Determination of Hematinic Acid Produced by Oxidative Cleavage of Hemoglobin Heme in Red Blood Cells

Our previous studies on the mechanism of phenylhydrazine-induced hemolytic anemia have shown that hematinic acid, one of oxidative cleavage products of heme, is formed by the reaction of hemoglobin with phenylhydrazine. Develoment of the determination of hematinic acid formed by this reaction in red blood cells (RBC) was required to study the mechanism of the hemolysis. Hemolysates prepared by lysis of fresh human RBC with water was mixed with standard hematinic acid. A solution consisting of hydrochloric acid, methanol, and acetone was added, and most of hemoglobin precipitated was removed by centrifugation. Hematinic acid was derived to the methyl ester by incubation with methanol containing sulfuric acid. The ester was passed to two type of silica gel column to remove interferences, and was analysed on a reversedphase high-performance liquid chromatographic column. Hematinic acid could be determined in the range 1.0-20.0μmol/ml RBC. Recovery from hemolysate was 65.0% ±3.5%. Standard compounds of hematinic acid and its methyl ester were prepared by the oxidation of hemin with hydrogen peroxide, and were comfirmed by elemental analyses and mass spectra.