Synthesis and antimicrobial activity of 7α-amino-23,24-bisnor-5α-cholan-22-ol derivatives

A series of 7α-aminobisnorsteroids were synthesized and their in vitro antimicrobial activity was evaluated regarding Gram-positive and Gram-negative bacteria. The stereoselective reductive amination of 7-ketosteroid 3 with NH4OAc, in the presence of NaBH3CN, afforded a high yield of 7α-aminosteroid 4. The 3,7-diaminobisnorsteroids were obtained by the reductive amination of 4 with NH4OTf, Boc-spermidine, and Boc-spermine. 3α,7α-Diaminobisnorsterol dihydrochloride 15 showed the highest antimicrobial activity against Streptococcus pyogenes 308A with a MIC value of 1.6 μg/mL. Hemolytic activities of the compounds 13–20 were determined. Compound 13 showed MHC value at 100 μg/mL.