Biotransformation of methyl cholate by Aspergillus niger

Biotransformation of methyl cholate using Aspergillus niger was investigated. This led to the isolation of two derivatives: methyl 3α,7α,12α,15β-tetrahydroxy-5β-cholan-24-oate identified as a new compound, and a known compound methyl 3α,12α-dihydroxy-7-oxo-5β-cholan-24-oate. The structure elucidation of the new compound was achieved using 1D and 2D NMR, MS and X-ray diffraction.