Microbial modification of diosgenin and hecogenin

Abstract

On incubation with an unidentified bacterium diosgenin [(25R)-spirost-5-en-3β-ol](1) was converted into (25R)-9-oxode-AB-spirostane-8α-propionic acid (3). Incubation with Nocardia globerula produced the same oxo-acid (3) and also a small amount of its 1 7α-hydroxy-derivative. Surprisingly, hecogenin [(25R)-3β-hydroxy-5α-spirostan-12-one](2) was also converted into the oxo-acid (3) by the bacterium; thus in the course of metabolism a 12-oxo-group had been replaced by a methylene group. A metabolic pathway is suggested for that replacement, based on the isolation of the minor metabolite (25R)-12α-hydroxyspirost-4-en-3-one.