Abstract
Progesterone has been incubated with a suspension of human liver with added nicotin-amide, citrate and reduced triphosphopyridine nucleotide. Six metabolites have been isolated: 5[alpha]- and 5[beta]-pregnane-3,20-dione, 3[alpha]- and 3[beta]-hydroxy-5[alpha]-pregnan - 20 - one, 3[alpha]-hydroxy - 5[beta] - pregnan - 20 - one and 5[beta]-pregnane-3[alpha],20[alpha]-diol. The reductive metabolism of progesterone is discussed.