Dactylospongiaquinone, a new meroterpenoid from the Australian marine sponge Dactylospongia n. sp.

Chemical investigation of the sponge Dactylospongia n. sp. collected near Mooloolaba, S.E. Queensland, has led to the isolation of dactylospongiaquinone (7) together with the known quinones (2-5). The new metabolite 7 possesses a different carbon framework from the known dictyoceratidaquinone (9) and is suggested to possess a cis-fused ring junction by extensive NOESY studies combined with molecular modelling calculations. The relative stereochemistry of the previously described cyclospongiaquinone-1 (3) and dehydrocyclospongiaquinone-1 (4) is also assigned on the basis of NOESY analyses. Full NMR spectroscopic assignments are provided for all compounds.

The structure and stereochemistry of sesquiterpene quinones including dactylospongiaquinone (7) have been deduced by 2D NMR spectroscopic analysis and molecular modelling.