Molecular interaction between bleomycin and amsacrine in the presence of cupric ions.

The antineoplastic activity of m-AMSA [4'-(9-acridinylamino)-methanesulfon-m-anisidide] has been related to its ability to produce oxygenated free radical during its oxidation to a quinonimine form, in the presence of cupric ions. It has been demonstrated here that the rate of the oxidation is greatly increased by the addition of bleomycin (Blm), another antitumor agent, which is able to complex metallic ions. The catalytic role of Blm has been established on the basis of kinetics measurements and the occurrence of an intermediary ternary complex Blm-m-AMSA-Cu(II) has been demonstrated by circular dichroism and polarography experiments.