C20 steroids: The metabolism of 3-hydroxy-19-nor[21-14C]pregna-1,3,5(10)-trien-20-one in the rabbit

摘要

1. The metabolism of 3-hydroxy-19-norpregna-1,3,5(10)-trien-20-one, a possible product of the aromatization of progesterone or pregnenolone, has been studied. 2. After oral administration of this C20 steroid as the 21-14C-labelled compound to two groups of rabbits, the excretion pattern of metabolites in the urine was examined. 3. At 14 days after administration, 3·3–6·5% of the radioactivity had appeared in the urine, 71–79% in the faeces and approx. 10% remained in the gut. 4. A metabolite, isolated from urine mainly as the unconjugated steroid, was identified as 19-norpregna-1,3,5(10)-triene-3,20α-diol and constituted 18·5–22% of the total urinary radioactivity. 5. A minor component of the urinary unconjugated steroids was identified as 19-norpregna-1,3,5(10)-triene-3,17α,20α-triol. 6. A further 2–7·5% of the total urinary radioactivity, isolated only from the urinary sulphate fraction, was tentatively identified as an 18-oxygenated derivative of the administered steroid.