Serum lipid peroxide assayed by a new colorimetric method.

Serum lipid peroxide (LPO) in 72 healthy male subjects was studied using a newly developed assay method based on the reaction of LPO with methylene blue derivative (MCDP; 10-N-Methylcarbamoyl-3,7-dimethylamino-10 H-phenothiazine). This method is specific for lipid hydroperoxide and the relation is equimolar. The value obtained was 7.63 +/- 2.78 nmol/ml. Positive correlations were observed between LPO and height (r = 0.290), body weight (r = 0.244) and hemoglobin (r = 0.248). However, no significant correlation was observed between serum LPO level and other clinical data, including age. In addition, serum LPO value measured by this method did not show significant correlation with that measured by the thiobarbituric acid method in rat serum. This discrepancy might be due to the differences in substrates measured by each method.