A new kavalactone dimer, named kavalactone A (1), and three known compounds, desmethoxyyangonin (2), yangonin (3), and 11-methoxyyangonin (4), were isolated from the leaves of Piper methysticum (kava). Their structures were determined by spectroscopic methods, mainly 1D and 2D NMR and mass spectrpscopic data. Primary bioassays showed that compound 3 had very strong cytotoxicity against A549 and NCI-H460 Cells with IC50 values of 13.6 and 13.7 μg/mL, respectively, compound 2 had moderate cytotoxicity against A549 and NCI-H460 cells (with IC50 values of 35.8 and 37.6 μg/mL, respectively), and compounds 1 and 4 had very weak cytotoxicity against A549 and NCI-H460 cells.

中文翻译：

---

来自 Piper methysticum 的新 Kavalactone 二聚体

一种新的卡瓦内酯二聚体，命名为卡瓦内酯 A (1)，以及三种已知的化合物去甲氧基仰光素 (2)、仰光素 (3) 和 11-甲氧基仰光素 (4)，从胡椒 (卡瓦) 的叶子中分离出来。它们的结构是通过光谱方法确定的，主要是一维和二维核磁共振和质谱数据。初步生物测定表明，化合物3对A549和NCI-H460细胞具有很强的细胞毒性，IC50值分别为13.6和13.7 μg/mL，化合物2对A549和NCI-H460细胞具有中等的细胞毒性（IC50值为35.8和376。 μg/mL），化合物 1 和 4 对 A549 和 NCI-H460 细胞具有非常弱的细胞毒性。