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 IC50 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.
Marta P. Carrasco a, Ana S. Newton a, Lídia Gonçalves a, Ana Góis b, Marta Machado c, Jiri Gut d, Fátima Nogueira c, Thomas Hänscheid b, Rita C. Guedes a, Daniel J.V.A. dos Santos a,1, Philip J. Rosenthal d, Rui Moreira a
a Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia, Universidade de Lisboa, Av. Prof. Gama Pinto 1649-003 Lisboa, Portugal
b Unidade de Microbiologia Molecular e Infecção, Instituto de Medicina Molecular, Faculdade de Medicina de Lisboa, 1649-028 Lisboa, Portugal
c Centro de Malária e outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, 1349-008 Lisboa, Portugal
d Department of Medicine, San Francisco General Hospital, University of California, San Francisco, Box 0811, San Francisco, CA 94143, USA