The effect of bilirubin on lipid peroxidation and antioxidant enzymes in cumene hydroperoxide-treated erythrocytes

Recently, it has been suggested that bilirubin may act as a potent biologic al chain-breaking antioxidant. To observe the effects of free bilirubin on antioxidant reactions in cumene hydroperoxide-treated erythrocytes (15 g he moglobin/dl), we added bilirubin at four different concentrations (0.5, 1, 5, and 10 mg/dl). We measured the thiobarbituric acid-reactive substance an d reduced,glutathione levels, and some antioxidant enzyme activities, namel y superoxide dismutase, catalase, and glucose-6-phosphate dehydrogenase. Th iobarbituric acid-reactive substance and chemiluminescent signals decreased during the incubation. Superoxide dismutase activities also decreased but not as much as in the control group. Glucose-6-phosphate dehydrogenase acti vities and reduced glutathione levels increased, but catalase activities re mained the same as the control group. Our results suggest that bilirubin - in the concentrations we have used - partially prevented the oxidant effect s of cumene hydroperoxide.