New sesquiterpene/quinones from two sponges of the genus Hyrtios

Two sponges of the genus Hyrtios have been found to contain new sesquiterpe ne/quinones identified by detailed spectroscopic analysis. Four new compoun ds with a 4,9-friedodrim-3-ene skeleton [hyrtiophenol (2), 5-epihyrtiopheno l (3), 18-hydroxy-5-epihyrtiophenol (4), and 18-hydroxyhyrtiophenol (5)] Ne re isolated from Hyrtios sp. (Seychelles Islands) along with isospongiaquin one (1). Moreover, the new compound 21-hydroxy-19-methoxyarenarone (8), whi ch bears the 4,9-freedodrim-4(15)-ene skeleton, was isolated from Hyrtios t ubulatus (Curacao) along with arenarol (6) and 5-epiilimaquinone (7). Assig nment of the C-13 NMR signals of four types of 3,9-friedodrimene skeletons found in sponges is presented.