Three new oxylipins from an Okinawan marine sponge Plakortis sp.

Abstract Three new oxylipins, manzamenone P ( 1 ), 6′- O -methylmanzamenone K ( 2 ), and 6′- O -ethylmanzamenone K ( 3 ), were isolated from an Okinawan marine sponge Plakortis sp. Manzamenone P ( 1 ) is a unique oxylipin possessing two long acyl chains and a novel core unit consisting of spiro-bonded cyclohexanone and β-keto-γ-lactone rings. The structures of 1 – 3 were elucidated on the basis of spectroscopic evidences including 2D NMR and FABMS/MS spectra as well as a comparison of DFT calculated NMR data with those experimental data.