Pharmacomodulation on the 3-acetylursolic acid skeleton: Design, synthesis, and biological evaluation of novel N-{3-[4-(3-aminopropyl)piperazinyl]propyl}-3-O-acetylursolamide derivatives as antimalarial agents.

A series of new piperazine derivatives of ursolic acid was synthesized and tested against Plasmodium falciparum strains. They were also tested on their cytotoxicity effects upon MRC-5 cells. Seven new piperazinyl analogues showed significant activity in the nanomolar range (IC(50)=78-167nM) against Plasmodium falciparum CQ-resistant strain FcB1. A possible mechanism of interaction implicating binding of these compounds to beta-hematin was supported by in vitro tests. Moreover, the importance of the hydrophilic framework attached at the terminal nitrogen atom of the bis-(3-aminopropyl)piperazine joined to the triterpene ring was also explored through molecular dynamic simulations.