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

Abstract

The biotransformation of 13α,17-dihydroxystemodane (3) with the fungus Cephalosporium aphidicola afforded 13α,17,18-trihydroxystemodane (4), 3β,13α,17-trihydroxystemodane (5), 13α,17-dihydroxy- stemodan-18-oic acid (6), 3β,11β,13α,17-tetrahydroxystemodane (7), 11β,13α,17,18-tetrahydroxystemodane (8) and 3β,13α, 17,18-tetrahydroxystemodane (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(β) and C-11(β) hydroxylations seem to indicate a xenobiotic biotransformation.