Synthesis, Antimalarial Activity, and Molecular Modeling of New Pyrrolo[1,2-<i>a</i>]quinoxalines, Bispyrrolo[1,2-<i>a</i>]quinoxalines, Bispyrido[3,2-<i>e</i>]pyrrolo[1,2-<i>a</i>]pyrazines, and Bispyrrolo[1,2-<i>a</i>]thieno[3,2-<i>e</i>]pyrazines

Abstract

Three pyrrolo[1,2-a]quinoxalines, 15 bispyrrolo[1,2-a]quinoxalines, bispyrido[3,2-e]pyrrolo[1,2-a]pyrazines, and bispyrrolo[1,2-a]thieno[3,2-e]pyrazines were synthesized from various substituted nitroanilines or nitropyridines and tested for their in vitro activity upon the erythrocytic development of Plasmodium falciparum strains with different chloroquine-resistance status. Bispyrrolo[1,2-a]quinoxalines showed superior antimalarial activity with respect to monopyrrolo[1,2-a]quinoxalines. The best activity was observed with bispyrrolo[1,2-a]quinoxalines linked by a bis(3-aminopropyl)piperazine. Moreover, it was observed that the presence of a methoxy group on the pyrrolo[1,2-a]quinoxaline nucleus increased the pharmacological activity. Drug effects upon beta-hematin formation were assayed and showed similar or higher inhibitory activities than CQ. A possible mechanism of interaction implicating binding of pyrroloquinoxalines to beta-hematin was supported by molecular modeling.