New Rosane Diterpenoids and Their Analogs from Euphorbia ebracteolata Hayata

Phytochemical investigation of the roots of Euphorbia ebracteolata Hayata resulted in the isolation of three new rosane diterpenoids, euphebracteolatins C–E ( 1 – 3 ), along with fourteen known analogs ( 4 – 17 ). Their structures were determined on the basis of extensive spectroscopic analysis including HR-ESI-MS, 1D and 2D NMR. Euphebracteolatin C ( 1 ) contains a C-1/C-10 double bond and a keto group at C-7, and euphebracteolatins D and E ( 2 – 3 ) possess an aromatic ring-A in their skeleton. The plausible biogenetic pathways of all the isolates were also proposed. Furthermore, compounds 1 and 9 showed selective cytotoxicity against HepG2 cells with IC₅₀ values of 14.29 and 12.33 μM, respectively, and 2 – 3 displayed moderate cytotoxicity against three human cancer lines, with IC₅₀ values ranging from 23.69 to 39.25 μM.