Cytotoxic lignans from the roots and rhizomes of Diphylleia sinensis, a China's endemic plant species

Eight new arylnaphthalide lactone lignans, diphylignan A−H ( 1 − 8 ), one new dibenzyltyrolactone lignan, diphylignan I ( 9 ), two new natural products ( 11 and 14 ), together with four known metabolites ( 10 , 12 , 13 , 15 ), were isolated from the roots and rhizomes of Diphylleia sinensis. Their structures and stereochemistry were elucidated by the analysis of NMR spectroscopic and ECD data. The cytotoxic activities of all isolated compounds were tested against A-549 and SMMC-7721 cell lines. Among the tested compounds, compound 2 with IC₅₀ values of 10.27 µM and 11.58 µM showed the most potent cytotoxicities against A-549 and SMMC-7721 cell lines. Moreover, it was more active than the positive control cisplatin.