Diterpenoids and Triterpenoids from the Aerial Parts of and Their Biological Activities.

Five undescribed diterpenoids, serranins A-E (-), and four novel triterpenoids, serratic acids A-D (-), along with 32 known terpenoids (-) were isolated from the aerial parts of . The planar structures of - and their relative configurations were established on the basis of extensive spectroscopic analysis. Structurally, compounds - are the first examples of 18,19--ursane -coumaric or ferulic esters, while compounds - further enriched the plant's diterpene profile. Bioactivity evaluation revealed that four diterpenoids (, , , and ) exhibited potent cytotoxic activity against four cancer cell lines (B16-F10, A375, A549, and MDA-MB-231) with IC values below 10 μM. Remarkably, and exhibited a comparable antimelanogenesis effect to that of positive control (kojic acid) in B16-F10 cells.