Dehydrogenated and Aromatized ent-Cleistanthane Diterpenoids From the Roots of Glochidion philippicum

The first comprehensive phytochemical investigation of Glochidion philippicum roots resulted in the isolation and characterization of seven new ent-cleistanthane-type diterpenoids, glochiphenols A-G (1-7), along with two known analogs (8 and 9). Compounds 1-6 all feature a rare alkynyl group, with 1-3 representing highly aromatized 20-nor-ent-cleistanthane diterpenoids. Their structures were elucidated by comprehensive spectroscopic analysis, and absolute configurations were established via electronic circular dichroism (ECD) calculations. Notably, bioactivity assays revealed that compounds 1 and 7 display potent inhibitory effects against DGKζ with IC₅₀ values of 1.19 and 1.28 µM, respectively.