CONVERSION OF SOME SYNTHETIC PROGESTINS TO OESTROGEN

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Abstract
The effects of oral administration of synthetic progestins on the urinary estrogen excretion were examined. 17[alpha]-Ethynyl-19-nortestosterone (ENT) or 17[alpha]-ethynyl-estr-4-en-17[beta]-ol (EEL) caused a significant rise of estrogen output in urine. It appeared that the increased output of estrogen was due to the conversion of ENT or EEL to ethynyl-estradiol (EE2). Such a conversion of pro-gestin was also observed with 17[alpha] -methy 1-19-nortestosterone. To obtain the direct evidence for the conversion of ENT to EE2, human placental homogenates were incubated in vitro first with 19-nortestoste-rone. The approximate yield of estrone was 20% of that observed with testosterone. However, a conversion of ENT to EE2 was not detected.