Effect of chromium on oxygen free radical metabolism, inhibition of superoxide dismutase and enhancement of 6-hydroxydopamine oxidation.

The effect of chromium on superoxide dismutase activity (SOD) as well as on the rate of hydroxydopamine oxidation was studied in vitro, since chromium is known as an environmental and occupational carcinogen and oxygen free radicals are implicated in carcinogenic processes. Chromium is a strong inhibitor of SOD activity in this system. The degree of inhibition is directly proportional to the chromium concentration (tested chromium range 0.166-0.33 mg/L in reaction mixture), to reaction time (tested range up to 10 minutes), and to substrate concentration. Autoxidation of 6-hydroxydopamine was increased by chromium concentration of 15 mg/L. The combination of excessive oxygen free radical production and inhibition of their elimination by inhibition of SOD activity may contribute to the toxic effects of chromium.