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151.
Apyrimidinic/apurinic sites feature among the most prevalent DNA lesions. If not repaired, it has been recently evidenced that they are prone to react in situ with vicinal nucleobases, evolving toward more complex and highly mutagenic interstrand cross-links. Information concerning the structure and the multi-step reactivity leading to such clustered defects is scarce due to their low formation yield. This study reports a DFT exploration of the condensation reaction between a ketoaldehyde (derived from an oxidized C4’ abasic site) and three nucleobases featuring an amino group. They are found to present a very similar intrinsic reactivity, indicating in turn that differences of reactivity arise more from the relative positioning of the two reactive fragments within a flexible B-DNA. We also probe the role of a vicinal water molecule for the formation of the aminol and the requirements to reach an adequate estimate of this strongly exothermic reaction, which drives the DNA damage process. 相似文献
152.
Dr. Anna Notaro Marta Jakubaszek Severin Koch Dr. Riccardo Rubbiani Dr. Orsolya Dömötör Dr. Éva A. Enyedy Mazzarine Dotou Dr. Fethi Bedioui Mickaël Tharaud Dr. Bruno Goud PD Dr. Stefano Ferrari Prof. Dr. Enzo Alessio Dr. Gilles Gasser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(22):4997-5009
Cancer is one of the main causes of death worldwide. Chemotherapy, despite its severe side effects, is to date one of the leading strategies against cancer. Metal-based drugs present several potential advantages when compared to organic compounds and they have gained trust from the scientific community after the approval on the market of the drug cisplatin. Recently, we reported the ruthenium complex ([Ru(DIP)2(sq)](PF6) (where DIP is 4,7-diphenyl-1,10-phenantroline and sq is semiquinonate) with a remarkable potential as chemotherapeutic agent against cancer, both in vitro and in vivo. In this work, we analyse a structurally similar compound, namely [Ru(DIP)2(mal)](PF6), carrying the flavour-enhancing agent approved by the FDA, maltol (mal). To possess an FDA approved ligand is crucial for a complex, whose mechanism of action might include ligand exchange. Herein, we describe the synthesis and characterisation of [Ru(DIP)2(mal)](PF6), its stability in solutions and under conditions that resemble the physiological ones, and its in-depth biological investigation. Cytotoxicity tests on different cell lines in 2D model and on HeLa MultiCellular Tumour Spheroids (MCTS) demonstrated that our compound has higher activity than cisplatin, inspiring further tests. [Ru(DIP)2(mal)](PF6) was efficiently internalised by HeLa cells through a passive transport mechanism and severely affected the mitochondrial metabolism. 相似文献
153.
Dr. Karl P. J. Gustafson Arnar Guðmundsson Dr. Éva G. Bajnóczi Dr. Ning Yuan Prof. Xiaodong Zou Prof. Ingmar Persson Prof. Jan-E. Bäckvall 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(15):3411-3419
The activation process of a known Ru-catalyst, dicarbonyl(pentaphenylcyclopentadienyl)ruthenium chloride, has been studied in detail using time resolved in situ X-ray absorption spectroscopy. The data provide bond lengths of the species involved in the process as well as information about bond formation and bond breaking. On addition of potassium tert-butoxide, the catalyst is activated and an alkoxide complex is formed. The catalyst activation proceeds via a key acyl intermediate, which gives rise to a complete structural change in the coordination environment around the Ru atom. The rate of activation for the different catalysts was found to be highly dependent on the electronic properties of the cyclopentadienyl ligand. During catalytic racemization of 1-phenylethanol a fast-dynamic equilibrium was observed. 相似文献
154.
155.
Interaction of PiB‐Derivative Metal Complexes with Beta‐Amyloid Peptides: Selective Recognition of the Aggregated Forms 下载免费PDF全文
Dr. André F. Martins David M. Dias Dr. Jean‐François Morfin Dr. Sara Lacerda Dr. Douglas V. Laurents Dr. Éva Tóth Prof. Carlos F. G. C. Geraldes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5413-5422
Metal complexes are increasingly explored as imaging probes in amyloid peptide related pathologies. We report the first detailed study on the mechanism of interaction between a metal complex and both the monomer and the aggregated form of Aβ1–40 peptide. We have studied lanthanide(III) chelates of two PiB‐derivative ligands (PiB=Pittsburgh compound B), L1 and L2, differing in the length of the spacer between the metal‐complexing DO3A macrocycle (DO3A= 1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid) and the peptide‐recognition PiB moiety. Surface plasmon resonance (SPR) and saturation transfer difference (STD) NMR spectroscopy revealed that they both bind to aggregated Aβ1–40 (KD=67–160 μM ), primarily through the benzothiazole unit. HSQC NMR spectroscopy on the 15N‐labeled, monomer Aβ1–40 peptide indicates nonsignificant interaction with monomeric Aβ. Time‐dependent circular dichroism (CD), dynamic light scattering (DLS), and TEM investigations of the secondary structure and of the aggregation of Aβ1–40 in the presence of increasing amounts of the metal complexes provide coherent data showing that, despite their structural similarity, the two complexes affect Aβ fibril formation distinctly. Whereas GdL1, at higher concentrations, stabilizes β‐sheets, GdL2 prevents aggregation by promoting α‐helical structures. These results give insight into the behavior of amyloid‐targeted metal complexes in general and contribute to a more rational design of metal‐based diagnostic and therapeutic agents for amyloid‐ associated pathologies. 相似文献
156.
Macrocyclic Gd3+ Complexes with Pendant Crown Ethers Designed for Binding Zwitterionic Neurotransmitters 下载免费PDF全文
Dr. Fatima Oukhatar Hervé Meudal Dr. Céline Landon Prof. Dr. Nikos K. Logothetis Prof. Dr. Carlos Platas‐Iglesias Priv.‐Doz. Dr. Goran Angelovski Dr. Éva Tóth 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11226-11237
A series of Gd3+ complexes exhibiting a relaxometric response to zwitterionic amino acid neurotransmitters was synthesized. The design concept involves ditopic interactions 1) between a positively charged and coordinatively unsaturated Gd3+ chelate and the carboxylate group of the neurotransmitters and 2) between an azacrown ether appended to the chelate and the amino group of the neurotransmitters. The chelates differ in the nature and length of the linker connecting the cyclen‐type macrocycle that binds the Ln3+ ion and the crown ether. The complexes are monohydrated, but they exhibit high proton relaxivities (up to 7.7 mM ?1 s?1 at 60 MHz, 310 K) due to slow molecular tumbling. The formation of ternary complexes with neurotransmitters was monitored by 1H relaxometric titrations of the Gd3+ complexes and by luminescence measurements on the Eu3+ and Tb3+ analogues at pH 7.4. The remarkable relaxivity decrease (≈80 %) observed on neurotransmitter binding is related to the decrease in the hydration number, as evidenced by luminescence lifetime measurements on the Eu3+ complexes. These complexes show affinity for amino acid neurotransmitters in the millimolar range, which can be suited to imaging concentrations of synaptically released neurotransmitters. They display good selectivity over non‐amino acid neurotransmitters (acetylcholine, serotonin, and noradrenaline) and hydrogenphosphate, but selectivity over hydrogencarbonate was not achieved. 相似文献
157.
A. A. Ladatko I. D. Sadekov L. N. Étmetchenko V. I. Minkin 《Chemistry of Heterocyclic Compounds》1989,25(5):577-580
10-Telluroniaanthracene perchlorates react with nucleophiles (X–=halide, hydroxide, methoxide) via intermediate free telluroxanthyl radicals. With 9-aryl-10-telluroniaanthracene perchlorates, high yields of 9-aryl-9-X-telluroxanthenes are obtained, but with 10-telluroniaanthracene the principal product is 9,9-bis(telluroxathenyl) as a result of rapid competitive dimerization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 691–695, May, 1989. 相似文献
158.
S. B. Érenburg L. N. Mazalov N. V. Bausk M. K. Drozdova 《Journal of Structural Chemistry》1994,35(4):517-522
SKα, SKβ, ClKβ, ClKβ, and PdLβ2 X-ray fluorescent and PdK EXAFS spectra were obtained for some organic solutions of dialkyl sulfide complexes with palladium
chloride. Solvent effects on the electronic and spatial structure of complexes in solution are discussed. In the benzene solution
of [PdCl22(C6H13)2S], complex molecules interact with solvent molecules along a coordinate that is perpendicular to the plane of the complex
molecule.
Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurmal Strukturnoi Khimii, Vol. 35, No. 4, pp. 105c111, July–August, 1994.
Translated by L. Smolina 相似文献
159.
The reaction of 2-(2 pyridytcarbonyl)benzoic acid with thionyl chloride affords an unexpected product of the intramolecular acylation of the pyridine nitrogen atom, namely, 6,11-dioxo-6,11-dihydrobenzo[blquinotizinium chloride. At the same time, 2-(2-quinotylcarbonyl)benzoic acid forms the expected cyclic acid chloride, namely, 3-(2-gitinotyl)-3-chlorophthalide in this reaction. Both compounds acylate ammonia and primary amines, including those with bulky alkyl groups (tert-butyl, 1-adamantyl, and 1,1,3,3-tetramethylbutyl) with the formation of 2-R-3-hydroxy-3-(2pyridyl- or 2-quinolyl)isoindolines. The protonation of the pyridine nitrogen atom of N-(1,1,3,3-tetramethylbutyl)-2-(2pyridylcarbonyl)benzamide, obtained in the open amide form, is accompanied by the closing of the isoindotinone ring; the deprotonation is accompanied by ring opening.Riga Technical University, Riga LV-1048. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 499–504, April, 1994. Original article submitted March 17, 1994. 相似文献
160.
Within the Born-Oppenheimer adiabatic perturbation theory, an equation was obtained for the intensity of fast electron scattering
by polyatomic molecules. All of its parameters are explicitly defined by vibronic interaction in a molecule; due to this,
quantum chemical calculations are fully applicable to electron diffraction studies of molecular geometries.
Engels Anti-Aircraft Missile Higher Military School. Translated fromZhurmal Strukturnoi Khimii, Vol. 35, No. 2, pp. 40–45, March–April, 1994.
Translated by L. Smolina 相似文献