Synthesis of carbazoloquinone derivatives and their antileukemic activity via modulating cellular reactive oxygen species.

Carbazoloquinone alkaloids are of great interest as privileged structures for anticancer drug molecules. The purpose of this study was to investigate the structure-activity relationships of carbazoloquinone derivatives as anticancer agents. A series of carbazoloquinones including murrayaquinone A, koeniginequinones A and B, and related analogues were therefore prepared. Palladium-catalyzed intramolecular cyclization reaction mechanism was well elucidated by DFT calculations. Treatment of the synthesized derivatives showed cytotoxicity on human leukemia HL-60 cells in a dose-dependent fashion. In addition, murrayaquinone A and ß-brazanquinone elevated cellular levels of reactive oxygen species (ROS), thereby triggering apoptosis. Our findings emphasize the excellent potential of carbazoloquinone derivatives as ROS-inducing anticancer agents.