A New Kavalactone Dimer from Piper methysticum.

A new kavalactone dimer, named kavalactone B (1), and three known compounds, 11-methoxy-5,6-dihydroyangonin (2), methysticin (3), dihydromethysticin (4), were isolated from the leaves of Piper methysticum (kava). Their structures were determined by spectroscopic methods, mainly 1D, 2D NMR, and mass spectrometric data. Primary bioassays showed that compound 2 had very strong cytotoxicity against A549 and NCI-H460 cells with IC50 values of 10.6 and 10.7 μg/mL, respectively, whereas compounds 1, 3, and 4 had very weak cytotoxicity against A549 and NCI-H460 cells. [ABSTRACT FROM AUTHOR]