Free radicals are generated from both internal and external factors including too much sun exposure, pollution, cigarette smoke, fried food, and even your own intrinsic stress
Clemente-Postigo M, Munoz-Garach A, Serrano M, et al
and actually SARS-CoV-2 causing COVID-19, all are characterized by persistent inflammation, continuous production of reactive oxygen/nitrogen species and oxidative stress that predominate over the antioxidant defenses (GSH and free radical scavenger enzymes) resulting in cell/tissue/organ aging associated with early (premature) chronic inflammation/inflammaging. We propose that, although inflammaging was introduced for the aging process (276289), it could also apply to early (premature) tissue and organ aging associated with cell and tissue damage caused by excessive oxidative stress and lack of adequate antioxidant defenses, especially low GSH levels, in younger individuals
This suggests that it is likely that acetylphenylhydrazine undergoes a cyclic redox reaction that results in the production of hydrogen peroxide, which in turn oxidises glutathione