Fungal transformation of isosteviol lactone and its biological evaluation for inhibiting the AP-1 transcription factor

Compounds 9-14 and seven known compounds (1 and 3-8) were isolated from the microbial transformation of isosteviol lactone (2). Compounds 2-5, 8, 9, 11, and 12 showed significant suppression of the expression of AP-1 target genes, with 3 exhibiting greater inhibition than dexamethasone.