EXTINCTION OF EXPERIMENTAL MAMMARY CANCER, I. ESTRADIOL-17β AND PROGESTERONE

days, the culture was green and thriving.This strain has been isolated and desig- nated Chlorella pyrenoidosa C-37-2-G4.The modified strain grows well in the presence of progesterone.Cultures of the modified strain to which progesterone has been added deteriorate at a much slower rate than those cultures of the original strain to which androstenedione or dehydroisoandrosterone had been added.Furthermore, thin-layer silica-gel chromatography indicates that metabolic prod- ucts from progesterone are formed by this modified strain.The incubation of dehydroisoandrosterone for 432 hr with Chlorella pyrenoidosa C-37-2 produced at least four different compounds.These were detected by means of thin-layer silica gel chromatography.From the position of the products on the chromatograms, it is probable that one of these was 5-androstene-3f3,17f3-diol while another was an hydroxylated 5-androstene-3#,17,3-diol. The structures of all the indicated conversion products and the possible transformation of steroids by other species and strains of algae are being investigated currently.