Inhibition of DNA topoisomerase II by azaelliptitoxins functionalized in the variable substituent domain.

A series of novel C11-substituted derivatives of azaelliptitoxin (azatoxin) have been synthesized and tested for their inhibitory activity against human DNA topoisomerase II. Incorporation of a C11 polyamine or amine resulted in an increase in the intercalation properties of the drug and a decrease of topoisomerase II activity. The structure-activity relationship (SAR) profile of the nonintercalating C11 anilino azatoxin class follows the SAR of the (anilino)acridine family. 11-(4-Cyanoanilino)azatoxin (14) was found to be the most active analog in this series, exhibiting approximately 10-fold higher activity than azatoxin 12 and etoposide.

Effect of mitonafide analogs on topoisomerase II of Leishmania chagasi.

Mitonafide (4-nitro-benzoisoquinolinedione) and a number of structural analogs were synthesized and studied in order to determine the structural requirements for inhibition of leishmanial nuclear and kinetoplast topoisomerase II and human topoisomerase II. The structure-activity relationship studies with the mitonafide analogs demonstrated that there was selective targeting of leishmanial nuclear topoisomerase II and human topoisomerase II and differential targeting of kinetoplast over nuclear topoisomerase II in the parasite. Mitonafide analogs appeared to have multiple mechanisms of action leading to death of leishmanias, but several compounds that affected kinetoplast but not nuclear topoisomerase II were not cytotoxic as determined by short-term assays. These studies provide new insight into the differential sensitivities of leishmanial nuclear and kinetoplast topoisomerase II to topoisomerase II-targeting drugs.