Diverse Types of Diterpenoids with an Aromatized C Ring from the Twigs of Podocarpus imbricatus

An ethanol extract of the powdered twigs of Podocarpus imbricatus afforded 14 new diterpenoids (1–14), which all share an aromatized C ring. These isolates belong to five diterpenoid types that include abietanes (1–3), semperviranes (4–9), totaranes (10–12), a C-17 norabietane (13), and an icetexane (14). Their structures were assigned mainly by analysis of the spectroscopic data, and the absolute configuration of 1 was determined by X-ray crystallography. A biosynthetic pathway for five of the biogenetically related types of diterpenoids was proposed. Compound 7 showed moderate inhibitory activity against Zika virus with an IC50 value of 2.5 μM.