Pro-oxidants are chemicals that induce oxidative stress, either by generating reactive oxygen species or by inhibiting antioxidant systems.
While thermodynamically very favored, reduction of molecular oxygen or peroxide to superoxide or hydroxyl radical respectively is spin forbidden.
It may be that oxidative stress produced by such agents mimics a normal physiological signal for fibroblast conversion to myofibroblasts.
[7][8] The metal ion in this reaction can be reduced, oxidized, and then re-reduced, in a process called redox cycling that can generate reactive oxygen species.
These agents may show specific toxicity towards cancer cells because of the low level of antioxidant defenses found in tumors.
The light excites the photosensitizer, causing it to generate reactive oxygen species, which can damage or destroy diseased or unwanted tissue.