Three new ent-pimarane diterpenoids from Siegesbeckia pubescens and their anti-vascular endothelial injury activity

A phytochemistry investigation on the aerial parts of medicinal plant Sigesbeckia pubescens led to the discovery of three new ent-pimarane diterpenoids, sigesbecenes A-C (1-3), along with ten known analogues (4-13). The chemical structures of the new compounds were elucidated based on extensive spectroscopic techniques, chemical method, electronic circular dichroism (ECD) analysis, and single-crystal X-ray diffraction (SCXRD) analysis. Among the isolates, compounds 1, 2, 4, 10, and 13 showed potential in vitro anti-vascular endothelial injury activity in oxidized low-density lipoprotein (ox-LDL)-induced human vein endothelial cells (HUVECs).