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

Eight novel arylnaphthalide lactone lignans, designated as diphylignan A−H (1−8), and a new dibenzyltyrolactone lignan, designated as diphylignan I (9), were isolated from the roots and rhizomes of Diphylleia sinensis, along with two additional novel natural products (11 and 14) and four known metabolites (10, 12, 13, 15). The structural and stereochemical characterization of these compounds was accomplished using NMR spectroscopy and electronic circular dichroism (ECD) analysis. The cytotoxic activities of all isolated compounds were assessed against A-549 and SMMC-7721 cell lines. Notably, compound 2 demonstrated the most significant cytotoxicity, with IC₅₀ values of 10.27 and 11.58 µmol·L⁻¹ against A-549 and SMMC-7721 cell lines, respectively, exhibiting greater potency than the positive control, cisplatin.