Effect of the anticancer drug oracin on mouse liver topoisomerases I and II

The inhibitory effect of oracin on the activities of topoisomerases I and II isolated from the nuclei of mice liver tissue was studied. This drug showed a 100% inhibitory effect at 5 mu M and 50% inhibition at 1 mu M on topoisomerase II activity, while the activity of topoisomerase I at these concentrations was not inhibited.