Stilbene derivatives from Hydrangea davidii and their antimalarial activities

For the purpose to better understand the antimalarial substance from Hydrangea davidii, two new stilbene derivatives, hydavidioside A (1) and hydavidioside B (2), and a new natural stilbene derivative, hydavidioside C (3), together with fifteen known analogous compounds (4-18), were isolated and identified. All the compounds were obtained from this plant for the first time, and part of them were examined for their antimalarial activity. Compounds 3, 5, 12, 14, 15, and 16 showed significant antimalarial activities against Plasmodium falciparum 3D7 with IC₅₀ values of 0.52, 0.03, 14.78, 1.26, 7.33, and 4.33 μM, respectively. Moreover, 5 showed broad-spectrum efficacy against both P. falciparum Dd2 and P. falciparum 803 with IC₅₀ values of 0.046 and 0.057 μM. To explore 5's active mechanism, an in silico molecular docking approach was employed. In addition, the possible biogenetic pathways and the antimalarial structure-activity relationship for the isolated stilbene derivatives 1-18 were briefly discussed.