Abstract
^<14>C-(2)-Riboflavin tetrabutyrate, synthesized from ^<14>C-(2)-riboflavin and butyric anhydride, was administered to the normal rats by injection or per os. At 24 hours after the administration, the radioactivities were measured in the FAD, FMN, and riboflavin fractions extracted from the liver, kidney, heart, and small intestine of the rats. The results showed that the largest part of the total radioactivity was found in the flavins of the liver followed by the kidney and the small intestine. The trace of the radioactivity was found in the flavins of the heart. From these results, it was concluded that the riboflavin moiety of the butyrate administered by injection or per os can be incorporated into FMN and FAD of these organs.
