Fungal Transformation of Dydrogesterone and Inhibitory Effect of Its Metabolites on the Respiratory Burst in Human Neutrophils

Abstract The biotransformation of the synthetic hormone dydrogesterone ( 1 ) by a number of fungal strains – including Cephalosporium aphidicola, Rhizopus stolonifer, Cunninghamella elegans , and Fusarium lini – afforded ten different metabolites, compounds 2 – 11 . From a structural point of view, these transformations involved a combination of hydroxylation, oxidation, reduction, and/or epoxidation. The pregnane‐based metabolites 10 and 11 are new compounds. All the known compounds were obtained for the first time from 1 by fungal transformation. The metabolites 3, 5 , and 8 showed more‐potent respiratory‐burst inhibitory activity than the substrate 1 in a neutrophil‐based cellular assay ( Table 3 ).