Potential antitumor agents. 55. 6-Phenylphenanthridine-4-carboxamides: a new class of DNA-intercalating antitumor agents.

Derivatives of the DNA-intercalating agent N-[2-(dimethylamino)ethyl]phenanthridine-4-carboxamide have been prepared and shown to have moderate in vivo antitumor activity against both the P388 leukemia and Lewis lung carcinoma. This demonstrates that the effective pharmacophore in the broad class of tricyclic carboxamides is not limited to linear tricyclic chromophores. Both 7 and the 6-phenyl derivative 10 have identical DNA binding properties, suggesting that the phenyl ring of 10 is not involved in the DNA intercalation site. A series of phenyl-substituted derivatives of 10 was evaluated. Aza substituents led to compounds with the highest in vivo cytotoxicity and in vivo P388 activity, but the in vivo solid tumor activity of the substituted 6-phenylphenanthridine-4-carboxamides was in general low.