Iridal-type triterpenoids with ichthyotoxic activity from Belamcanda chinensis

Ichthyotoxic activity-guided fractionation of the hexane and ether extracts of Belamcanda chinensis (Iridaceae) has resulted in the isolation of eleve n iridal-type triterpenoids including six new compounds, 3-O-tetradecanoyl- 16-O-acetylisoiridogermanal (4), 3-O-decanoyl-16-O-acetylisoiridogermanal ( 5), belachinal (7), anhydrobelachinal (9), epianhydrobelachinal (10), and i soanhydrobelachinal (11). Structures of the new iridals were determined by spectral and chemical methods. The absolute configuration of isoiridogerman al (1) at C-16 was determined to be R by the modified Mosher's method. Of t hese compounds, 16-O-acetylisoiridogermanal (3), 7, and spiroiridal (12) ex hibited potent ichthyotoxic activity against killiefish (Oryzias Latipes).