A new 7,20-epoxy kaurane diterpenoid, 15-acetyldemethylkamebacetal A (1) and six known kaurane diterpenoids (2-7) were isolated from the aerial parts of Isodon inflexus in nuclear transcription factor-κB (NF-κB)-dependent reporter gene assay-guided fractionation. Their chemical structures were determined on the basis of extensive spectroscopic analysis (UV, IR, MS, 1D- and 2D-NMR) and comparison with literature data. The isolated compounds were evaluated for their inhibitory effects on TNF-α-induced NF-κB activation, and all compounds exhibited NF-κB inhibitory activities with IC50 values ranging from 1.91 to 20.15 μM.
Keywords: Isodon inflexus; NF-κB; kaurane diterpenoid; structure elucidation.