Anti-Pneumocystis carinii pneumonia activity of dicationic carbazoles

A series of 2,7- and 3,6-bis cationic carbazoles was synthesized and evaluated for activity against a rat model of Pneumocystis carinii pneumonia (PCP). The compounds were also tested for inhibition of topoisomerase II and binding to DNA. Several of the compounds proved to be more potent and less toxic than a standard anti-PCP drug (pentamidine). While no quantitative correlation was seen between anti-PCP activity, topoisomerase inhibition and DNA binding, a minimal level of DNA binding was found to be necessary for antimicrobial activity.