New oxandrolone derivatives by biotransformation using Rhizopus stolonifer

Structural transformation of the steroidal lactone, oxandrolone (1), by suspended-cell cultures of the plant pathogen fungus Rhizopus stolonifer, resulted in the production of three new metabolites. These metabolites were identified as 11α-hydroxyoxandrolone (2), 6α-hydroxyoxandrolone (3) and 9α-hydroxyoxandrolone (4), by different spectroscopic methods and single-crystal X-ray diffraction analysis for metabolite 2. Compounds 1 and 3 showed a significant β-glucuronidase inhibitory activity.