- 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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- Probing the aurone scaffold against Plasmodium falciparum: Design, synthesis and antimalarial activity
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A library comprising 44 diversely substituted aurones derivatives was synthesized by straightforward aldol condensation reactions of benzofuranones and the appropriately substituted benzaldehydes. Microwave enhanced synthesis using palladium catalyzed protocols was introduced as a powerful strategy for extending the chemical space around the aurone scaffold. Additionally, Mannich-base derivatives, containing a 7-aminomethyl-6-hydroxy substitution pattern at ring A, were also prepared. Screening against the chloroquine resistant Plasmodium falciparum W2 strain identified novel aurones with IC 50 values in the low micromolar range. The most potent compounds contained a basic moiety, with the ability to accumulate in acidic digestive vacuole of the malaria parasite. However, none of those aurones revealed significant activity against hemozoin formation and falcipain-2, two validated targets expressed during the blood stage of P. falciparum infection and functional in digestive vacuole of the parasite. Overall, this study highlight (i) the usefulness of aurones as platforms for synthetic procedures using palladium catalyzed protocols to rapidly deliver lead compounds for further optimization and (ii) the potential of novel aurone derivatives as promising antimalarial compounds.
- Carrasco, Marta P.,Newton, Ana S.,Gon?alves, Lídia,Góis, Ana,Machado, Marta,Gut, Jiri,Nogueira, Fátima,H?nscheid, Thomas,Guedes, Rita C.,Dos Santos, Daniel J.V.A.,Rosenthal, Philip J.,Moreira, Rui
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p. 523 - 534
(2014/05/20)
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