Synthesis of 19-substituted steroids of the 16α,17α-cyclohexanopregnane series and study of their interactions with rat uterine cytosol and blood serum proteins

Abstract

New 16α,17α-cyclohexanopregnanes (pregna-D′6-pentaranes) containing alkyl or heteroatomic substituents in position 19, namely, 19-methylidene-, 19-methyl-, 19-methoxyimino-, and 19-(3-methoxycarbonylpropoxyimino)-16α,17α-cyclohexanopregn-4-ene-3,20-diones were synthesized, and their interactions with the progesterone receptor and pentarane-binding proteins of rat uterus cytosol and rat blood serum was studied. The same substituent in position 19 of the steroid molecule can affect in opposite direction its affinity to these proteins. These results suggest differences in the structures of the ligand-binding pockets of the three proteins in the region surrounding the C(10) atom of the steroid nucleus.