The fruits of Amomum tsao-ko have been used as traditional medicine for nausea, abdominal distension, diarrhea, and malaria.[1] In the course of our research program for the isolation of bioactive constituents from medicinal plants, the fruits of A. tsao-ko were extracted with MeOH, and sequentially partitioned with n-hexane, CH2Cl2, EtOAc, and n-BuOH. Four new prenylated flavonone compounds (1 - 4), along with nine known compounds, alpinetin (5), 5-methoxynaringenin (6), naringenin (7), hesperetin (8), 2′,4′,6′-trihydroxy-4-methoxychalcone (9), boesenbergin B (10), 4′′-hydroxyboesenbergin B (11), tsaokoin (12), and tsaokoarylone (13) were isolated from the CH2Cl2 and ethyl acetate fraction of the fruits of A. tsao-ko by using various chromatographic methods.[2] The structures of these compounds were elucidated on the basis of spectroscopic data interpretation, especially 2D NMR spectra such as HSQC, HMBC, and HR-ESI-MS. In addition, CD spectroscopy was used to determine the absolute configuration of four new compounds. All compounds were evaluated for their inhibitory effects on the NO production against LPS- induced RAW 264.7 macrophages.
[1] Moon SS, Lee JY, Cho SC. J Nat Prod. 2004, 67(5): 889-891.
[2] Hsu CL, Shyu MH, Lin JA, YenGC, Fang SC, Food Chem. 2011, 127(1), 127-134.