The biotransformation of manoyl oxide derivatives by Gibberella fujikuroi: The fungal epimerization of an alcohol group

Abstract

The microbiological transformations of jhanol (18-hydroxymanoyl oxide) and jhanidiol (1β,18-dihydroxymanoyl oxide) with the fungus Gibberella fujikuroi have been studied. In the biotransformation of the first compound there exists a preference for hydroxylation at C-1(α) and in lower yield at C-11(α or β), while in that of the second, which possesses a 1β-hydroxylation, the mainly reaction observed is the oxidation of this 1β-hydroxyl to an oxo group. This product is then mainly reduced to the 1α-alcohol or, in minor yield, hydroxylated at C-11(β), C-6(β) and C-2(α). The fungal epimerization of a hydroxyl group, as occurs in the biotransformation of the 1β-alcohol of jhanidiol to the 1α-alcohol, is a very rare process.