The metabolism of estriol-3-glucosiduronate and estriol in the rabbit.

Urinary metabolites of [6,7-3H]-estriol-3-glucosiduronate and of [6, 7-3H]-estriol in intact female rabbits were analyzed. The separation of urinary metabolites was performed by countercurrent distribution followed by DEAE-Sephadex A-25 column chromatography. Each conjugate was then hydrolyzed with the enzymes and the aglycone thus liberated was identified. In either case, major urinary metabolites were found to be diconjugates, a considerable part of which was glucosiduronate-N-acetylglucosaminide of 17-epiestriol. In addition, estriol-16-glucosiduronate or monoglucosiduronate of 17-epiestriol was identified as a minor urinary metabolite of [6,7-3H]-estriol. From these results, it was concluded that the greater part of the estriol-3-glucosiduronate was converted to diconjugates and that estriol-3-glucosiduronate was probably an intermediate metabolite in the conversion pathway from estriol to diconjugates in this species.