Redox cycling

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Of redox cycling occurs when a molecule a cycle of increased and then decreased oxidation levels by running, especially if the process takes place within living cells. Redox cycling can be enzymatic or non-enzymatic. For example, the toxicity of quinone derivatives , including chemotherapeutically active substances such as doxorubicin or mitomycin C, is related to redox cycling.

During this process, the corresponding semiquinones are formed and, during the subsequent regression of the quinone system , reactive oxygen species are formed by reaction with molecular oxygen (Sartorelli, 1982; Kappus, 1986; Merk and Jugert, 1991). Such redox cycling can lead to the cell's detoxification capacity for toxic oxygen species being exceeded and the cell being damaged.


  • H. Kappus: Overview of enzyme systems involved in bioreduction of drugs and in redoxcycling , in: Biochemical Pharmacology 20 (1986), pp. 1-6.
  • HF Merk, FK Jugert: Cutaneous NAD (P) H: quinione reductase: a xenobiotica-metabolizing enzyme with potential cancer and oxidation stress-protecting properties , in: Skin Pharmacology 4 (1991), Suppl 1, pp. 95-100.
  • AC Sartorelli: Hypoxic cell specific chemotherapeutic agents , in: Advances in Enzyme Regulation 20 (1982), pp. 233-244.