Sesquiterpenes from the rhizomes of Alpinia japonica and their inhibitory effects on nitric oxide production.
Abstract A novel norsesquiterpene ( 1 ), three new bisabolenes sesquiterpenes ( 2 – 4 ), along with 7 known compounds ( 5 – 11 ), were isolated from the rhizomes of Alpinia japonica . The structures of the new compounds were elucidated by analysis of spectroscopic data. The absolute configuration of C-1 in 3 was deduced via the circular dichroism data of the in situ formed [Rh 2 (OCOCF 3 ) 4 ] complexes. Inhibitory effects of the isolates on nitric oxide production in lipopolysaccaride-activated RAW264.7 macrophages were evaluated. Compound 6 showed significant inhibitory activity with IC 50 value of 5.3 μΜ, and compounds 1 , 3 , 5 and 7 – 10 exhibited moderate inhibitory activities with IC 50 values between 24.5 and 46.3 μM.