Synthesis and Biological Evaluation of Itraconazole Derivatives: Design in an Old Scaffold

Antimicrobial resistance is a major global problem for public health, indicating the need for the development of new anti-infective drugs, among other actions (i.e., better stewardship, diagnostics, etc.). A common strategy in medicinal chemistry is to modify existing drugs with an organometallic moiety to enhance their efficacy or overcome resistance. One notable example is ferroquine, an organometallic derivative of chloroquine. Here, we describe the design, in-depth characterization, and in vitro evaluation of seven new derivatives of the antifungal drug itraconazole (ITZ) against parasitic and fungal pathogens. ITZ was selected as a privileged scaffold because it targets ergosterol biosynthesis, which is an essential component of cell membranes in fungi and trypanosomatid parasites. While none of the compounds were active against Trypanosoma cruzi and Leishmania infantum, the ferrocenyl derivatives proved to be 1.5- to 1.9-fold more potent than ITZ toward Trypanosoma brucei. Of particular interest, all of the compounds exhibited high antifungal activity against the azole-susceptible clinical isolates. Furthermore, the ferrocenyl-containing compound was the most active against Aspergillus. Despite showing 10-fold lower activity than ITZ, these organometallic derivatives constitute an interesting starting point for further pharmacomodulation since we confirmed that they blocked the ERG11 enzyme, the main target of azoles.