Strongylophorines, meroditerpenoids from the marine sponge Petrosia corticata, function as proteasome inhibitors.

Abstract Two new strongylophorine derivatives, along with six known strongylophorines, were isolated from the marine sponge Petrosia corticata as proteasome inhibitors. Of these, a hemiacetal mixture of strongylophorines-13/-14 was the strongest inhibitor of the proteasome with an IC 50 of 2.1 μM.