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