The production of free radicals during the autoxidation of cysteine and their effect on isolated rat hepatocytes.

Autoxidizing cysteine has been shown to produce thiyl and hydroxyl radicals. Hydrogen peroxide increased the yield of both radicals which was inhibited by catalase but stimulated by copper/zinc superoxide dismutase. This effect is due to increased hydrogen peroxide production by copper/zinc superoxide dismutase as a result of superoxide dismutation. The production of superoxide radicals could not be detected probably because of its low reactivity, however, measurement of oxygen uptake and reduction of ferricytochrome c by autoxidizing cysteine clearly implicate the involvement of super oxide radicals. The production of hydroxyl radicals is postulated to proceed through a fenton reaction, however, this may not necessarily be metal ion controlled. Autoxidizing cysteine disrupts the integrity of hepatocytes causing release of glutathione, adenosine triphosphate and lactate dehydrogenase indicating that it is of little use as a therapeutic agent.