In an effort to generate new steroidal aromatase inhibitors, formestane (4-hydroxyandrost-4-ene-3,17-dione) (1) was biotransformed by Rhizopus oryzae to yield the known 4 beta,5 alpha-dihydroxyandrostane-3,17-dione as the major product (5) and bioconverted by Beauveria bassiana to afford the known reduced 4,17 beta-dihydroxyandrost-4-en-3-one (6) and 3 alpha,17 beta-dihydroxy-5 beta-androstan-4-one (7) and the new 4,11 alpha,17 beta-trihydroxyandrost-4-en-3-one (8). All the metabolites showed more potent activities than their parent congener in the aromatase and MCF-7 breast cancer assays. The bioactivities and structural elucidation of these metabolites as well as the semisynthesis of formestane (1) from testosterone (2) are reported herein.
In an effort to generate new steroidal aromatase inhibitors, formestane (4-hydroxyandrost-4-ene-3,17-dione) (1) was biotransformed by Rhizopus oryzae to yield the known 4 beta,5 alpha-dihydroxyandrostane-3,17-dione as the major product (5) and bioconverted by Beauveria bassiana to afford the known reduced 4,17 beta-dihydroxyandrost-4-en-3-one (6) and 3 alpha,17 beta-dihydroxy-5 beta-androstan-4-one (7) and the new 4,11 alpha,17 beta-trihydroxyandrost-4-en-3-one (8). All the metabolites showed more potent activities than their parent congener in the aromatase and MCF-7 breast cancer assays. The bioactivities and structural elucidation of these metabolites as well as the semisynthesis of formestane (1) from testosterone (2) are reported herein.