Antitumor agents, 99. Synthetic ring C aromatized podophyllotoxin analogues as potential inhibitors of human DNA topoisomerase II.

Several ring C aromatized analogues of podophyllotoxin were synthesized for testing against human DNA topoisomerase II. The results indicate that aromatization of ring C gave rise to no inhibition of this enzyme at 200 microM. A comparison of the cytotoxicity among these compounds also demonstrates that a free hydroxyl group at C-4 contributes to significant cytotoxicity.