An attempt was made to obtain more potent antitumor compounds by chemically modifying asterriquinones. Amino-and aziridinyl-asterriquinone were newly synthesized, but showed no activity. However, dimethylallylation of asterriquinone Cl, which had no effect in vivo, yielded an active compound, with a change in pK_a value from 5.0 to 7.2. This suggests that other active compounds may be obtained by the chemical modification of asterriquinones with various other functional groups.