Abietane Diterpenoids from the Rhizomes of Kaempferia roscoeana and Their Anti-Inflammatory Activities.

Six new abietane diterpenes, roscoeananes A-F (1-6), along with two known compounds (7-8) were isolated from the rhizomes of Kaempferia roscoeana. The structures of all compounds were elucidated by analysis of spectroscopic data, and the absolute configurations were assigned by a comparison of the theoretical and experimental electronic circular dichroism (ECD) spectra and a comparison with literature values. The unreported compound 5 is an ether-linked dimer of roscoeanane B (2). Most of the isolated compounds were tested for their nitric oxide inhibitory effects in lipopolysaccharide-activated RAW264.7 cells. Among them, roscoeanane A (1) was found to reduce NO levels in murine macrophage cells with an IC50 value of 3.58 ± 0.95 μM and exhibited low cytotoxicity (IC50 > 50 μM).