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 3alpha,7alpha,12alpha,15beta-tetrahydroxy-5beta-cholan-24-oate identified as a new compound, and a known compound methyl 3alpha,12alpha-dihydroxy-7-oxo-5beta-cholan-24-oate. The structure elucidation of the new compound was achieved using 1D and 2D NMR, MS and X-ray diffraction.