The biotransformation of ent-kaur-16-en-19-oic acid by Rhizopus stolonifer

Microbial transformation of ent-kaur-16-en-19-oic acid was carried out with R. stolonifer. After seven days of incubation, two metabolites, ent-7 alpha-hydroxy-kaur-16-en-19-oic acid and ent-12 beta-hydroxy-kaur-9(11),16-dien-19-oic acid, were isolated as a result of hydroxylation and hydroxylation/dehydrogenation, respectively. Incubation for 15 days also afforded ent-16 beta,17-dihydroxy-kauran-19-oic acid. The metabolites were identified by spectroscopic methods.