Fungal metabolites of (E)-guggulsterone and their antibacterial and radical-scavenging activities.

Fungal transformation of (E)-guggulsterone (= (17E)-pregna-4,17-diene-3,16-dione; 1) by Rhizopus stolonifer, Fusarium lini, Cunninghamella elegans, or Gibberella fujikuroi afforded ten hydroxylated metabolites (2-11; Scheme), which were fully characterized. Compounds 4-11 have not been described yet. Some of these novel hydroxylated metabolites, as well as acetylated derivatives thereof, exhibited significant antibacterial and radical-scavenging activities (Table 3).