Acanthosulfate, a Sulfated Hydroxyhydroquinone Sesterterpenoid from the Sponge Acanthodendrilla sp.

The marine sponge Acanthodendrilla sp. contains the proteasome inhibitor acanthosulfate (4), a disulfated merosesterterpene having a scalarane-type skeleton. The structure of acanthosulfate (4), which possesses an unusual configuration, was elucidated by interpretation of spectroscopic data.