THE METABOLISM OF TRIACETIC LACTONE (TAL)

Triacetic acid lactone (TAL) labeled with C 14 in three carbon atoms has been synthesized. The C 14 of small oral doses of C 14 -TAL fed to rats (250–350 mg/kg) and rabbits (50–60 mg/kg) was mostly excreted in the expired air and urine within 24 hours. In 3 days, rats excreted 45–50% in the respiratory CO 2 , 20% in the urine, and 7% in the feces; 10–20% remained in the tissues. Rabbits, in about the same period, excreted 50–60% as CO 2 , 30% in the urine, and 4% in the feces; 10–20% remained in the tissues. With both rats and rabbits most of the radioactivity in the urine occurs as unchanged TAL (13–25% of dose) together with small amount of urea (2–11% of dose). In the urines of rabbits only, a third unidentified metabolite accounting for 10% of the dose, and probably a degradation product of TAL, was detected. Paper chromatography did not reveal the presence of DHA, hydroxy-DHA, or compound X in the urines of rats or rabbits dosed with C 14 -TAL. C 14 -TAL is more rapidly oxidized to CO 2 by rat kidney slices than by liver slices. DHA, hydroxy-DHA, and compound X were not detected as in vitro metabolites of TAL. Unlike DHA, TAL does not appear to combine with tissue proteins.