Distribution of 8 alpha-hydroxyriboflavin in rat organs

From a survey of flavin compounds using a high performance liquid chromatograph equipped with a fluorescence detector, 8 alpha-hydroxyriboflavin, its derivative, riboflavin, FMN, and FAD were found in rat organs. The derivative of 8 alpha-hydroxyriboflavin was purified from the kidney sequentially by DEAE column chromatography, paper chromatography, and high performance liquid chromatography, and was determined to be 8 alpha-hydroxyriboflavin 5'-phosphate. The amount of 8 alpha-hydroxyriboflavin in the brain, heart, liver, and kidney of the rat was calculated to be 0.010, 0.026, 0.172, and 0.103 nmol per g of wet tissue, respectively. The amount of 8 alpha-hydroxyriboflavin 5'-phosphate in the brain, heart, and liver was less than 0.002 nmol, while that in the kidney was 0.330 nmol, per g of wet tissue. On the other hand, we could not detect 7 alpha-hydroxyriboflavin in the organ extracts, even though it was excreted into human urine along with 8 alpha-hydroxyriboflavin. This is the first reported occurrence of 8 alpha-hydroxyriboflavin and 8 alpha-hydroxyriboflavin 5'-phosphate in higher animal organs.