In contrast to five-membered E-ring analogues, 7-oxyiminomethyl derivatives of homocamptothecins showed ability to form stable ternary complexes with DNA and topoisomerase I. The 7-oxyiminomethyl derivatives of homocamptothecins were evaluated as a racemic mixture. Following the isolation of the two enantiomers, the 20 (R)-hydroxy isomer confirms the best activity. By using a panel of human tumor cells, all tested ...