The Relation of the Antifibromatogenic Activity of Certain Steroids to Their Molecular Structure and to Various Actions of These Hormones

Three different synthetic steroids, progesterone, desoxycorticosterone acetate, and testosterone propionate, have been shown to have the capacity of preventing abdominal fibroids elicited by estrogens. The question arises as to which are the special molecular structures responsible for the antifibromatogenic activity of these compounds. Different structures are of interest here (Fig. i ) : first, the ketonic oxygen in position 3 and the double bond, • 4-5, in the ring I which are common to the three steroids; second, the short side chain of carbons 20 and 2I attached in position 17 by which treated with subcutaneous tablets of estradiol only; other groups were of animals in which tablets of estradiol and of one of the above-mentioned four steroids were simultaneously present. The 27 animals of the control group (a) of Table II were chosen from different experimental series; only animals in which absorption of estradiol per day was not greater than in the remaining groups were used. On account of the great variation one meets in this kind of experiment, a second series of 20 animals, group (b) in Table II, was included in the control group. This