Metabolism of [¹⁴C]emodin in the rat

Abstract

1. Absorption, excretion, tissue distribution and metabolism of the anthraquinone [¹⁴C]emodin was studied after a single oral administration (approx. 50mg/kg) to rats.

2. Urinary excretion amounted to 18\pm 5)% dose in 24h and to 22(\pm 6)% in 72 h.

3. Metabolites found in pooled urine (0-72 h) were mostly free anthraquinones (emodin and emodic acid, 16% dose); 3% was conjugated and 3% was non-extractable radioactivity.

4. In 24h, 48 \pm 11% and in 120 h, 68\pm8% dose was excreted in the faeces, mostly in the free anthraquinone form.

5. In two cannulated rats biliary excretion reached a maximum at approx. 6h and amounted to 49% dose within 15 h; 70% of biliary activity was in the form of conjugated emodin.

6. The content of radioactivity in most organs decreased significantly between 3 and 5 days. In kidneys, however, the ¹⁴C activity was still equiv. to 4.33 p.p.m. emodin after five days. Mesenterium and fat tissue showed increasing ¹⁴C activity from 72 to 120 h.