The photodeactivation of hedamycin, an antitumor antibiotic of the pluramycin type

Abstract

The cytotoxicities of hedamycin and photohedamycin A as well as of kidamycin and isokidamycin were determined using HeLa cell cultures. Photohedamycin A proved to be 15 times less cytotoxic than hedamycin thus explaining the loss of biological activity observed for solutions of hedamycin left in daylight. The fact that photohedamycin A is less active than hedamycin, and isokidamycin less than kidamycin points to the important role the rings E and F play in the biological activity of hedamycin and kidamycin.