The Incubation of 13a,17-Dihydroxystemodane with Cephalosporium aphidicola

Abstract

The biotransformation of 13a,17-dihydroxystemodane (<strong>3</strong>) with the fungus <em>Cephalosporium aphidicola </em>afforded 13a,17,18-trihydroxystemodane (<strong>4</strong>), 3b,13a,17-tri-hydroxystemodane (<strong>5</strong>), 13a,17-dihydroxy-stemodan-18-oic acid (<strong>6</strong>), 3b,11β,13a,17-tetra-hydroxystemodane (<strong>7</strong>), 11β,13a,17,18-tetrahydroxystemodane (<strong>8</strong>) and 3b,13a,17,18-tetra-hydroxystemodane (<strong>9</strong>). The hydroxylation at C-18 of the substrate points to a biosynthetically-directed transformation, because aphidicolin (<strong>2</strong>) is hydroxylated at this carbon. However, the C-3(b) and C-11(b) hydroxylations seem to indicate a xenobiotic biotransformation.