BIOLOGICAL PROPERTIES OF 9,10-ISOMERIC STEROIDS

Abstract

ABSTRACT Progestational activity of four 9β,10α steroids (»retro-steroids«) has been studied. These new compounds have the hydrogen atom on carbon atom 9 in the β position, and the 19-methyl group on carbon atom 10 in the α position, which is the reverse of the normal 9α,10β structure. The following compounds were subjected to the Clauberg test, both after subcutaneous and oral administration: I retro-progesterone II 6-dehydro-retro-progesterone* III 17α-acetoxy-retro-progesterone IV 6-dehydro-17α-acetoxy-retro-progesterone. All four compounds were orally active. In the subcutaneous route the maximum effect (comparable total dose of progesterone 10 mg), was obtained for the compounds I, II, III and IV with total doses of 5 mg, 1 mg, 1 mg and 0.5 mg, respectively. In the oral route these figures were respectively 50 mg, 10 mg, 2.5 mg and 1.25 mg (compared with progesterone 10 mg s. c.). Compound IV was within the 95% confidence limit 3.5–12.6 times orally more active than progesterone s. c.