MICROBIAL TRANSFORMATION OF TETRACYCLIC DITERPENES - CONVERSION OF ENT-KAURENONES BY CURVULARIA AND RHIZOPUS STRAINS

We have biotransformed several ent-kaur-15-enones and ent-kaur-16-enones with Curvularia lunata and Rhizopus nigricans cultures. Incubation of ent-18-acetoxykaur-15-ene-3, 7-dione with C. lunata led to its 17-hydroxy derivative, and with R. nigricans to 17-hydroxy and 13-hydroxy derivatives. Incubation of ent-18-acetoxykaur-15-en-3-one with C. lunata also gave the 17-hydroxyderivative, while incubation with R. nigricans produced 13-hydroxy- and 3,13-dihydroxyderivatives. Moreover, biotransformation of ent-18-acetoxykaur-16-ene-3,7-dione with C. lunata gave its (16R), 17-epoxy, (16R), 17- and (16S), 17-dihydroxy, and (7S)-hydroxy derivatives. The structures of the metabolites have been determined by spectroscopy and chemical correlations. © 1990, American Chemical Society. All rights reserved.