Radioactivity-Guided Isolation and Characterization of the Bicyclic Pseudopterosin Diterpene Cyclase Product from Pseudopterogorgia elisabethae

The intermediate representing the first committed step in the pseudopterosin biosynthetic pathway has been discovered using a radioactivity-guided isolation. This diterpene cyclase product was identified from a cell-free extract of the marine soft coral, Pseudopterogorgia elisabethae, which was incubated with 3H-geranylgeranyl diphosphate. Structural studies of the compound have revealed an unexpected bicyclic skeleton suggesting that the pseudopterosins are related to the seco-pseudopterosins through a common bicyclic intermediate. In addition, the intermediacy of this metabolite in pseudopterosin biosynthesis has been confirmed utilizing a cell-free extract of P. elisabethae.