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991.
The syntheses of the K-imine derivatives of 1,7-phenanthroline, phenaleno[1,9-g,h]quinoline, and dibenzo[a,h]phenazine are described. The parent heterocyclic compounds 4, 9 and 14 were oxidized to the corresponding K-oxides, 5, 10 and 15 , which in turn were reacted with sodium azide in aqueous acetone. The resulting trans-azido alcohols were then cyclized with tributylphosphine to the title compounds 6, 11 and 16 . 相似文献
992.
993.
Oksana V. Salomatina Nadezhda S. Dyrkheeva Irina I. Popadyuk Alexandra L. Zakharenko Ekaterina S. Ilina Nina I. Komarova Jhannes Reynisson Nariman F. Salakhutdinov Olga I. Lavrik Konstantin P. Volcho 《Molecules (Basel, Switzerland)》2022,27(1)
A series of deoxycholic acid (DCA) amides containing benzyl ether groups on the steroid core were tested against the tyrosyl-DNA phosphodiesterase 1 (TDP1) and 2 (TDP2) enzymes. In addition, 1,2,4- and 1,3,4-oxadiazole derivatives were synthesized to study the linker influence between a para-bromophenyl moiety and the steroid scaffold. The DCA derivatives demonstrated promising inhibitory activity against TDP1 with IC50 in the submicromolar range. Furthermore, the amides and the 1,3,4-oxadiazole derivatives inhibited the TDP2 enzyme but at substantially higher concentration. Tryptamide 5 and para-bromoanilide 8 derivatives containing benzyloxy substituent at the C-3 position and non-substituted hydroxy group at C-12 on the DCA scaffold inhibited both TDP1 and TDP2 as well as enhanced the cytotoxicity of topotecan in non-toxic concentration in vitro. According to molecular modeling, ligand 5 is anchored into the catalytic pocket of TDP1 by one hydrogen bond to the backbone of Gly458 as well as by π–π stacking between the indolyl rings of the ligand and Tyr590, resulting in excellent activity. It can therefore be concluded that these derivatives contribute to the development of specific TDP1 and TDP2 inhibitors for adjuvant therapy against cancer in combination with topoisomerase poisons. 相似文献
994.
Aleksander Fedoseev Iraida Charushnikova Nina Budantseva Grigory Andreev 《无机化学与普通化学杂志》2019,645(22):1296-1302
Behavior of UVI, NpVI and PuVI in water‐acetonitrile solutions was studied spectrophotometrically with the successive addition of the polar organic ligands (dimethyl sulfoxide or hexamethylphosphoric triamide) and the NCS– ion. The detected spectral effects – changes in the absorption intensity, bathochromic shifts in the absorption bands, the absence of isosbestic points, a change in the color of the solution – indicate complex competitive processes occurring in the studied solutions. In the case of NpVI, its partial reduction to NpIV by NCS– ion is observed. Solid UVI complex, [UO2(HMPA)2(NCS)2], was isolated, its crystal structure was determined using X‐ray diffraction. In contrast to known AnO22+ compounds with the NCS– ion, this complex exhibits tetragonal bipyramidal environment of the U atom. [UO2(HMPA)2(NCS)2] is also characterized by UV/Vis, IR and luminescence spectroscopy. 相似文献
995.
Zinicovscaia Inga Ciocarlan Alexandru Lupascu Lucian Aricu Aculina Dragalin Ion Ciocarlan Nina Yushin Nikita 《Journal of Radioanalytical and Nuclear Chemistry》2019,321(1):349-354
Journal of Radioanalytical and Nuclear Chemistry - For the first time the elemental composition of Tanacetum corymbosum (L.) Sch. Bip. of Moldavian origin was determined by means of neutron... 相似文献
996.
Dr. Cecilia Lindgren Dr. Nina Forsgren Norman Hoster Christine Akfur Elisabet Artursson Dr. Lotta Edvinsson Dr. Richard Svensson Dr. Franz Worek Dr. Fredrik Ekström Prof. Anna Linusson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(40):e202200678
Reactivators are vital for the treatment of organophosphorus nerve agent (OPNA) intoxication but new alternatives are needed due to their limited clinical applicability. The toxicity of OPNAs stems from covalent inhibition of the essential enzyme acetylcholinesterase (AChE), which reactivators relieve via a chemical reaction with the inactivated enzyme. Here, we present new strategies and tools for developing reactivators. We discover suitable inhibitor scaffolds by using an activity-independent competition assay to study non-covalent interactions with OPNA-AChEs and transform these inhibitors into broad-spectrum reactivators. Moreover, we identify determinants of reactivation efficiency by analysing reactivation and pre-reactivation kinetics together with structural data. Our results show that new OPNA reactivators can be discovered rationally by exploiting detailed knowledge of the reactivation mechanism of OPNA-inhibited AChE. 相似文献
997.
Nina Declas John R. J. Maynard Laure Menin Natalia Gasilova Sebastian Gtze Jakob L. Sprague Pierre Stallforth Stefan Matile Jerome Waser 《Chemical science》2022,13(43):12808
Hypervalent iodine reagents have recently emerged as powerful tools for late-stage peptide and protein functionalization. Herein we report a tyrosine bioconjugation methodology for the introduction of hypervalent iodine onto biomolecules under physiological conditions. Tyrosine residues were engaged in a selective addition onto the alkynyl bond of ethynylbenziodoxolones (EBX), resulting in stable vinylbenziodoxolones (VBX) bioconjugates. The methodology was successfully applied to peptides and proteins and tolerated all other nucleophilic residues, with the exception of cysteine. The generated VBX were further functionalized by palladium-catalyzed cross-coupling and azide–alkyne cycloaddition reactions. The method could be successfully used to modify bioactive natural products and native streptavidin to enable thiol-mediated cellular uptake.A tyrosine bioconjugation for the introduction of hypervalent iodine onto biomolecules is described. The transformation was applied to peptides and proteins and was used to modify native streptavidin to enable thiol-mediated cellular uptake. 相似文献
998.
Nina E. Wezynfeld Arkadiusz M. Bonna Dawid Ponka Wojciech Bal Tomasz Frczyk 《Molecules (Basel, Switzerland)》2022,27(17)
Nickel is toxic to humans. Its compounds are carcinogenic. Furthermore, nickel allergy is a severe health problem that affects approximately 10–20% of humans. The mechanism by which these conditions develop remains unclear, but it may involve the cleavage of specific proteins by nickel ions. Ni(II) ions cleave the peptide bond preceding the Ser/Thr-Xaa-His sequence. Such sequences are present in all four enzymes of the melatonin biosynthesis pathway, i.e., tryptophan 5-hydroxylase 1, aromatic-l-amino-acid decarboxylase, serotonin N-acetyltransferase, and acetylserotonin O-methyltransferase. Moreover, fragments prone to Ni(II) are exposed on surfaces of these proteins. Our results indicate that all four studied fragments undergo cleavage within tens of hours at pH 8.2 and 37 °C, corresponding with the conditions in the mitochondrial matrix. Since melatonin, a potent antioxidant and anti-inflammatory agent, is synthesized within the mitochondria of virtually all human cells, depleting its supply may be detrimental, e.g., by raising the oxidative stress level. Intriguingly, Ni(II) ions have been shown to mimic hypoxia through the stabilization of HIF-1α protein, but melatonin prevents the action of HIF-1α. Considering all this, the enzymes of the melatonin biosynthesis pathway seem to be a toxicological target for Ni(II) ions. 相似文献
999.
Sara Ali Astrid Hendriks Rob van Dalen Thomas Bruyning Nico Meeuwenoord Prof. Dr. Herman S. Overkleeft Dr. Dmitri V. Filippov Prof. Dr. Gijs A. van der Marel Dr. Nina M. van Sorge Prof. Dr. Jeroen D. C. Codée 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(40):10461-10469
Wall teichoic acids (WTAs) are important components of the cell wall of the opportunistic Gram-positive bacterium Staphylococcus aureus. WTAs are composed of repeating ribitol phosphate (RboP) residues that are decorated with d -alanine and N-acetyl-d -glucosamine (GlcNAc) modifications, in a seemingly random manner. These WTA-modifications play an important role in shaping the interactions of WTA with the host immune system. Due to the structural heterogeneity of WTAs, it is impossible to isolate pure and well-defined WTA molecules from bacterial sources. Therefore, here synthetic chemistry to assemble a broad library of WTA-fragments, incorporating all possible glycosylation modifications (α-GlcNAc at the RboP C4; β-GlcNAc at the RboP C4; β-GlcNAc at the RboP C3) described for S. aureus WTAs, is reported. DNA-type chemistry, employing ribitol phosphoramidite building blocks, protected with a dimethoxy trityl group, was used to efficiently generate a library of WTA-hexamers. Automated solid phase syntheses were used to assemble a WTA-dodecamer and glycosylated WTA-hexamer. The synthetic fragments have been fully characterized and diagnostic signals were identified to discriminate the different glycosylation patterns. The different glycosylated WTA-fragments were used to probe binding of monoclonal antibodies using WTA-functionalized magnetic beads, revealing the binding specificity of these WTA-specific antibodies and the importance of the specific location of the GlcNAc modifications on the WTA-chains. 相似文献
1000.
A. A. Wassilieff und Nina N. Martianoff 《Fresenius' Journal of Analytical Chemistry》1935,103(3-4):103-106
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