- Hemiindigo: Highly Bistable Photoswitching at the Biooptical Window
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Hemiindigo is a long known chromophore that absorbs in the blue part of the spectrum but has almost completely been ignored as potential photoswitch. Herein we show how the absorption of hemiindigo is shifted to the red part of the visible spectrum and how nearly perfect photoswitching can be achieved using blue or green and red light. Five derivatives were investigated giving very high isomeric yields in both switching directions, i.e. >90% E isomer after irradiation with 470 to 530 nm light and 99% Z isomer with 590 up to 680 nm light. At the same time the thermal bistability is extraordinarily high leading to half-lives of the pure isomeric states of up to 83 years at 25 °C. The herein developed photoswitches show photochromism in the visible enabling the two isomeric states to be distinguished by the naked eye. Substituted hemiindigos therefore constitute extremely promising new photoswitches with excellent properties for applications in biology, chemistry, or material sciences.
- Petermayer, Christian,Thumser, Stefan,Kink, Florian,Mayer, Peter,Dube, Henry
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- Azaaurones as Potent Antimycobacterial Agents Active against MDR- and XDR-TB
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Herein we report the screening of a small library of aurones and their isosteric counterparts, azaaurones and N-acetylazaaurones, against Mycobacterium tuberculosis. Aurones were found to be inactive at 20 μm, whereas azaaurones and N-acetylazaaurones emerged as the most potent compounds, with nine derivatives displaying MIC99 values ranging from 0.4 to 2.0 μm. In addition, several N-acetylazaaurones were found to be active against multidrug-resistant (MDR) and extensively drug-resistant (XDR) clinical M. tuberculosis isolates. The antimycobacterial mechanism of action of these compounds remains to be determined; however, a preliminary mechanistic study confirmed that they do not inhibit the mycobacterial cytochrome bc1 complex. Additionally, microsomal metabolic stability and metabolite identification studies revealed that N-acetylazaaurones are deacetylated to their azaaurone counterparts. Overall, these results demonstrate that azaaurones and their N-acetyl counterparts represent a new entry in the toolbox of chemotypes capable of inhibiting M. tuberculosis growth.
- Campani?o, André,Carrasco, Marta P.,Njoroge, Mathew,Seldon, Ronnett,Chibale, Kelly,Perdig?o, Jo?o,Portugal, Isabel,Warner, Digby F.,Moreira, Rui,Lopes, Francisca
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p. 1537 - 1546
(2019/08/02)
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- Design, synthesis and investigation of water-soluble hemi-indigo photoswitches for bioapplications
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A series of hemi-indigo derivatives was synthesized and their photoswitching properties in aqueous medium were studied. The dimethoxy hemi-indigo derivative with the best photochromic performance in water was identified as a promising platform for the dev
- Berdnikova, Daria V.
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p. 2822 - 2829
(2019/12/11)
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- Probing the Azaaurone Scaffold against the Hepatic and Erythrocytic Stages of Malaria Parasites
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The potential of azaaurones as dual-stage antimalarial agents was investigated by assessing the effect of a small library of azaaurones on the inhibition of liver and intraerythrocytic lifecycle stages of the malaria parasite. The whole series was screened against the blood stage of a chloroquine-resistant Plasmodium falciparum strain and the liver stage of P. berghei, yielding compounds with dual-stage activity and sub-micromolar potency against erythrocytic parasites. Studies with genetically modified parasites, using a phenotypic assay based on the P. falciparum Dd2-ScDHODH line, which expresses yeast dihydroorotate dehydrogenase (DHODH), showed that one of the azaaurone derivatives has the potential to inhibit the parasite mitochondrial electron-transport chain. The global urgency in finding new therapies for malaria, especially against the underexplored liver stage, associated with chemical tractability of azaaurones, warrants further development of this chemotype. Overall, these results emphasize the azaaurone chemotype as a promising scaffold for dual-stage antimalarials.
- Carrasco, Marta P.,Machado, Marta,Gon?alves, Lídia,Sharma, Moni,Gut, Jiri,Lukens, Amanda K.,Wirth, Dyann F.,André, Vania,Duarte, Maria Teresa,Guedes, Rita C.,dos Santos, Daniel J. V. A.,Rosenthal, Philip J.,Mazitschek, Ralph,Prudêncio, Miguel,Moreira, Rui
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p. 2194 - 2204
(2016/10/19)
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- Color and Constitution. Part 8 . Some Novel Dyestuffs Containing Indoxyl Residues
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Novel dyes containing C-linked indoxyl residues are prepared by two routes: (a) by the reaction of C-electrophiles with N-acetylindoxyl and (b) by the reaction of active methylene compounds with 2-chloroindole-3-one.The visible absorption spectra are recorded and discussed.
- Katritzky, Alan R.,Li, Qiao-Ling,Fan, Wei-Qiang
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p. 1287 - 1292
(2007/10/02)
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- Indigoid dyes
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A series of novel water-soluble sulfonated indoxyl derivatives have been prepared, including their base salts with pharmacologically acceptable cations. These particular compounds are useful as food dyes or as cosmetic colorants. 2,2'-(1,4-phenylenedimeth
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