Abstract
Antioxidant activity of exogenous cytochrome c was investigated in vitro using the whole brain homo-genate, mitochondrial fraction and postmitochondrial supernatant containing microsomes prepared from rat brains. Increments in the amount of lipid peroxides were observed in each fraction when incubated at 30°C, while the addition of cytochrome c (200 mM) effectively suppressed the production of peroxides. This depressive effect of cytochrome c was more prominent in the supernatant than in the mitochondrial fraction. Although the peroxidation was enhanced markedly by the addition of NADPH (2mM). particularly in the mitochondrial fraction, cytochrome c was able to prevent its acceleration. This inhibitory mechanism might be explained by the fact that cytochrome c deprived superoxide radicals of electrons generated in ischemic insult. The results of the present study suggest that exogenous cytochrome c has free radical scavenging or antioxidant activity. which might be responsible in part for its cerebral protective action during ischemia.