COMPARISON OF THE CONJUGATED METABOLITES OF INTRAVENOUSLY AND INTRADUODENALLY ADMINISTERED OESTRIOL

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Abstract
The metabolism of estriol-16-14C(14C-OE3***) and estriol-15-3H(3H-OE3) was studied in a 28 year-old man with normal liver function, who had undergone cholecystectomy and whose bile was being drained via a T-tube. 14C-OE3 was injected into the duodenum through the T-tube and shortly later, 3H-OE3 was injected into the antecubital vein. Bile and urine were collected continuously at intervals for 30 and 43 hr. respectively. Each fraction was assayed. The excretion of 3H was more rapid than that of 14C in both fluids. Twenty per cent of the injected 3h and 17% of the 14C were found in the bile, while 55% of the 3H and 76% of the 14C were excreted in the urine. Isolation and identification of the conjugated metabolites were carried out by the use of column chromatography on alumina and celite, paper chromatography, high voltage electrophoresis, enzyme hydrolysis, chromatography of the free steroid on silica gel and crystallization to constant specific activity. Estriol-16-glucosiduronate (OE3-16G), was the predominant urinary metabolite, comprising about 79% of 3H and 70% of the 14C excreted in the urine. Small amounts of both isotopes (3H = 8.1%, 14C = 7.3%) were identified as estriol-3-sulphater16-glucosiduronate (OE3-3S,16G). Estriol-3-glucosiduronate (OE3-3G) was also found in the urine, but this conjugate contained only 14C (13.4%), In contrast, OE3-3S,16G was the predominant biliary metabolite (3H = 81%, 14C = 80%). Some OE3-16G (3H = 11.1%, 14C = 7.9%), but no OE3-3G was detected in the bile. The results indicated that OE3-3G is an intestinal metabolite of estriol in vivo. The preferred biliary excretion of OE3-3S,16G is confirmed.