Metabolism of 14C-rhein and 14C-rhein anthrone in rats.

The two radioactive compounds were administered intracaecally to rats, and the recovery rates amounted to 89.9% for 14C-rhein and to 97.4% for 14C-rhein anthrone after 5 days. All organs and tissues showed for both compounds a significant clearance of radioactivity with exception of the kidneys where high levels persisted even after 5 days. Different metabolites could be detected in urine as well as in faeces where also nonanthraquinone fractions could be found.