Microbial transformation of 17α-cyanomethyl-17-hydroxy-4,9-estradien-3-one (STS 557) and 17α-cyanomethyl-19-nortestosterone by Mycobacterium smegmatis

Abstract Microbial transformation of the new progestagen STS 557 (17α-cyanomethyl-17-hydroxy-4,9-estradien-3-one) by Mycobacterium smegmatis yielded predominantly ring A-aromatized compounds: 17α-cyanomethyl-1,3,5(10),9(11)-estratetraene-3, 17-diol, 17α-cyanomethyl-1,3,5(10)-estratriene-3, 17-diol and the corresponding 3-methyl ethers. The analogous compound without the 9(10) double bond, 17α-cyanomethyl-19-nortestosterone, was transformed mainly to 5α-hydrogenated metabolites: 17α-cyanomethyl-17-hydroxy-5α-estran-3-one, 17α-cyanomethyl-17-hydroxy-5α-1-estren-3-one, 17α-cyanomethyl-5α-estrane-3α, 17-diol, and 17α-cyanomethyl-5α-estrane-3β, 17-diol. From these results, it is concluded that 4,9-dien-3-oxo compounds are not substrates for enzymatic 5α-hydrogenation.