Characterization and cytotoxicity of ellagitannins from Stachyurus praecox fruit

This study aimed to characterize and evaluate the cytotoxicities of ellagitannins from S. praecox fruit. Fractionation of an acetone extract of the fruit led to isolation of five new ellagitannins—stachyuranin D (15), stachyuranin E (16), stachyuranin F (17), stachyugluconin (18), and stachyuglyconin (19)—along with seven ellagitannins previously isolated from S. praecox leaves and seven known ellagitannins isolated from Stachyuraceae for the first time. Two-dimensional NMR and other spectroscopic methods enabled complete elucidation of the structures of the new compounds. Structure of flavanoellagitannin (16) was confirmed by ¹H NMR comparison with synthetic analogs. The configuration of stachyuglyconin (19) with a C₈-aldonic acid core was established with the aid of density functional theory calculations. A MTT assay revealed 5-desgalloylpterocarinin A (11) and hippophaenin B (9) had the highest cytotoxicities among the compounds against HeLa (IC₅₀ = 35.35 μM) and HepG2 (IC₅₀ = 60.00 μM) cells, respectively.