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

Abstract

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

Keywords

• Cephalosporium aphidicola
• biotransformations
• diterpenes
• stemodane