H2O2 generation during the redox cycle of mitomycin C and dna-bound mitomycin C.

Reduction of mitomycin C by NaBH4 or by NADPH in the presence of a cell extract followed by exposure to air results in the generation of H2O2. This phenomenon occurs not only with free mitomycin but also with mitomycin irreversibly bound to DNA. In view of these findings, the antibiotic activity of mitomycin was tested in two bacterial systems: a facultative aerobic bacterium grown in the presence or absence of oxygen and obligate anaerobic bacterium. No oxygen effect could be demonstrated in either case in the growth-inhibitory and bactericidal activity of the drug. Nevertheless, the H202 generating capacity of mitomycin-DNA complexes inside the nucleus may play a role in the drug-induced biological damage to the genetic material of cells.