Metabolism of Progesterone in Human Proliferative Endometrium1

Proliferative endometrial tissue was incubated in vitro with progesterone-4-14C. Eight products have been isolated and 4 have been identified by reverse isotope dilution, chromatographic techniques, and crystallization to constant specific activity. The products identified were 5α- and 5β-pregnan-3,20-dione, Δ4-pregnen- 20α-ol-3-one and Δ4-pregnen-6β-ol-3,20-dione. Presumptive evidence was obtained for the formation of allopregnan-20α-ol-3-one, pregnan-20β-ol-3-one and Δ4-pregnen-20β-ol-3-one. The structure of an unknown dihydroxy compound is still under investigation. As allopregnanedione is a major product of progesterone metabolism in the endometrium, it is concluded that urinary pregnanediol is primarily a product of liver metabolism and does not reflect the metabolism of progesterone at target sites. (Endocrinology81: 729, 1967)