Synthesis and antitumor activity of fused quinoline derivatives.

Some tetracyclic quinolines (9 and 14) with a [2-methoxy-4-[(methylsulfonyl)amino]phenyl]amino side chain were prepared and their deoxyribonucleic acid (DNA) intercalative properties, KB cytotoxicity, antitumor activity (P388 leukemia), and ability to induce topoisomerase II dependent DNA cleavage were investigated. The indoloquinoline derivative 9 exhibited the most potent activity (dose = 6.3 mg, T/C% = 300) in this series. The steric structural features of the chromophores of the compounds previously and newly synthesized were studied by a computer-associated molecular graphics technique. Relationships between the steric structural features of the chromophores and biological activities are also discussed.