Bioassay-guided isolation and identification of anti-obesity phytochemicals from fruits of Amomum tsao-ko

Abstract Amomum tsao-ko (Zingiberaceae), an important traditional medicinal herb, possesses many biological activities, including anti-inflammatory effects. Though the anti-obesity properties of the crude ethanol extract of A. tsao-ko fruits have been reported, the anti-adipogenic properties of its phytochemical constituents have not been reported. Therefore, in the present study, we isolated the active constituents of A. tsao-ko and investigated their anti-adipogenic effects. The bioassay-guided isolation of the phytochemicals from the ethanol extract of A. tsao-ko fruits identified four bioactive compounds, comprising one fatty acid ( 1 ), one sesquiterpene alcohol ( 2 ), and two phenolic compounds ( 3 and 4 ). Their structures were elucidated by a combination of 1D and/or 2D nuclear magnetic resonance and mass spectrometry. The anti-adipogenic activities of the four compounds evaluated by Oil Red O staining in 3T3-L1 cells revealed that the treatment with the isolated compounds 1 and 3 reduced the lipid accumulation in 3T3-L1 adipocytes more strongly than the compounds 2 and 4 , in a dose-dependent manner.