Coumarin Dimers From <i>Hydrangea davidii</i> and Their Antimalarial Activities

Two new coumarin dimers, hydradavins A and B (1 and 2), along with a coumarin-phenylpropanoid adduct (3), were isolated from the 95% EtOH extract of roots and stems of Hydrangea davidii. Their structures were determined by comprehensive analyses of the spectroscopic data and physicochemical properties. Hydradavins A and B (1 and 2) are the first examples of coumarin dimers from the genus Hydrangea. In addition, compound 3 exhibited significant in vitro antimalarial activity with IC₅₀ value of 1.7 ± 0.1 μM.