Lysis of egg phosphatidylcholine vesicles by tricyclic carboxamide antitumor agents

The stability of small unilamellar vesicles formed by egg phosphatidylcholine has been examined in the presence of 38 tricyclic carboxamide DNA-intercalating agents (19 phenylquinolines, 17 phenylbenzimidazoles, an acridine and an anthracene). Lysis of the vesicular membrane is time-dependent and also dependent on the concentration of the cytotoxic agent. The relative concentration of agent to cause a fixed degree of lysis in a fixed time, as measured by the release of encapsulated 6-carboxyfluorescein, is directly related to the relative hydrophobicity of the agents.