:000359538500368
Hannover, GERMANY
Olga Arlt
Anja Schwiebs
Kathrin Pfarr
Annika Ranglack
Ferreiros Nerea Bouzas
Yannick Schreiber
Corinna Neuber
Burkhard Kleuser
Josef M. Pfeilschifter
Heinfried H. Radeke
Institut für Chemie
Referiert
37316
2014
2014
eng
28
31
4
10
article
Elsevier
Amsterdam
1
--
--
--
3-Oxo-14 alpha, 15 alpha-epoxyschizozygine: A new schizozygane indoline alkaloid from Schizozygia coffaeoides
The stem bark extract of Schizozygia coffaeoides (Apocynaceae) showed moderate antiplasmodial activity (IC50 = 8-12 mu g/mL) against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum. Chromatographic separation of the extract led to the isolation of a new schizozygane indoline alkaloid, named 3-oxo-14 alpha, 15 alpha-epoxyschizozygine. In addition, two dimeric anthraquinones, cassiamin A and cassiamin B, were identified for the first time in the family Apocynaceae. The structures of the isolated compounds were deduced on the basis of spectroscopic evidence. The schizozygane indole alkaloids showed good to moderate antiplasmodial activities (IC50 = 13-52 mu m). (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
Phytochemistry letters
10.1016/j.phytol.2014.07.003
1874-3900
1876-7486
wos:2014
WOS:000347915800026
Yenesew, A (reprint author), Univ Nairobi, Dept Chem, POB 30197-00100, Nairobi, Kenya., ayenesew@uonbi.ac.ke
German Academic Exchange Services (DAAD) through Natural Products
Research Network for Eastern and Central Africa (NAPRECA); International
Science Program (ISP, Sweden) [KEN-02]
Yoseph Atilaw
Matthias Heydenreich
Albert Ndakala
Hoseah M. Akala
Edwin Kamau
Abiy Yenesew
eng
uncontrolled
Schizozygia coffaeoides
eng
uncontrolled
Schizozygane indoline alkaloid
eng
uncontrolled
3-Oxo-14 alpha, 15 alpha-epoxyschizozygine
eng
uncontrolled
Dimeric anthraquinone
eng
uncontrolled
Cassiamin A
eng
uncontrolled
Cassiamin B
Institut für Chemie
Referiert
37799
2014
2014
eng
2952
2960
9
18
article
Wiley-VCH
Weinheim
1
--
--
--
Efficient palladium(II) precatalysts bearing 4,5-dicyanoimidazol-2-ylidene for the Mizoroki-Heck reaction
The new N-heterocyclic carbene (NHC) complex [PdCl2{(CN)(2)IMes}(PPh3)] (2) ({(CN)(2)IMes}: 4,5-dicyano-1,3-dimesitylimidazol-2-ylidene) and the NHC palladacycle [PdCl(dmba){(CN)(2)IMes}] (3) (dmba: N,N-dimethylbenzylamine) have been synthesized by thermolysis of 4,5-dicyano-1,3-dimesityl-2-(pentafluorophenyl) imidazoline (1) in the presence of suitable palladium(II) precursors. The acyclic complex 2 was formed by ligand exchange using the mononuclear precursor [PdCl2(PPh3)(2)] and the palladacycle 3 was formed by cleavage of the dinuclear chloro-bridged precursor [Pd(mu-Cl)(dmba)](2). The new NHC precursor 1-benzyl-4,5-dicyano-2-(pentafluorophenyl)-3-picolylimidazoline (5) was formed by condensation of pentafluorobenzaldehyde with N-benzyl-N'-picolyldiaminomaleonitrile (4). The NHC palladacycle [PdCl2{(CN)(2)IBzPic}] (6) ({(CN)(2)IBzPic}: 1-benzyl-4,5-dicyano-3-picolylimidazol-2-ylidene) was prepared by in situ thermolysis of 5 in the presence of [PdCl2(PhCN)(2)]. The three palladium(II) complexes were characterized by NMR and IR spectroscopy, mass spectrometry and elemental analysis. In addition, the molecular structures of 2 and 3 were determined by X-ray diffraction. The pi-acidity of (CN)(2)IBzPic was compared with (CN)(2)IMes and perviously reported pi-acidic imidazol-2-ylidenes by NBO analysis. The Mizoroki-Heck (MH) reactions of various aryl halides with n-butyl acrylate were performed in the presence of complexes 2, 3 and 6. The new precatalysts showed high activity in the MH reactions giving good-to-excellent product yields with 0.1 mol-% pre-catalyst. The nature of the catalytically active species of 2, 3 and 6 was investigated by poisoning experiments with mercury and transmission electron microscopy. It was found that palladium nanoparticles formed from the precatalysts were involved in the catalytic process.
European journal of inorganic chemistry : a journal of ChemPubSoc Europe
10.1002/ejic.201402040
1434-1948
1099-0682
wos:2014
WOS:000338033200009
Holdt, HJ (reprint author), Univ Potsdam, Dept Inorgan Chem, Karl Liebknecht Str 24-25, D-14476 Golm, Germany., Holdt@uni-potsdam.de
Heiko Baier
Philipp Metzner
Thomas Körzdörfer
Alexandra Kelling
Hans-Jürgen Holdt
eng
uncontrolled
Homogeneous catalysis
eng
uncontrolled
Palladium
eng
uncontrolled
Cross coupling
eng
uncontrolled
Carbene ligands
Institut für Chemie
Referiert
37584
2014
2014
eng
13803
13823
21
9
19
review
MDPI
Basel
1
--
--
--
Molecular processes studied at a single-molecule level using DNA origami nanostructures and atomic force microscopy
DNA origami nanostructures allow for the arrangement of different functionalities such as proteins, specific DNA structures, nanoparticles, and various chemical modifications with unprecedented precision. The arranged functional entities can be visualized by atomic force microscopy (AFM) which enables the study of molecular processes at a single-molecular level. Examples comprise the investigation of chemical reactions, electron-induced bond breaking, enzymatic binding and cleavage events, and conformational transitions in DNA. In this paper, we provide an overview of the advances achieved in the field of single-molecule investigations by applying atomic force microscopy to functionalized DNA origami substrates.
Molecules
10.3390/molecules190913803
25191873
1420-3049
wos:2014
WOS:000343093100057
Bald, I (reprint author), Univ Potsdam, Inst Chem Phys Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., bald@uni-potsdam.de; adrian.keller@uni-paderborn.de
Marie Curie FP7 Integration Grant within the 7th European Union Framework Programme; Deutsche Forschungsgemeinschaft (DFG)
<a href="https://doi.org/10.25932/publishup-47584">Zweitveröffentlichung in der Schriftenreihe Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe ; 1146</a>
Ilko Bald
Adrian Keller
eng
uncontrolled
DNA origami
eng
uncontrolled
atomic force microscopy
eng
uncontrolled
single-molecule analysis
eng
uncontrolled
DNA radiation damage
eng
uncontrolled
protein binding
eng
uncontrolled
enzyme reactions
eng
uncontrolled
G quadruplexes
Institut für Chemie
Referiert
Open Access
47584
2014
2021
eng
13803
13823
21
9
postprint
1
2021-09-08
2021-09-08
--
Molecular processes studied at a single-molecule level using DNA origami nanostructures and atomic force microscopy
DNA origami nanostructures allow for the arrangement of different functionalities such as proteins, specific DNA structures, nanoparticles, and various chemical modifications with unprecedented precision. The arranged functional entities can be visualized by atomic force microscopy (AFM) which enables the study of molecular processes at a single-molecular level. Examples comprise the investigation of chemical reactions, electron-induced bond breaking, enzymatic binding and cleavage events, and conformational transitions in DNA. In this paper, we provide an overview of the advances achieved in the field of single-molecule investigations by applying atomic force microscopy to functionalized DNA origami substrates.
Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
10.25932/publishup-47584
urn:nbn:de:kobv:517-opus4-475843
1866-8372
online registration
Molecules 19 (2014) 9, 13803-13823 DOI: 10.3390/molecules190913803
<a href="http://publishup.uni-potsdam.de/37584">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
true
true
CC-BY - Namensnennung 4.0 International
Ilko Bald
Adrian Keller
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
1146
eng
uncontrolled
DNA origami
eng
uncontrolled
atomic force microscopy
eng
uncontrolled
single-molecule analysis
eng
uncontrolled
DNA radiation damage
eng
uncontrolled
protein binding
eng
uncontrolled
enzyme reactions
eng
uncontrolled
G quadruplexes
Chemie und zugeordnete Wissenschaften
open_access
Institut für Chemie
Referiert
Green Open-Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/47584/pmnr1146.pdf
7340
2014
2014
eng
6825
6829
5
13
4
article
Royal Society of Chemistry
1
--
2014-01-06
--
On the role of fluoro-substituted nucleosides in DNA radiosensitization for tumor radiation therapy
Gemcitabine (2′,2′-difluorocytidine) is a well-known radiosensitizer routinely applied in concomitant chemoradiotherapy. During irradiation of biological media with high-energy radiation secondary low-energy (<10 eV) electrons are produced that can directly induce chemical bond breakage in DNA by dissociative electron attachment (DEA). Here, we investigate and compare DEA to the three molecules 2′-deoxycytidine, 2′-deoxy-5-fluorocytidine, and gemcitabine. Fluorination at specific molecular sites, i.e., nucleobase or sugar moiety, is found to control electron attachment and subsequent dissociation pathways. The presence of two fluorine atoms at the sugar ring results in more efficient electron attachment to the sugar moiety and subsequent bond cleavage. For the formation of the dehydrogenated nucleobase anion, we obtain an enhancement factor of 2.8 upon fluorination of the sugar, whereas the enhancement factor is 5.5 when the nucleobase is fluorinated. The observed fragmentation reactions suggest enhanced DNA strand breakage induced by secondary electrons when gemcitabine is incorporated into DNA.
RSC Advances : an international journal to further the chemical sciences
10.1039/C3RA46735J
2046-2069
online registration
Au-006606
<a href="http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-73412">Zweitveröffentlichung als Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe ; 167</a>
Ilko Bald
Adrian Keller
Janina Kopyra
eng
uncontrolled
low-energy electrons
eng
uncontrolled
single-strand breaks
eng
uncontrolled
gas-phase
eng
uncontrolled
chemoradiation therapy
eng
uncontrolled
molecular-mechanisms
eng
uncontrolled
resonant formation
eng
uncontrolled
damage
eng
uncontrolled
attachment
eng
uncontrolled
drugs
Chemie und zugeordnete Wissenschaften
Institut für Chemie
Referiert
Open Access
RSC
7341
2014
2014
eng
6825
6829
5
postprint
1
2015-03-13
2014-01-06
--
On the role of fluoro-substituted nucleosides in DNA radiosensitization for tumor radiation therapy
Gemcitabine (2′,2′-difluorocytidine) is a well-known radiosensitizer routinely applied in concomitant chemoradiotherapy. During irradiation of biological media with high-energy radiation secondary low-energy (<10 eV) electrons are produced that can directly induce chemical bond breakage in DNA by dissociative electron attachment (DEA). Here, we investigate and compare DEA to the three molecules 2′-deoxycytidine, 2′-deoxy-5-fluorocytidine, and gemcitabine. Fluorination at specific molecular sites, i.e., nucleobase or sugar moiety, is found to control electron attachment and subsequent dissociation pathways. The presence of two fluorine atoms at the sugar ring results in more efficient electron attachment to the sugar moiety and subsequent bond cleavage. For the formation of the dehydrogenated nucleobase anion, we obtain an enhancement factor of 2.8 upon fluorination of the sugar, whereas the enhancement factor is 5.5 when the nucleobase is fluorinated. The observed fragmentation reactions suggest enhanced DNA strand breakage induced by secondary electrons when gemcitabine is incorporated into DNA.
urn:nbn:de:kobv:517-opus4-73412
online registration
Au-006606
RSC Advances, 13 (2014) 4, S. 6825–6829. - DOI 10.1039/C3RA46735J
<a href="http://publishup.uni-potsdam.de/opus4-ubp/frontdoor/index/index/docId/7340">Bibliographieeintrag der Originalveröffentlichung/Quelle</a>
Ilko Bald
Janina Kopyra
Adrian Keller
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
paper 167
eng
uncontrolled
low-energy electrons
eng
uncontrolled
single-strand breaks
eng
uncontrolled
gas-phase
eng
uncontrolled
chemoradiation therapy
eng
uncontrolled
molecular-mechanisms
eng
uncontrolled
resonant formation
eng
uncontrolled
damage
eng
uncontrolled
attachment
eng
uncontrolled
drugs
Chemie und zugeordnete Wissenschaften
open_access
Institut für Chemie
Referiert
Open Access
Universität Potsdam
https://publishup.uni-potsdam.de/files/7341/pmnr167.pdf
37589
2014
2014
eng
34
9
23
review
World Scientific
Singapore
1
--
--
--
Excitation of muonic molecules dd mu and dt mu by super-intense attosecond soft X-ray laser pulses: Shaped post-laser-pulse muonic oscillations and enhancement of nuclear fusion
The quantum dynamics of muonic molecular ions dd mu and dt mu excited by linearly polarized along the molecular (z)-axis super-intense laser pulses is studied beyond the Born-Oppenheimer approximation by the numerical solution of the time-dependent Schrodinger equation within a three-dimensional model, including the internuclear distance R and muon coordinates z and rho. The peak-intensity of the super-intense laser pulses used in our simulations is I-0 = 3.51 x 10(22) W/cm(2) and the wavelength is lambda(l) = 5nm. In both dd mu and dt mu, expectation values < z > and <rho > of muon demonstrate "post-laser-pulse" oscillations after the ends of the laser pulses. In dd mu post-laser-pulse z-oscillations appear as shaped nonoverlapping "echo-pulses". In dt mu post-laser-pulse muonic z-oscillations appear as comparatively slow large-amplitude oscillations modulated with small-amplitude pulsations. The post-laser-pulse rho-oscillations in both dd mu and dt mu appear, for the most part, as overlapping "echo-pulses". The post-laser-pulse oscillations do not occur if the Born-Oppenheimer approximation is employed. Power spectra generated due to muonic motion along both optically active z and optically passive rho degrees of freedom are calculated. The fusion probability in dt mu can be increased by more than 11 times by making use of three sequential super-intense laser pulses. The energy released from the dt fusion in dt mu can by more than 20 GeV exceed the energy required to produce a usable muon and the energy of the laser pulses used to enhance the fusion. The possibility of power production from the laser-enhanced muon-catalyzed fusion is discussed.
International journal of modern physics : E, Nuclear physics
10.1142/S0218301314300148
0218-3013
1793-6608
wos:2014
1430014
WOS:000341935600001
Bandrauk, AD (reprint author), Univ Sherbrooke, Fac Sci, Chim Theor Lab, Sherbrooke, PQ J1K 2R1, Canada., andre.dieter.bandrauk@usherbrooke.ca; gk.parmon@gmail.com
Andre D. Bandrauk
Guennaddi K. Paramonov
eng
uncontrolled
Muonic molecules
eng
uncontrolled
super-intense laser pulses
eng
uncontrolled
laser-enhanced nuclear fusion
Institut für Chemie
Referiert
38365
2014
2014
eng
144
158
15
1
16
article
Royal Society of Chemistry
Cambridge
1
--
--
--
Vibrationally resolved absorption, emission and resonance Raman spectra of diamondoids: a study based on time-dependent correlation functions
Physical chemistry, chemical physics : a journal of European Chemical Societies
10.1039/c3cp53535e
24226411
1463-9076
1463-9084
wos:2014
WOS:000327667500016
Saalfrank, P (reprint author), Univ Potsdam, Inst Chem, Karl Liebknecht Str 24-25, D-14476 Potsdam, Germany., peter.saalfrank@uni-potsdam.de
Leibniz Graduate-School, Dynamics in New Light; DFG-Forschergruppe 1282
[Sa 547/11-1]
Shiladitya Banerjee
Peter Saalfrank
Institut für Chemie
Referiert